Polysaccharides in fabrication of membranes: A review.

Sustainability concerns have motivated and directed a great deal of interest over the past decade towards the development of green technologies. Polysaccharides are green polymers, which experienced growing demand to substitute chemically synthetic polymers. Different types of polysaccharides i.e. cellulose-, starch-, chitin- alginate-, and chitosan-based carbohydrate polymers have been applied in the fabrication of separation membranes. The purpose of the current review was to summarize, classify, and discuss the state-of-the-art the fabrication of membranes with carbohydrate polymers. Specific attention was paid to highlight the strategies used in the successful development of such membranes. First, a brief review of different types of polysaccharides was performed. Next, the application of these polysaccharides in the fabrication of liquid filtration, gas separation, adsorption, pervaporation and proton exchange membranes were comprehensively reviewed. Computational evaluations were also reviewed. Eventually, concluding remarks together with challenging aspects of the future perspective over application of polysaccharide membranes were discussed.

Determination of the effect of proteoliposome concentration on Aquaporin Z incorporated nanofiltration membranes.

We report on the fabrication of AqpZ immobilized flat sheet membranes. The effects of interfacial polymerization conditions as well as proteoliposome concentration were evaluated. Commercial AqpZ were used as positive control for cloned AqpZ. Specific permeate flux of membranes at higher proteoliposome concentrations increased up to 25 times higher than thin film composite membranes; however; MgSO4 rejection is lowered almost to 1.5%. FTIR and SEM confirm immobilization of proteoliposomes. Thermal analysis showed that increasing proteoliposome concentration has no positive effect on the incorporation of proteoliposomes into polyamide structures. On the contrary, at lower proteoliposome concentrations, incorporation of proteoliposomes was found better. When combined membrane performances were compared in terms of specific permeate flux; MgSO4 and humic rejection and flux recovery after humic acid filtration, the performance of cloned AqpZ incorporated membranes (having 0.1 mg/mL proteoliposome concentration and polyamide formed with 2 min piperazine reaction time) improved 1.7 times regarding TFC membranes. According to the results, increasing proteoliposome concentration did not improve nanofiltration membrane performance. On the contrary, lower proteoliposome concentrations were found to be more effective in increasing membrane performance.

Risk assessment of trace metals in an extreme environment sediment: shallow, hypersaline, alkaline, and industrial Lake Acigöl, Denizli, Turkey.

The major and trace element component of 48 recent sediment samples in three distinct intervals (0-10, 10-20, and 20-30 cm) from Lake Acigöl is described to present the current contamination levels and grift structure of detrital and evaporate mineral patterns of these sediments in this extreme saline environment. The spatial and vertical concentrations of major oxides were not uniform in the each subsurface interval. However, similar spatial distribution patterns were observed for some major element couples, due mainly to the detrital and evaporate origin of these elements. A sequential extraction procedure including five distinct steps was also performed to determine the different bonds of trace elements in the < 60-µ particulate size of recent sediments. Eleven trace elements (Ni, Fe, Cd, Pb, Cu, Zn, As, Co, Cr, Al and Mn) in nine surface and subsurface sediment samples were analyzed with chemical partitioning procedures to determine the trace element percentage loads in these different sequential extraction phases. The obtained accuracy values via comparison of the bulk trace metal loads with the total loads of five extraction steps were satisfying for the Ni, Fe, Cd, Zn, and Co. While, bulk analysis results of the Cu, Ni, and V elements have good correlation with total organic matter, organic fraction of sequential extraction characterized by Cu, As, Cd, and Pb. Shallow Lake Acigöl sediment is characteristic with two different redox layer a) oxic upper level sediments, where trace metals are mobilized, b) reduced subsurface level, where the trace metals are precipitated.