Preparation Of Chitosan-bagasse Activated Carbon And Its Performance On The Treatment Of Organic Pesticide Pollutants

In recent years,due to the large and unreasonable use of pesticides,organic pesticide residues in the surrounding environment,through a variety of ways to enter the water,to the surrounding environment and human health has brought serious harm.How to remove organic pesticide pollutants in the environment has become a hot research topic for researchers.In order to solve this problem,many related processing techniques are corresponding.Compared with most treatment techniques,the adsorbent materials used in the physical adsorption process are widely available,relatively inexpensive,and have a strong ability to deal with the pollution of organic pesticides,resulting in less secondary pollution.Therefore,the method has been widely used in the treatment of organic pesticide pollution.Bagasse,an agricultural waste,has a large biomass and is rich in cellulose.However,most of bagasse is used in low value.For example,most of bagasse is discarded and burned in agricultural production,which is not only a waste of natural resources,but also a pollution to the environment.In the existing high-value utilization of bagasse,bagasse was prepared into activated carbon adsorbent to remove environmental pollutants,which provided the research basis and theoretical basis for this study.Chitosan,as a kind of natural macromolecule compound,is widely used in many fields because of its good flocculation and innocuity,because of its wide range of sources,low price and easy to obtain.In the control of environmental pollution has also had better results.Based on the above understanding,the main contents of this paper are as follows:?1?Bagasse activated carbon was prepared from agricultural waste bagasse by ZnCl₂ activation method.The optimum preparation conditions were determined as follows:the mass fraction of zinc chloride solution was 5%,the mass ratio of zinc chloride solution to raw material was 2:1,the activation temperature was 450?and the activation time was 120 min.The yield of activated carbon prepared is 49%and57%.Chitosan-bagasse composite activated carbon was prepared by crosslinking bagasse activated carbon with chitosan in the presence of 5%acetic acid water and glutaraldehyde as crosslinking agent.?2?The characterization results of chitosan-bagasse activated carbon show that the activated carbon has amorphous structure and abundant pore structure on the surface,mainly composed of C and O,and the specific surface area of BET of bagasse activated carbon is 859.6 m²/g.The specific surface area of composite activated carbon with the ratio of chitosan and bagasse activated carbon at 1:3 is 156.9 m²/g.Fourier transform infrared spectroscopy?FT-IR?analysis showed that the main functional groups of 1:3 compound activated carbon were hydroxyl,carbonyl group and methyl group.?3?Chitosan/bagasse activated carbon was used to treat aqueous solution containing acetamidine and dichlorvos.When the concentrations of acetamiprid and dichlorvos were 5 mg/L and 1 mg/L,respectively,and the temperature was 30?,the adsorption equilibrium of the two organic pesticides was achieved after the adsorption of the two organic pesticides by the composite activated carbon containing 1:3 ratio of acetamidine and dichlorvos after 60 min and 30 min,the adsorption amounts are 1.4mg/g and 0.33 mg/g.When the concentration of acetamiprid and dichlorvos was 50mg/L and 20 mg/L respectively,the maximum adsorption capacity of the composite activated carbon with 1:3 ratio was 11.56 mg/g and 16.06 mg/g,respectively.Bagasse and bagasse The removal rate of unit specific surface area of activated carbon was higher than that of bagasse activated carbon,and the effect of 1:3 ratio was better than that of 6:4 composite activated carbon.?4?Langmuir isothermal adsorption model and Freundlich isotherm adsorption model were used to simulate the adsorption process of acetamidine and dichlorvos on composite activated carbon at 1:3 and 6:4.The results showed that both isothermal adsorption models could describe the adsorption process well.The adsorption isotherm model of monolayer adsorption.Freundlich showed that the adsorption capacity of the composite activated carbon at 1:3 and 6:4 was large,and the adsorption of acetamidine and dichlorvos was easy.According to the fitting results,the composite activated carbon with ratio of 1:3 has stronger affinity to acetamiprid and dichlorvos.Greater adsorption capacity.?5?Using the quasi two order kinetic equation to describe the adsorption process of the composite activated carbon with 1:3 and 6:4,it can reach a significant level.Under the optimum conditions,the adsorption amount of the composite activated carbon,which is calculated by the quasi two order kinetic equation and the ratio of 1:3and 6:4,is in accordance with the adsorption amount of organic pesticides.The process can be used to predict the adsorption process of acetamiprid and dichlorvos with compound activated carbon with 1:3 and 6:4.There is a certain amount of adsorption site on the surface of activated carbon.The maximum adsorption capacity depends on the number of adsorption sites.When the adsorption site on the surface of activated carbon is close to saturation,the adsorption rate will tend to be slow.?6?The removal mechanism of acetamidine and dichlorvos by chitosan bagasse activated carbon was described.The mechanism was divided into three aspects:hydrolysis process of organic pesticides.The removal of acetamiprid and dichlorvos?including the active carbon itself and the interaction between activated carbon and chitosan?and the removal of acetamiprid and dichlorvos by functional groups on the composite activated carbon.The cost of raw materials,the cost of preparation equipment and the estimated economic value of chitosan/bagasse composite activated carbon were analyzed.It can be concluded that the material has good economic benefits.