Bio-sorption for effective removal of chromium(VI) from wastewater using Moringa stenopetala seed powder (MSSP) and bana

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(2020) 14:71 Badessa et al. BMC Chemistry https://doi.org/10.1186/s13065-020-00724-z

Open Access

RESEARCH ARTICLE

Bio‑sorption for effective removal of chromium(VI) from wastewater using Moringa stenopetala seed powder (MSSP) and banana peel powder (BPP) Tolera Seda Badessa*, Esayas Wakuma and Ali Mohammed Yimer

Abstract  Chromium is an extremely toxic metal in the form of Cr(VI) that causes severe environmental and health problems. Therefore, the aim of this study was to remove chromium ions from wastewater by using cost effective and environmentally friendly bio-sorbents; Moringa stenopetala seed powder (MSSP), and banana peel powder (BPP) and to evaluate its adsorption capacities as bio-sorbents. FT-IR characterization of the adsorbents showed that there was a change in the functional groups of the structure of both adsorbents before and after the adsorption that might be due to the adsorption processes taken place on the surface of adsorbent. Adsorption experiments were carried out as batch studies with different contact times, pH, adsorbent dose, initial metal ion concentration, and temperature. Results showed maximum removal efficiency for Cr(VI) at 120 min contact time, adsorbent dose of 20 g/L and pH 2 by MSSP and pH 4 by BPP. The percentage removal of Cr(VI) increased with increasing adsorbent dose (from 5 to 20 g/L) and contact time (from 60 to 120 min). Freundlich isotherm model showed a better fit to the equilibrium data than the Langmuir model. The kinetics of adsorption for chromium was well represented by pseudo-second order kinetic model and the calculated equilibrium sorption capacity of the model showed good agreement with the sorption capacity obtained from experimental results. Keywords:  Moringa stenopetala, Banana peel, Chromium(VI), FT-IR, Adsorption isotherms Introduction Chromium is a naturally occurring metal found in the environment commonly in trivalent, Cr(III), and hexavalent, Cr(VI) forms [1, 2]. The trivalent state of chromium [Cr(III)] is essential for carbohydrate metabolism in humans, whereas hexavalent chromium [Cr(VI)] is considered to be toxic [3, 4]. The hexavalent chromium is a 100-fold more toxic than trivalent form of chromium [5, 6]. This is due to the fact that it is a strong oxidizing agent that can release free radicals *Correspondence: [email protected] Department of Chemistry, College of Natural Sciences, Arba Minch University, Arba Minch, Ethiopia

that can have carcinogenic effects on cells [4]. Chromium containing compounds in the form of hexavalent is used widely in different industries such as leather industry, electroplating, textile dyeing, and metal fabrication and finishing [7]. Chromium containing wastewater is one of the major pollutants of the environment. Hence, industries must treat the effluents to reduce the Chromium ions concentration in water and wastewater to acceptable levels before releasing it into the natural environment. Various conventional and advanced treatment methods have been employed for the removal of Cr ions from water and waste