Dynamics of zinc sorption from aqueous matrices using plantain (<i>Musa sp.</i>) peel biomass

Abstract

The influence of climate change on freshwater resources has undoubtedly affected the availability and quality of freshwater resources. However, the demand for water for agricultural, domestic, industrial and recreational purposes increases by the day globally. The need for remediation and reuse of large volumes of industrial wastewaters being generated globally therefore cannot be over-emphasized. The potential ability of plantain peel (Musa sp.) biomass to remove metal ions (Zn²⁺) from aqueous matrices was studied. Influence of contact time, adsorbent weight, pH, metal concentration, temperature and shaking speed were investigated. Physico-chemical characterization (proximate and infra-red spectroscopic analyses) of the biomass was carried out to elucidate information on adsorption mechanisms. Desorption studies were also performed to determine possible recovery potential of Zn2+ and the re-usability of the biomass. Zn²⁺ adsorption increased with increasing metal concentration in solution, adsorbent weight and contact period. Optimal pH value for adsorption was 3 after which Zn²⁺ uptake decreased. Corresponding values for contact time, biomass weight and Zn²⁺ concentration were 150 min, 24 g/L and 600 mg/L, respectively. Experimental data fitted into Freundlich’s isotherm. Carboxylic and hydroxyl groups were among the prominent functional groups on the surface of the biomass. Desorption of Zn²⁺ from the biomass was less than 10%. Alternative compounds may be further investigated to improve on metal desorption from plantain peel biomass. This cannot be over-emphasized if the several advantages of this biomass (lesser cost than for synthetic resins, abundance and biodegradability) will be utilized for industrial applicability especially in emerging economies like Africa.

Key words: Adsorption, zinc, isotherms, waste utilization, wastewaters.