CN103933951A

CN103933951A - Method for preparing chitosan-based adsorbent for adsorbing hexavalent chromium

Info

Publication number: CN103933951A
Application number: CN201410199659.4A
Authority: CN
Inventors: 漆新华; 郝乙龙; 谭腾飞
Original assignee: 农业部环境保护科研监测所
Priority date: 2014-05-13
Filing date: 2014-05-13
Publication date: 2014-07-23
Also published as: CN103933951B

Abstract

The invention discloses a method for preparing a chitosan-based adsorbent for adsorbing hexavalent chromium. Chitosan which is readily available in the natural world generates hydrothermal reaction in a high-pressure hydrothermal reaction kettle to obtain a novel carbon material adsorbent which is rich in hydroxyl and amino and can resist acid. The adsorbent can stably exist within a wide pH value range and cannot be dissolved in an acidic solution; the adsorbent is high in adsorption performance and cyclic utilization performance to hexavalent chromium in the aqueous solution. The raw materials used in the method are readily available, natural and non-toxic; the preparation method is simple; the obtained carbon material adsorbent has a good effect for adsorbing, recycling and cyclically utilizing hydrophilic ion liquid in wastewater and is a new adsorbent for treating hexavalent chromium-containing wastewater.

Description

A kind of preparation method of adsorbent of the adsorbing hexavalent chromium based on shitosan

Technical field

The invention belongs to chitosan-based adsorbent and preparation method thereof, specially refer to a kind of material for adsorbing hexavalent chromium ions and preparation method thereof.

Background technology

Chromium and compound is widely used in the industries such as plating, tanning, pigment, metallurgy, paint, occupies critical role in national economy.But the chromate waste water of the industry discharges such as the water pollution that the chromium slag of traditional high-temperature roasting chrominm salt production technology discharge causes and plating, tanning, printing and dyeing, causes severe contamination to environment.Especially wherein Cr VI toxicity is larger, has strong impulse and corrosivity, enters people's physical efficiency and makes cell produce canceration, also very large to the other biological harm in environment.So chromium pollution water reparation and chromate waste water purified treatment are of great significance improving environment.Absorption method is to remove the common methods of metal ion in waste water, has that treating capacity is large, adsorbent is reusable, cost is low and can reclaim the advantages such as heavy metal.Yet, during some traditional adsorbent adsorbing hexavalent chromium ions, exist the on the low side or absorption of adsorbance and reach the long shortcoming of balance required time.

Shitosan (Chitosan) is a kind of natural cation polysaccharide making by chitin deacetylase base; extensively be present in the premium properties such as shrimp, microbic resolvability by all trades and professions extensive concern, being widely applied of the numerous areas such as medicine, food, chemical industry, cosmetics, water treatment, METAL EXTRACTION and recovery, biochemistry and biomedical engineering.Wherein, owing to containing a large amount of hydroxyls and amido in chitosan structure, thereby can be by static or the complexing pollutant such as adsorbing metal ions from waste water.But, because shitosan is unstable in acidic aqueous solution, easily there is to dissolve and form colloid, therefore its pH value scope of the application of shitosan in water treatment is very limited, conventionally cannot directly under acid condition, use, and in the absorption of pollutant the pH value of a solution very important influence factor often, some pollutant can only just can have good adsorption effect under acid condition.Therefore conventionally will by shitosan by the mode modification such as crosslinked or with the formation composite such as cellulose, montmorillonite after used again.These preparation process chitin modified or composite are complicated, and need to use a large amount of organic solvents, and its adsorption capacity also can decline conventionally to some extent, thereby need to find preparation method more easy, green and effective chitosan absorbent.

In the present invention, we utilize the incomplete hydrothermal carbonization of shitosan, obtain a kind of material with carbon element adsorbent of black, and this material can retain a large amount of hydroxyls and amine groups, but can in the acid solution of pH=2, keep stable, its pH range of application is widened greatly.It is applied to chromic adsorption treatment, has embodied good adsorption capacity and reusable edible.Preparation method's technique of the chitosan-based material with carbon element adsorbent proposing in the present invention is simple, without with an organic solvent, it is to chromic absorption rapidly and efficiently.

Summary of the invention

The problem that the object of the invention is can occur in acid solution for existing shitosan to dissolve and cannot use in acid solution, a kind of method of preparing novel chitosan base material with carbon element adsorbent is provided, this adsorbent is in the situation that retain a large amount of amido and oh group, can be in the acid solution compared with strong stable existence and not dissolving, be applied to Adsorption Cr VI from waste water, embodied very high adsorption efficiency and adsorption capacity, and can recycle.

The preparation method of the adsorbent of the adsorbing hexavalent chromium that the present invention proposes, be to take shitosan as raw material, generate the material with carbon element of black in autoclave after incomplete hydrothermal carbonization, this material with carbon element carbon content is 37 ~ 50%, oxygen content is 30 ~ 50%, and nitrogen content is 6 ~ 9%.Specifically comprise the following steps:

(1) under magnetic agitation, successively add the shitosan of 1 ~ 4 mass parts and the distilled water of 10 mass parts, continue to stir 30min;

(2) the mixed liquor thing of step (1) preparation is proceeded in the stainless steel autoclave of inner liner polytetrafluoroethylene to heated sealed to 160 ~ 230 ^oc isothermal reaction 4 ~ 16 h, 1000 revs/min of rotating speeds stir;

(3) reaction is cooled to room temperature after finishing, and distilled water and alternately washing of ethanol for the black powder of generation, remove whole moisture in 80 ℃ of freeze-day with constant temperature 12h, obtains being the material with carbon element of the adsorbing hexavalent chromium of black.

[advantage of the present invention and good effect]:

The present invention has following advantages: the one, and the raw material sources of absorbent preparation are the shitosans that nature extensively exists, they are reproducible, wide material sources; The 2nd, the hydrothermal carbonization method technique adopting in absorbent preparation process is simple, easy operating; The 3rd, the adsorbent preparing is rich surface hydroxyl and amido not only, and it can keep stable and any decomposition does not occur (1-14) in the wider pH value scope of application.Utilize this adsorbent to carry out the hexavalent chromium in Adsorption water, the rate of adsorption is fast, and adsorption capacity can reach 350 mg/g, and adsorbent is easy to separated and can repeatedly recycles.

[accompanying drawing explanation]:

Fig. 1 is ESEM (SEM) figure of the chitosan-based adsorbent prepared in the present invention

[specific embodiment]:

embodiment 1:

(1) under magnetic agitation, successively add the shitosan of 10 g and the distilled water of 50 mL, continue to stir 30min;

(2) the mixed liquor thing of step (1) preparation is proceeded in the stainless steel autoclave of inner liner polytetrafluoroethylene to heated sealed to 180 ^oc isothermal reaction 10 h, 1000 revs/min of rotating speeds stir;

(4) this material with carbon element proves that after SEM, FT-IR and elementary analysis it is contain-OH of rich surface ,-NH ₂the black carbon material of group.This material carbon content 38.4%, nitrogen content 6.7%, oxygen content 48.9%.

(5) test shows, this material with carbon element adsorbent prepared by the present embodiment, 20 ^othe hexavalent chromium water solution (pH 2.0) that is 100 mg/L to 20 mL concentration under C carries out Static Adsorption, and this adsorbent of 0.05 g reaches 96% at 30 min with the interior clearance to hexavalent chromium.Adsorption isotherm result of the test shows that its maximal absorptive capacity reaches 389 mg/g.

embodiment 2:

(1) under magnetic agitation, successively add the shitosan of 15 g and the distilled water of 50 mL, continue to stir 30min;

(2) the mixed liquor thing of step (1) preparation is proceeded in the stainless steel autoclave of inner liner polytetrafluoroethylene to heated sealed to 200 ^oc isothermal reaction 10 h, 1000 revs/min of rotating speeds stir;

(4) this material with carbon element proves that after SEM, FT-IR and elementary analysis it is contain-OH of rich surface ,-NH ₂the black carbon material of group.This material carbon content 37.9%, nitrogen content 7.6%, oxygen content 47.2%.

(5) test shows, this material with carbon element adsorbent prepared by the present embodiment, 20 ^othe hexavalent chromium water solution (pH 2.0) that is 100 mg/L to 20 mL concentration under C carries out Static Adsorption, and this adsorbent of 0.05 g reaches 91% at 30 min with the interior clearance to hexavalent chromium.Adsorption isotherm result of the test shows that its maximal absorptive capacity reaches 352 mg/g.

embodiment 3:

(2) the mixed liquor thing of step (1) preparation is proceeded in the stainless steel autoclave of inner liner polytetrafluoroethylene to heated sealed to 180 ^oc isothermal reaction 14 h, 1000 revs/min of rotating speeds stir;

(4) this material with carbon element proves that after SEM, FT-IR and elementary analysis it is contain-OH of rich surface ,-NH ₂the black carbon material of group.This material carbon content 51.3%, nitrogen content 8.3%, oxygen content 30.7%.

(5) test shows, this material with carbon element adsorbent prepared by the present embodiment, 20 ^othe hexavalent chromium water solution (pH 2.0) that is 100 mg/L to 20 mL concentration under C carries out Static Adsorption, and this adsorbent of 0.05 g reaches 90% at 30 min with the interior clearance to hexavalent chromium.Adsorption isotherm result of the test shows that its maximal absorptive capacity reaches 343 mg/g.

Claims

1. the preparation method of the adsorbent of the adsorbing hexavalent chromium based on shitosan, it is characterized in that take that the shitosan that nature extensively exists is raw material, in autoclave, after incomplete hydrothermal carbonization, generate the material with carbon element of black, this material with carbon element carbon content is 37 ~ 50%, oxygen content is 30 ~ 50%, and nitrogen content is 6 ~ 9%.

2. the preparation method of the adsorbent of the adsorbing hexavalent chromium based on shitosan as claimed in claim 1, is characterized in that the method is through following steps:

(3) reaction is cooled to room temperature after finishing, and distilled water and alternately washing of ethanol for the black powder of generation, remove whole moisture in 80 ℃ of freeze-day with constant temperature 12h, obtains being the adsorbent of the adsorbing hexavalent chromium of black.

3. according to the chitosan-based adsorbent described in right 2, be applied to the hexavalent chromium in adsorbed water, it is characterized in that: 20 ~ 50 ^oc, the initial concentration of hexavalent chromium is at 20 ~ 1000 mg/L, and pH value of solution is between 2 ~ 10, and the quantity of sorbent adding is at 0.005-0.05g absorption 1-24 h, and the adsorbance of hexavalent chromium on adsorbent can reach 200 ~ 400 mg/g.