Search

Vegetable oils (VOs) can be used as plasticizers or as biodegrading additives for commercial polymers. According to the literature, the use of concentrations higher than 5% of oils added to polymers or their mixtures indicated loss of mechanical properties on the final product. However, VOs can be used as a compatibilizer for the mixture of synthetic polymers with biopolymers (PM) under concentrations higher than 5%. Moringa oleifera oil (MO) was used as a compatibilizer to PM mixtures using oil concentrations higher than 5%, 10% and 15% in mass. PMs were analysed at first based on mechanical properties which indicated a better concentration at 15% of MO. This article presents a study of MO influence on biodegradation behaviour of PM, which was composed of low-density polyethylene obtained from food bags and biopolymers (PB) obtained in market plastic bags. PM doped with different concentrations of MO was submitted to studies of mechanical, chemical, morphological and thermal properties and their biodegradation behaviour was evaluated. The concentration of 15% of MO increased the thermal resistance of PM, improved the biodegradation behaviour according to controlled and free tests and reduced its stiffness without a loss of important mechanical properties. The results of this work showed that MO influenced positively the biodegradation of the PM mixture by improving 30% of the degrading speed. [ABSTRACT FROM AUTHOR]

Batch and continuous adsorption of Co2+ and Cu2+ from aqueous solutions by oxidized sugarcane bagasse (SBox) and oxidized cellulose (Cox) were investigated. The oxidation reaction of sugarcane bagasse and cellulose was made with a mixture of H3PO4‒NaNO2 to obtain SBox and Cox, with the introduction of high number of carboxylic acid functions, 4.5 and 4.8 mmol/g, respectively. The adsorption kinetics of Co2+ and Cu2+ on SBox and Cox were modeled using two models (pseudo-first-order and pseudo-second-order) and the rate-limiting step controlling the adsorption was evaluated by Boyd and intraparticle diffusion models. The Sips and Langmuir models better fitted the isotherms with values of maximum adsorption capacity Q max of 0.68 and 0.37 mmol/g for Co2+ and 1.20 and 0.57 mmol/g for Cu2+ adsorption on Cox and SBox, respectively. The reuse of both spent adsorbents was evaluated. Adsorption of Cu2+ and Co2+ on SBox in continuous was evaluated using a 22 factorial design with spatial time and initial metal concentration as independent variables and Q max and effective use of the bed as responses. The breakthrough curves were very well described by the Bohart–Adams original model and the Q max values for Co2+ and Cu2+ were 0.22 and 0.55 mmol/g. SBox confirmed to be a promising biomaterial for application on a large scale. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Sugarcane bagasse cellulose mixed ester succinate phthalate (SBSPh) was synthesized by a novel one-pot reaction method. The effects of temperature, time and mole fraction of succinic anhydride (χ SA) on the responses weight gain (wg), number of carboxylic acid groups (n T,COOH), and adsorption capacity (q) of Co2+ and Ni2+ were evaluated by a 23 experimental design. The chemical structure of the material was elucidated by Fourier transform infrared, 13C Multiple Cross-Polarization solid-state NMR spectroscopy and 1H NMR relaxometry. The best SBSPh synthesis condition (100 °C, 11 h, χ SA of 0.2) yielded a wg of 59.1%, n T,COOH of 3.41 mmol g−1, and values of q Co 2+ and q Ni 2+ of 0.348 and 0.346 mmol g−1, respectively. The Sips model fitted better the equilibrium data, and the maximum adsorption capacities (pH 5.75 and 25 °C) estimated by this model were 0.62 and 0.53 mmol g−1 for Co2+ and Ni2+, respectively. The Δ ads H ° values estimated by isothermal titration calorimetry were 8.43 and 7.79 kJ mol−1 for Co2+ and Ni2+, respectively. Desorption and re-adsorption efficiencies were evaluated by a 22 experimental design, which showed that SBSPh adsorbent can be recovered and reused without significant loss of adsorption capacity. [ABSTRACT FROM AUTHOR]

Abstract: This work describes the preparation of new chelating materials derived from sugarcane bagasse for adsorption of heavy metal ions in aqueous solution. The first part of this report deals with the chemical modification of sugarcane bagasse with succinic anhydride. The carboxylic acid functions introduced into the material were used to anchor polyamines, which resulted in two yet unpublished modified sugarcane bagasse materials. The obtained materials were characterized by elemental analysis and infrared spectroscopy (IR). The second part of this reports features the comparative evaluation of the adsorption capacity of the modified sugarcane bagasse materials for Cu2+, Cd2+, and Pb2+ ions in aqueous single metal solution by classical titration. Adsorption isotherms were studied by the Freundlich and Langmuir models. [Copyright &y& Elsevier]