Preparation Of Thiol Modified Cellulose Materials And Study On Adsorption Performance Of Mercury Ions And Acid Red B Dye

The continuous development of modern science and industrial technology has brought convenience to people’s lives,however,a large number of harmful pollutants were produced at the same time.There is going to bring a great threat to the survival of human beings and other organisms in the biosphere if the wastewater containing various pollutants were discharged randomly without any treatment.Due to the advantages of low cost,strong practicability,less secondary pollution,and high removal performance against pollution,adsorption method has been widely used in industrial wastewater treatment.Cellulose was the most abundant and easy available natural resource in nature,it has the characteristics of biodegradable and good biological compatibility and it can extracted from forestry and agricultural residues and various plants,which was a high utilization value natural polymer.However,natural cellulose usually suffer poor active site and slightly solubility,which do limit its practical application.Therefore,to obtain more adsorption sites and improve cellulose’s adsorption performance,it is necessary to modify cellulose to introduce some functional groups.Firstly,the thiol cellulose aerogel（MCC-SH）was prepared by freeze-drying method under certain conditions using modifier propylene sulfide and microcrystalline cellulose as raw materials,and the adsorption performance against Hg（Ⅱ）ions was investigated.The results showed that the thiol concentration of MCC-SH reached 0.6 mmol/g;the adsorption of Hg（Ⅱ）on the MCC-SH was a spontaneous and endothermic process,and its adsorption isotherm could be described by Langmuir model,and the maximum adsorption capacity for Hg（Ⅱ）is 415.6 mg/g at the conditions of 25℃and p H=6;MCC-SH has a fast adsorption rate,and follows a pseudo-second-order kinetic model,which mainly removes Hg（Ⅱ）ions in aqueous solution through electrostatic adsorption and chemical coordination.Under the coexistence of other divalent metal ions(Cu²⁺、Pb²⁺、Co²⁺、Zn²⁺),the removal rate against specified concentration Hg（Ⅱ）solution by MCC-SH can still be as high as 90%.After 3adsorption/desorption cycles,the removal rate of Hg（Ⅱ）ions in the specified concentration solution by the MCC-SH is slightly reduced to 90%.In a word,MCC-SH has some excellent adsorption performances against Hg（Ⅱ）,such as high efficiency,high selectivity and renewable.Secondly,thiol-modified degreasing cotton（TDC）adsorbent was prepared through ring-open modify method under alkaline condition using propylene sulfide and degreasing cotton as raw materials.And then acid red B dye was used as the model pollutant to study the adsorption properties of TDC for acid red B dye in dye wastewater.The results indicated that:compared to the unmodified degreasing cotton,the adsorption performance of acid red B dye on TDC was clearly enhanced.The adsorption of acid red B on TDC has both physical and chemical adsorption,and it was a spontaneous and endothermic process,and its adsorption isotherm conforms to the Langmuir model.At 25℃and p H=6,the removal rate against 20 mg/L acid red B of 400 mg/L TDC was 95%.TDC could still maintain good adsorption performance in the weak acidic（p H=3）environments of most industrial wastewater containing acid dyes.TDC could reach the adsorption equilibrium quickly（within 90 min）,and its adsorption kinetics follows the pseudo-second-order kinetic model.The adsorbed TDC can be eluted（desorption）by sodium hydroxide solution.After elution,the removal rate for 20 mg/L acid red B solution could still reach more than 75%.This indicates that TDC was an excellent adsorbent that can effectively treat acid red B dye in wastewater.In this paper,to produce an excellent adsorbent for Hg（Ⅱ）ions and acid red B dye in wastewater,propylene sulfide was innovatively used as a modifier of cellulose materials.The disadvantages of tradiotional thiol modification method such as high cost,harsh reaction conditions and low content of thiol group could be made up by the propylene sulfide method.This paper could provide a new idea for the development of thiol functional adsorption materials.