Column studies into the adsorption of chromium (VI) using sphagnum moss peat

Previous batch studies have shown that moss peat is a potentially useful biosorbent for treating metalcontaminated wastewaters. This paper examines the use of peat for the continuous adsorption of hexavalent chromium in columns. Adsorption at two pH values, 2•0 and 2•5, was examined and two flow-rates were used at each pH value. The results show that both adsorption and reduction occurs in the columns and that the maximum adsorption capacity of hexavalent chromium (65•87 mg/g) was obtained at a pH value of 2•0 and a flow-rate of 80 ml/min. However, the higher flow rates also enhanced the reduction reactions in the columns. The data were also tested against the Bed-Depth-Service-Time model and it was found that, although the compliance was non-linear, the model was appropriate for design purposes.