Highly efficient and antibacterial ion exchanger based on graphene oxide for removal of chromate and nitrate from water: synthesis, characterization and application

A novel recyclable antibacterial anion exchanger based on graphene oxide (GO) and quaternary ammonium chloride (TMSQA) as a crosslinker/ion exchanger was prepared and used for the removal of chromate and nitrate from water.

Allergen Removal and Transfer with Wiping and Cleaning Methods Used in Retail and Food Service Establishments

ABSTRACT Preventing the transfer of allergens from one food to another via food contact surfaces in retail food environments is an important aspect of retail food safety. Existing recommendations for wiping and cleaning food contact surfaces is mainly focused on preventing microorganisms, such as bacteria and viruses, from contaminating foods. The effectiveness of these wiping and cleaning recommendations for preventing the transfer of food allergens in retail and food service establishments remains unclear. This project investigated (i) allergen removal from surfaces by wiping with paper wipes, terry cloth, and alcohol quaternary ammonium chloride (quat) sanitizing wipes; (ii) cleaning of allergen-contaminated surfaces by using a wash–rinse–sanitize–air dry procedure; and (iii) allergen transfer from contaminated wipes to multiple surfaces. Food contact surfaces (stainless steel, textured plastic, and maple wood) were contaminated with peanut-, milk- and egg-containing foods and subjected to various wiping and cleaning procedures. For transfer experiments, dry paper wipes or wet cloths contaminated with allergenic foods were wiped on four surfaces of the same composition. Allergen-specific lateral flow devices were used to detect the presence of allergen residues on wiped or cleaned surfaces. Although dry wipes and cloths were not effective for removing allergenic foods, terry cloth presoaked in water or sanitizer solution, use of multiple quat wipes, and the wash–rinse–sanitize–air dry procedure were effective in allergen removal from surfaces. Allergens present on dry wipes were transferred to wiped surfaces. In contrast, minimal or no allergen transfer to surfaces was found when allergen-contaminated terry cloth was submerged in sanitizer solution prior to wiping surfaces. The full cleaning method (wash–rinse–sanitize–air dry) and soaking the terry cloth in sanitizer solution prior to wiping were effective at allergen removal and minimizing allergen transfer. HIGHLIGHTS

Efficacy of Commercial Sanitizers Used in Food Processing Facilities for Inactivation of Listeria monocytogenes, E. Coli O157:H7, and Salmonella Biofilms

Bacteria entrapped in biofilms are a source of recurring problems in food processing environments. We recently developed a robust, 7-day biofilm microplate protocol for creating biofilms with strongly adherent strains of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella serovars that could be used to examine the effectiveness of various commercial sanitizers. Listeria monocytogenes 99-38, E.coli O157:H7 F4546, and Salmonella Montevideo FSIS 051 were determined from prior studies to be good biofilm formers and could be recovered and enumerated from biofilms following treatment with trypsin. Extended biofilms were generated by cycles of growth and washing daily, for 7 days, to remove planktonic cells. We examined five different sanitizers (three used at two different concentrations) for efficacy against the three pathogenic biofilms. Quaternary ammonium chloride (QAC) and chlorine-based sanitizers were the least effective, showing partial inhibition of the various biofilms within 2 h (1–2 log reduction). The best performing sanitizer across all three pathogens was a combination of modified QAC, hydrogen peroxide, and diacetin which resulted in ~6–7 log reduction, reaching levels below our limit of detection (LOD) within 1–2.5 min. All treatments were performed in triplicate replication and analyzed by one way repeated measures analysis of variance (RM-ANOVA) to determine significant differences (p < 0.05) in the response to sanitizer treatment over time. Analysis of 7-day biofilms by scanning electron microscopy (SEM) suggests the involvement of extracellular polysaccharides with Salmonella and E. coli, which may make their biofilms more impervious to sanitizers than L. monocytogenes.

Anion Metathesis in Facile Preparation of Olefin Metathesis Catalysts Bearing a Quaternary Ammonium Chloride Tag

Easy and efficient method for preparation of all-chloro ruthenium catalysts bearing a quaternary ammonium tag was developed. The key anion metathesis reaction was made with AgCl, and the facile recycling of silver wastes was demonstrated. The developed method transforms more accessible, yet poorly characterised mixed chloro/iodo Ru complexes into valuable all-chloro catalysts, useful in aqueous metathesis. Practical utility of the developed anion metathesis reaction was demonstrated by preparation of a commercial Ru catalyst, StickyCat™, on a 5 gram scale.

Influence of Nanoparticle Pretreatment on the Thermal, Rheological and Mechanical Properties of PLA-PBSA Nanocomposites Incorporating Cellulose Nanocrystals or Montmorillonite

Nanoparticles based on cellulose nanocrystals (CNC) and montmorillonite clay (MMT) were prepared using spray freeze-drying. The nanoparticles were then used as reinforcement to prepare nanocomposites with poly(lactic acid) (PLA) as the polymer matrix. The effect of spray freeze-dried CNC (SFD-CNC) and spray freeze-dried MMT (SFD-MMT) on the rheological and mechanical properties of PLA and its blends with poly[(butylene succinate)-co-adipate)] (PBSA) were investigated. An epoxy chain extender was used during preparation of the blends and nanocomposites to enhance the mechanical properties of the products. Different methods such as scanning electron microscopy, X-ray diffraction and adsorption/desorption analyses were used to characterize the prepared nanoparticles and their localization in the blends. Dynamic oscillatory shear behavior, elongational viscosity and mechanical characteristics of the nanocomposites of PLA and the blends were evaluated. The results obtained for nanocomposites filled with unmodified SFD-MMT were compared with those obtained when the filler was a commercial organically modified montmorillonite nanoclay (methyl-tallow-bis(2-hydroxyeethyl) quaternary ammonium chloride) (C30B), which was not spray freeze-dried.