Impact of industrial air pollution on the quality of atmospheric water production.

The atmospheric water generator (AWG) is a commercially available device that produces water from the air in large volumes over short times. This method can be applied in most regions of the world to solve chronic and acute drinking water scarcity. However, knowledge of the effects of air chemical composition on AWG-produced water quality is still very limited. In this study, a comprehensive survey of AWG-produced water quality was conducted in a heavily polluted industrial environment; 83 AWG water samples were analyzed for 99 different quality parameters, including organic, inorganic, and microbial contamination. Two parameters-nickel (15 samples) and dichloromethane (2 samples)-exceeded sporadically their drinking water standards of EPA, EU and IL. Ammonia was the only parameter consistently above standard limits of 0.5 mg/L (61% of samples, relevant to 47 countries) and even higher than 1.5 mg/L. Comparison to real air concentrations of volatile pollutants in the same environment did not reveal any significant correlations; while some pollutants were found at high concentrations in the air, this was not reflected by their presence in the produced water. The findings show that even in areas that are considered excessively polluted relative to the natural environment, the water produced from the air by AWG could be considered suitable for drinking, with careful attention to very specific contaminants.

Air-water interactions: The signature of meteorological and air-quality parameters on the chemical characteristics of water produced from the atmosphere.

Atmospheric water is considered an alternative sustainable solution for global water scarcity. We analyzed the effects of meteorological and air-quality parameters on the chemical characteristics of atmospheric water. First, we measured the chemical characteristics of water produced by a unique atmospheric water generator (AWG) apparatus in Tel Aviv, Israel. To examine the complex air-water relationships, we obtained atmospheric data from several sources: adjacent air-quality-monitoring stations, aerosol robotic network (AERONET), aerosol pollution profile using PollyXT lidar, and air back-trajectory simulation (HYSPLIT). We found a strong impact of different pollution sources on the water quality. The integration between HYSPLIT, AERONET and lidar analyses shows that the pathway crossed by the air parcel three days before arrival at the site affected the chemical properties of the produced water. Nearby sea salt aerosols from the Mediterranean were persistently observed in the water (medians: sodium 69 µg/L, chloride ions 120 µg/L), corresponding to lidar identification of a sea-breeze layer (30-50 sr lidar ratio in lower elevation). Seasonal variability in climatic conditions affected the concentration of dust-related elements in the water. During dust-storm events, calcium was the most dominant element (median 900 µg/L). Thus, the chemical characteristics of the water can be considered a "footprint" of both regional, local, and phenological composition of the atmosphere.

Antimicrobial N-brominated hydantoin and uracil grafted polystyrene beads.

Hydantoin-N-halamine derivatives conjugated on polystyrene beads are promising disinfectants with broad antimicrobial activity affected by the gradual release of oxidizing halogen in water. The objective of this work was to identify and test of hydantoin-like molecules possessing urea moiety, which may provide N-haloamines releasing oxidizing halogens when exposed to water at different rates and release profiles for tailored antimicrobial agents. In this work, several hydantoin (five member ring) and for the first time reported, uracil (six member ring) derivatives have been conjugated to polystyrene beads and tested for their lasting antimicrobial activity. Four molecules of each series were conjugated onto polystyrene beads from the reaction of the N-potassium hydantoin or uracil derivatives onto chloromethylated polystyrene beads. A distinct difference in bromine loading capacity and release profiles was found for the different conjugated derivatives. All tested materials exhibit strong antimicrobial activity against Escherichia coli and bacteriophages MS2 of 7 and ~4 log reduction, respectively. These results highlight the antimicrobial potential of halogenated cyclic molecules containing urea groups as water disinfection agents.

N-bromo-dimethylhydantoin polystyrene resin for water microbial decontamination.

N-bromo-dimethylhydantoin polystyrene beads were synthesized and tested as antimicrobial agents for water microbial decontamination. Optimization of synthetic process was thoroughly investigated, including solvents used, ratio of reactants and reaction conditions, kilogram scale production, and detailed spectral analysis. The microbial inactivation efficiency was studied according to the NSF-231 Guide Standard and Protocol for Testing Microbiological Water Purifiers against Escherichia coli and MS2 phage. The tested resins maintained their activity for 550 L. Thus, N-bromo-dimethylhydantoin-polystyrene beads synthesized under optimized conditions at kilogram quantities have a potential use in water purification filters.

Quaternary ammonium polyethylenimine nanoparticles for treating bacterial contaminated water.

This study highlights the potential application of antimicrobial quaternary ammonium nanomaterials for water disinfection. Quaternary ammonium polyethylenimine (QA-PEI) nanoparticles (NPs) were synthesized by polyethylenimine crosslinking and alkylation with octyl iodide followed by methyl iodide quaternization. Particles modified with octyldodecyl alkyl chains were also prepared and evaluated. The antimicrobial activity of QA-PEI NPs was studied after anchoring in non-leaching polymeric coatings and also in aqueous suspension. Particles at different loadings (w/w) were embedded in polyethylene vinyl acetate and polyethylene methacrylic acid coatings and tested for antimicrobial activity against four representative strains of bacteria in static and dynamic modes. Coatings embedded with fluorescent labelled particles tracked by Axioscope fluorescence microscope during the antimicrobial test indicates no particles leaching out. Coatings loaded with 5% w/w QA-PEI exhibited strong antibacterial activity. Aqueous suspension was tested and found effective for bacterial decontamination at 0.1 ppm and maintains its activity for several weeks.

Quaternary ammonium poly(diethylaminoethyl methacrylate) possessing antimicrobial activity.

Quaternary ammonium (QA) methacrylate monomers and polymers were synthesized from a N-alkylation of N,N-diethylaminoethyl methacrylate (DEAEM) monomer. Linear copolymers, and for the first time reported crosslinked nanoparticles (NPs), based QA-PDEAEM were prepared by radical polymerization of the quaternized QA-DEAEM monomers with either methyl methacrylate (MMA) or a divinyl monomer. QA-PDEAEM NPs of 50-70 nm were embedded in polyethylene vinyl acetate coating. QA-polymers with N-C8 and N-C18 alkyl chains and copolymers with methyl methacrylate were prepared at different molar ratios and examined for their antimicrobial effectiveness. These coatings exhibited strong antibacterial activity against four representative Gram-positive and Gram-negative bacteria.

Controlled iodine release from polyurethane sponges for water decontamination.

Iodinated polyurethane (IPU) sponges were prepared by immersing sponges in aqueous/organic solutions of iodine or exposing sponges to iodine vapors. Iodine was readily adsorbed into the polymers up to 100% (w/w). The adsorption of iodine on the surface was characterized by XPS and SEM analyses. The iodine loaded IPU sponges were coated with ethylene vinyl acetate (EVA), in order to release iodine in a controlled rate for water decontamination combined with active carbon cartridge, which adsorbs the iodine residues after the microbial inactivation. The EVA coated IPU were incorporated in a water purifier and tested for iodine release to water and for microbial inactivation efficiency according to WQA certification program against P231/EPA for 250l, using 25l a day with flow rate of 6-8min/1l. The antimicrobial activity was also studied against Escherichia coli and MS2 phage. Bacterial results exceeded the minimal requirement for bacterial removal of 6log reduction throughout the entire lifespan. At any testing point, no bacteria was detected in the outlet achieving more than 7.1 to more than 8log reduction as calculated upon the inlet concentration. Virus surrogate, MS2, reduction results varied from 4.11log reduction under tap water, and 5.11log reduction under basic water (pH9) to 1.32 for acidic water (pH5). Controlled and stable iodine release was observed with the EVA coated IPU sponges and was effective in deactivating the bacteria and virus present in the contaminated water and thus, these iodinated PU systems could be used in water purification to provide safe drinking water. These sponges may find applications as disinfectants in medicine.