Removal of nitrate and phosphate by chitosan composited beads derived from crude oil refinery waste: Sorption and cost-benefit analysis

A granular composite sorbent (LC-CF) was synthesized from acid-leached carbon waste using chitosan and FeCl3, and its feasibility for nitrate and phosphate removal was investigated in this study. The sorption data was well described by the pseudo-second-order kinetic model, and the maximum sorption capacity of LC-CF predicted by Langmuir model for nitrate and phosphate were 41.90 mg g−1 and 62.72 mg g−1, respectively. In comparison, LC-CF had a greater affinity for phosphate and exhibited a better reusability for nitrate removal during the sorption-desorption cycles. Ion exchange, electrostatic interaction, and hydrogen bond are the potential sorption mechanisms. In light of the cost-benefit analysis, the proposed treatment of carbon waste was more economically feasible as compared with existing incineration scheme. These results illuminated that synthesis of granular sorbent with carbon waste could achieve the harmless disposal of hazardous industrial waste as well as the production of value-added sorbent for water treatments.