Preparation of hemicellulose-based hydrogels from biomass refining industrial effluent for effective removal of methylene blue dye.

Cold caustic extraction (i.e. CCE) is an essential technique for removing hemicellulose from paper-grade pulp and thus obtaining high-purity dissolving pulp in pulp and paper industry. The generated wastewater from the CCE process contains large amounts of valuable hemicellulose which should be properly treated in a cost-effective way. Therefore, in this research, the hemicellulose has been used as a raw material for preparing hemicellulose-graft-polyacrylamide (hemi-g-pAAm) hydrogel particles for efficiently adsorbing methylene blue (MB) from aqueous solutions. The mass transfer kinetic behaviours of hemicellulose during a multiple CCE process were also studied. The MB adsorption kinetic test results showed that the removal efficiency can be higher than 90% for the simulated wastewater containing 500 mg/L of MB. Of note, the maximum removal capacities for the wastewater samples containing 500 and 1000 mg/L of MB could be reached up to ∼1800 and ∼2300 (mg/g) respectively with the equilibrium time of ∼40 min. Compared to other reported materials, the superior adsorption performance of the prepared hemicellulose-based hydrogel proved its great potential for application in the wastewater treatment of dye industry.

Removal of SO2 from smelting flue gas by using copper tailings with MnSO4: factors optimization by response surface methodology.

The abatement of SO2 and the utilization of copper tailings are identified as two attention-attracting environmental issues in the copper smelter. In this study, to improve the flue gas desulfurization performance and the utilization of copper tailings, SO2 removal from smelting flue gas by using copper tailings combined with MnSO4·H2O was investigated. The effects of operation variables, including inlet SO2 concentration, absorption temperature, slurry concentration, and MnSO4·H2O amount, on the flue gas desulfurization performance were studied based on the response surface method. It was found that the effect of operation variables on SO2 removal follows the descending order: the inlet SO2 concentration, MnSO4·H2O concentration, absorbent temperature, and solid-liquid ratio. The interaction between the inlet SO2 concentration and MnSO4·H2O concentration is an important factor for breakthrough sulfur capacity. Elevated temperature and high initial SO2 concentration inhibited the efficient removal of SO2. Moreover, a proposed equation exhibits good consistency in the prediction for the breakthrough sulfur dioxide capacity. Therefore, the results can provide a reliable reference and basis for industrial application for flue gas desulfurization with copper tailings.

Synthesis of NiMo/La-Al2O3 powders for efficient catalytic transesterification of triglyceride with the high yield of 95.2.

Enhancement of the transesterification efficiency of triglyceride has come under heated study in biodiesel-making industry. In this research, the NiMo/La-Al2O3 nanopowders have been prepared for producing biodiesel efficiently. The screening test showed that the NiMo/La-Al2O3 catalyst has the best catalytic activity for triglyceride transesterification. Besides, the process parameters including reaction temperature, time, oil-to-alcohol ratio and catalyst loading etc., also have been investigated for optimization of the transesterification process. The results showed that with 5 wt% of catalyst loading, and oil to methanol molar ratio of 1:9, the conversion yield of triglyceride could be up to 95.2% within 120 min at 160°C. The NiMo/La-Al2O3 catalyst has the outstanding recycle property, which proved that the prepared NiMo/La-Al2O3 powders can be suitable for biodiesels' production.