Advances in ammonium remediation: Sustainable adsorption and electrochemical reduction using biomass-derived carbon and graphene oxide composites

Ammonium (NH₄⁺) contamination in aquatic environments has surfaced as an urgent environmental and public health concern because of its toxicity, effects on eutrophication, and contribution to greenhouse gas emissions. Traditional treatment approaches to remediate ammonium are effective but complicated by cost, scalability, and operational stability challenges. Biomass-derived carbon materials and graphene oxide (GO)-based composites represent sustainable alternatives for the removal of ammonium through adsorption and then electrochemical reduction. Whereas earlier reviews have considered the topics of adsorption and electrochemical remediation separately, this review takes an integrative approach by critically discussing the two processes through composite materials that combine biomass-derived carbon with graphene oxide. This paper contrasts various activation approaches, material characteristics, adsorption capabilities, electrocatalytic activity, regenerability, and scale-up, and points out the most important relationships and gaps in knowledge regarding this transition from the lab to practical wastewater treatment. The review highlights activation strategies, hybrid material conceptualization, adsorption isotherms and kinetics, as well as catalytic electron transfer processes. Industrial information was discussed, such as technological and economic feasibility, also including Agri-waste valorization and acidic and alkaline additives in GO for scalable treatment applications. Despite some promising developments, continued work is needed on long-term electrode stability, regeneration, and in the context of real wastewater applications. It is evident from the review that composite materials made from biomass-based carbon and GO have synergistic properties to achieve ammonium cleanup through their high adsorption capability, electron transfer efficiency, and enhanced ability to regenerate. The review provides an integrated strategy of adsorption and electroreduction approach that can be used to remove nitrogen efficiently in line with the principles of circular economy and sustainability.