Synthesis of sodium lignosulfonate-guar gum composite hydrogel for the removal of Cu2+ and Co2+

As an emerging pollutant treatment material, hydrogel is known for its good adsorption capacity and environmental friendliness. In this study, a composite material of acrylic acid as the polymerization monomer grafted sodium lignosulfonate and guar gum was prepared, which provided a channel for adsorbing metal ions with its abundant active functional groups and porous structure. The optimized synthesized product was applied to the removal of Cu2+ and Co2+ in a one-component system and a multi-component system, and the maximum ion adsorption capacities obtained were determined to be 709 mg g−1 of Cu2+, 601 mg g−1 of Co2+, respectively. The adsorption kinetics and isotherms were well fitted by the pseudo second-order kinetic model and the Langmuir isotherm, showing that the adsorption of Cu2+ and Co2+ by the adsorbent belongs to the chemisorption on monolayer. XPS results confirmed the successful adsorption of Cu2+ and Co2+ by GG/SLS. Surface complexation was proposed to be the main mechanism for GG/SLS adsorbent to remove heavy metal ions. In addition, the use of recycling research showed that the adsorbent has good chemical stability. These results provided valuable information for designing highly efficient adsorbents that can be used as a high-quality wastewater treatment material.