Competitive removal of compound pollution via nano-magnetic Enteromorpha prolifera hydrogel: The binding ability of Cr(VI) is stronger than methyl orange

Abstract

The contamination of water with heavy metals and dyes has caused severe environmental issues on a global scale, which is further worsened by the interaction of organic and inorganic pollutions. Correspondingly, controlling water contamination by heavy metals and dyes is crucial. Enteromorpha prolifera is improper management results in severe environmental issues. Enteromorpha prolifera was cross-linked to create a hydrogel in this study. Subsequently, a nano-magnetic Enteromorpha prolifera hydrogel fabricated through by the hydrolytic co-precipitation of ferrous ions and its base. It was then used to remove methyl orange (MO) and hexavalent chromium [Cr(VI)] from water. Additionally, the adsorption of MO reached equilibrium in ∼ 30 min with a maximum adsorption capacity of 261.3 mg/g, whereas Cr(VI) adsorption reached equilibrium in just 15 min with a maximum adsorption capacity of 54.2 mg/g. Moreover, MM-EP-HD demonstrated outstanding recovery (magnetic recovery for the fifth time was ≥ 83%). Subsequently, the effects of initial concentration, dosage, contact time, pH, and temperature on the adsorption of MO and Cr(VI) were investigated. Moreover, during the competitive adsorption of MO and Cr(VI) composite pollutants, the hydrogel's adsorption capacity for pollutants in the composite system was higher and faster for Cr(VI) than for MO. A high concentration of Cr(VI) will have a great impact on MO removal, the maximum effect can reduce 73% removal rate, on the contrary, Cr(VI) removal effect is only 25%. The findings demonstrate that MO was adsorbed via hydrogen bonding, ion exchange, and electrostatic interaction, whereas Cr(VI) was adsorbed via electrostatic attraction, ion exchange, and multi-component chelation of surface acid functional groups. The nano-magnetic Enteromorpha prolifera hydrogel has the advantages of high adsorption capacity, good thermal stability, and recyclability. As a functional material with simple preparation and excellent performance, it has good application potential and research value.