Phosphate removal from water using activated carbon derived from ampelodesmos mauritanicus stems : equilibrium and kinetic studies

Abstract

This paper describes the synthesis and characterization of Ampelodesmos mauritanicus stem-derived activated carbon (AMSAC). The activated carbon was produced by phosphoric acid activation followed by carbonisation and was characterized by N2 adsorption–desorption isotherm, scanning electron microscopy, energy-dispersive X-ray analysis, and Fourier-transform infrared (FTIR) spec-troscopy. The sorption potential of AMSAC for the removal of phosphate ions from the water was investigated. The effects of contact time, initial pH, and initial phosphate concentration on the sorption process were studied. The optimum contact time and pH for removal of phosphate ions was 75 min and pH 6–7. The experimental data showed that AMSAC had a high Brunauer–Emmett–Teller surface area of 1,293 m2/g and abundant pores with a specific volume of 1.23 m3/g. FTIR analysis revealed various functional groups on the surface of the AMSAC, which can play an important role in the adsorption process. A Langmuir isotherm model fits the equilibrium data for the sorbent well compared to the Freundlich, Temkin, and Dubinin–Radushkevich isotherm models. The monolayer −3 sorption capacity of AMSAC for PO4 ions was determined to be 4.52 mg/g at 25°C. The experimental data were also modelled using the sorption kinetic models. It was found that the kinetic data were described better by the pseudo-second-order adsorption kinetic model. Therefore, AMSAC is a prom-ising low-cost phosphate sorbent that can be produced from plentiful and annually renewable plants