Removal of a basic dye from aqueous solution by adsorption using rice hulls

The removal of dyes from colored effluents, particularly from textile industries, is one of the major
environmental concerns these days. Current methods for removing dyes from wastewaters are
costly and cannot effectively be used to treat wide range of such wastewaters. This work describes
the use of grounded rice hull as adsorbent material. Aqueous solutions of various methylene blue
dye concentrations (5-25 mg l-1) were shaken with certain amount of adsorbents to determine the
adsorption capacity. Both treated and untreated rice hulls were used for methylene blue adsorption.
The effects of adsorbents dose, initial pH, initial dye concentration and contact time on dye removal
have been studied. Maximum dye was sequestered from the solution within 60-90 min after the
beginning of every experiment. The adsorption capacity increased from 72 to 94 % with increasing
the pH from 3 to 10. Pretreatment of rice hulls with citric acid did not reveal any beneficial effect.
Rice hulls were more effective compared to commercial used adsorbents used. The results showed
that ground rice hulls can be considered as potential adsorbents for methylene blue removal from
dilute aqueous solutions.