sheng Hu

Study on pyrolytic kinetics and behavior: The co-pyrolysis of microalgae and polypropylene

In the current work, the co-pyrolysis kinetics of Dunaliella tertiolecta and PP were investigated via TGA, while TG-FTIR and TG-MS were used for the analysis of gas-phase components and volatiles transition. The TGA results show that PP with certain small particle size accelerates the pyrolysis process of the microalgae, while the existence of D. tertiolecta delayed that of PP. This significant interaction achieves maximum when mass ratio of PP and D. tertiolecta is 6:4. The activation energy estimated from FWO kinetic model also supports this interaction. The TG-FTIR and TG-MS results show that a significant decrease of CO2 occurs at PP and D. tertiolecta mass ratio of 6:4, indicating that small molecules (such as radicals) released by PP might react with CO2 produced by D. tertiolecta or carbonyl groups in the microalgae.

Thermal characterization and kinetic analysis of nesquehonite, hydromagnesite, and brucite, using TG–DTG and DSC techniques

Nesquehonite, hydromagnesite, and brucite are important precursors for the preparation of high-purity magnesia (MgO) using magnesium resources from salt lake as raw materials. In this paper, TG–DTG and DSC were used to investigate the thermal decomposition behaviors of the three precursors. Decomposition kinetic parameters at each stage were evaluated based on the TG data using the iso-conversional method. Decomposition mechanisms were determined using the master-plots method. The decomposition temperature range, heat absorption, and kinetic parameters of the three phases were then compared. The most probable mechanism of each stage from the perspective of crystal structure was found to be consistent with the calculation results from the master-plots method. Results led to the conclusion that nesquehonite is the most appropriate precursor for the preparation of high-purity MgO. Further studies on precursor selection and calcining condition selection for the preparation of MgO using bischofite will benefit from this research.

Co-liquefaction of microalgae and polypropylene in sub-/super-critical water

In the current study, Dunaliella tertiolecta (D. tertiolecta) and polypropylene (PP) were chosen to investigate the co-liquefaction process of microalgae and plastic. The results show that a maximum synergistic effect was found when the mass ratio of D. tertiolecta to PP was 8 : 2. The addition of PP mainly impacts the composition of the bio-oil products, particularly reducing the acid content. When D. tertiolecta was liquefied individually, the relative content of acid in bio-oil could reach 18.73%, while for D. tertiolecta and PP co-liquefaction in a ratio of 8 : 2, the acid content of bio-oil was lower than the detection limit of GC-MS (lower than 100 ppm). The reaction mechanism for the co-liquefaction process of PP and the main components of microalgae has also been studied. The addition of PP has a significant effect on the transformation pathways of carbohydrates in microalgae, and this also promotes the Maillard reaction between carbohydrates and proteins or their hydrolysates.

ZrMn Oxides for Aqueous-Phase Ketonization of Acetic Acid: Effect of Crystal and Porosity

Aqueous-phase ketonization of bio-based acetic acid is important to improve the conversion efficiency of biomass resources. In this study, ZrMn mixed oxides (ZrMnOx ) with high aqueous-phase ketonization activity are synthetized through a carbonization/oxidation method (COM) and solvothermal method (STM). The results show that ZrMnOx prepared by COM possesses tetragonal ZrO2 , and hausmannite Mn3 O4 is observed only at a high oxidation temperature of 750 °C. Low-temperature and long oxidation results in decreased crystallinity and crystallite size, which is related to highly dispersed Mnn+ species. The catalysts with improved acid sites possess high ketonization activity. Surface areas and pore size of ZrMnOx synthetized by STM are controlled by the solvents for thermal treatment. Compared with water as solvent, ethanol increases the surface area and pore size, resulting in high ketonization activity.

Decomposition of Thiocyanate in Wastewater by Electron Beam Radiolysis

Abstract-Wastewater from cyanidation leaching of gold from ore, coal coking, and electroplating processes contains high concentration of thiocyanate, an anionic toxin of particular concern to aquatic environments. This study investigated potential use of electron beam radiolysis of thiocyanate in aqueous solution. Results showed that in 500 mg/L thiocyanate solution with pH of 7 and 12, as irradiation dose increased from 60 to 550 KGy, the conversion percentage that sulfur element in thiocyanate into sulfate was 47.1 - 84.5% and 26.9 - 67.7%; carbon element into carbonate were 1 - 11% and 5 - 31%, conversion into α-amnio acid were 56 - 57% and 58 - 68%, and conversion into urea were 2 - 8.3% and 2 - 8.4%, with a total carbon mass balances of 61 - 71 % and 75-97% respectively. The highest decomposition efficiencies were 98.61% and 99.46% for the solution of pH of 7 and 12 respectively, at a dose of 550 kGy and an initial concentration of 500 mg/L. The thiocyanate decomposition mechanism is postulated to be a series of radical reactions. The reaction steps were that thiocyanate firstly formed cyanide ion by removal of sulfur atom, and then the cyanide ion reacts with radicals such as •OH, •H and e-aq to form intermediate such as OCN-, H4C2N2, and HCNO.