Selective adsorption of cationic dye utilizing poly(methacrylic acid-co-ethylene dimethacrylate) monolith from wastewater

Abstract

In this study, poly(methacrylic acid-co-ethylene dimethacrylate (poly(MAA-co-EDMA)) monolith was prepared for the selective adsorption of acidic dye, namely methylene blue (MB), from wastewater. The fabrication of the monolith was carried out by photoinitiation polymerization by irradiating a mixture of methacrylic acid (MAA), ethylene dimethacrylate (EDMA), porogenic solvents and an initiator. Batch adsorption assays were performed to examine the impact of monolith dosage and initial dye concentration on the adsorption capacity and efficiency of the monolith towards MB dye molecules. This adsorption kinetic study revealed that MB adsorption on the monolith followed pseudo-second-order model and equilibrium adsorption behavior was best modeled by Langmuir adsorption isotherm indicating a monolayer adsorption with a maximum adsorption capacity of 50.00 mg g-1. Owing to the presence of negative binding sites on the monolith surface, cationic MB molecules are selectively adsorbed from MB/methyl orange (MO) mixture with an adsorption efficiency of 99.54% at equilibrium time. Moreover, the MB adsorbed monolith was regenerated up to four cycles and the percentage removal efficiency of MB on the monolith dropped to 67.64 % after the fourth cycle. Finally, the monolith effectively adsorbed MB from the tap water in presence of competing ions and the maximum adsorptive capacity obtained was 47.62 mg g-1 with 84.5% adsorption efficiency. Hence, poly(MAA-co- EDMA) monolith is an adequate sorbent for the treatment of cationic dyes in the presence of other dyes and competing ions from wastewater.