Abstract
Water is second most essential for human being. Contamination of water makes it unsuitable for human consumption. Chromium ion is released to water bodies from various industries having high toxicity which affects the biota life in these waters. In this study aluminum oxide hydroxide was tested for its efficiency to remove trivalent chromium from aqueous solutions through batch mode experiments. Chromium concentrations in aqueous solutions and tannery waste water before and after adsorption experiments were determined using flame atomic absorption spectrometry. The effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(III) were studied. The study revealed that more than 99 % removal of Cr(III) was achieved over wide range of initial pH (3–10). The optimum conditions for the removal of Cr(III) were found to be at pH 4–6 with 40 g/L adsorbent dose at 60 min of contact time. The adsorption capacity was assessed using Langmuir and Freundlich isotherms. The equilibrium data at varying adsorbent dose obeyed the two isotherms. The adsorbent was found to be efficient for the removal of Cr(III) from tannery waste effluent.
Highlights
Heavy metals are toxic even at trace levels and their presence in the environment is of major concern to many forms of life on the earth (Selvaraj et al 2003; Igwe and Abia 2006)
Chromium occurs in the environment primarily in Bedemo et al SpringerPlus (2016) 5:1288 two valence states, trivalent chromium, Cr(III) and hexavalent chromium, Cr(VI)
The results indicated more than 98 % removal of Cr(III) with 20 g/L adsorbent dose after 60 min of contact time
Summary
Heavy metals are toxic even at trace levels and their presence in the environment is of major concern to many forms of life on the earth (Selvaraj et al 2003; Igwe and Abia 2006). Most metal contamination comes to the aqueous environments through various industrial processes. Toxic metals are not biodegradable and their concentrations need to be reduced to acceptable levels prior to discharge of industrial effluents to the water bodies. Chromium compounds are widely used in many industries, resulting in disposal of large amounts chromium ions into the environment. The toxicity of chromium varies greatly among a wide variety of chromium compounds, its oxidation state and its solubility in water (Salimi et al 2006). Chromium occurs in the environment primarily in Bedemo et al SpringerPlus (2016) 5:1288 two valence states, trivalent chromium, Cr(III) and hexavalent chromium, Cr(VI). Less toxic trivalent chromium can be oxidized to hexavalent chromium in the presence of oxidizing impurities
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