Original Article | 2012, Vol.34, No.1, pp. 117-123
Removal of reactive dyes from wastewater by shale
Sairoong Nopkhuntod, Somchai Dararat and Jareeya Yimrattanabovorn
pp. 117 - 123
Abstract
Colored textile effluents represent severe environmental problems as they contain mixture of chemicals, auxiliaries and dyestuffs of different classes and chemical constitutions. Elimination of dyes in the textile wastewater by conventional wastewater treatment methods is very difficult. At present, there is a growing interest in using inexpensive and potential materials for the adsorption of reactive dyes. Shale has been reported to be a potential media to remove color from wastewater because of its chemical characteristics. In this study, shale was used as an adsorbent. The chosen shale had particle sizes of : A (1.00 < A < 2.00 mm), B (0.50 < B < 1.00 mm), C (0.25 < C < 0.50 mm), D (0.18 < D < 0.25 mm) and E (0.15 < E < 0.18 mm). Remazol Deep Red RGB (Red), Remazol Brilliant Blue RN gran (Blue) and Remazol Yellow 3RS 133% gran (Yellow) were used as adsorbates. Batch adsorption experiments were performed to investigate the effect of contact time, pH, temperature and initial dye concentration. It was found that the equilibrium data were best described by the Langmuir isotherm model, with the maximum monolayer adsorption capacities of 0.0110-0.0322 mg/g for Red, 0.4479-1.1409 mg/g for Blue and 0.0133- 0.0255 mg/g for Yellow, respectively. The maximum adsorption capacity of reactive dye by shale occurred at an initial pH of 2, initial concentration of 700 Pt-Co and temperature 45°C. Reactive dye adsorption capacities increased with an increase of the initial dye concentration and temperature whereas with a decrease of pH. The fixed bed column experiments were applied with actual textile wastewater for estimation of life span. The results showed that COD and color removal efficiencies of shale fix bed column were 97% and 90%, respectively. Also the shale fixed bed columns were suitable for using with textile effluent from activated sludge system because of their COD and color removal efficiencies and life expectancy comparison using with dyebath wastewater and raw wastewater.
