Chemically Functionalized Polysaccharide-Based Chelating Agent for Heavy Metals and Nitrogen Compound Remediation from Contaminated Water

Abstract

The aim of this research was to develop chemically functionalized polysaccharide-based chelating materials with unique heavy metal and nitrogen compound absorptive properties from cellulose, butane tetracarboxylic acid (BTCA), and chitosan. The BTCA was incorporated onto cellulose through an esterification reaction in the presence of sodium phosphate dibasic dihydrate as catalyst and then cross-linked with chitosan. The effect of BTCA concentration, modification time, and temperature on the carboxylic acid content percentage of modified cellulose was analyzed. Furthermore, modified cellulose was cross-linked with chitosan to produce water-insoluble chelating materials for heavy metals and nitrogen compound remediation from contaminated water. Characterization of the modified cellulose and its water-insoluble chelating foam materials including chemical, structural, heavy metals, and nitrogen compound uptake analyses. The modified cellulose–chitosan foam can absorb up to 8.91–66.45 mg/g arsenic, 6.57–29.1 mg/g mercury, 10–75.6 mg/g lead, 10–45.47 mg/g cadmium, and 6.45–21.2 mg/g selenium when the foam was treated with 100–1000 ppb contaminated water. The heavy metal uptake of modified cellulose–chitosan foam in contaminated water was significantly greater than modified cellulose, cellulose, and commercial metal-chelating agent PuroliteFerrIX A33E. The interesting thing is that only 0.2gram foam material is enough to decrease of 1liter arsenic concentration from 100 to 11 ppb, which meets the EPA standards. However, the modified cellulose–chitosan foam also can absorb about 0.2 g/g ammonium nitrate, 0.14 g/g ammonium chloride, and 0.29 g/g ammonia when it was treated with 0.1% nitrogen compound contaminated water. The modified cellulose and modified cellulose–chitosan foam was characterized with TGA, DSC, FTIR, and SEM, confirming the cross-linking of the materials.