Powdered grape seeds (PGS) as an alternative biosorbent to remove pharmaceutical dyes from aqueous solutions

An alternative, low-cost and efficient biosorbent, powdered grape seeds (PGS), was prepared from wastes of a wine industry, and used to remove brilliant blue (BB) and amaranth red (AR) dyes from aqueous solutions. The biosorbent was properly characterized before and after the biosorption operation. The potential of PGS to remove BB and AR dyes was investigated thought kinetic, isotherm and thermodynamic studies. The biosorption of BB and AR was favored at pH 1.0 using biosorbent dosage of 0.500 g L⁻¹, being attained more than 85% of removal percentage. For BB and AR dyes, pseudo-second-order and Elovich models were able to explain the biosorption kinetic. The biosorption equilibrium of BB on PGS was well represented by the Langmuir model, while for AR, the Sips model was the most adequate. The maximum biosorption capacities were 599.5 and 94.2 mg g⁻¹ for BB and AR, respectively. The biosorption of BB and AR on PGS was a spontaneous, favorable and endothermic process. These findings indicated that PGS is a low-cost and efficient biosorbent, which can be used to treat dye containing waters.