CN110961087A - PX adsorbent and preparation method thereof - Google Patents

PX adsorbent and preparation method thereof Download PDF

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CN110961087A
CN110961087A CN201911174660.0A CN201911174660A CN110961087A CN 110961087 A CN110961087 A CN 110961087A CN 201911174660 A CN201911174660 A CN 201911174660A CN 110961087 A CN110961087 A CN 110961087A
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adsorbent
crab shell
crab
temperature
hydrochloric acid
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CN110961087B (en
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纪丽丽
陈瑛娜
郭健
宋文东
王亚宁
蔡璐
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Zhejiang Ocean University ZJOU
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    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28011Other properties, e.g. density, crush strength
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
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    • B01J20/28054Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28057Surface area, e.g. B.E.T specific surface area
    • B01J20/28066Surface area, e.g. B.E.T specific surface area being more than 1000 m2/g
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
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    • B01J20/28054Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28069Pore volume, e.g. total pore volume, mesopore volume, micropore volume
    • B01J20/28076Pore volume, e.g. total pore volume, mesopore volume, micropore volume being more than 1.0 ml/g
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    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
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    • B01J20/28054Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28078Pore diameter
    • B01J20/2808Pore diameter being less than 2 nm, i.e. micropores or nanopores
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    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28054Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28078Pore diameter
    • B01J20/28083Pore diameter being in the range 2-50 nm, i.e. mesopores
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00Aspects relating to sorbent materials
    • B01J2220/40Aspects relating to the composition of sorbent or filter aid materials
    • B01J2220/48Sorbents characterised by the starting material used for their preparation
    • B01J2220/4875Sorbents characterised by the starting material used for their preparation the starting material being a waste, residue or of undefined composition
    • B01J2220/4881Residues from shells, e.g. eggshells, mollusk shells

Abstract

The invention relates to the field of removal of paraxylene, in particular to a PX adsorbent, a preparation method thereof and a method for adsorbing paraxylene by using the PX adsorbent. The PX adsorbent is prepared by taking crab shells as raw materials and adopting a high-temperature oxygen-free hybridization technology, has a black carbon appearance, a pore diameter of 1-5nm and a pore volume of 1.023-1.149cm3Per gram, specific surface area of 1650.22-2045.68m2Analysis by X-ray diffraction spectrometer shows that the sample has two diffraction peaks at 20.3 deg. and 43.1 deg., and infrared spectrum at 3472cm‑1,2351cm‑1,1531cm‑1,1439cm‑1,1068cm‑1,862cm‑1There is an absorption peak. The PX adsorbent can efficiently remove PX remained in a water body, the PX removal rate in five minutes is up to 87.5%, and the highest adsorption quantity is 393.10 mg/g; the invention is high in crab shell waste resourceThe method provides a new idea for valued utilization, develops a new adsorbing material for PX removal, and has very important significance for solving the increasingly serious PX pollution problem in China.

Description

PX adsorbent and preparation method thereof
Technical Field
The invention relates to the field of removal of paraxylene, in particular to a PX adsorbent and a preparation method thereof, and a method for adsorbing paraxylene by using the PX adsorbent.
Technical Field
PX (para xylene), which is common chemical products of aromatic hydrocarbon series, is mainly used for preparing terephthalic acid or polyester, and is a raw material for producing various industrial plastics. According to incomplete statistics, the total yield of PX in 2017 in China reaches 1380 ten thousand tons, and the capacity tends to increase year by year. In addition, 4000 million tons of Zhejiang petrochemical/year refining integrated first-term project has been put into operation in Zhoushan green petrochemical base in 5 months in 2019, wherein the annual output of PX is as high as 400 million tons. However, with the increase of the PX yield, the environmental problems brought with the PX production are increasingly prominent, leakage and other problems inevitably exist in the PX production, processing and transportation processes, and the PX exposed in the air and the water body can cause certain harm and even damage to the human health. Therefore, in recent years, PX removal has been a focus of attention for researchers. At present, the main methods for removing PX are chemical oxidation, catalytic degradation, adsorption, biological treatment, etc., wherein the adsorption is the most economical and widely used method for removing PX. At present, the existing adsorbent has poor adsorption effect on PX, so that a PX adsorbent having high adsorption capacity, high removal rate, reusability and stable structure has been a hot point of research.
Disclosure of Invention
The PX adsorbent is prepared by taking crab shells as raw materials and adopting a high-temperature oxygen-free hybridization technology, has a black carbon appearance, a pore diameter of 1-5nm and a pore volume of 1.023-1.149cm3Per gram, specific surface area of 1650.22-2045.68m2Analysis by X-ray diffraction spectrometer shows that the sample has two diffraction peaks at 20.3 degrees and 43.1 degrees, and the infrared spectrum shows that the sample is at 3472cm-1,2351cm-1,1531cm-1,1439cm-1,1068cm-1,862cm-1Has an absorption peak。
The invention adopts a specific surface area and pore diameter analyzer to determine N of PX adsorbent2The adsorption isotherm, and the related determination result shows that the adsorption isotherm of the PX adsorbent is an IV-type isotherm at P/P0>The presence of a hysteresis loop at 0.4 indicates the presence of mesopores.
Furthermore, the invention adopts a BET method to analyze the pore diameter and the specific surface area, the pore diameter distribution of the PX adsorbent is mainly in the range of 1-5nm, and the PX adsorbent consists of micropores and mesopores and is porous biochar; the specific surface area of the PX adsorbent is as high as 2045.68m2Per g, pore volume 1.149cm3(ii)/g; the PX adsorbent disclosed by the invention has the advantages of large specific surface area, high and uniform porosity and contribution to improving the PX adsorption capacity.
The invention utilizes an X-ray diffraction spectrometer to analyze the crystal structure and the phase structure of the PX adsorbent, wherein the PX adsorbent has two diffraction peaks of 20.3 degrees and 43.1 degrees, which shows that the PX adsorbent has the characteristics of chitin (21-2) plane and crystalline graphite (100) plane; the diffraction peak is at 43.1 degrees, which indicates that the PX adsorbent has amorphous carbon, and the adsorption efficiency of PX can be enhanced.
The surface chemical functional groups are determined by Fourier transform infrared spectroscopy, and the infrared spectroscopy of the PX adsorbent shows that the surface chemical functional groups are about 3472cm-1,2351cm-1,1531cm-1,1439cm-1,1068cm-1,862cm-1Has an absorption peak. The infrared spectrum of the PX adsorbent shows that the PX adsorbent has a characteristic peak of chitin, which is consistent with an XRD (X-ray diffraction) pattern; in addition, the spectrum of oxygen-containing functional groups such as-OH, C ═ O and the like is also observed as potential adsorption sites, so that the adsorption performance of PX is more excellent.
According to the invention, the surface morphology of the PX adsorbent is observed by using a scanning electron microscope, and the effective arrangement of mesoporous layered porous of the crab shell carbon is found, so that more pits and cracks exist; presenting a rich porous structure.
A preparation method of PX adsorbent comprises using crab shell as raw material, soaking in hydrochloric acid to remove calcium carbonate, pulverizing, high temperature anaerobic carbonizing, grinding into powder for activating, washing with distilled water repeatedly to neutrality, and oven drying to obtain PX adsorbent.
Further, a preparation method of the PX adsorbent comprises the following steps:
1) crab shell pretreatment
Soaking crab shell in hydrochloric acid solution for 12 hr to remove calcium carbonate, washing with distilled water to remove residual hydrochloric acid and salt on surface, and drying in oven at 60-80 deg.C for 24 hr;
2) charring crab shell
Crushing the crab shells pretreated in the step 1), placing the crushed crab shells in a tube furnace, and performing reaction in a reactor N2Carrying out high-temperature carbonization under the protection of atmosphere;
3) crab shell activation
Grinding the crab shells carbonized in the step 2) into powder with the granularity of 100-200 meshes for subsequent activation experiments, naturally cooling the activated crab shell powder, repeatedly washing crab shell carbon with distilled water until the crab shell carbon is neutral, and drying in an oven at the temperature of 60-80 ℃ for 24 hours to obtain the PX adsorbent.
Preferably, the concentration of the hydrochloric acid in the step 1) is 2 mg/L.
Preferably, the weight-to-volume ratio (unit g/mL) of the crab shells to the hydrochloric acid in the step 1) is 1: 2.
Preferably, the carbonization condition in the step 2) is N2The flow rate of the tube furnace is 200mL/min, the temperature of the tube furnace is raised to 600-800 ℃ at the speed of 10 ℃/min, and then the temperature is maintained for 2-3 h.
Preferably, the activation conditions in step 3) are: mixing the carbonized crab shell powder with KOH solid according to the weight ratio of 1:1-2:1, placing the mixture in a tubular furnace for activation, and adding N2The flow rate of (2) is 200mL/min, the temperature is raised to 800 ℃ at a rate of 10 ℃/min, and then the temperature is maintained for 1-2 h.
A method of adsorbing PX with a PX adsorbent, comprising the steps of:
1) adding a PX adsorbent to a PX aqueous solution, wherein the weight-to-volume ratio (g/L) of the PX adsorbent to the PX aqueous solution is 1: 5;
2) adjusting the pH value of the mixed solution to 7 by adding 0.1mol/L hydrochloric acid or 0.1mol/L sodium hydroxide, and adsorbing at 25 ℃;
3) and (3) centrifuging the mixed solution at 4000r/min for 5min, taking supernate, measuring the OD value of the supernate, and calculating the adsorption quantity of PX by the formula (1).
Preferably, the concentration of PX in the PX aqueous solution in said step 1) is 80 mg/L.
Preferably, the adsorption time in step 2) is 5-60 min.
The inventor is continuously dedicated to developing a high specific surface area biochar material, and early researches find that biochar has high specific surface area, is rich in various mineral elements and active groups, and can be used as an ideal PX adsorbent material; the invention adopts high-temperature anaerobic hybridization technology to prepare the waste crab shells into a novel charcoal adsorbent, which can efficiently remove PX remained in a water body, wherein the PX removal rate in five minutes is up to 87.5%, and the maximum adsorption amount is up to 393.10 mg/g; the invention provides a new idea for the high-value utilization of crab shell waste resources, develops a new adsorbing material for removing PX, and has very important significance for solving the increasingly serious PX pollution problem in China.
Drawings
Fig. 1 is a plot of the specific surface area and pore size of the PX adsorbent in example 1.
FIG. 2 is an XRD pattern of PX adsorbent in example 1 and crab shell feedstock in comparative example 1;
wherein, a is the XRD pattern of the crab shell raw material in the comparative example 1, and b is the XRD pattern of the PX adsorbent prepared in the example 1.
FIG. 3 FTIR plots of PX adsorbent in example 1 and crab shell feed in comparative example 1;
wherein, a is the FTIR spectrum of the crab shell raw material in the comparative example 1, and b is the FTIR spectrum of the PX adsorbent prepared in the example 1.
FIG. 4 is an SEM image of PX adsorbent in example 1 and crab shell feed in comparative example 1;
wherein a is an electron microscope image of crab shell raw material in comparative example 1 magnified 5000 times, b is an electron microscope image of crab shell raw material in comparative example 1 magnified 10000 times, c is an electron microscope image of PX adsorbent in example 1 magnified 5000 times, and d is an electron microscope image of PX adsorbent in example 1 magnified 10000 times.
Fig. 5 is a graph of the effect of different concentrations on the adsorption efficiency of PX adsorbent.
Fig. 6 is a graph of the effect of different times on the adsorption efficiency of PX adsorbents.
Fig. 7 is a graph of the effect of different pH on the adsorption efficiency of PX adsorbents.
Detailed Description
The following examples are intended to further illustrate the present invention, but they are not intended to limit or restrict the scope of the invention.
Crab shell sources are as follows: zhoushan City aquatic product market
Tube furnace SGL-1700- Ш Zhengzhou Hong Lang Instrument Equipment Co., Ltd
Oven: HH.S11-6 Tianjin Tesla Co Ltd
The solvent used in the present invention is not particularly limited, and a commercially available conventional solvent can be used, for example, the hydrochloric acid is analytically pure and is available from Shanghai pharmaceutical chemical Co.
The X-ray powder diffraction instrument and the test conditions related by the invention are that the change of the X-ray diffraction intensity of a sample along with 2 theta is measured by adopting a D/max2500X ray diffractometer of Shimadzu Japan so as to obtain the crystallinity of the sample.
The infrared spectrometer and the test conditions adopted by the invention are that the American Nicolet Nexus 6700FTIR Fourier transform infrared spectrometer is used for detecting and analyzing the chemical structure and the functional group of the sample. In the scanning range of 500cm-1-4000cm-1Under the condition (2), the obtained infrared spectrogram can be used as a basis for judging the composition of the sample.
The electron microscope and the test conditions adopted by the invention are that a sample is analyzed by using Japan Quanta 200F, 10mg of the sample is uniformly covered on a test board, and then the appearance and the specific structure of the sample are observed by using a scanning electron microscope under different multiples.
The specific surface area and pore size analysis tester adopted by the invention has the test conditions that 30-40mg of sample is weighed by using BK122T-B type specific surface area and porosity analyzer, the system is heated to 300 ℃, the Q value is measured after the liquid nitrogen rises until the two results are less than 0.001h, and the liquid nitrogen is added under the test conditions by using a multipoint BET method: the specific surface area of the biochar was measured at a liquid nitrogen temperature (77k), and the pore size distribution was measured by the DFT method.
The invention relates to the calculation of the adsorption rate of PX adsorbent to PX adsorption:
Figure BDA0002289647460000041
wherein q ist(mg/g) is the amount of PX adsorbed by the adsorbent, C0(mg/L) and Ct(mg/L) is the initial concentration and the concentration at a certain reaction time point, V is the volume of the solution (L), and m (g) is the weight of the adsorbent.
Comparative example 1 preparation of crab shell feed
Soaking 40g of swimming crab shells in 80mL of hydrochloric acid solution with the concentration of 2mg/L for 12 hours, removing calcium carbonate, washing with distilled water to remove residual hydrochloric acid and salts on the surfaces, and then drying in an oven at 70 ℃ for 24 hours; then crushed into powder with the granularity of 200 meshes.
Example 1 preparation of PX adsorbent
1) Crab shell pretreatment
Soaking 40g of swimming crab shells in 80mL of hydrochloric acid solution with the concentration of 2mg/L for 12 hours to remove calcium carbonate, washing with distilled water to remove residual hydrochloric acid and salts on the surfaces, and then drying in an oven at 70 ℃ for 24 hours;
2) charring crab shell
Crushing the swimming crab shells pretreated in the step 1), placing the crushed swimming crab shells in a tube furnace, and performing reaction in a reactor N2High temperature carbonization under the protection of atmosphere, N2The flow rate of (2) is 200mL/min, the temperature of the tube furnace is raised to 700 ℃ at the speed of 10 ℃/min, and then the temperature is maintained for 2 h;
3) crab shell activation
Grinding the portunus trituberculatus shells carbonized in the step 2) into powder with the granularity of 200 meshes for subsequent activation experiments; mixing the carbonized crab shell powder with KOH solid according to the weight ratio of 2:1, placing the mixture in a tubular furnace for activation, and adding N2At a flow rate of 200mL/min, toAnd raising the temperature to 800 ℃ at the speed of 10 ℃/min, maintaining the temperature for 2 hours, naturally cooling, repeatedly washing with distilled water until the temperature is neutral, and drying in an oven at the temperature of 80 ℃ for 24 hours to obtain 4.2g of PX adsorbent.
The PX adsorbent is carbon black in appearance, and the specific surface area of the PX adsorbent is determined to be 2045.68m2G, pore diameter of 1-5nm and pore volume of 1.149cm3The specific surface area and the pore diameter diagram are shown in figure 1; the X-ray diffraction spectrometer analyzes that the X-ray diffraction spectrometer has two diffraction peaks of 20.3 degrees and 43.1 degrees, and an XRD pattern is shown in figure 2; the infrared spectrum showed that it was 3472cm-1,2351cm-1,1531cm-1,1439cm-1,1068cm-1,862cm-1Has absorption peaks, and the infrared spectrum is shown in figure 3;
10mg of the PX adsorbent in example 1 and the crab shell raw material in comparative example 1 were uniformly covered on a test board, and then the morphology and specific structure of the PX adsorbent and the crab shell raw material were observed under different multiples by a scanning electron microscope, and the results are shown in FIG. 4.
Example 2 preparation of PX adsorbent
1) Crab shell pretreatment
Soaking 30 g of hairy crab shells in 60mL of hydrochloric acid solution with the concentration of 2mg/L for 12 hours to remove calcium carbonate, washing with distilled water to remove residual hydrochloric acid and salts on the surfaces, and then drying in an oven at 60 ℃ for 24 hours;
2) charring crab shell
Crushing the pretreated crab shells of the hairy crabs in the step 1), putting the crushed crab shells into a tube furnace, and putting the crushed crab shells into a furnace N2High temperature carbonization under the protection of atmosphere, N2The flow rate of (2) is 200mL/min, the temperature of the tube furnace is raised to 600 ℃ at the speed of 10 ℃/min, and then the temperature is maintained for 2 h;
3) crab shell activation
Grinding the crab shells of the hairy crabs carbonized in the step 2) into powder with the granularity of 100 meshes for subsequent activation experiments; mixing the carbonized crab shell powder with KOH solid according to the weight ratio of 1:1, placing the mixture in a tubular furnace for activation, and adding N2At a flow rate of 200mL/min, the temperature was raised to 800 ℃ at a rate of 10 ℃/min, and then maintained at that temperature for 1And h, naturally cooling, repeatedly washing with distilled water until the solution is neutral, and drying in an oven at 60 ℃ for 24h to obtain 3g of PX adsorbent.
The PX adsorbent is carbon black, and the specific surface area is determined to be 1650.22m2Per g, pore diameter of 2-5nm and pore volume of 1.023cm3Analysis by X-ray diffraction spectrometer shows that the sample has two diffraction peaks at 20.3 deg. and 43.1 deg., and infrared spectrum at 3472cm-1,2351cm-1,1531cm-1,1439cm-1,1068cm-1,862cm-1There is an absorption peak.
Example 3 preparation of PX adsorbent
1) Crab shell pretreatment
50g of blue crab shell is soaked in 100mL of hydrochloric acid solution with the concentration of 2mg/L for 12 hours to remove calcium carbonate, and then is washed by distilled water to remove residual hydrochloric acid and salts on the surface, and then is dried in an oven at 80 ℃ for 24 hours.
2) Charring crab shell
Crushing the blue crab shells pretreated in the step 1), placing the crushed blue crab shells in a tube furnace, and performing reaction in a reactor N2High-temperature carbonization under the protection of atmosphere, N2The flow rate of (2) was 200mL/min, and the tube furnace temperature was raised to 800 ℃ at a rate of 10 ℃/min and then maintained at that temperature for 2 hours.
3) Crab shell activation
Grinding the crab shells of the blue crabs carbonized in the step 2) into powder with the granularity of 200 meshes for subsequent activation experiments. Mixing the carbonized crab shell powder with KOH solid according to the weight ratio of 1:1, placing the mixture in a tubular furnace for activation, and adding N2The flow rate of the PX adsorbent is 200mL/min, the temperature is increased to 800 ℃ at the speed of 10 ℃/min, then the temperature is maintained for 2 hours, the PX adsorbent is naturally cooled, repeatedly washed by distilled water until the temperature is neutral, and then dried in an oven at the temperature of 60 ℃ for 24 hours, so that 5.2 g of the PX adsorbent is obtained.
The PX adsorbent is carbon black, and the specific surface area is determined to be 1865.05m2G, pore diameter of 1-5nm and pore volume of 1.092cm3Analysis by X-ray diffraction spectrometer shows that the sample has two diffraction peaks at 20.3 deg. and 43.1 deg., and infrared spectrum at 3472cm-1,2351cm-1,1531cm-1,1439cm-1,1068cm-1,862cm-1There is an absorption peak.
Example 4 adsorption of PX by PX adsorbent (different concentrations)
1) 0.01g of the PX adsorbent prepared in example 1 was mixed with 50mL of PX aqueous solution with the concentration of 10, 20, 40, 60, 80, and 100mg/L, respectively, and adsorption was performed at 25 deg.C, and the influence of PX with different initial concentrations on adsorption efficiency was analyzed.
2) The pH of the mixed solution was adjusted to 7 by adding 0.1mol/L hydrochloric acid or 0.1mol/L sodium hydroxide, and the adsorption time was 60 min.
3) The mixed solution was centrifuged at 4000r/min for 5min, the OD value of the supernatant was measured, and the adsorption amount of PX was calculated by the formula (1), and the results are shown in table 1 and fig. 5.
As can be seen from table 1: the adsorption amount of PX increases with the increase of the concentration of the PX aqueous solution, and at 80mg/L, the adsorption amount of PX reaches the maximum, and then decreases with the increase of the concentration of the PX aqueous solution.
TABLE 1 influence of adsorption concentration on the adsorption efficiency of PX
PX aqueous solution concentration (mg/L) Amount of PX adsorbed (mg/g)
10 44.00
20 107.45
40 211.52
60 295.40
80 393.10
100 380.21
Example 5 adsorption of PX by PX adsorbent (different time)
1) 0.01g of PX adsorbent in example 1 is taken and respectively mixed with 50mL of PX aqueous solution with the concentration of 80 mg/L;
2) adjusting the pH value of the mixed solution to 7 by adding 0.1mol/L hydrochloric acid or 0.1mol/L sodium hydroxide, and analyzing the influence of different adsorption times on the adsorption efficiency at 25 ℃ for adsorption time from 5min to 120 min;
3) the mixed solution was centrifuged at 4000r/min for 5min, the OD value of the supernatant was measured, and the adsorption amount of PX was calculated by the formula (1), and the results are shown in table 2 and fig. 6.
As can be seen from table 2, the adsorption amount of PX increases with the increase of the adsorption time, the adsorption rate can reach 87.5% at 5min, and the adsorption amount of PX reaches the maximum at 60min, and the adsorption rate can reach 98.3%, and then decreases with the increase of the adsorption time.
TABLE 2 Effect of different time on the adsorption efficiency of PX
Adsorption time (min) Amount of PX adsorbed (mg/g)
0 0
5 350.00
30 378.20
60 393.10
90 389.15
120 380.20
Example 6 adsorption of PX by PX adsorbent (different PH)
1) 0.01g of PX adsorbent in example 1 is mixed with 50mL of PX aqueous solution with the concentration of 80 mg/L;
2) the pH of the mixed solution was adjusted to 5, 6, 7, 8 and 9 by adding 0.1mol/L hydrochloric acid or 0.1mol/L sodium hydroxide, respectively, and the mixture was adsorbed at 25 ℃ for 60 min.
3) Centrifuging the mixed solution at 4000r/min for 5min, collecting supernatant, measuring OD value, calculating PX adsorption amount by formula (1), and the results are shown in Table 3 and figure7As shown.
As can be seen from Table 3, the adsorption amount of PX was the largest at a pH value of 7.
TABLE 3 Effect of different pH on the adsorption efficiency of PX
Different pH value Amount of PX adsorbed (mg/g)
5 382.50
6 375.80
7 393.10
8 390.50
9 368.10
Example 7 adsorption of PX by PX adsorbent
1) 0.01g of PX adsorbent in example 1 is mixed with 50mL of PX aqueous solution with the concentration of 80 mg/L;
2) the pH of the mixed solution was adjusted to 7 by adding 0.1mol/L hydrochloric acid or 0.1mol/L sodium hydroxide, and the mixture was adsorbed at 25 ℃ for 60 min.
3) The mixed solution was centrifuged at 4000r/min for 5min, the supernatant was taken to measure its OD value, and the adsorbed amount of PX was calculated by the formula (1) to be 393.10 mg/g.
Example 8 the inventors searched for PX adsorbents in the prior art and listed the corresponding adsorption effects, and the results are shown in table 4.
TABLE 4
Figure BDA0002289647460000091
Wherein Chin et al, 2007 refers to Chin, C.M., Shih, L., Tsai, H., Liu, T.2007.Adsorption of o-xylene and p-xylene from water by SWCNTs, Carbon, 45(6),1254 + 1260;
carvalho et al, 2012 refers to Carvalho, M., Da Motta, M., Benachour, M., salts, D., Abreu, C.2012.evaluation of BTEX and phenol removal from aqueous solution on to inorganic absorption on to particulate matter J Hazard Mater 239, 95-101;
anjum et al, 2019 refers to Anjum, H., Johanari, K., Gnanasundaram, N., Apmushy, A., Thanabalan, M.2019.impact of surface modification on adaptive removal, BTX on activated carbon.J. Mol Liq,280, 238-;
moura et al, 2011 refers to Moura, C.P., Vidal, C.B., Barros, A.L., Costa, L.S., Vasconcellos, L.C., Dias, F.S., Nasciento, R.F.2011.Adorption of BTX (benzene, toluene, o-xylene, and p-xylene) from aqueous solutions by modified periodic Interface Sci,363(2),626 well 634;
yu et al, 2012 refers to Yu, F, Wu, Y, Ma, J.2012. injection of the pore and surface chemistry on adsorption of ethylene and xylene monomers by KOH-activated multi-wall carbon nanotubes, J.Hazard Mater, 237, 102-;
mangin et al, 2001 refers to mangin, c.l., Yue, z., economi, j., Maloney, s., kemmes, p., Cropek, d.2001.adsorption of organic contaminants from water using ac fs.chem.mater, 13(7), 2356-;
kim et al, 2013 refers to Kim, S., Park, J., Lee, C.2013.surface-functional silica nanoparticles as adsorbents for BTEX. J.Port Mater, 20(5), 1087-.

Claims (10)

1.A PX adsorbent, characterized by: the PX adsorbent is prepared from crab shells as a raw material by adopting a high-temperature oxygen-free hybridization technology, and has a black carbon appearance, a pore diameter of 1-5nm and a pore volume of 1.023-1.149cm3Per gram, specific surface area of 1650.22-2045.68m2Analysis by X-ray diffraction spectrometer of the powder with two diffraction peaks of 20.3 and 43.1 shows that the infrared spectrum is 3472cm-1,2351cm-1,1531cm-1,1439cm-1,1068cm-1,862cm-1There is an absorption peak.
2. The method for preparing PX adsorbent according to claim 1, wherein: the crab shell is taken as a raw material, calcium carbonate is removed after the crab shell is soaked in hydrochloric acid, high-temperature anaerobic carbonization is carried out after the crab shell is crushed, the crab shell is further ground into powder after the carbonization for activation, the powder is repeatedly washed to be neutral by distilled water, and then the crab shell is dried to obtain the crab shell.
3. The method for preparing PX adsorbent of claim 2, characterized by comprising the following steps:
1) crab shell pretreatment
Soaking crab shell in hydrochloric acid solution for 12 hr to remove calcium carbonate, washing with distilled water to remove residual hydrochloric acid and salt on the surface, and drying in oven at 60-80 deg.C for 24 hr;
2) charring crab shell
Crushing the crab shells pretreated in the step 1), placing the crushed crab shells in a tube furnace, and performing reaction in a reactor N2Carrying out high-temperature carbonization under the protection of atmosphere;
3) crab shell activation
Grinding the crab shells carbonized in the step 2) into powder with the granularity of 100-200 meshes for subsequent activation experiments, naturally cooling the activated crab shell powder, repeatedly washing crab shell carbon with distilled water until the crab shell carbon is neutral, and drying in an oven at the temperature of 60-80 ℃ for 24 hours to obtain the PX adsorbent.
4. The method for preparing PX adsorbent according to claim 3, wherein the concentration of the hydrochloric acid in step 1) is 2 mg/L.
5. The method for preparing PX adsorbent of claim 3, wherein the weight to volume ratio g/ml of said crab shell and hydrochloric acid in step 1) is 1: 2.
6. The method for preparing PX adsorbent of claim 3, wherein said carbonizing condition in step 2) is N2The flow rate of the tube furnace is 200mL/min, the temperature of the tube furnace is raised to 600-800 ℃ at the speed of 10 ℃/min, and then the temperature is maintained for 2-3 h.
7. The method for preparing PX adsorbent of claim 3, wherein said activating in step 3) isThe conditions are as follows: mixing the carbonized crab shell powder with KOH solid according to the weight ratio of 1:1-2:1, placing the mixture in a tubular furnace for activation, and adding N2The flow rate of (2) is 200mL/min, the temperature is raised to 800 ℃ at a rate of 10 ℃/min, and then the temperature is maintained for 1-2 h.
8. A method of adsorbing PX with a PX adsorbent, comprising the steps of:
1) adding a PX adsorbent to a PX aqueous solution, wherein the weight-to-volume ratio (g/L) of the PX adsorbent to the PX aqueous solution is 1: 5;
2) adjusting the pH value of the mixed solution to 7 by adding 0.1mol/L hydrochloric acid or 0.1mol/L sodium hydroxide, and adsorbing at 25 ℃;
3) and (3) centrifuging the mixed solution at 4000r/min for 5min, taking supernate, measuring the OD value of the supernate, and calculating the adsorption quantity of PX by the formula (1).
9. The method of claim 8 where a PX adsorbent adsorbs PX with a concentration of 80mg/L in the PX aqueous solution in step 1).
10. The method of claim 8 for adsorbing PX with a PX adsorbent, wherein said adsorbing time in step 2) is 5-60 min.
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