This study evaluated the copper ion adsorption capacity of sugarcane bagasse in natura and chemically modified with citric acid and sodium hydroxide. Adsorption analyses in batch system were carried out in function of contact time with the adsorbent and adsorbate concentration. Flame atomic absorption spectrometry was used to determine the copper concentrations. Adsorption experimental data were fitted to Langmuir and Freundlich linear models, and the maximum adsorption capacity was estimated for copper ions in function of modifications. The chemical modifications were confirmed at 1,730 cm −1 peak in infrared spectra, referring to the carboxylate groups. The required time for the adsorption to reach equilibrium was 24 h and the kinetics follows the behavior described by the pseudo-second order equation. Besides, a significant improvement of the copper adsorption has been observed after the bagasse treatment, where the maximum adsorption capacity was 31.53 mg g −1 for copper using modified bagasse with nitric acid according to Langmuir isotherm linear model. The high uptake of copper ions from aqueous medium verified by chemically modified sugarcane bagasse makes this material an attractive alternative for effluent treatment and avoids environmental contamination.

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This study evaluated the adsorption capacity of chemically modified sugarcane bagasse with citric acid (B-CA), sodium hydroxide (B-S) and citric acid and sodium hydroxide (B-CAS) for Pb2+ ion adsorption in aqueous medium. Infrared spectroscopy (FT-IR) was used to characterise the materials, where the chemical modification was confirmed by the presence of carboxylate groups created at 1,730 cm(-1) peak. All assays related to Pb2+ ion adsorption onto adsorbent, i.e. equilibrium time between Pb2+ ions and adsorbate (24 h), as well as Pb2+ ion concentration, were performed in batch system. The initial and final Pb2+ ion concentration after shaking time was determined by Flame Atomic Absorption Spectrometry (FAAS). Isotherm adsorptions were applied to Langmuir and Freundlich linear models and maximum adsorption capacity (MAC) of materials towards Pb2+ ions was calculated in function of modifications. A significant improvement regarding Pb2+ ion adsorption after the bagasse treatment with citric acid, in which MAC was 52.63 mg g(-1), was observed. The adsorptions followed the behaviour described by the Langmuir linear model and its kinetics follow the behaviour described by the pseudo-second-order equation.

The present paper focuses on improving chromium (III) uptake capacity of sugarcane bagasse through its chemical modification with citric acid and/or sodium hydroxide. The chemical modifications were confirmed by infrared spectroscopy, with an evident peak observed at 1730 cm-1, attributed to carbonyl groups. Equilibrium was reached after 24 h, and the kinetics followed the pseudo-second-order model. The highest chromium (III) maximum adsorption capacity (MAC) value was found when using sugarcane bagasse modified with sodium hydroxide and citric acid (58.00 mg g-1) giving a MAC value about three times greater (20.34 mg g-1) than for raw sugarcane bagasse

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Studies on the immobilization of acetylcholinesterase onto a SAM gold electrode and the use of the fabricated biosensor for the determination of carbaryl and parathion are presented. The influence of pH, ionic strength, enzyme loading and concentration of glutaraldehyde on the response of the biosensor was investigated . The amperometric biosensor developed in this study provided linearity to parathion and carbaryl in the 2.0 a 30.0 Â 10 À6 mol L À1 concentration range. The detection limits under the optimum working conditions were found to be 9.3 mg L À1 for parathion and 9.0 mg L À1 for carbaryl. The enzyme electrode was found to be stable for 7 days.