Fabrication, tuning and optimization of poly (acrilonitryle) nanofiltration membranes for effective nickel and chromium removal from electroplating wastewater

In the present study, response surface methodology (RSM) is employed according to central composite design (CCD) for modeling and optimization NF membranes fabricated and tuned for effective removal of Ni and Cr from electroplating wastewater streams. The effect of concentration of poly(acrylonitrile) (PAN: 21–25 wt.%) as the main membrane material as well as poly(ethylene glycol) (PEG: 0–1.5 wt.%) and titanium dioxide nanoparticles (TiO2: 0–1 wt.%) as the additives and their mutual interaction on membrane performance and morphology were investigated. According to the quadratic polynomial model, independent factors were statistically significant and the obtained models were accurate. The optimized responses for Ni and Cr rejection and pure water flux were 87.093 (%), 83.271 (%) and 71.801 (Lit m−2 h−1) respectively at optimum membrane formulations of PAN: 23.93%, PEG: 0.41% and TiO2: 0.82%. The results of validation experiment confirm the data for predicted model at optimum point (Ni rejection: 88.093%, Cr rejection: 80.271% and pure water flux: 76.801 Lit m−2 h−1). Both Ni and Cr rejections increased from 60.87% to 80.36% and from 56.35% to 78.64%, respectively upon increasing PAN concentration in the dope from 21 wt.% to 25 wt.%. It was also found that decreasing PEG concentration led to increase in Ni and Cr rejections and decrease in pure water flux. Using of TiO2 nanoparticles led to increase of Ni and Cr rejections and pure water flux at different PAN concentrations. From the morphological perspective, increase in polymer concentration led to change of porous to spongy like structure while increasing PEG concentration led to increase in macrovoids area. Both porosity and mean pore size reduced by increase of PAN concentration and decrease of PEG concentration

Significance, evolution and recent advances in adsorption technology, materials and processes for desalination, water softening and salt removal

Desalination and softening of sea, brackish, and ground water are becoming increasingly important solutions to overcome water shortage challenges. Various technologies have been developed for salt removal from water resources including multi-stage flash, multi-effect distillation, ion exchange, reverse osmosis, nanofiltration, electrodialysis, as well as adsorption. Recently, removal of solutes by adsorption onto selective adsorbents has shown promising perspectives. Different types of adsorbents such as zeolites, carbon nanotubes (CNTs), activated carbons, graphenes, magnetic adsorbents, and low-cost adsorbents (natural materials, industrial by-products and wastes, bio-sorbents, and biopolymer) have been synthesized and examined for salt removal from aqueous solutions. It is obvious from literature that the existing adsorbents have good potentials for desalination and water softening. Besides, nano-adsorbents have desirable surface area and adsorption capacity, though are not found at economically viable prices and still have challenges in recovery and reuse. On the other hand, natural and modified adsorbents seem to be efficient alternatives for this application compared to other types of adsorbents due to their availability and low cost. Some novel adsorbents are also emerging. Generally, there are a few issues such as low selectivity and adsorption capacity, process efficiency, complexity in preparation or synthesis, and problems associated to recovery and reuse that require considerable improvements in research and process development. Moreover, large-scale applications of sorbents and their practical utility need to be evaluated for possible commercialization and scale up. (C) 2018 Elsevier Ltd. All rights reserved

Effect of cow´s milk elimination from children diet on chronic constipation

Background and Objective: Children constipation is one of the common causes of abdominal pain. Cow´s milk in children diet is suggested to be one of the main cause of chronic constipation. This study was performed to determine the effect of cow´s milk elimination from children diet with chronic constipation. Methods: This quasi-experimental study, was performed on 80 children with chronic constipation. Rome-III criteria were considered for disease diagnosis. Cow’s milk was eliminated for three weeks from children’s diet and the clinical symptoms in children were surveyed, subsequently. Results: Constipation was cured in 33.8% of children as result of cow's milk free diet. The rate of treatment response in affecting children whom their disease in began under 2 years of age (52.6%) was significantly higher than others (16.6%) (P<0.05). Children treatment was not significantly related to child’s gender and amount of milk consumption. Conclusion: Eliminating of cow's milk from the diet improves the chronic constipation in children