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

• Published in: Water, air, and soil pollution Vol. 225; no. 5; pp. 1 - 12
• Main Authors: Su, Claire Xin-Hui, Teng, Tjoon Tow, Alkarkhi, Abbas F. M, Low, Ling Wei
• Format: Journal Article
• Language: English
• Published: Cham Springer-Verlag 01-05-2014; Springer International Publishing; Springer; Springer Nature B.V
• Subjects: Adsorbents; Adsorption; Analysis; Aqueous solutions; Atmospheric Protection/Air Quality Control/Air Pollution; Biomass; Bioremediation; Chemical oxygen demand; Climate Change/Climate Change Impacts; Color; Color removal; decolorization; Design of experiments; Dosage; Dyes; Earth and Environmental Science; Environment; Environmental monitoring; Equilibrium; Hydrogeology; Imperata cylindrica; Methylene blue; Optimization; Oxidation; pH effects; Process engineering; Reduction; Research methodology; response surface methodology; Soil Science & Conservation; Studies; Surface chemistry; Water pollution; Water Quality/Water Pollution; Water treatment; weeds; Malaysia; Basic dye; Response surface methodology (RSM); Optimization
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-014-1941-x

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.