Membrane distillation for achieving high water recovery for potable water reuse.

Achieving high water recovery using reverse osmosis membranes is challenging during water recycling because the increased concentrations of organics and inorganics in wastewater can cause rapid membrane fouling, necessitating frequent cleaning using chemical agents. This study evaluated the potential of membrane distillation to purify reverse osmosis-concentrated wastewater and achieve 98% overall water recovery for potable water reuse. The results indicate that membrane fouling during membrane distillation treatment was low (4% reduction in permeability) until 98% water recovery. In contrast, membrane fouling during reverse osmosis treatments was high (73% reduction in permeability) before reaching 90% water recovery. Furthermore, membrane distillation showed superior performance in removing dissolved ions (99.9%) from wastewater as compared with reverse osmosis (98.9%). However, although membrane distillation removed most trace organic chemicals tested in this study, a negligible rejection (11%) was observed for N-nitrosodimethylamine, a disinfection byproduct regulated in potable water reuse. In contrast, RO treatment exhibited a high removal of N-nitrosodimethylamine (70%). Post-treatment (e.g., advanced oxidation) after reverse osmosis and membrane distillation may be needed to comply with the N-nitrosodimethylamine regulations. Overall, the membrane distillation process had the capacity to purify reverse osmosis concentrate with insignificant membrane fouling.

Fabrication of bioactive glass coating on pure titanium by sol-dip method: Dental applications.

This study aimed to assess the mechanical and biological properties of bioactive glass (BG) coating on titanium (Ti). Bioinert Ti substrates were coated by BG to induce bioactivity to the surface. The sol-gel derived BG 58S sol was successfully prepared and coated on the abraded and blasted Ti surface using the sol-dip method. The characterization and cell study for all substrates' surface was carried out. Adhesion test confirmed that a firmly adhered BG coating layer was formed on the abraded and blasted Ti. The measured bonding strength between the coating and the blasted Ti substrate was the highest among all samples, which was 41.03±2.31 MPa. In-vitro cell viability and alkaline phosphatase activity (ALP) tests results also showed that BG coating on the Ti substrate improved the biological properties of the surface. The BG sol-dip coating method could be used to fabricate Ti substrate with a bioactive surface.

Groundwater fluoride removal using modified mesoporous dung carbon and the impact of hydrogen-carbonate in borehole samples.

There have been many research reports pertained to the interference of co - ions including hydrogen carbonate against the removal of fluoride from water. In this context, the present research explores the fluoride removal efficiency of ammonium carbonate modified dung derived carbon (DDC500) in the absence and presence of hydrogen carbonate using synthetically made fluoride solutions and groundwater samples. The adsorbent DDC500 was found to achieve the highest removal of 80% of fluoride at pH 6.95 than the washed carbon (DDC500W) and dung ash (DA) of 48% and 23% respectively. In DDC500, the carbon base in concert with inorganic residues actively functioned in the fluoride removal process and chosen for synthetic fluoride solutions (2-5 mg L-1) and 16 groundwater samples (2.1-3.6 mg L-1) from 10 locations of Usilampatti Taluk in Madurai District, South India. After the removal of hydrogen carbonate in groundwater, the percentage of samples was increased in accordance with the safe limits of World Health Organization (WHO) and Bureau of Indian Standard (BIS). Langmuir isotherm model (R2 = 0.9379) was in concordance with the adsorption of fluoride from groundwater free from hydrogen carbonate. The dynamics of other groundwater quality parameters at conditions and the independency between F-/HCO3- ratio and DE were illustrated by scatter plots. Characterization studies for the dried dung (CD110), derived carbons (DDC500 and DDC500W) and ashes (CD110A, DDC500A and DDC500WA) using FE-SEM, XRD, FTIR, Raman and TGA - EGA were done to understand the nature and behavior of materials.

Enantioselective C--C bond formation to sulfonylimines through use of the 2-pyridinesulfonyl group as a novel stereocontroller.

Enantioselective C--C bond formation to 2-pyridinesulfonylimines afforded products with good enantioselectivity. Dynamic induction of chirality on the sulfur by coordination of a chiral Lewis acid to the pyridine nitrogen and one of the prochiral sulfonyl oxygens induces enantioselectivity. Since the 2-pyridinesulfonyl group can easily be removed after the reaction, it acts not only as an activating group but also as an efficient stereocontroller.