Modification of tea biochar with Mg, Fe, Mn and Al salts for efficient sorption of PO43− and Cd2+ from aqueous solutions

There is a requirement to provide more efficient, sensitive, low-cost materials for remediation of contaminated water. Biochar as a sorbent is an effective and low-cost material to remove contaminants in water but its adsorption properties can be improved by impregnation of metals on the surface. In this study, a biochar derived from industrial tea waste was modified with Mg, Fe, Mn and Al salts to create different composites, which were tested for PO43− and Cd2+ sorption. The modifications created biochars with the (hydr)oxides of each metal and changed the characterization parameters and surface functionality. Cd2+ was efficiently removed by all the materials even at high Cd2+ loadings in the water (100 mg Cd2+ L−1), the biochar with Mg being the most efficient in Cd2+ removal. The biochar with Mg also achieved the best sorption of PO43−, sorbing up to 30% at 20 mg PO43− L−1. Tea waste biochar can be modified with metal salts to enhance inorganic pollutant removal from waters, especially with Mg salts.