Removal of methylene blue by bentonite based adsorbent film characterizations and performances study
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Date
2016-09-01
Authors
Tuan Syahiira Tuan Zarawi
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Abstract
Color wastewater especially from the textile industry must be taken seriously due to their hazardous properties which can caused harm to environment and also our daily water sources. Various color wastewater treatments already be introduced by researchers. However, some of them have some drawbacks. Adsorption is the best treatment for color wastewater due to their high separation performance. The aim of this research is to introduce new applications of adsorbent film for dye removal. The adsorbent film was fabricated in a casting method by using 1-Methyl-2-pyrrolidan (NMP) as the solvent, polysulfone (PSf) as the binder and raw or acid activated bentonite as the adsorbent. The performance of raw and acid activated bentonite film was compared and the acid activated bentonite (AAB) film was later employed as an efficient adsorbent to remove Methylene Blue (MB) in an aqueous solution. The AAB loading was also investigated for new formulation of AAB film and 4 g of AAB was chosen. The physical characteristics of AAB film were analyzed and it was found that the adsorbent well distributed on the surface of the film with sponge-like structure film’s cross section. The surface area of the AAB was 61.42 m2/g, larger than raw bentonite, 23.00 m2/g with the zeta potential of -19.9 mV and -46.3 mV respectively. The effect of initial solution concentration (100 – 700 mg/L), temperature (30, 40, 50, 60 and 70 oC) and pH (3-11) were investigated. Results showed that the maximum adsorption capacity of AAB film was 166.67 mg/g at 30 oC. The AAB film gave high percentage removal at high temperature of 70 oC and the time consuming to reach 99.99% MB removal also decreased two times at 70 oC. The values of pH from 3 to 11 gave no significant effect on the AAB film adsorption efficiency. Instead of removal of MB, the AAB film also able to remove Congo Red (CR) and Direct Yellow 8 (DY8). Reusability of AAB film result showed that it can be recycled till 10th times before reached saturation. Kinetic and isotherm studies revealed that Methylene Blue adsorption described well with pseudo-second order and Langmuir isotherm models. While, the thermodynamic data showed that the adsorption process undergoes endothermic, spontaneous and the randomness increased during the adsorption process. The outcomes from this study indicate that AAB film has high potential for dye removal in wastewater.