Optimisation of sugar cane activated carbon for arsenic(V) and arsenic(III) removal from water

Abstract

This paper addresses the development of low-cost adsorbents for removal of arsenic from water in support of mitigation programmes in low and middle income countries. Activated carbon (AC) is a well established water treatment technology, but has high cost and low selectivity in respect of arsenic. AC made from agricultural by-products is a low-cost alternative to coal-based AC. In this study, the preparation parameters of sugar-cane activated carbon (SCAC) were optimised for arsenic(V) and arsenic(III) adsorption. The effect of preparation parameters on arsenic removal was investigated with a 23 factorial experiment. SCAC was characterised by the pH of zero charge, surface area, pore width distribution, particle size distribution and imaging under scanning electron microscopy. Activation temperature (AT) has a profound effect on arsenic adsorption; arsenic(V) adsorption increased from 2.8% at an AT of 873 K to 87.6% at an AT of 1,173 K. The percentage of arsenic removal from water has a strong positive correlation with surface area, and a strong negative correlation with micropore/pore volume ratio and the percentage in volume of particles with a size of 60–2,000 μm. In conclusion, this research shows that low-cost AC can be manufactured for removal of target pollutants, such as arsenic, from water.