Sorption of acid dyes of chemically modified peanut hulls

The potential of quaternized peanut hulls in the removal of acid dyes from synthetic solution and textile effluent as a low-cost biomaterial was studied. The sorption capacities of natural peanut hull (NPH) and quaternized peanut hull (QPH) were tested on the dye Acid Blue 25. The ability of NPH and QPH to remove various basic dyes was only 2 per cent of the total dye. Acid dyes were adsorbed more readily. QPH had a greater capacity for dye removal than NPH. Uptake increased between pH 5.0 to pH 2.1 and was considered as an ion-exchange between the anionic component of the dye and the chloride of the quaternary ammonium salt of the peanut hull. The sorption capacity of QPH was comparable with that of activated carbon AB25. Pseudo-equilibrium was reached in 4 h and plots of adsorption followed the general pattern of higher percentage uptake with decreasing concentrations. Quaternized peanut hulls were useful sorbents of acid dyes and their commercial use was being investigated further.