Experimental Evaluation of Sorptive Removal of Boron Using Laterite Soi

Abstract

Ground water is essential resource that requires protection can continue to sustain the human life and the various ecosystems that depend on it. Many pollutants that occur naturally in soil, sediments and rocks for example boron can also degrade quality of groundwater. Boron exists abundantly in the surrounding the form of boric acid or borate salts. In industry, boron minerals are used for manufacturing glass, fertilizers, food preservatives and detergents. The main objective of this study is to investigate the sorption of Boron using LS under batch experimental setup. The chemical characterization of the LS used was determined by Ethiopian Geological Survey Laboratory and the Adsorption Procedure Effect of Contact Time, pH, initial Concentration¸ adsorbent Dose, co-existing ions, Adsorption Kinetics and Isotherm were assessed. The result of this study was the optimum contact time occurred at 60 min, it was considered as equilibrium with removal efficiency of 90.500% and adsorption capacity of 0.302 mg/g. The optimum adsorbent dose is 2 g/L, at this dose percentage of boron adsorbed 92.200% and amount of boron adsorbed 0.307 mg/g. The equilibrium pH ~ 8, in this pH the removal efficiency is 94.500% and adsorption capacity is 0.315 mg/g, at shaking speed 200 rpm and grain size between 0.075 – 0.425 mm in all adsorption procedure. The boron adsorption kinetics data followed the pseudo-second order equation with the correlation coefficient, R2 = 0.99 and this implies that the adsorption process is chemical adsorption. The Langmuir and Redlich - Peterson isotherms are better fitted model with the correlation coefficient, R 2 = 0.99 described the boron adsorption giving an adsorption capacity of 2.07 mg/g and 2.13 mg/g respectively. The presences of competing anions (bicarbonate) slightly influence boron adsorption efficiency while chloride and fluoride were not significantly interfering. The adsorption/desorption of adsorbent was tested using NaOH solution on two concentration so; the efficiency was increased from 67.72% to 83.28%. The adsorbent was reduced 5 mg/L boron spiked ground water in to 0.55 mg/L which is within the permissible range of WHO guidelines. From the results of this study we concluded that LS can be used in water treatment for removal boron is highly efficient adsorbent.