Removal of reactive blue 19 from aqueous solution using rice straw fly ash

The adsorption behavior of reactive blue 19 dye (rb19) from aqueous solution onto rice straw fly ash (rsfa) was investigated in order to identify the ability of this waste adsorbent to remove colored textile dyes from wastewater. the effect of different variables in the batch method as a function of solution ph,contact time,concentration of adsorbate,adsorbent dosage and temperature were investigated and optimal experimental conditions were ascertain. more than 85 % removal efficiency was obtained within 60 min. at adsorbent dose of 0.09 g for initial dye concentration of 30-100mg/l at ph 1. the brunauer-emmett-teller (bet) surface area and barrett-joyner-halenda (bjh) pore volume were calculated and found to be 67.4 m2g-1and 0.134 cm3g-1,respectively. the point of zero charge (phpzc) of acrs was determined and found to be 7.the experimental equilibrium data were tested by the isotherm models namely,langmuir and freundlich adsorption and the isotherm constants were determined. the kinetic data obtained with different initial concentration and temperature were analyzed using a pseudo-first-order and pseudo-second-order equations. the activation energy of adsorption was also evaluated and found to be +18.87 kj.mol-1 indicating that the adsorption is physisorption. thermodynamic parameters,such as gibbs free energy,enthalpy and entropy of adsorption of the dye-rice straw fly ash systems were evaluated and it was found that the reaction was spontaneous and exothermic in nature.