BINDING OF HEAVY METAL IONS IN HYDROCARBON PRODUCED WATER BY PHOSPHORUS OXYCHLORIDE MODIFIED PEANUT (ARACHIS HYPOGAEA L.)TESTA EXTRACT

Abstract

Technological activities in the oil industry lead to the release of heavy metal ions in the environment through the discharge of hydrocarbon produced water. In this study, peanut testa extract was reacted with phosphorus oxychloride at different ratios (3:1, 2:1 and 1:1) to produce chemically modified peanut testa extract resins, which served as cation exchange resins. The resins were characterised by FTIR, CEC, pHzpc and other physical parameters. The appearance of  new IR absorption bands at 1350 cm-1, 1240cm-1, 990cm-1 and 950cm-1 revealed the creation of  -C-O-P-, -P=O and HO-P-O-C- bonds respectively as a result of the reactions. Hydrocarbon produced water from an oil producing facility in the oil rich Niger delta of Nigeria contaminated with Cu2+, Fe2+ and Zn2+ ions was treated through a batch adsorption process with the phosphorus oxychloride- peanut testa extract resins. Quantitative removal was achieved and the efficiency of the resins in removing the heavy metal ions followed the order: Fe2+> Cu2+ > Zn2+. The product that resulted from the reaction of phosphorus oxychlorideand peanut testa extract in a 1: 1 ratio yielded a cation exchange resin with the highest Fe2+, Cu2+ and Zn2+ ions removal efficiencies from hydrocarbon produced water. The efficiency was compared with that of a peanut testa extract metal ion adsorbent with terminal phosphate ends and a commercial ion exchange resin (Bio-Rex 70). The result suggests that phosphorus oxychloride - crosslinked peanut testa extract cation exchange resins hold a great potential in removing heavy metal ions from hydrocarbon produced water and other metal overload sites. This is a useful way of utilising waste material [peanut testa] for sustainable development.  Keywords: Produced water, Peanut testa extract, Crosslinking, Phosphorus oxychloride, Ion exchange resin, Heavy metal ions