TO STUDY ADSORPTION OF METHYLENE BLUE DYE ON ACTIVATED RICE HUSK

Abstract

Many industries like pulp and paper, textile, food processing, etc. dye their goods. Dyeing of products consumes water and releases colored wastewater. Colored wastewater further goes into waterways, lakes, pools, etc. Wastewater comprises many man-made chem-icals, refractory compounds and lethal substances. Colored wastewater disturbs the life of aquatic animals by obstructing the sunlight to pass through it. These chemicals go into body of aquatic animals and human being eats them. Thus, it enters into body of human being and causes toxicity. Methylene blue dye has many adverse effects on human body like itchiness of skin, eyes and even oncogenic. Therefore, treatment of dyed wastewater is of huge concern. Many treatment practices has been used for the elimination of dyes like photo catalytic deg-radation, physic-chemicals treatments, ozonation , etc. But these techniques are too expen-sive. Adsorption process has got interest due to its easiness, being economical and has good dye elimination capacity. Activated carbon is the primary choice for adsorption but it has drawback of high-cost and reusability So, search for substitute non-conventional adsorbent is continued. I studied the adsorption of methylene blue dye on NaOH activated rice husk. I found good adsorption capacity of activated rice husk (4558 mg of dye/g of ARU). Secondly, it's very cheap, easily available and reusable. EXPERI NI ENTA L Rice husk has been purchased from rice mill. It has been properly cleaned and treated with 10% NaOH for activation. Main components of rice husk are cellulose, hemi-cellulose, lignin and Silica. It has negative charge on it and entices more preferably positively charged organic dyes thus gives a higher uptake of cationic dyes. Methylene blue dye has been selected for adsorption studies. The concentration of aqueous solutions of dye has been assessed spectrophotometrically by drawing calibration curve at their 1 0- Batch method has been adopted, because of its ease of assessment of adsorption parameters. I g of NaOH activated rice husk is equilibrated with 1000 mg/I of adsorbate solu-tion. The residual dye concentration in solution is assessed spectrophotometrically. Adsorp-tion isotherm has been drawn at temperature and pH studied RESULTS Adsorption Studies The plot of MB dye elimination and time of contact indicates that the removal of dye occurred in two phases. Adsorption of MB dye was very fast in first 30 min i.e. 29.5 rng of dye adsorbed out of 30 mg/i and then it slow down and all the active sites were occupied Iqr after 3 h. 1-lence, equilibrium time of 3 h has been taken for further experiments. Adsorption of MB dye increased with increasing concentration of dye. At 50mg/i adsorbate concentration, adsorption was 49.8 mg/g of adsorbent. At 5000 mg/I adsorbate concentration, adsorption was 4558 mg/g of adsorbent. This shows that NaOH activated rice husk is excellent adsorbent for MB removal. Adsorption of MB was minimum at pH 2.7 (673 mg/g). Adsorption increased with increasing pH and maximum adsorption was seen at pH 11.5 (987mg/g). Adsorption of MB dye has been found to increases with increasing temperature. Hence, it is endothermic process. Adsorption was minimum at temperature 25 °C (458 mg/(.;) and maximum adsorption was seen at temperature 40 °C (906 tng/g). Overall adsorption of MB dye increased, on increasing doses of NaOl-1 activated rice husk. But, adsorption per gram of adsorbent decreased on increasing adsorbent doses.