Simultaneous removal of Ni2+, Cd2+ and Cr6+ from an aqueous solution by using native algal biomass loaded in Ca-alginate beads

In this research, biosorption process is used for the simultaneous removal of Ni2+, Cd2+ and Cr6+ from an aqueous solution by using algae (Cladophora sp.) as adsorbent. Ca-alginate loaded algal beads were prepared by mixing algal biomass powder in sodium alginate solution and then adding drop wise into CaCl2 solution. Column was prepared by placing glass wool at the bottom followed by a layer of Ca-alginate loaded algal beads (weighing 2.4 g). To make column packing uniform distilled water was passed through the column before passing metal ions solution. Scanning electron microscopy confirms the rough and porous surface of blank and metal loaded Ca-alginate algal beads. Simultaneous biosorption of metal ions was supported by Fourier-transform infrared spectroscopy which indicates the presence of various functional groups like –COOH, –OH, NH2 and NO2 on algal biomass which are responsible for adsorption. These results indicated 83.3%, 97.3% and 98.3% removal of Ni2+, Cd2+ and Cr6+, respectively in 60 min at pH 3.0 for 150 μg/mL concentration of metal ions mixtures and 0.4 g of adsorbent dose. Metal uptake capacity was 14.71, 14.53 and 69.53 mg/g for Ni2+, Cd2+ and Cr6+, respectively.