Simultaneous removal of Methylene blue and Cadmium from aqueous solution by a novel sulfonated material: Characterization, mechanism and application

Abstract

Remediation of water bodies contaminated by organic or inorganic pollution has attracted widespread attention, only a few research focused on the remediation of organic-inorganic combined water pollution. In this study, a novel sulfonated material (HMFA), modified from coal fly ash (CFA) through alkali fusion and hydrothermal methods, was synthesized for the simultaneous removal of Methylene blue (MB) and Cadmium (Cd(II)) from wastewater, achieving the waste-control-waste strategy. Characterization results showed that functional groups such as hydroxyl and sulfonic acid groups are favorable for adsorption. The environmental factors exerted influence on the adsorption, with the presence of competing ions producing the most significant inhibitory effect. Under optimal conditions, the adsorption amounts of MB and Cd(II) were 116.69 and 93.53 mg g-1 in single system and 100.23 and 85.49 mg g-1 in binary system, respectively. The results of model fitting showed that the removal of MB and Cd(II) by HMFA in single system was consistent with pseudo-second-order kinetic model and Langmuir model. Apart from electrostatic attraction, the primary adsorption mechanisms on HMFA include hydrogen bonding for MB, as well as ion exchange and complexation for Cd(II), quantitative calculations have been carried out. HMFA remained favorable recyclability, and had higher selectivity on MB in natural water bodies. In conclusion, as a low-cost and efficient adsorbent material, HMFA has great potential for dye and heavy metal pollution control, which can provide more reference and theoretical support for solid waste resource utilization and dye/heavy metal removal in wastewater.