Comparison of the Performance of Activated Carbon Produced from Rice Straw and Mango Kernel in Removing Chromium (VI) in Paint Manufacturing Wastewater: A Case Study

Author : Buenviaje, Mia Andrea D.
Major Adviser : Gatdula, Kristel M.
Committee Members : Arocena, Rhebner E.; Del Barrio, Marilyn C.
Year : 2021
Month : August
Type : Thesis
Degree: BS
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Paint manufacturing industry releases toxic heavy metals in their wastewater including the hexavalent chromium, Cr (VI). Adsorption is considered as one of the common methods used to remove heavy metals in the wastewater but adsorbents that are commercially available are often expensive, that is why continuous research on agricultural wastes as raw materials for activated carbon adsorbents is being done. In this study, activated carbons derived from mango kernels and rice straws were considered, and their adsorption performances were evaluated using different operating factors (initial solution pH, contact time, initial Cr (VI) concentration, and adsorbent dosage. For the effect of initial solution pH, maximum Cr (VI) adsorption of mango kernel activated carbon (MKAC) was observed at pH 2.0 with a value of 68.75%. while for activated carbon from rice straw (ACRS), maximum adsorption occurred at pH 8.0 with a value of 90%. Maximum Cr (VI) adsorption occurred at 150 minutes and 100 minutes of contact time for MKAC and ACRS, respectively. For the effect of adsorbent dosage, maximum adsorption of MKAC occurred at 1.0 g/100 mL with a value of 100% and at 9.0 g/L for ACRS with a value of 97.12%. Lastly, for the effect of Cr (VI) initial concentration, maximum adsorption of MKAC occurred at 80 mg/L and for ACRS it occurred at 5.0mg/L. Generally, same trends were observed in MKAC and ACRS—highest Cr (VI) adsorption on highest contact time, highest adsorbent dosage, and highest initial Cr (VI) concentration. The only exception is for the effect of pH on ACRS, where the maximum adsorption occurred at basic solution, when in previous studies, highest adsorption occurs at acidic solution. In adsorption isotherm study, MKAC better fitted the Langmuir isotherm with an R² value of 0.993, while ACRS better fitted the Freundlich isotherm with an R² value of 0.717. When treating 100 mL of paint manufacturing wastewater, the total cost estimate was lower if MKAC would be used. MKAC will only cost 18.85 pesos compared to 22.27 pesos for ACRS.

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