Removal of Chromium (VI) from Tannery Effluent Using Bio-Char of <i>Phoenix reclinata</i> Seeds

Abstract

The potential of the Senegal date palm (Phoenix reclinata) seed bio-char to remove chromium (VI) ions from aqueous solutions by adsorption was investigated. Adsorption experiments were performed on the tannery effluent and standard aqueous solutions of chromium (VI) for varying adsorbent doses, contact times, pH, temperatures, and interfering anionic ions by batch mode. Phoenix reclinata seeds (PRS) bio-char was used in the investigation and the residual chromium (VI) was determined using the atomic absorption spectrophotometer (AAS). Results showed that the bio-char removed up to 86% of chromium (VI) ions in the effluent at pH 2. The highest percentage adsorption registered was 97% in an aqueous solution of chromium (VI) at pH 1 and this dropped to less than 10% at pH greater than 2. A general increase in adsorption with the increase in temperature was observed but reduced when the temperature was raised beyond 60˚C. The presence of interfering anions caused a reduction in the adsorption of chromium (VI) ions. The adsorption process fitted both Langmuir and Freundlich adsorption models and the maximum adsorption capacity, Q o , was 0.6593 mg/g. Thus, PRS bio-char can therefore be used by industries and institutions like secondary schools to treat effluents that contain chromium (VI).

Enhanced Removal of As(V) and Pb(II) from Drinking and Irrigating Water Effluents Using Hydrothermally Synthesized Zeolite 5A

“…The increase in dose from 1 g L −1 to 4 g L −1 showed a slight increase in the percentage removal, because of the greater the mass of the adsorbent and the greater availability of adsorption sites; however, the adsorption amount decreases with increasing dose. The maximum retention capacity of an active site cannot be reached as there are too many active sites available to adsorb the few As ions [52,53]. On the other hand, it could be because not all sites are easily accessible and were not fully occupied [54].…”

Hexavalent chromium adsorption by watermelon peels from tannery wastewater

“…Its teratogenic and carcinogenic properties have become a significant health concern [4]. While the majority of Chrome Hexavalent Cr (VI) compounds are poisonous and can have carcinogenic effects, Chrome Trivalent Cr(III) is necessary for human nutrition, especially in the metabolism of glucose [18].…”