Manganese Biosorption from Aqueous Solution by Penicillium camemberti Biomass in the Batch and Fix Bed Reactors: A Kinetic Study

Biosorption of manganese(II) using suspended and immobilized cells of fungal Penicillium camemberti (biomass) and nano-P. camemberti (nano-biomass) was studied by evaluating the physicochemical parameters of the solution such as initial manganese ion concentration, pH, temperature, dosage, and contact time in both batch system and fixed bed column. The maximum biosorption obtained from the batch process was 91.54 and 71.08 % for nano-biomass and biomass in initial concentration of 5 ppm, respectively. The Langmuir, Freundlich, Temkin, and BET isotherms isotherm models were used in the equilibrium modeling. The correlation coefficient of more than 0.90 turned out that the adsorption process of Mn(II) on biomass and nano-biomass were in accordance with both Langmuir and Freundlich isotherms. The sorption process followed a second-order rate kinetics indicating the process to be diffusion controlled. The results also demonstrate that an intra-particle diffusion mechanism plays a significant role in the sorption process. The structure of P. camemberti was characterized by FT-IR spectrums.     

Computer-aided cooling curve thermal analysis and microstructural evolution of Mg–5Zn–xY cast alloys

The organo-montmorillonite (MT), combined with a DOPO-based oligomer (PDAP), was used to improve the flame retardancy of epoxy thermoset. The thermal stabilities and flame-retardant properties of thermosets were investigated by thermogravimetric analysis, limiting oxygen index (LOI) and UL-94 tests. The synergistic effect of MT and PDAP was studied by Py–GC/MS, Fourier transform infrared spectroscopy, elemental analysis, laser Raman spectroscopy and scanning electron microscope. Results revealed that 0.5 mass% MT combined with 4 mass% PDAP showed obvious synergistic effect on enhancing the flame retardancy of thermoset. The corresponding thermoset achieved an LOI value of 35.5% and V-0 rating in UL-94 test, which was attributed to the intense blowing-out effect during combustion. The synergistic mechanism was probably ascribed to the formation of silicoaluminophosphate (SAPO) originating from the reaction between MT and PDAP. The SAPO serving as a solid acidic catalyst, coupled with the acid sites from the decomposition of organomodifier in MT, could promote the charring process. With the further increase in MT content, the charring process was strongly promoted and more phosphorus element was retained in the condensed phase, which inevitably resulted in the remarkable decrease of the amount of pyrolytic gases containing phosphorus-based radicals and nonflammable gases. These factors were responsible for the diminished blowing-out effect during combustion, which was adverse to the further improvement of flame retardancy.