Utilization of Bakuhan seki for the removal of cationic dye from aqueous solutions

The extensive use of dyes causes pollution problems in the form of colored wastewater discharged into environmental water storages. It is essential to find out an effective and economic method for removing dyestuff in dyeing waste water flowing out of a drainage of a dyeing machine. Therefore, the present study investigates a simple and economic method to effectively remove dyestuff in dyeing waste water by using Bakuhan seki. "Bakuhan seki-healing stone" is used to designate a Japanese stone which is a kind of igneous rock, and its principal ingredients are alkali feldspar and quartz. It is very porous in nature and it is also known to adsorb residual chlorine, heavy metals, organic matter and bacteria in water and thereby remove these materials from water. Methylene blue adsorption by the Japanese Bakuhan seki was investigated under different conditions (adsorbent dosage, pH, time and temperature). It exhibits the property of adsorption due to its porosity and charged surface. Its suitability for adsorption was demonstrated by fitting the adsorption data with Langmuir and Freundlich isotherms, and a favorable adsorption of methylene blue on the Bakuhan seki surface was derived. The equilibrium adsorption capacity was found to be 7.716, 9.615 and 10.00 mg g(-1) at 283, 298 and 313 K, respectively, using the Langmuir equation. Thermodynamic parameters, Delta H degrees, Delta S degrees and Delta G degrees, showed endothermic and spontaneous adsorption accompanied by a rise in entropy.