CN111195513A - Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent - Google Patents

Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent Download PDF

Info

Publication number
CN111195513A
CN111195513A CN202010092878.8A CN202010092878A CN111195513A CN 111195513 A CN111195513 A CN 111195513A CN 202010092878 A CN202010092878 A CN 202010092878A CN 111195513 A CN111195513 A CN 111195513A
Authority
CN
China
Prior art keywords
straw
dithio
carboxylated
straws
heavy metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202010092878.8A
Other languages
Chinese (zh)
Inventor
王刚
杨凯
未碧贵
程小龙
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lanzhou Jiaotong University
Original Assignee
Lanzhou Jiaotong University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lanzhou Jiaotong University filed Critical Lanzhou Jiaotong University
Priority to CN202010092878.8A priority Critical patent/CN111195513A/en
Publication of CN111195513A publication Critical patent/CN111195513A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/24—Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/286—Treatment of water, waste water, or sewage by sorption using natural organic sorbents or derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds

Abstract

The invention discloses a preparation method of dithio-carboxylated straw, a product and application of the dithio-carboxylated straw as a heavy metal adsorbent2Continuously stirring for reaction for a period of time, and then heating for continuous reaction; and standing the mixed solution, performing suction filtration, washing the filter residue with distilled water until the pH value of the filtrate is constant, and drying the filter residue to constant weight to obtain the dithio-carboxylated straw. According to the invention, through chemical modification, the dithio-carboxyl group of the functional group is grafted to the molecular structure of the straw, so that the adsorption property of the straw is greatly improved, and the adsorption property of the straw is obviously improvedThe removal rate of the heavy metal by the straw is high.

Description

Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent
Technical Field
The invention relates to the technical field of heavy metal sewage treatment, in particular to a preparation method and a product of dithio-carboxylated straw and application of the dithio-carboxylated straw as a heavy metal adsorbent.
Background
With the rapid development of the industries such as electroplating, mining, tanning, battery and the like, a large amount of wastewater containing heavy metals such as zinc, copper, nickel, mercury, cadmium, lead, chromium and the like is generated, and the wastewater which is not treated and is discharged randomly can cause serious pollution to surface water, underground water, soil environment and the like. The adsorption method is one of the most economic and effective methods for removing heavy metals in wastewater at present. Adsorbents such as activated carbon, adsorbent resin, activated aluminum and the like which are commonly used for removing heavy metals in water generally have the problems of high price or low adsorption quantity. The crop straws are large in production amount and low in utilization rate in China, mainly comprise cellulose, hemicellulose, lignin and other substances, and have strong chemical adsorption capacity due to the fact that the molecules of the crop straws contain functional groups such as hydroxyl, carboxyl, amino and the like with strong coordination capacity, and the pollutants in industrial wastewater can be removed. However, researches show that natural crop straws have weak adsorption capacity and small adsorption capacity to heavy metal ions, so that the researches have attracted extensive attention of researchers to modify the natural crop straws to improve the adsorption performance of the natural crop straws so as to obtain the cheap and efficient heavy metal adsorbent.
At present, the methods for modifying the crop straws mainly comprise acid, alkali, salt treatment, thermal modification and the like, wherein researches on introducing heavy metal ion coordination groups into the crop straws are mostly concentrated on N-containing and O-containing groups, and researches on introducing S-containing groups are less.
In patent CN103447005, epichlorohydrin is firstly subjected to etherification with hydroxyl groups in the straw to perform crosslinking, so that although the hydrophilicity of the straw is improved, a certain amount of hydroxyl groups are also consumed; the added carbon disulfide and sodium hydroxide mainly perform sulfonation reaction with hydroxyl in the straw, so that the effective amount of the hydroxyl participating in the sulfonation reaction is reduced, and the type and the amount of reactants are increased by adding epichlorohydrin, so that the prepared straw adsorbing material has longer adsorption time, and the highest adsorption rate and the maximum adsorption amount are required to be further improved.
In patent CN109012617A, after straw is soaked in a mixed solution of sodium hydroxide and thiourea, a modifier polyamine, aldehyde and a catalyst triethylamine (or mercaptoethylamine) are added for reaction, the added polyamine and aldehyde mainly have a Mannich reaction with hydroxyl in the straw to introduce an amino group, and the amino group has a sulfonation reaction with carbon disulfide and sodium hydroxide to introduce a dithioamino group.
Disclosure of Invention
In order to solve the technical problems, the invention provides a preparation method of dithio-carboxylated straws, a product and application of the dithio-carboxylated straws as a heavy metal adsorbent. Provides technical parameters and theoretical basis for the preparation of the high-efficiency and low-cost heavy metal adsorbent.
One of the technical schemes of the invention is a preparation method of dithio-carboxylated straw, which comprises the following steps:
(1) carrying out impurity removal, cleaning, drying, crushing and sieving pretreatment on straws;
(2) putting the pretreated straws into a stirring container, adding sodium hydroxide and water, stirring and soaking for a period of time, and adding CS2Pre-reacting for a period of time, raising the reaction temperature, and reacting for a period of time to obtain a reaction mixed solution;
(3) and standing the reaction mixed liquor for a period of time, performing suction filtration, washing the filter residue with water until the pH value of the filtrate is constant, and drying the filter residue to constant weight to obtain the dithio-carboxylated straw.
Preferably, the grain diameter of the straw pretreated in the step (1) is 10-80 meshes;
further preferably, the grain size of the pretreated straws is 10 meshes.
The excessive straw particle size easily causes incomplete dithiocarboxylation of the straw, influences the adsorption capacity, and the micronization easily occurs when the particle size is too small, so that the spatial structure of the straw is damaged, and the straw and CS are not favorable2NaOH reacts to influence the adsorption capacity of the prepared dithio-carboxylated straws on heavy metals, and the prepared dithio-carboxylated straws have the particle size of 10 meshesThe adsorption performance is optimal.
Preferably, in the step (2), the mass fraction of the straws in the solution in the step (2) is 6%, and the straws and CS are2The adding mass ratio of the sodium hydroxide is 1: 1-3;
further preferably, straw, CS2And the adding mass ratio of the sodium hydroxide is 1: 2.
On one hand, NaOH can open a straw cellulose crystallization area, improve the swelling property of the straw, increase the porosity and increase the reaction point position; on the other hand, NaOH and hydrophobic non-polar substance CS2The reaction generates ionized water-soluble substance sodium xanthate with high reaction activity, and then the xanthation reaction is carried out to generate dithio-carboxylated straw, so that the relative content of NaOH is properly increased, the adsorption performance of the prepared dithio-carboxylated straw can be improved, and the straw and CS can be used for preparing dithio-carboxylated straw2And the adsorption performance of NaOH is optimized by taking the mass ratio of 1:1: 2.
Preferably, the soaking time in the step (2) is 15-60 min;
more preferably, the soaking time is 45 min.
The soaking stage is mainly characterized in that the straws and sodium hydroxide are reacted, so that the straws become loose and porous, more internal structures are exposed, and the reaction stage is a later stage of the straws and CS2The reaction with NaOH provides more reaction points, the soaking time is too short, the internal structure of the straw cannot be completely exposed, the subsequent dithio-carboxylation modification is not facilitated, the soaking time is too long, the influence on the adsorption performance of heavy metals is not great, and the proper soaking time is selected to be 45min from the aspects of time saving and energy.
Preferably, the pre-reaction time in the step (2) is 15-45min, and the pre-reaction temperature is 20-30 ℃;
further preferably, the pre-reaction time is 30min and the pre-reaction temperature is 25 ℃.
The pre-reaction stage mainly comprises NaOH and CS2The process of generating sodium xanthate by reaction takes too short time for NaOH and CS2The reaction is insufficient, but the sodium xanthate may be decomposed for too long a reaction time, so that the number of dithio carboxyl groups introduced into dithio-carboxylated straws is reducedTherefore, the pre-reaction time is selected to be 30 min;
the reaction rate is accelerated by raising the temperature, the effective collision times among reactants are increased, the content of dithio carboxyl in dithio carboxylated straws is increased, and the heavy metal adsorption performance of the dithio carboxylated straws is improved; however, the CS in the reaction system is increased by further increasing the temperature2The volatilization of the dithio-carboxylated straw causes the content of dithio-carboxyl in the dithio-carboxylated straw to be reduced, thereby reducing the removal performance of heavy metals, and the pre-reaction temperature is 25 ℃.
Preferably, the reaction time in the step (2) is 1-3h, and the reaction temperature is 40-70 ℃;
more preferably, the reaction time is 1 hour and the reaction temperature is 40 ℃.
Side reactions occur when the reaction time is long, the synthesis of dithio-carboxylated straws is not facilitated, and the adsorption performance reaches the optimum when the main reaction time is 1 hour;
the reaction stage is mainly the reaction of sodium xanthate and straw, the reaction is exothermic, so the reaction can be promoted only by properly heating the reaction environment, and with the rise of the temperature, part of CS which does not participate in the reaction2The method is easy to volatilize, reduces the content of dithio carboxyl in dithio carboxylated straws, reduces the removal rate of heavy metals in the dithio carboxylated straws, and optimally selects the reaction temperature of 40 ℃.
Preferably, the filtrate obtained in the step (3) is used for removing heavy metal ions;
the obtained filtrate mainly contains sodium xanthate (NaOH and CS) which does not react with the straws2Reaction product), and the molecular chain also contains S atoms which can generate chelation with heavy metal ions, so the method can be used for treating heavy metal wastewater. The highest removal rate of the filtrate to Cd (II) with the concentration of 25mg/L under different pH values is as follows: when the pH value is 4.0, the removal rate of Cd (II) is 99.56 percent; when the pH value is 5.0, the removal rate of Cd (II) is 99.78%; when the pH value is 6.0, the removal rate of Cd (II) is 99.02%; when the pH was 7.0, the removal rate of Cd (ii) was 100%. The highest removal rate of the filtrate to different Cd (II) concentrations when the pH value is 6.0 is as follows: when the concentration of Cd (II) is 15mg/L, the removal rate of Cd (II) is 92.60%; when the concentration of Cd (II) is 15mg/L, the removal rate of Cd (II) is 99.02 percent; when the concentration of Cd (II) is 50mg/L, the removal rate of Cd (II) is 97.94%.
The second technical scheme of the invention is as follows: the dithio-carboxylated straw prepared by the preparation method of the dithio-carboxylated straw.
The third technical scheme of the invention is as follows: the dithio-carboxylated straw is used as a heavy metal adsorbent in heavy metal polluted wastewater.
Preferably, the addition amount of the dithio-carboxylated straw in the heavy metal wastewater is 2.5-15 g/L;
preferably, the concentration of heavy metal ions in the heavy metal wastewater is 5-100 mg/L.
Compared with the prior art, the invention has the following beneficial effects:
the straws contain a large amount of active group hydroxyl which can be subjected to sulfonation reaction with carbon disulfide and sodium hydroxide to introduce dithio carboxyl which can be chelated with heavy metal ions, so that the adsorption capacity of the heavy metals can be greatly improved; however, due to the high content of the hydroxyl groups in the straw, a large number of hydrogen bonds are formed between molecular chains and inside the molecular chains, and the activity of the chemical reaction is limited. Because the straw surface structure is compact, the specific surface area is small, and the adsorption capacity is not high, the invention uses sodium hydroxide to soak the straw, so that the straw surface becomes loose, the swelling property is improved, more active groups (hydroxyl, amino and the like) are exposed, the reactive site position of the straw is increased, and then CS is added2Reacting NaOH with CS2The pre-reaction is carried out to generate sodium xanthate, the sodium xanthate and the straws are further subjected to chemical reaction by raising the reaction temperature to graft the dithio-carboxyl group of the functional group into the molecular structure of the straws, and the content of the dithio-carboxyl group in the straws is further increased by controlling the parameters of the reaction process, so that the adsorption performance of the straws is greatly improved;
in the prior art, in order to fully destroy the straw structure and facilitate subsequent modification treatment in the process of preparing the adsorbent by using the straws, the soaking time is usually limited to be more than 3 hours and even as long as 24 hours, but in the technical scheme of the invention, the soaking time of only 15-60min is needed to meet the subsequent modification requirement, the soaking time is shortened, the preparation efficiency is improved, meanwhile, the straw adsorbent prepared in the prior art is poor in storage stability, magnesium sulfate is often needed to be added for fixing so as to increase the stability of the product, and the removal rates of Cd (II) are respectively 100%, 99.02%, 98.54% and 97.78% after the product prepared by the method is stored for 1, 10, 20, 25 and 30 days. Therefore, the product still has good stability when placed at normal temperature under the condition of not adding magnesium sulfate.
Meanwhile, the filtrate obtained by suction filtration can also be used for removing heavy metal ions, so that the reuse of the filtrate is realized, and the environmental pollution caused by the direct discharge of the filtrate is avoided.
When the dithio-carboxylated straw prepared by the method is used for removing Cd (II) from a Cd (II) -containing water sample with the initial concentration of 50mg/L, pH value of 6.0, the removal rate of Cd (II) can reach 100% when the adding amount of the dithio-carboxylated straw is 5g/L under the optimal condition, and the removal rate of Cd (II) is only 35.73% at most when the adding amount of the straw is 12.5g/L under the same condition. The invention obviously improves the adsorption capacity of the straw to the heavy metal.
Drawings
FIG. 1 shows the influence of straw particle size on the removal of Cd (II) by DTCS;
FIG. 2 is a graph showing the effect of soaking time on the DTCS removal of Cd (II);
FIG. 3 is a graph of the effect of reactant ratios on DTCS for Cd (II) removal;
FIG. 4 is a graph of the effect of pre-reaction temperature on DTCS Cd (II) removal;
FIG. 5 is a graph of the effect of pre-reaction time on DTCS for Cd (II) removal;
FIG. 6 is a graph of the effect of the main reaction temperature on DTCS for Cd (II) removal;
FIG. 7 is a graph of the effect of main reaction time on DTCS for Cd (II) removal;
FIG. 8 is a graph comparing the effect of removing Cd (II) from CS with DTCS;
FIG. 9 is an infrared signature of CS and DTCS;
FIG. 10 shows the effect of DTCS on Cd (II) removal at different Cd concentrations;
FIG. 11 shows the effect of DTCS on Cd (II) removal at different storage times;
FIG. 12 is the filtrate pair Cd at different pH2+The removal effect of (3);
FIG. 13 shows the effect of filtrate on Cd (II) removal at different Cd (II) concentrations.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.
1. The preparation process of the dithio-carboxylated corn straw comprises the following steps:
removing dead leaves of the corn straws, cutting into sections, washing for a plurality of times by using water to remove dust on the surface, and naturally drying; crushing the air-dried corn straws by a crusher, and sieving; then dried in a drying oven at 50 ℃ for 24h and stored in a brown jar for later use.
Weighing a certain amount of corn straws in a three-necked bottle, adding a certain amount of NaOH and 50mL of distilled water, and placing on a magnetic stirrer; mixing and stirring for a certain time t0(noted as soak time) then add a volume of CS2Adjusting the temperature T required for the reaction1(note as pre-reaction temperature) at which the reaction is continued with stirring for a certain time t1(noted as pre-reaction time); then the temperature is adjusted to the desired temperature T2(as the main reaction temperature), and continuing the reaction for a certain time t2(note as main reaction time); taking out the mixed solution, standing for 6h, performing suction filtration, washing the filter residue with distilled water until the pH value of the filtrate is constant, and drying the filter residue to constant weight to obtain the dithio-carboxylated corn straw (DTCS).
2. Adsorption experiments
Respectively weighing 0.05 g, 0.10g, 0.15 g, 0.20 g, 0.25 g and 0.30g of DTCS, adding into an iodometry bottle, and adding 20.0mL of water sample containing Cd (II) with the initial concentration of 50mg/L, pH value of 6.0; placing the iodine bottle in a gas bath constant temperature oscillator, oscillating for 2h at 40 deg.C and oscillation rate of 200 times/min, and filtering; and (3) determining the residual concentration of Cd (II) in the filtrate by using an atomic absorption spectrophotometer.
3. Influence of corn stalk particle size on adsorption performance
Fixed t0For 15min, CS2NaOH in a mass ratio of 1:3:2, T1At 20 ℃ t1Is 30min, T2At 50 ℃ t2Changing the straw particle size d for 2.5h, and carrying out an adsorption experiment on a water sample containing Cd (II) by using DTCS prepared under the condition, wherein the result is shown in figure 1.
As can be seen from figure 1, the influence of the straw particle size on the performance of removing Cd (II) from the prepared DTCS is large, when the addition amount of CS in a synthesis reaction system is certain, the removal rate of Cd (II) from the DTCS prepared by the straw passing through an 80-mesh (0.20mm) sieve is minimum, and when the straw particle size is 10-mesh (2.0mm), the DTCS is addedWhen the amount is 12.5g/L, the removal rate of Cd (II) by DTCS is 93.21% at most. This is probably because the spatial structure of the straw is easily damaged by micronization when the straw particle size is too small, which is not beneficial to CS and CS2And NaOH reacts to influence the adsorption capacity of the DTCS on Cd (II).
4. Influence of corn stalk soaking time on adsorption performance
The grain diameter d of the fixed straw is 10 meshes (2.0mm), and the grain diameters of the fixed straw are CS and CS2NaOH in a mass ratio of 1:3:2, T1At 20 ℃ t1Is 30min, T2At 50 ℃ t2At 2.5h, change t0The DTCS prepared under the condition is used for carrying out adsorption experiments on water samples containing Cd (II), and the results are shown in figure 2.
As can be seen from FIG. 2, the removal effect of the prepared DTCS on Cd (II) is obviously better than that of Cd (II) in 15min and 30min when the soaking time is 45min and 60 min. When the soaking time is 45min and the DTCS adding amount is 15g/L, the removal rate of the DTCS on Cd (II) reaches 95.17 percent, and the stage mainly comprises the step that straws and NaOH act to enable the straws to become loose and porous and expose more internal structures, and the stage is a main reaction stage of straws and CS2Reacting with NaOH provides more sites for reaction. The soaking time is too short, the internal structure of the straw can not be completely exposed, and the subsequent dithio-carboxylation modification is not facilitated. In addition, the highest removal rate of Cd (II) by DTCS prepared by soaking for 45min and 60min has small difference, and the proper soaking time is selected to be 45min from the aspects of time saving and energy.
5. Effect of reactant ratio on adsorption Performance
The grain diameter d of the fixed straw is 10 meshes (2.0mm), t0Is 45min, T1At 20 ℃ t1Is 30min, T2At 50 ℃ t2Changing CS and CS for 2.5h2And the mass ratio of NaOH and the DTCS prepared under the condition are used for carrying out adsorption experiments on the water sample containing Cd (II), and the result is shown in figure 3.
As can be seen from FIG. 3, the influence of the reactant ratio on the performance of preparing DTCS Cd (II) removal is large, the performance of the prepared DTCS Cd (II) removal is obviously superior to that of other ratios when the mass ratio of the reactants is 1:1:2, and the performance of the prepared DTCS Cd (II) removal is the worst when the mass ratio is 1:1: 1. When the CS is used,CS2And when the mass ratio of NaOH is 1:1:2 and the addition amount of DTCS is 7.5g/L, the highest removal rate of the DTCS on Cd (II) can reach 100%. On one hand, NaOH is used for treating straws, a cellulose crystallization area is opened, the swelling property of the straws is improved, the porosity is increased, and the reaction point position is increased; on the other hand, NaOH and hydrophobic non-polar substance CS2The reaction generates ionized water-soluble substance sodium xanthate with high reaction activity, and then the xanthation reaction is carried out to generate DTCS, so the relative content of NaOH should be properly increased, and the CS and CS in the preparation of DTCS2And the mass ratio of NaOH is 1:1: 2.
6. Effect of Pre-reaction temperature on adsorption Performance
The grain diameter d of the fixed straw is 10 meshes (2.0mm), t0For 45min, CS2NaOH with the mass ratio of 1:1:2, t1Is 30min, T2At 50 ℃ t2At 2.5h, change T1The DTCS prepared under the condition is used for carrying out adsorption experiments on water samples containing Cd (II), and the results are shown in figure 4.
As can be seen from FIG. 4, different T1The total removal rate of the DTCS prepared under the condition on Cd (II) in a water sample shows a trend of increasing firstly and then decreasing when T is1The removal rate of Cd (II) by the DTCS prepared at 25 ℃ is higher. When T is1When the temperature is 25 ℃ and the addition amount of DTCS is 7.5g/L, the highest removal rate of the DTCS on Cd (II) can reach 98.60%. The reaction rate is accelerated by raising the temperature, the effective collision times among reactants are increased, the content of dithio carboxyl in the DTCS is increased, and the Cd (II) removal performance of the DTCS is improved; however, the CS in the reaction system is increased by further increasing the temperature2The volatilization of (2) results in the reduction of the dithiocarboxyl group content in the DTCS, thereby reducing the Cd (II) removal performance, so that the pre-reaction temperature is 25 ℃.
7. Effect of Pre-reaction time on adsorption Properties
The grain diameter d of the fixed straw is 10 meshes (2.0mm), t0For 45min, CS2NaOH in a mass ratio of 1:1:2, T1At 25 ℃ and T2At 50 ℃ t2At 2.5h, change t1The DTCS prepared under the condition is used for carrying out adsorption experiments on water samples containing Cd (II), and the results are shown in figure 5.
As can be seen from FIG. 5, t is different1The total removal rate of the DTCS prepared under the condition on Cd (II) in a water sample is increased and then reduced, wherein when the pre-reaction time is 30min and the DTCS addition amount is 10g/L, the maximum removal rate of the DTCS on Cd (II) is 99.35 percent. The pre-reaction stage mainly comprises NaOH and CS2The process of generating sodium xanthate by reaction takes too short time for NaOH and CS2The reaction was insufficient, but the sodium xanthate was likely to decompose for too long a reaction time, resulting in a decrease in the number of dithiocarboxyl groups introduced into the DTCS, so that the pre-reaction time was selected to be 30 min.
8. Effect of the principal reaction temperature on adsorption Performance
The grain diameter d of the fixed straw is 10 meshes (2.0mm), t0For 45min, CS2NaOH in a mass ratio of 1:1:2, T1At 25 ℃ t1Is 30min, t2At 2.5h, change T2The DTCS prepared under the condition is used for carrying out adsorption experiments on water samples containing Cd (II), and the results are shown in figure 6.
As can be seen from FIG. 6, T2The performance of the prepared DTCS for removing Cd (II) has great influence with T2The removal rate of Cd (II) by the prepared DTCS is gradually reduced overall. This is probably because the reaction of sodium xanthate with straw is exothermic in the main reaction stage, and the lower temperature is favorable for the reaction; with increasing temperature, part of CS not yet reacted2The catalyst is easy to volatilize, the content of dithio carboxyl in DTCS is reduced, the removal rate of the DTCS on Cd (II) is reduced, and therefore the main reaction temperature is selected to be 40 ℃.
9. Effect of the Main reaction time on the adsorption Properties
The grain diameter d of the fixed straw is 10 meshes (2.0mm), t0For 45min, CS2NaOH in a mass ratio of 1:1:2, T1At 25 ℃ t1Is 30min, T2At 40 ℃ and varying t2The DTCS prepared under the condition is used for carrying out adsorption experiments on water samples containing Cd (II), and the results are shown in figure 7.
As can be seen from FIG. 7, different t2The removal rate of the prepared DTCS to Cd (II) is increased and then reduced along with the increase of the DTCS addition amount, and the prepared DTCS to Cd (II) is used when the main reaction time exceeds 1.5hThe removal effect of (2) becomes poor. When the main reaction time is 1h and the addition amount of DTCS is 5g/L, the maximum removal rate of Cd (II) by DTCS is 100 percent. This may be detrimental to the synthesis of DTCS due to side reactions that occur during longer reaction times. Thus the main reaction time was taken to be 1 h.
Comparison of the effects of CS on Cd (II) removal by DTCS
Different amounts of pretreated CS with the grain diameter of 10 meshes (2.0mm) and DTCS prepared under the optimized condition are weighed, and the results of adsorption experiments on water samples containing Cd (II) are shown in figure 8.
As can be seen from FIG. 8, the removal rate of Cd (II) by DTCS is significantly higher than that of CS. When the addition amount of CS is 12.5g/L, the maximum removal rate of Cd (II) by CS is 35.73%; when the DTCS addition amount is 5g/L, the removal rate of Cd (II) is 100 percent at most. The corn straw has compact surface structure, small specific surface area and low adsorption capacity; in the pre-reaction stage, the surface of the corn straw is loosened by treating with sodium hydroxide, more active groups (hydroxyl, amino and the like) are exposed, and in the main reaction stage, the dithio-carboxyl functional group is grafted to the molecular structure of the straw by chemical modification, so that the adsorption performance of the straw is greatly improved.
Infrared characterization of CS and DTCS
The CS and DTCS pretreated in the same way are subjected to infrared spectrum characterization by a KBr tabletting method, and the result is shown in figure 9.
As can be seen from FIG. 9, the DTCS spectrum is 1026cm in comparison with the IR spectrum of CS-1、896cm-1New absorption peaks appear and are respectively assigned to a C ═ S stretching vibration peak and a C-S stretching vibration peak, which shows that dithio carboxyl (— C ═ S) -S is successfully accessed into a CS molecule-). 1047cm in CS spectrogram-1The stretching vibration peak of the hydroxyl group (-OH) is shifted to the left of 1053cm in a DTCS spectrogram-1Here, the change in these peaks indicates that the dithiocarboxylation reaction mainly occurs on the hydroxyl group of the CS molecular structure.
12. Preparation of DTCS under optimal conditions
DTCS prepared according to the method described in example 1, with the following conditions defined: the grain diameter of the straw is 10 meshes (2.0mm), the soaking time is 45min, and the reactants CS and CS2And preparing DTCS by using NaOH with the mass ratio of 1:1:2, the pre-reaction temperature of 25 ℃, the pre-reaction time of 30min, the main reaction temperature of 40 ℃ and the main reaction time of 1 h.
Adsorption experiment:
the prepared DTCS is used for removing the Cd (II) -containing water sample with the initial concentration of 50mg/L, pH value of 6.0 by using the heavy metal sewage treatment method described in the embodiment 1, and the result is that: when the addition amount is 5g/L, the removal rate of 120min can reach 100%. Indicating the use of CS2The DTCS prepared from the NaOH modified corn straws is a novel adsorption material capable of effectively removing Cd (II) in water.
The prepared DTCS is respectively used for heavy metal removal experiments of Cd (II) water samples with initial concentrations of 5, 15, 25, 50 and 100mg/L, and the results are shown in figure 10. As can be seen from FIG. 10, the highest removal rate of Cd (II) by DTCS was 93.89% when the initial concentration of Cd (II) was 5mg/L, and the highest removal rate of Cd (II) by DTCS was 100% when the initial concentration of Cd (II) was 15, 25, 50, 100 mg/L. The DTCS is shown to have excellent adsorption effect on 5-100mg/L Cd (II).
When the prepared DTCS is used for removing the cadmium, copper, nickel, mercury, lead, zinc and hexavalent chromium sewage with the initial concentration of 50mg/L, the result shows that the removal rate can reach more than 99% in 120min, so the DTCS prepared by the invention has good removal effect on the cadmium, copper, nickel, mercury, lead, zinc and hexavalent chromium sewage.
Adsorption equilibrium time determination experiment: accurately weighing 0.10g of DTCS, adding the DTCS into a 50mL iodine flask, and transferring 20.0mL of water containing Cd (II) with the initial concentration of 50mg/L and the initial pH value of 6.0 into the DTCS; placing the iodine content bottle in a gas bath constant temperature oscillator, respectively oscillating (200r/min) at 40 deg.C for 10, 20, 30, 40, 50, 60, 90, 120, 150, 180min, taking out, standing for 10min, filtering with filter paper, and measuring the residual concentration of Cd (II) in the filtrate with atomic absorption spectrophotometer. As a result, the maximum adsorption capacity of the DTCS prepared by the invention to heavy metal Cd (II) is 26.03mg/g, and the time for reaching adsorption equilibrium is 120 min.
Stability test:
the prepared DTCS is stored at room temperature, DTCS is taken in different storage time (1, 10, 20, 25 and 30d) to carry out adsorption experiments on a water sample containing Cd (II) with the initial concentration of 50mg/L, pH value of 6.0, the DTCS adding amount is 10g/L, and the result is shown in figure 11. From FIG. 11, it can be seen that: when the Cd (II) is stored for 10 days, the removal rate of the Cd (II) by the DTCS is basically unchanged and is still 100 percent; after 20, 25 and 30 days of storage, the removal rate of Cd (II) is 99.02%, 98.54% and 97.78%, respectively. Therefore, the prepared DTCS has better storage stability.
The obtained filtrate is used for removing and verifying heavy metal Cd (II):
flocculation experiment: taking water samples containing Cd (II) with different Cd (II) concentrations, adjusting different pH values, placing on a program-controlled coagulation test stirrer, adding different amounts of filtrate, rapidly stirring at a rotating speed of 140min/r for 2min, slowly stirring at a rotating speed of 50r/min for 20min, then settling for 15min, taking a liquid surface lower clear liquid, and measuring the residual concentration of Cd (II) by using an atomic absorption spectrophotometer, wherein the result is shown in figures 12-13. The results show that the highest removal rates of the filtrate on Cd (II) with the concentration of Cd (II) of 25mg/L at pH values of 4.0, 5.0, 6.0 and 7.0 are respectively 99.56%, 99.78%, 99.02% and 100%; the highest removal rates of the filtrate on Cd (II) with the concentration of 15mg/L, 25mg/L and 50mg/L at the pH value of 6.0 are 92.60%, 99.02% and 97.94% respectively. Therefore, the obtained filtrate also has good effect of removing heavy metal ions.

Claims (10)

1. A preparation method of dithio-carboxylated straws is characterized by comprising the following steps:
(1) carrying out impurity removal, cleaning, drying, crushing and sieving pretreatment on straws;
(2) putting the pretreated straws into a stirring container, adding sodium hydroxide and water, stirring and soaking for a period of time, and adding CS2Pre-reacting for a period of time, raising the reaction temperature, and reacting for a period of time to obtain a reaction mixed solution;
(3) and standing the reaction mixed liquor for a period of time, performing suction filtration, washing the filter residue with water until the pH value of the filtrate is constant, and drying the filter residue to constant weight to obtain the dithio-carboxylated straw.
2. The method for preparing dithiocarboxylated straws as claimed in claim 1, wherein the grain size of the pretreated straws in the step (1) is 10-80 meshes.
3. The method for preparing dithiocarboxylated straws as claimed in claim 1, wherein the mass fraction of the straws in the solution in the step (2) is 6%, and the straws and the CS are2The adding mass ratio of the sodium hydroxide is 1: 1-3.
4. The method for preparing dithiocarboxylated straw according to claim 1, wherein the soaking time in the step (2) is 15-60 min.
5. The preparation method of dithiocarboxylated straw as claimed in claim 1, wherein the pre-reaction time in step (2) is 15-45min, the pre-reaction temperature is 20-30 ℃, the reaction time is 1-3h, and the reaction temperature is 40-70 ℃.
6. The method for preparing dithiocarboxylated straw according to claim 1, wherein the filtrate obtained in the step (3) is used for removing heavy metal ions.
7. A dithio-carboxylated straw prepared according to the preparation method of the dithio-carboxylated straw in any one of claims 1 to 6.
8. The application of the dithio-carboxylated straw as the heavy metal adsorbent in heavy metal polluted wastewater.
9. The application of the dithio-carboxylated straws as the heavy metal adsorbent according to claim 8, wherein the addition amount of the dithio-carboxylated straws in the heavy metal wastewater is 2.5-15 g/L.
10. The application of dithio-carboxylated straw as a heavy metal adsorbent according to claim 9, wherein the concentration of heavy metal ions in the heavy metal wastewater is 5-100 mg/L.
CN202010092878.8A 2020-02-14 2020-02-14 Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent Pending CN111195513A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010092878.8A CN111195513A (en) 2020-02-14 2020-02-14 Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010092878.8A CN111195513A (en) 2020-02-14 2020-02-14 Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent

Publications (1)

Publication Number Publication Date
CN111195513A true CN111195513A (en) 2020-05-26

Family

ID=70742469

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010092878.8A Pending CN111195513A (en) 2020-02-14 2020-02-14 Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent

Country Status (1)

Country Link
CN (1) CN111195513A (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102690218A (en) * 2012-04-27 2012-09-26 中南大学 Method for synthesizing xanthate
CN103785361A (en) * 2014-03-05 2014-05-14 北京师范大学 Method for preparing heavy metal ion absorbent through xanthation of granule sludge
CN103977773A (en) * 2014-05-20 2014-08-13 华中农业大学 Preparation method and application of eichhornia crassipes cellulose xanthate calcium salt
CN105080511A (en) * 2015-08-06 2015-11-25 中国科学院地理科学与资源研究所 Preparation method and application of corn stalk cellulose xanthic acid magnesium salt
WO2017111103A1 (en) * 2015-12-25 2017-06-29 レンゴー株式会社 Cellulose xanthate nanofibers
CN107626284A (en) * 2016-09-13 2018-01-26 塔里木大学 The method that cotton stalk adsorbent is prepared using carbon disulfide modification
CN110354819A (en) * 2019-08-15 2019-10-22 广州大学 A kind of plant cellulose absorption sponge, preparation method and its application

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102690218A (en) * 2012-04-27 2012-09-26 中南大学 Method for synthesizing xanthate
CN103785361A (en) * 2014-03-05 2014-05-14 北京师范大学 Method for preparing heavy metal ion absorbent through xanthation of granule sludge
CN103977773A (en) * 2014-05-20 2014-08-13 华中农业大学 Preparation method and application of eichhornia crassipes cellulose xanthate calcium salt
CN105080511A (en) * 2015-08-06 2015-11-25 中国科学院地理科学与资源研究所 Preparation method and application of corn stalk cellulose xanthic acid magnesium salt
WO2017111103A1 (en) * 2015-12-25 2017-06-29 レンゴー株式会社 Cellulose xanthate nanofibers
CN107626284A (en) * 2016-09-13 2018-01-26 塔里木大学 The method that cotton stalk adsorbent is prepared using carbon disulfide modification
CN110354819A (en) * 2019-08-15 2019-10-22 广州大学 A kind of plant cellulose absorption sponge, preparation method and its application

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
PAN, QINGSHAN等: "Preparation of Rice Straw Cellulose Xanthate and Study on Its Adsorption Properties of Cadmium(II) from Aqueous Solutions", 《ASIAN JOURNAL OF CHEMISTRY》 *
WEI, WANG等: "Study on TEMPO-mediated selective oxidation of alkaline natural cellulose pulp and properties of its products", 《JOURNAL OF DONGHUA UNIVERSITY 》 *
刘雪琴: "植物秸秆改性制备的纤维素黄原酸钙盐吸附特性与工艺优化研究", 《中国优秀博硕士学位论文全文数据库（硕士） 工程科技I辑》 *
吕喜风等: "改性棉秸秆对Cr(Ⅵ)吸附性能的研究", 《塔里木大学学报》 *
林琦海等: "木薯秸杆黄原酸酯的制备及其对重金属Cr~(3+)吸附性能的研究", 《湖南文理学院学报(自然科学版)》 *

Similar Documents

Publication Publication Date Title
Guleria et al. Cellulose-g-poly-(acrylamide-co-acrylic acid) polymeric bioadsorbent for the removal of toxic inorganic pollutants from wastewaters
CN108499544B (en) Preparation method of polystyrene microsphere cellulose-based heavy metal adsorbent
CN110272085A (en) A kind of modified cyanobacteria biology carbon composite and the application in processing electroplating wastewater
CN108325506A (en) A kind of preparation method of the modified cellulose aeroge of absorption heavy metal
US11369943B2 (en) Starch-based carbon composite and use thereof in selective and efficient adsorption of mercury ion and methylene blue
CN113398889B (en) Multi-adsorption-site biomass-based hyperbranched multi-metal ion adsorption material and preparation method and application thereof
CN112340830B (en) Application of catalyst taking waste adsorbent after adsorption-desorption as raw material in treating high-salt organic wastewater by activating persulfate
CN110614083A (en) Polyethyleneimine modified sawdust heavy metal adsorbent and preparation method thereof
CN110683540A (en) Nitrogen-rich hierarchical pore biomass charcoal and application thereof
CN115055170A (en) Wood-based modified nano-cellulose water purification material with high adsorption performance and preparation method and application thereof
CN104084185A (en) Modified activated carbon as well as preparation method and application thereof
Nure et al. Adsorption of Black MNN reactive dye from tannery wastewater using activated carbon of Rumex Abysinicus
CN111195513A (en) Preparation method of dithio-carboxylated straw, product and application of product as heavy metal adsorbent
CN116440866B (en) Preparation method and application of three-dimensional spongy porous heavy metal ion adsorbent based on activated eggshells
CN103785361A (en) Method for preparing heavy metal ion absorbent through xanthation of granule sludge
Mustapha et al. Preparation and characterization of Bio-Adsorbent from coconut husk for remazol red dye removal
CN111530436A (en) Method for modifying shells
CN115155534A (en) Preparation method and application of composite polysaccharide biomass gel adsorbent
CN108671897A (en) A kind of preparation and its application of modified straw fiber adsorbing material
CN108636365A (en) A kind of modified straw fiber adsorbing material and its application method
CN107051379A (en) A kind of preparation method of the modified straw charcoal biogas desulfurizer of loaded metal ion
CN100434180C (en) Fiber base grafted polyglutamic acid ion exchange material and its preparing method and use in treating waste water
CN112875848A (en) Alkali pretreatment activated sludge adsorbent and preparation method and application thereof
Chauhan et al. A study of the synthesis, kinetics, and characterization of reactive graft copolymers of poly (vinyl imidazole) and cellulose for use as supports in enzyme immobilization and metal ion uptake
CN109225174A (en) A kind of modified calcium alginate fibre heavy-metal adsorption material and preparation method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication

Application publication date: 20200526

RJ01 Rejection of invention patent application after publication