Plant-derived biosorbents for metal removal

The bio sorption capacities of milled peat and a marine biomass, Laminaria digitata (a species of kelp), were investigated for removal of metal ions from solution and for the treatment of industrial wastewaters Because industrial solutions generally contain a mixture of more than one component, mixed metal solutions were also investigated. In particular, adsorption of cationic Cr(III) and anionic Cr(VI) was studied as these two species often occur together in wastewater. Peat and kelp adsorbed chromium, copper, cadmium, calcium, magnesium and strontium from aqueous solution between pH2 and pH7 Biosorption by acid- and calcium-treated L digitata and peat is also reported. Kelp was chosen as an inexpensive and readily available biomass as it is common in shallow coastal waters in the northwestern Atlantic. Its bio sorption characteristics are compared to peat which is recognised for its bio sorptive properties L digitata was consequently used to treat tannery effluent. Untreated kelp outperformed peat and pre-treated kelp as a biosorbent Uptake of Cr(IIl) by L digitata at pH4 was significantly higher (1 12mmol/g biomass dry weight) than with other biomass as reported in the literature High uptake levels were also seen for Cr(VI) and copper. Kelp can reduce Cr(Vl) to Cr(lH) at low pH. These findings outline the suitability of L digitata as a biosorbent for industrial chromium solutions