Phosphate removal from water by modified pine bark using ionic liquid analog

Abstract

Pine bark (PB) wood residues were chemically modified and used as anion exchange resins to remove phosphate (PO) from water. The modification process involved reacting a choline-based ionic liquid analog, comprised of a mixture of choline chloride derivative and urea, with natural PB in the presence of imidazole. Batch sorption tests showed that the modified PB has a maximum PO–P uptake capacity of 2.09 mmol/g (64.8 mg g−1). The changes at the surface of the PB due to chemical modification and phosphate uptake were monitored using Fourier transform infrared spectroscopy analysis and Zeta potential measurements. The adsorption was found to be concentration and ionic strength dependent, exothermic, spontaneous, and is best described by a pseudo-second-order kinetics. The modified residues were used for the removal of PO from an effluent of a dairy farm anaerobic digester and from a wastewater treatment plant sludge centrate.