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The work reports a modeling analysis of single-compound and binary adsorption of Pb2+ and Cd2+ ions from polluted water onto the activated carbon at room temperature. The homogeneous model for single adsorption (HM) and the exclusive extended monolayer model for binary adsorption (EEMM) are applied for the interpretation of the experimental data set. The adopted models correlate the entire set of adsorption data, allowing a thorough description of the occurring phenomena. The overall objective of the study is to determine the adsorption mechanisms, also through a comparative analysis between the single-compound and binary modeling data. The parameters of both models are used for to retrieve useful indications about the adsorption of these two ions. In particular, the number of ions adsorbed per single functional groups changed from single-compound to binary adsorption, allowing to explain the competitive behavior of the investigated system. The adsorption energy values vary between 21.39 (Pb2+) and 24.06 kJ/mol (Cd2+), and 27.17 (Pb2+) and 32.59 kJ/mol (Cd2+) in single-compound and binary systems, respectively, indicating that adsorption is a physisorption process.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer, whose applicability is limited by its relatively poor mechanical properties and narrow processing window. In this paper, a natural polyphenolic additive, tannic acid (TA) was used as thermal and processing stabilizer for PHB. The thermal stability of both neat and TA-doped PHB samples was studied by rheology and calorimetry. The experimental results show that the neat PHB massively degrades and that the addition of tannic acid enhances the thermal stability of PHB, thus widening the processing window of the polymer. Physical and chemical interactions between the polymer and the additive were considered as key factors to interpret the experimental data. The described results are of interest for the development of sustainable alternatives to synthetic polymer additives, by increasing the applicability of bio-based materials. (C) 2014 Elsevier Ltd. All rights reserved.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer, whose applicability is limited by its relatively poor mechanical properties and narrow processing window. In this paper, different natural phenol-based additives, including tannic acid (TA), grape bagasse extract (EP), and a lignocellulosic biomass (LC) were used as thermal and processing stabilizers for PHB. The thermal stability of both neat and doped PHB samples was studied by rheology and calorimetry. The experimental results showed that neat PHB massively degrades and that the addition of phenol additives enhances the thermal stability of PHB, preserving the polymer molecular weight after processing. This finding was in agreement with the slower decay in viscosity observed through rheological tests. Physical and chemical interactions between polymer and additive were considered as key factors to interpret the experimental data. LC affected the melt crystallization kinetics of PHB enhancing crystallization upon cooling. This finding suggests th...