Fabrication of a Ceramic Membrane with Antifouling PTFE Coating for Gas-Absorption Desulfurization

The influence of H2O or/and O2 introduction during the low-temperature gas-phase sulfation of organic COS + CS2 on the conversion and deposition of sulfur-containing species in the sulfated CeO2-OS catalyst for NH3-SCR

Herein, the typical components of blast furnace gas, including H2O and O2, were introduced to improve the NH3-SCR activity of the sulfated CeO2-OS catalyst during the gas-phase sulfation of organic COS + CS2 at 50 °C. The characterization results demonstrate that the introduction of O2 or H2O during gas-phase sulfation enhances the conversion of organic COS + CS2 on a cubic fluorite CeO2 surface and reduces the formation of sulfur and sulfates in the catalyst, but decreases the BET surface area and pore volume of the sulfated CeO2-OS catalyst. However, the introduction of O2 or H2O during the gas-phase sulfation increases the molar ratios of Ce3+/(Ce3+ + Ce4+) and Oβ/(Oα + Oβ + Oγ) on the sulfated CeO2-OS catalyst surface, thus promoting the formation of surface oxygen vacancies and chemisorbed oxygen, and these properties of the catalyst are further enhanced by the co-existence of O2 and H2O. Furthermore, the reduction of sulfates formed under the action of O2 or H2O decreases the weak acid sites of the sulfated CeO2-OS catalyst, but the few and highly dispersive sulfates present stronger reducibility, and the proportion of medium-strong acid sites of the catalyst increases. These factors help to improve the NH3-SCR activity of the sulfated CeO2-OS catalyst. Thus, there exists a synergistic effect of H2O and O2 introduction during gas-phase sulfation on the physical-chemical properties and catalytic performance of the sulfated CeO2-OS catalyst by organic COS + CS2 at 50 °C.

Synthesis and Evaluation of Asymmetric Mesoporous PTFE/Clay Composite Membranes for Textile Wastewater Treatment

Asymmetric mesoporous composite PTFE membranes wit 40, 50, and 85 wt.% of a clay (kaolin) were fabricated and characterized using a scanning electron microscope equipped with EDX for morphology and elemental analysis. The surface chemistry of the membranes was checked using Fourier transform infrared spectroscopy. The effect of incorporating the clay on the hydrophilicity, permeability, morphology, and antifouling properties of the fabricated membranes was investigated. It was observed that incorporating kaolin particles improved the mechanical properties but decreased the contact angle of the membranes, thereby resulting in an improvement in the membrane permeability. The performance of the three composite UF membranes was evaluated through the treatment of a real textile effluent sample containing indigo dye. The results confirmed that these membranes are effective in the removal of COD, color, and turbidity. Indeed, at a transmembrane pressure of 2.5 bar, almost total removal of the turbidity, COD removal > 85%, and color removal > 97% were attained. Furthermore, membrane A85 (with 85% clay) showed the best performance, with a water flux of 659.1 L·h^-1·m^-2·bar^-1. This study highlights the potential of incorporating low-cost clay material for the enhancement of the performance of mixed organic/inorganic matrix membranes, which can be applied to textile wastewater treatment.