Imperata cylindrica (Cogongrass) as an Adsorbent for Methylene Blue Dye Removal: Process Optimization

Su, Claire Xin-Hui; Teng, Tjoon Tow; Alkarkhi, Abbas F. M.; Low, Ling Wei

Imperata cylindrica (Cogongrass) as an Adsorbent for Methylene Blue Dye Removal: Process Optimization

2014

Su, Claire Xin-Hui | Teng, Tjoon Tow | Alkarkhi, Abbas F. M. | Low, Ling Wei

A common weed, Imperata cylindrica (cogongrass), was used as a low-cost adsorbent for the adsorption of methylene blue (MB) and the process optimized. The effects of four factors, namely, shaking speed (100–300 rpm), pH (3–9), contact time (10–40 min) and adsorbent dosage (0.4–1.0 g), on colour removal and chemical oxygen demand (COD) reduction of MB were studied and optimized using fractional factorial design and response surface methodology. The two factors that play a vital role in the adsorption process are pH and adsorbent dosage. From the results, colour removal and COD reduction recorded coefficient of determination (r ²) values of 0.9600 and 0.9594, respectively. Optimum adsorption conditions, resulting in 99.09 % colour removal and 97.87 % COD reduction, were achieved at shaking speed of 100 rpm, pH 9, 40 min contact time and adsorbent dosage of 1.0 g. The adsorption systems for MB dye were found to fit the pseudo-second order model instead of the pseudo-first order model, while equilibrium studies showed that the adsorption process followed the Langmuir isotherm.

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