Preparation Of Two Biosorbents Modified By Xanthate And Their Adsorption Properties For Pb(Ⅱ) And Malachite Green

The insufficiency of water resources is an inevitable problem in the world,and water pollution makes the lack of water sources increasingly scarce and threatens human health.Nowadays,a large amount of heavy metals and dye pollutants are discharged into the water environment every year,which not only pollute the environment and destroy the ecology,but also cause harm to the organisms.Up to now,researchers have explored various methods for removing heavy metals and dyes,such as physical,biological,and chemical methods.Among them,adsorption technology is considered to be a commonly used method to effectively remove heavy metals and dye pollutants.Since"green thinking"has always been emphasized in the treatment of environmental pollution,and biological materials just meet this idea,green economical biosorbents are often considered and widely used in practice because of their environmental friendliness.In summary,this article combines biological materials and adsorption methods to prepare environmentally friendly,non-secondary pollution green biosorbents to remove heavy metals and dyes.In this study,using Na OH and CS₂ as modifiers,corn cob（CC）and chestnut shell（CS）as primary material materials,we prepared by xanthate-modified corn cob and chestnut shell biosorbent（X-CC and X-CS）.The samples were characterized by scanning electron microscope（SEM）,X-ray energy spectrum analyzer（EDS）,Fourier transform infrared spectroscopy（FTIR）,and specific surface area analyzer（BET）.In addition,the effects of various factors such as p H,time,temperature,and pollutant concentration on the removal of Pb（Ⅱ）and malachite green（MG）were explored.The adsorption model and adsorption mechanism of Pb（Ⅱ）and malachite green（MG）by X-CC and X-CS were also analyzed.Experiments show that CC and CS modified by xanthate have higher adsorption capacity.In a single system,it takes 60 min for X-CC and X-CS to adsorb Pb（Ⅱ）to reach adsorption equilibrium,and the increase in temperature can increase the removal rate of Pb（Ⅱ）.For X-CC and X-CS adsorption of MG,it only takes 10 minutes to reach the adsorption equilibrium,and the increase in temperature makes the removal rate of MG first increase and then decrease.When removing Pb（Ⅱ）,the optimum p H is 5,and the optimum p H for removing MG is 7.In addition,the adsorption capacity of X-CC and X-CS on MG is much greater than that of Pb（Ⅱ）.From the kinetic temperature model,it can be seen that the kinetic model fitting of X-CC and X-CS to Pb（Ⅱ）and MG is more in line with the quasi-secondary kinetic equation model;the fitting correlation coefficients of the X-CC and X-CS to the Pb（Ⅱ）quasi-secondary kinetic equation are 0.999 and 0.998,respectively,and the fitted equilibrium adsorption capacities are86.91 and 87.72 mg g^-1,respectively;while the fitting correlation coefficients of the X-CC and X-CS to the MG quasi-secondary kinetic equation are respectively 0.997 and 0.999,the fitted equilibrium adsorption capacities are 204.082 and 206.719 mg g^-1,respectively,and the fitting results are similar to the experimental results;The fitting of X-CC and X-CS isotherm adsorption models for Pb（Ⅱ）and MG is more in line with the Langmuir model.It can be seen that the maximum adsorption capacity of Pb（Ⅱ）by X-CC and X-CS is 166.39 and 124.84 mg g^-1,respectively,while the maximum adsorption capacity of Pb（Ⅱ）by X-CC and X-CS is398.41 and 344.83 mg g^-1,respectively.This result also shows that these two biosorbents are single-layer adsorption when adsorbing pollutants,and the adsorbed particles are completely independent;In the ternary system,that is,when Pb（Ⅱ）,Cu（Ⅱ）and Cd（Ⅱ）coexist,the adsorption order of X-CC is Pb（Ⅱ）>Cd（Ⅱ）>Cu（Ⅱ）,and X-The adsorption order of CS is Pb（Ⅱ）>Cu（Ⅱ）>Cd（Ⅱ）.It can be seen that X-CC and X-CS have selective adsorption to Pb（Ⅱ）.When MG and methylene blue coexist,X-CC and X-CS can selectively adsorb MG.In addition,we also found that X-CC and X-CS also have a better removal effect on Pb（Ⅱ）in actual wastewater.By comparing the changes of EDS and FTIR of X-CC and X-CS before and after adsorption,it can be seen that the adsorption of Pb（Ⅱ）by X-CC and X-CS is mainly electrostatic,ion exchange and surface complexation,while X-CC and X-The adsorption of MG by CS is mainly electrostatic,surface hydrogen bonding,and functional effects such as C=S and CSS.The research of this experiment shows that X-CC and X-CS biosorbent materials have good adsorption properties and can effectively remove Pb（Ⅱ）and MG.They are a kind of biosorbents with practical application prospects,so they are also biological adsorbents.The synthesis and application of adsorbent materials provide a new research direction and theoretical basis.