Adsorption Of Heavy Metal On Activated Carbon Modified By Dithiocarbamate

With the rapid development of electronic industry,mining and papermaking industry,the discharge of heavy metal wastewater has increased year by year.This not only destroys the ecological balance of natural water body,but also pose a threat to human health.Adsorption is one of the effective methods to control heavy metal pollution in water.Activated carbon adsorption has been widely used in the treatment of heavy metal pollution due to its advantag es of wide source of raw materials,easy operation,high adsorption capacity and renewability.However,because of its strong hydrophobicity,easy agglomeration and limited number of surface functional groups,the traditional activated carbon has a slow ad sorption rate and a small adsorption capacity,so it needs to be chemically modified to improve its adsorption capacity for heavy metals.In this paper,The active carborn modified by dithiocarbamate?DTC-AC?was synthesized,and and its adsorption capacity for Pb²⁺,Cd²⁺and Cu²⁺was investigated.?1?IR results showed that the new adsorption peaks at 1112,960 and 1430 cm-1,which can be assgned to the streching vibration of the were attributed to C=S,C–S and-NCSS-group,respectively,indicaring that the DTC group successfully grafted onto the active carborn.The results of elemental analysis showed that the contents of nitrogen and sulfur in DTC-AC were 2.15%and 1.77%,respectively,which were higher than the active carborn.?2?The active carborn modified by dithiocarbamate?DTC-AC?was synthesized by stepwise modification with nitric acid,tetraethylenepentamine?TEPA?and carbon disulfide?CS₂?.The synthesized adsorbent was characterized by N₂ adsorption-desorption,SEM,EA and IR.The influence of initial pH,adsorbent dosage,contact time,initial metal concentration and temperature on the adsorption of Pb²⁺,Cd²⁺and Cu²⁺onto DTC-AC was studied in batch experiments.?3?The optimum adsorption conditions of Pb²⁺,Cd²⁺and Cu²⁺for DTC-AC were determined.The optimum pH values of Pb²⁺,Cd²⁺and Cu²⁺were 5.0,6.0and 5.0,respectively.The optimum adsorbent amount was 0.4 g/L.The adsorption equilibrium time was 20 min.?4?The results of kinetic study show that the adsorption of Pb²⁺,Cd²⁺and Cu²⁺onto DTC-AC all could be well described by both pseudo-first-order kinetic mode and pseudo-second-order kinetic model.The adsorption isotherms were investigated by Langmuir,Freundlich and Temkin isother m models,the datas indicated adsorption processes of DTC-AC for Pb²⁺,Cd²⁺and Cu²⁺were well described by Langmuir modelisotherm,and the maximum uptakes were 203.36?102.89 and 53.13 mg/g for Pb²⁺,Cd²⁺and Cu²⁺,respectively.Moreover,thermodynamic parameters showed that the nature of adsorption process is a spontaneous and endothermic.?5?DTC-AC displayed excellent adsorption selectivity to Pb²⁺in the ternary metal species system.Moreover,the heavy metal removal efficiency of DTC-AC is still above 85%after five adsorption-desorption cycles.Given all that,DTC-AC has great application potential in the remediation of heavy metal ions in polluted water.