CN108325503B

CN108325503B - Amino-activated carbon composite medicament for removing anionic pollutants

Info

Publication number: CN108325503B
Application number: CN201810154020.2A
Authority: CN
Inventors: 冯成洪; 田晨浩
Original assignee: Beijing Normal University
Current assignee: Beijing Normal University
Priority date: 2018-02-22
Filing date: 2018-02-22
Publication date: 2021-03-16
Anticipated expiration: 2038-02-22
Also published as: CN108325503A

Abstract

The invention discloses an amino-activated carbon composite medicament for removing anionic pollutants, which is prepared by the following steps: epoxide chemical modification of the activated carbon, amination modification of the modified activated carbon, and physical separation and drying of the product. The composite agent fully utilizes the selective modification capability of epoxide and the directional coupling capability of amido, has the advantages of low cost, high positive charge density, quaternary ammonium salt structure and the like, and has better removal effect on anionic pollutants in water, particularly inorganic complexes and organic pollutants of large and medium molecules.

Description

Amino-activated carbon composite medicament for removing anionic pollutants

Technical Field

The invention relates to the field of adsorption, and particularly relates to an amino-activated carbon composite medicament.

Background

Anionic pollutants mainly comprising cyanide, dye, nitride, nitrite, chloride, sulfide, fluoride, surfactant and the like are widely existed in industries such as mineral washing processing, electroplating, organic chemistry and the like, and have long-term potential harm to the environment and huge ecological risk. With the rapid development of economy, the anion pollution in the environment shows an increasingly serious trend, and the anion pollution of different degrees appears in underground water and surface water, so that the situation is very severe.

Adsorption and ion exchange have been considered as one of the most effective techniques for the removal of anionic contaminants from water. Compared with the ion exchange technology which has the defects of large generation amount of regenerated waste liquid, poor organic pollution resistance, long period and large salt consumption, the adsorption technology is considered as the anion pollutant removal technology with the most development potential in an efficient, economical and flexible operation mode. The key of the technology is the complexity of the research and development process and the synthesis process of the high-efficiency adsorbing material. The powdered activated carbon has the characteristics of higher specific surface area, chemical and mechanical stability, ion exchange capacity and the like, so the powdered activated carbon is generally considered to be a better adsorption material and can become a high-efficiency and low-cost material for removing anionic pollutants with great development prospect after being modified.

In previous researches, document 1 "Zhengjing Jingwei, Linjianwei, Zhanyanhui, Fangqiao, Yangjuan, Wanghong, Cetylpyridinium chloride modified activated carbon has an adsorption effect on nitrate in water [ J ]. environmental science, 2013, (11): 4325-; document 2 "Zhengxi, Linjianwei, Zhan-kuan, Yangjuan, Fangqiao. lanthanum and cationic surfactant jointly modify the adsorption of activated carbon on phosphate and nitrate in water [ J ]. environmental chemistry 2015, (05): 939-. Document 3 "Dai X, Breuer P L, Jeffrey M i.e. contrast of activated carbon and ion-exchange resins in a recovery scrubber from cyanamide solutions [ J ]. Hydrometallurgy,2010,101(1): 48-57" indicates that both activated carbon and resin have an adsorption effect on copper cyanide compounds and silver cyanide compounds, and that the adsorption of activated carbon has the advantage of being easier to elute than the adsorption of resin. The research proves that the capability of the activated carbon for adsorbing anionic pollutants after alkali modification can be obviously improved, mainly due to the fact that the density and the number of cationic groups on the surface of the activated carbon are obviously improved.

Based on the above, there is an urgent need to develop a medicament which has low cost and simple process, and can effectively remove inorganic complex and organic pollutants of large and medium molecules, so as to meet the market demand.

Disclosure of Invention

The invention aims to provide an amino-activated carbon (AmMAC) efficient composite agent for removing anionic pollutants in water, which takes cheap coal-based activated carbon as an original framework material and is modified by diethylamine, so that the AmMAC efficient composite agent has a good removal effect on the anionic pollutants in water, particularly inorganic complexes and organic pollutants of large and medium molecules.

An amido-active carbon composite medicament for removing anionic pollutants is prepared by the following process steps:

(1) preparation of improved activated carbon homogenate

Mixing the coal-based activated carbon powder with epoxy chloropropane and N, N-dimethylformamide, and continuously stirring the mixed solution in a constant-temperature water bath magnetic stirrer at the temperature of 40 ℃ to prepare an improved activated carbon homogenate activated by epoxy chloropropane; wherein, the raw material mixing proportion is that 100-150mmol of epichlorohydrin and 60-75mmol of N, N-dimethylformamide are added into each gram of coal-based activated carbon powder;

(2) preparation of amino modified activated carbon

Under the condition of constant temperature and uniform stirring, slowly dripping diethylamine into the improved activated carbon homogenate, wherein the addition amount of the diethylamine is 80-120mmol per gram of coal-based activated carbon powder, and preparing the amino-modified activated carbon homogenate;

(3) separation and drying

And (3) carrying out solid-liquid separation on the prepared amino modified activated carbon homogenate by using a sand core suction filtration device, intercepting solid particles on a filter membrane, drying the filter membrane covered with the modified material in an electric heating blast box, taking out and grinding to obtain a finished product.

Preferably, 125mmol of epichlorohydrin and 65mmol of N, N-dimethylformamide are added to each gram of coal-based activated carbon powder in the step (1).

Preferably, in the step (1), 100-150 mesh coal-based activated carbon powder is selected as a raw material.

Preferably, in step (1), the stirring speed is 120rpm, and the mixture is continuously stirred for 2 h.

Preferably, the adding amount of the diethylamine in the step (2) is 100mmol per gram of the coal-based activated carbon powder.

Preferably, in step (2), the titration rate is 0.15ml/min, the temperature is controlled at 40 ℃, the stirring speed is 120rpm, and the mixture is continuously stirred for 2 h.

Preferably, in the step (3), the drying temperature is 65 ℃, the drying time is 2 hours, and the grinding fineness is 100 meshes.

Compared with the traditional activated carbon adsorption, the medicament fully utilizes the selective modification capability of the epichlorohydrin and the directional coupling capability of the diethylamine, the modified activated carbon has a stable structure, a large number of positive charge groups and an obvious quaternary ammonium salt structure are carried on the surface, and the medicament has a good removal effect on anionic pollutants in a water body, particularly inorganic complexes and organic pollutants of large and medium molecules, and has the following advantages:

1. the preparation process is simple, the active carbon does not need to be subjected to pre-oxidation treatment, the cost is low, and the industrial production is easy to realize.

2. The invention carries out the reaction at the low temperature of 40 ℃, reduces the energy consumption,

3. the agent has a quaternary ammonium salt structure, and the removal amount of anionic pollutants (taking Congo red as an example) of the modified agent is improved by 3 times compared with that of unmodified activated carbon.

4. The medicament fully utilizes the performances of stable carbon structure skeleton, high-efficiency directional coupling capability of amido, high-density positive charges on the surface and the like, has the characteristics of high reaction speed, large capacity and high efficiency, can reach balance after reacting for 45 minutes, can reach 95 percent of the maximum removal rate within 5 minutes, and can reach 670mg/L of Congo red removal under the condition of pH 4.

Drawings

FIG. 1 is a scanning electron microscope image of an amino modified activated carbon composite medicament;

FIG. 2 is a comparison of kinetics of Congo red adsorption removal of an amino-modified activated carbon composite medicament and unmodified activated carbon;

FIG. 3 is a comparison of adsorption isotherms of various proportions of amino-modified activated carbon composite reagents and unmodified activated carbon against Congo red;

FIG. 4 shows the adsorption capacity of the amino-modified activated carbon composite reagent to Congo red at different pH values.

Detailed Description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

10g of raw material coal-based activated carbon powder with 100 meshes is mixed with 100mL of epoxy chloropropane and 50mL of N, N-dimethylformamide, and the mixture is shaken to ensure that the powdered activated carbon is not bonded and is uniformly dispersed in the mixed solution. The mixed solution was transferred to a constant temperature water bath magnetic stirrer, the temperature was controlled at 40 ℃ and the stirring speed was 120rpm, and the mixed solution was continuously stirred for 2 hours. Then, 100mL of diethylamine was slowly dropped into the activated carbon homogenate with uniform stirring at a rate of 0.15mL/min, a temperature of 40 ℃ and a stirring rate of 120rpm, and the mixture was continuously stirred for 2 hours. And (4) carrying out suction filtration on the turbid liquid by using a sand core suction filtration device, and intercepting the modified material particles on the filter membrane. And (3) placing the filter membrane covered with the modified material in an electric heating blast box, drying for 2h at 65 ℃, taking out, grinding to 100 meshes, and completing the separation and drying of the amine-based activated carbon to prepare 100-mesh amine-based modified activated carbon powder with a quaternary ammonium salt structure and used for efficiently removing anionic pollutants in water. FIG. 1 shows the appearance of an amino-modified activated carbon composite medicament.

Example 2

In the case of a typical anionic pollutant Congo red, a 1000mL glass beaker is used, 100mg/L of Congo red dye solution is added, and 500mg of the amino modified activated carbon agent in example 1 is added. The supernatant was filtered by stirring with a mechanical stirrer at 60rpm and at 0,1, 5, 10, 15, 20, 25, 30, 45, 60, 75, 90, 120, 180 minutes, respectively, and the residual absorbance was measured at 508nm wavelength using an ultraviolet-visible spectrophotometer and congo red dye reaction removal kinetics were calculated from a standard curve. The above process was repeated using unmodified activated carbon as the agent. The calculation results are shown in fig. 2.

Example 3

In the case of a typical anionic pollutant, Congo red, 0.1g of the amine-modified activated carbon agent of example 1 was added to each of 6 1000mL glass beakers, followed by 1, 2.5, 5, 10, 25, and 50mg/L of Congo red dye solution. A mechanical stirrer was used, and the rotation speed was set to 60 rpm. And (3) filtering the sample by using a 0.45-micron filter membrane, measuring the absorbance of the Congo red in the filtrate at the wavelength of 508nm by using an ultraviolet-visible spectrophotometer, and calculating the removal efficiency of the Congo red according to a standard curve. The above process was repeated using unmodified activated carbon as the agent.

Example 4

Taking a typical anionic pollutant Congo red as a case, a 1000mL glass beaker is used, 100mg/L of Congo red dye solution is added, 100mg of the amino modified activated carbon agent in example 1 is added, the pH value of the solution is adjusted, and the adsorption capacity of the agent on Congo red under different pH values of the solution is detected, which is shown in FIG. 4. As can be seen from FIG. 4, the amino modified activated carbon has a good removal effect on wastewater in different acid and alkali environments, particularly in strongly alkaline wastewater, and the removal efficiency can reach more than 200mg/g at most.

The amino modified activated carbon medicament can not only remove inorganic anion pollutants, but also has better removal effect on organic anion pollutants, has the maximum effective adsorption capacity up to 313mg/L, and has better removal effect on different acid-base environment wastewater.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. An amido-active carbon composite medicament for removing anionic pollutants is characterized by being prepared by the following process steps:

(1) preparation of improved activated carbon homogenate

Selecting 100-mesh 150-mesh coal-based activated carbon powder as a raw material, mixing the coal-based activated carbon powder with epichlorohydrin and N, N-dimethylformamide, continuously stirring the mixed solution in a constant-temperature water bath magnetic stirrer at the temperature of 40 ℃, wherein the stirring speed is 120rpm, and continuously stirring the mixed solution for 2 hours to prepare modified activated carbon homogenate activated by the epichlorohydrin; wherein the raw material mixing proportion is that each gram of coal-based activated carbon powder is added with 125mmol of epichlorohydrin and 65mmol of N, N-dimethylformamide;

(2) preparation of amino modified activated carbon

Slowly dripping diethylamine into the improved activated carbon homogenate at the constant temperature of 40 ℃ under the condition of uniform stirring, wherein the adding amount of the diethylamine is 100mmol added to each gram of coal-based activated carbon powder, and preparing the amino-modified activated carbon homogenate; the titration speed is 0.15mL/min, the stirring speed is 120rpm, and the mixed solution is continuously stirred for 2 hours;

(3) separation and drying

2. The composite pharmaceutical preparation according to claim 1, wherein in the step (3), the drying temperature is 65 ℃, the drying time is 2 hours, and the grinding fineness is 100 meshes.