Role of the Solution Environment in Nanofiltration for the Recovery of Ionic Liquids from Water

In this work,experiments to examine the recycling of ionic liquids(ILs)from aqueous solution by nanofiltration(NF)were conducted.The influences of pH,ionic strength,and macromolecular organic matter on filtration performance metrics including the volume flux(J_(v))and observed rejection(R_(obs))were systematically studied.Aqueous solutions of three widely studied ILs,specifically 1-butyl-3-methylimidazolium chloride([C_(4)mim]Cl),1-decyl-3-methylimidazolium chloride([C_(10)mim]Cl),and 1-buty 1-3-methylimidazolium tetrafluoroborate([C_(4)mim]BF_(4))were selected for this study.The mechanisms of interaction between the ILs and the NF membrane under different pH and ionic-strength conditions were revealed by quantum chemical calculations and molecular simulations.The results showed that with increasing pH,the J_(v) and R_(obs)values of the[C_(4)mim]Cl and[C_(10)mim]Cl aqueous solutions increased,while for the[C_(4)mim]BF_(4)aqueous solution,the J_(v) value increased and the R_(obs)value decreased.Furthermore,with increasing ionic strength,the J_(v) values of the[C_(4)mim]Cl and[C_(4)mim]BF_(4)aqueous solutions decreased,and their R_(obs)values increased;conversely,for the[C_(10)mim]Cl aqueous solution,the R_(obs)value decreased,and the J_(v) vale first increased and then decreased.In addition,it was found that the presence of macromolecular organic matter tends to cause membrane fouling and has a great influence on the separation of aqueous solutions of ILs by NF.In general,membrane fouling leads to an increase in the R_(obs)value but a decrease in the J_(v) value.

Quantification,morphology and source of humic acid,kerogen and black carbon in offshore marine sediments from Xiamen Gulf,China

Three types of macromolecular organic matters （MOMs）, i.e. humic acid （HA）, kerogen＋black carbon （KB）, and black carbon （BC） were extracted from marine sediments of Xiamen Gulf, southeast of China. The chemical composition, morphological property and source of the three extractions were characterized by elemental analyzer/isotope ratio mass spectrometry （EA/IRMS） and scanning electron microscope （SEM）. The results showed that KB was the predominant fraction in MOMs, which accounted for 61.79%-89.15% of the total organic content （TOC）, while HA consisted less than 5%. The relative high contents of kerogen and BC, and low contents of HA in the samples indicated that anthropogenic input might be the major source of organic matter in marine sediments near the industrial regions. The characterization of SEM, not only revealed morphological properties of the three fractions, but also allowed a better understanding of the source of MOMs. The δ 13 C values of the three fractions suggested that materials from terrestrial C 3 plants were predominant. Furthermore, the anthropogenic activities, such as the discharge of sewage, coal and biomass combustion from industry nearby and agricultural practices within drainage basin of the Jiulong River, were remarkably contributed to the variations in δ 13 C values of MOMs in the offshore marine sediments.