▎ 摘　　要

In this study, an environment-friendly adsorbent, magnetic calcium alginate-graphene oxide composite (MCA-GO), was synthesized and subsequently utilized for the removal of a commercial textile dye, Doracryl Red MD (DRMD). The composite was prepared by adding a mixture of graphene oxide (GO), magnetic iron oxide nanoparticles, sodium alginate, and calcium carbonate (1:0.3:3) into a 2% HCl solution using a needle. The XRD, FTIR, VSM, and SEM analyses were used to characterize the synthesized material. Surface charge, surface area, and surface roughness were determined using zeta potential, BET, and AFM analysis. Using an industrial cationic dye DRMD, we studied the adsorption capacity of our produced composite by varying solution pH, contact time, adsorbent dosages, temperature, and dye concentration. This thermodynamically favorable and spontaneous process of adsorption was best described by Langmuir and Freundlich adsorption isotherms, and the maximum adsorption capacity was calculated from the Langmuir isotherm, which was 1428.57 mg/gm. The adsorption kinetic data were well-fitted with the pseudo-first-order and pseudo-second-order models. The spent adsorbents could be easily regenerated by washing with 2% HCl solution several times, and the regenerated adsorbent showed a little reduction in adsorption capacity. The findings of this study indicated that this composite could be a potential eco-friendly absorbent to remove organic dyes from the waste-water owing to its enhanced capacity for adsorption, easy renderability, and re-usability.