Reduction of salinity and hardness of water using copolymerized biopolymers

摘要

In this study two adsorbents were systematically synthesized through grafting using different biomaterials to target specific pollutants. Ethyl acrylate was grafted to guar gum using potassium persulfate as initiator to form the guar gum-graft-poly(ethylacrylate) (GG-g-PEA) for the reduction of the hardness of solutions; while the polyacrylamide (PAM) was grafted on the backbone of chitosan to form chitosan-g-polyacrylamide (C-g-PAM) for the reduction of salinity of solutions. The adsorbents were characterized to confirm their properties using scanning electron microscope (SEM) and they were tested for the removal of calcium and magnesium, and sulfate respectively from solutions. The results show that the grafting process was successful for both GG-g-PEA and C-g-PAM formation. Both adsorbents showed good removal potential of the respective pollutant, and their adsorption behaviour was predicted by kinetic and isotherm models. It was observed that GG-g-PEA did not exhibit exactly the same behaviour for the removal of calcium and magnesium; as the adsorption capacity predicted by the pseudo second order kinetic model for the adsorption of Ca (qe = 32.87 mg/g) was relatively high compared to Mg (qe = 30.45 mg/g). The removal of sulfate by C-g-PAM fitted the Langmuir model (qm - 211.78 mg/g) and the pseudo-second order kinetic model (qe = 128.21 mg/g).The study has shown that improvement of the properties of biopolymers through grafting could allow their application in the reduction of hardness and salinity of water.