Copper sorption from aqueous solutions and sugar cane spirits by chemically modified babassu coconut (Orbignya speciosa) mesocarp

The present investigation explores the chemical modification of natural dry babassu coconut (Orbignya speciosa) mesocarp (BM), using a quasi solvent-free procedure in which the precursor was added to molten succinic (S), maleic (M) or phthalic (P) anhydrides, to give new products named BMS, BMM and BMP (babassu coconut mesocarp modified with succinic, maleic and phthalic anhydride, respectively). These synthesized biopolymers were characterized by infrared spectroscopy and thermogravimetry and the degree of substitution was calculated, based on the number of carboxylic groups covalently attached to the lignocellulosic polymer. The chemically modified biopolymers suspended in aqueous or hydroalcoholic solutions have the ability to remove copper from aqueous or aqueous-alcohol solutions in the order BMS > BMP > BMM. The kinetic process followed a pseudo-second-order model and the results for sorbents were better represented by the Langmuir sorption model. The effectiveness of these biopolymers for application to real samples of sugar cane spirits reflected in using only 1.0 g dm(-3) to reduce the copper to a value lower than 5.0 mg dm(-3) for all sorbents. Thus, these inexpensive chemically modified biopolymers may be useful to permit sugar cane spirits to meet the requirements of Brazilian legislation with respect to copper contamination. (C) 2010 Elsevier B.V. All rights reserved.