High Cu removal from water using water hyacinth fixed on alginate
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ORIGINAL PAPER
High Cu removal from water using water hyacinth fixed on alginate Courtie Mahamadi • Peter Zambara
Received: 22 January 2013 / Accepted: 12 April 2013 / Published online: 23 April 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract The occurrence of toxic metals in waters is a major health issue. Polluted waters can be cleaned by biosorption, which uses organisms such as algae, bacteria, fungi and plants that adsorb metals. In particular, water hyacinth—Eichhornia crassipes—is a promising biosorbent. Here we tested novel alginate-immobilised water hyacinth beads for the removal of Cu from aqueous solutions. Results show that successful service and regeneration continuous cycles were performed using a packed-bed, flow-through column of fixed internal diameter 1.2 cm, at room temperature and pH 5.1, with variation in initial metal concentration, bed depth and flow rate. The eluant used was 1 % w/v CaCl2 acidified at pH 3. A concentration factor of 12 and elution efficiency up to 98 % were observed in five service and regeneration cycles performed. The equilibrium adsorption capacity of Cu remained almost constant at about 29 mg/g. To conclude, we show for the first time that alginate-immobilised water hyacinth beads can uptake and adsorb Cu very efficiently in a continuous-flow mode, hence highlighting their great potential for removal of toxic metals from aquatic environments. Keywords Eichhornia crassipes Biosorption Continuous flow Copper Regeneration
Introduction There is an increasing awareness that anthropogenic activities have resulted in metal accumulation across C. Mahamadi (&) P. Zambara Chemistry Department, Bindura University of Science Education, Bag 1020, Bindura, Zimbabwe e-mail: [email protected]; [email protected]
trophic levels in the environment. For example, municipal sewage treatment plants are typically not designed to handle metal toxic wastes, resulting in their persistence in sludge (Volesky 2001). The removal of toxic heavy metal contaminants from aqueous waste streams is currently one of the most important environmental issues being researched. Although this issue has been studied for many years, effective treatment options are still limited. A number of physicochemical classical metal removal technologies, including chemical precipitation, adsorption, solvent extraction, ultrafiltration and ion exchange, are established (Vaca-Mier et al. 2001; Peric´ et al. 2004; Wang and Chen 2009). However, these methods can be inefficient at low metal concentration (1–100 mg/L), and they can be associated with production of secondary residues that present treatment problems (Aksu 2001; Ahluwalia and Goyal 2007). Biosorption, which involves metal removal from aqueous solution by passive linkage in live and dead biomasses in a mechanism that is not controlled by metabolic steps, is proving to be a popular alternative owing to its several advantages (Atkinson et al. 1998; Eccles 1999; Pandey et al. 2007; Pipiska et al. 2007; Prasad and Saxima 2004; Ravagnani et al. 2002;
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