Screening of hexavalent chromium biosorbent from marine algae

A highly chromate-selective biosorbent with high adsorption capacity was fo und by examining the chromate adsorption capacities of 48 species of red, b rown, or green marine algae sampled from the east coast of Korea. As a resu lt of screening, a red marine alga showed excellent adsorption characterist ics. It was identified as Pachymeniopsis sp. The timing of the sampling of Pachymeniopsis sp. did not affect the adsorption capacity of the alga but t he optimum period for mass collection was April-May. The alga also showed h igh selectivity for chromate and its adsorption capacity for other heavy me tal ions such as cadmium and manganese was relatively low. An investigation of the adsorption isotherm of Pachymeniopsis sp. as a dried powder for chr omate adsorption at 25 degreesC showed Langmuir-type dependence. The maximu m chromate adsorption capacity of the selected alga was about 225 mg/g. The desorption of adsorbed chromate from Pachymeniopsis sp. was done by treati ng samples with 1 N NaOH. It was confirmed that ion exchange type adsorptio n was observed with anion exchangers but not with cation exchangers. Theref ore it is believed that the chromate adsorption is based on the anionic exc hange of Pachymeniopsis sp.