Chromium Removal from Chrome Tannery Effluents after Alkali Precipitation by Adsorption using Cacao Pod Husk-derived Activated Carbon
Author : Avena, Leuwell Sevilla
Major Adviser : Detras, Monet Concepcion M.
Committee Members : Alfafara, Catalino G.; Migo, Veronica P.
Year : 2018
Month : June
Type : Thesis
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Chromium, in its two soluble forms Cr (III) and Cr (VI), poses serious environmental and health problems. Hence, it needs to be removed from industrial effluents by effective treatment processes prior to its release to the environment. In this study, chrome tanning wastewater that has undergone alkali precipitation was further treated through adsorption using cacao pod husk activated carbon (CPHAC) as a polishing treatment to meet the DENR standard limit for total chromium (0.5 ppm). Total chromium and Cr (VI) concentrations of the alkali precipitated effluent were found to be about 9.75 ppm and 0.0088 ppm, respectively. The effects of pH and adsorbent loading on chromium removal were evaluated by following a 2ᵏ factorial design. Results show that pH and adsorbent dosage have positive significant effects on the residual Crₜₒₜₐₗ concentration during adsorption using CPHAC. Optimization of the adsorption process using Response Surface Methodology (RSM) was also done to determine the conditions that maximize chromium removal. Optimum condition was found to be 0.01592 g/ml adsorbent dosage and pH 9. The actual Crₜₒₜₐₗ concentration using these values of adsorbent dosage and pH was measured to be equal to 0.401 ppm (95.89 % chromium removal). The performance of CPHAC was also compared to commercial activated carbon (CAC) using the optimum conditions for CPHAC. Commercial activated carbon was only able to reduce the Crₜₒₜₐₗ concentration to 2.68 ppm (72.48 % chromium removal). This shows the potential of CPHAC as activated carbon relative to the commercially used activated carbon at the said optimum condition.
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