Value Additions on Iron-Oxide Nanoparticles in Laterite Soils Available in South-West Sri Lanka: Development of Effective Filtering Techniques

Abstract

Environmental contamination by phosphate is on the rise with extensive and diffuse pollution. Answering these badly behaved with serious technologies is very costly. Soil has been commonly used in several wastewater treatment systems and showed to be an in effect substrate for phosphate removal and retention. Using natural sorbent such as laterite could be a way out. The removal of phosphate from aqueous solutions was investigated by using raw laterite in this study. In the adsorption process, the effect of pH, contact time, concentration, adsorbent dosage and salt concentrations were taken into consideration and experiments were carried out in the batch experiment system. Laterite proved to be an effective adsorbent and the removal efficiency remained around 90% of all cases. The optimal dosage was identified as 1g and the removal efficiency was more than 90%. Study of the adsorption as a function of contact time showed that 3 hours was sufficient time for maximum removal of phosphate. Acidic environments of pH values less than 5 facilitated the adsorption of phosphate and the removal efficiency decreased with increasing pH value of the solution. Based on the obtained results from this study, raw laterite is effective in removing phosphate from aqueous solutions and is a cost effective alternative for commercially available adsorbents that are currently used to remove contaminants from drinking water.