Super and selective adsorption of cationic dyes using carboxylate-modified lignosulfonate by environmentally friendly solvent-free esterification

Abstract

Herein, following the strategy of sustainable, environment protection, circular economy development, carboxylate-modification lignosulfonate polymer (M-LSP) was synthesized from lignosulfonate by solvent-free esterifying with maleic anhydride (MA) by one step, and was used to remove the dyes by adsorption. FT-IR and XPS were used to confirm successful preparation of M-LSP. The result is that: M-LSP is apt to adsorb cationic dye. In single system, the super adsorption performance of M-LSP for methylene blue (MB) is depended on the carboxyl content in M-LSP. M-LSP performs its remarkable adsorption performance for MB stably at pH 7.0 ~ 10.0, and the maximum adsorption capacity of M-LSP for MB is up to 613.5 mg/g according to Langmuir isotherm model. The Langmuir isotherm and pseudo-second-order kinetic models are more suitable to descript adsorption process of M-LSP for MB. In binary and ternary system, the M-LSP adsorbs the cationic dyes simultaneously, but selectively adsorbs MB. M-LSP can effectively remove cationic dyes in simulate dyestuff water. Moreover, the removal percentage of regenerated M-LSP decreases only 8.4% after 4 desorption-resorption cycles. The results indicated that M-LSP could be a candidate for remediation of real printing and dyeing or textile wastewater containing cationic dyes.