Parametric Study on the Removal of Chromium (VI) From Tannery Wastewater Using Graphene Oxide As Catalyst

Author : Magana, Kenneth David Manuel
Major Adviser : Gatdula, Kristel M.
Committee Members : Dizon, Lisa Stephanie H.; Sanchez, Denise Ester S.
Year : 2019
Month : June
Type : Thesis
Degree: BS
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Hexavalent chromium from tannery wastewater was treated via adsorption using Graphene Oxide (GO) catalyst. GO was synthesized using Modified Hummer’s Method where graphite was oxidized and delaminated using mixture of acids and permanganate. The morphology and pore size distribution of the synthesized adsorbent were characterized through Scanning Electron Microscope (SEM) and Barret-Joy-Halenda (BJH) analysis. Parametric study using three factors namely: pH, adsorbent loading and contact time was done through batch adsorption to evaluate which parameters impose significant effect on the removal of Cr (VI) in tannery wastewater. The highest percent removal of Cr (VI) was 89.51 % observed at pH 3 with 5 g/L adsorbent dosage and 180 minutes of contact time. All main factor effects were found to be significant as well as adsorbent loading-contact time interaction and pH-contact time interaction. Based on the results of the parametric runs, adsorption is favorable at acidic pH, higher adsorbent loading and longer contact time. Lower pH results to protonation of the GO surface and presence of more stable forms of Cr (VI). Moreover, increasing the adsorbent dosage increases the available adsorption sites and the effective surface area which also results to higher adsorption. In addition, at longer contact time more vacant adsorption sites are being occupied which also increases adsorption of Cr (VI). Lastly, Langmuir isotherm model was identified as the best fit isotherm model for the adsorption process with an R2 of 0.9855 which is more linear compared to Freundlich and Temkin isotherm models having R2 values of 0.9467 and 0.8334 respectively. The model indicates monolayer and homogeneous adsorption of Cr (VI) into GO.

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