Tackling the challenge of drying and redispersion of cellulose nanofibrils via membrane-facilitated liquid phase exchange.

It is generally acknowledged that to advance the application of cellulose nanofibrils (CNFs) in product formulations, challenges associated with the drying and redispersion of this material must be addressed. Despite increased research efforts in this area, these interventions still involve the use of additives or conventional drying technologies, which both have the capacity to drive up the cost of the final CNF powders. Herein, we prepared dried and redispersible CNF powders with varying surface functionalities without the use of additives nor conventional drying technologies. Rapid drying in air was achieved after liquid phase exchange from water to isopropyl alcohol. The surface properties, morphology and thermal stabilities were the same for the never-dried and redispersed forms. The rheological properties of the CNFs were also unaffected after drying and redispersion of unmodified and organic acid modified materials. However, for 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-mediated oxidised CNFs with higher surface charge and longer fibrils, the storage modulus could not be recovered to the never-dried state because of the possible non-selective reduction in length upon redispersion. Nevertheless, this method provides an effective and low-cost process for the drying and redispersion of unmodified and surface modified CNFs.

Cellulose: A Review of Water Interactions, Applications in Composites, and Water Treatment.

Cellulose is known to interact well with water, but is insoluble in it. Many polysaccharides such as cellulose are known to have significant hydrogen bond networks joining the molecular chains, and yet they are recalcitrant to aqueous solvents. This review charts the interaction of cellulose with water but with emphasis on the formation of both natural and synthetic fiber composites. Covering studies concerning the interaction of water with wood, the biosynthesis of cellulose in the cell wall, to its dispersion in aqueous suspensions and ultimately in water filtration and fiber-based composite materials this review explores water-cellulose interactions and how they can be exploited for synthetic and natural composites. The suggestion that cellulose is amphiphilic is critically reviewed, with relevance to its processing. Building on this, progress made in using various charged and modified forms of nanocellulose to stabilize oil-water emulsions is addressed. The role of water in the aqueous formation of chiral nematic liquid crystals, and subsequently when dried into composite films is covered. The review will also address the use of cellulose as an aid to water filtration as one area where interactions can be used effectively to prosper human life.

Amphiphilic Cellulose Nanocrystals for Aqueous Processing of Thermoplastics.

Conventional composite formulation of cellulose nanocrystals (CNCs) with thermoplastics involves melt compounding or in situ polymerisation. In this rather unconventional approach, polypropylene (PP) microparticles were finely suspended and stabilized, at varying weight loadings, in aqueous suspensions of amphiphilic CNCs to enable adsorption of the nanoparticles onto the thermoplastic. In order to achieve these suspensions, CNCs were modified with either octyl or hexadecyl groups. These modifications imparted hydrophobic properties to the CNCs, hence increasing interfacial adhesion to the PP microparticles. The modification, however, also retained the sulfate half ester groups that ensured dispersibility in aqueous media. The CNCs were evidently coated on the PP microparticles as revealed by confocal microscope imaging and had no detrimental effect on the melt properties of the PP-based composites. The approach is demonstrated to increase the Young's moduli of CNC-thermoplastic composites prepared in optimum suspension loadings of 0.5 wt. % octyl-modified and 0.1 wt % hexadecyl-modified CNCs. This procedure can be extended to other thermoplastics as the ability to aqueously process these composites is a major step forward in the drive for more sustainable manufacturing.

Target and Suspect Screening of Pharmaceuticals and their Transformation Products in the Klip River, South Africa, using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry.

In spite of recent reports about the presence of pharmaceuticals in African water bodies, their prevalence has still not been sufficiently quantified. The few available studies have mostly focused on a limited number of pharmaceuticals. In the present study, a suspect screening of 92 compounds (mainly pharmaceuticals and their transformation products) along the Klip River, South Africa was conducted, followed by target monitoring of 21 of the detected pharmaceuticals. The experimental approach was based on solid-phase extraction followed by analysis with ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UHPLC-QTOF-MS). The results revealed 47 pharmaceuticals, 31 of which were detected for the first time in South African waters. Seven detected pharmaceuticals (propyphenazole, sulfamerazine, levamisole, tryptophan, dibucaine, albuterol, and fenpropimorph) are not approved medications in South Africa. Six pharmaceutical metabolites were detected for the first time in South Africa. Pharmaceuticals with the highest concentrations in river water were flumequine (0.257 µg L-1 ), oxolinic acid (0.355 µg L-1 ), and acetaminophen (0.432 µg L-1 ). Oxolinic acid presented the highest hazard quotient, 48.6, indicating a risk of toxicity to aquatic organisms. Hazard quotients for other pharmaceuticals were below 1, except that of flumequine, which reached 1.285. These results suggest a need for further research into the fate of pharmaceuticals in surface waters, and a quantification of the risks associated with the identified drugs because they are likely to accumulate in the tissues of fish/aquatic organisms, thus affecting humans. Environ Toxicol Chem 2022;41:437-447. © 2021 SETAC.

Synthesis and application of cationised cellulose for removal of Cr(VI) from acid mine-drainage contaminated water.

Background: Acid mine drainage (AMD) leads to contamination of surface and ground water by high levels of toxic metals including chromium. In many cases, these waters are sources of drinking water for communities, and treatment is therefore required before consumption to prevent negative health effects. Methods: Cationised hemp cellulose was prepared by etherification with two quaternary ammonium salts: 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) and glycidyltrimethylammonium chloride (GTMAC) and examined for (i) the efficiency of Cr(VI) removal under acid mine-drainage (AMD) conditions, and (ii) antibacterial activity. Adsorbents were characterised by electron microscopy, Fourier transform infrared (FTIR), CP-MAS 13C nuclear magnetic resonance (NMR) spectroscopy, elemental composition and surface charge. Results: FTIR and solid state 13C NMR confirmed the introduction of quaternary ammonium moieties on cellulose. 13C NMR also showed that cationisation decreased the degree of crystallisation and lateral dimensions of cellulose fibrils. Nevertheless, 47 %  - 72 % of Cr(VI) ions were removed from solutions at pH 4, by 0.1 g of CHPTAC and GTMAC-cationised cellulose, respectively. Adsorption kinetics followed the pseudo-second order model and isotherms were best described by the Freundlich and Dubinin-Radushkevich models. When GTMAC-modified cellulose was applied to AMD contaminated water (pH 2.7); however, Cr(VI) removal decreased to 22% likely due to competition from Al and Fe ions. Cationised materials displayed considerable antibacterial effects, reducing the viability of Escherichia coli by up to 45 % after just 3 hours of exposure. Conclusions: Together, these results suggest that cationised cellulose can be applied in the treatment of Cr(VI)-contaminated mine water particularly if pre-treatments to reduce Fe and Al concentrations are applied.

Synthesis of bismuth oxyhalide (BiOBr zI (1- z)) solid solutions for photodegradation of methylene blue dye.

Background: The removal of textile wastes is a priority due to their mutagenic and carcinogenic properties.  In this study, bismuth oxyhalide was used in the removal of methylene blue (MB) which is a textile waste. The main objective of this study was to develop and investigate the applicability of a bismuth oxyhalide (BiOBr zI (1-z)) solid solutions in the photodegradation of MB under solar and ultraviolet (UV) light irradiation. Methods: Bismuth oxyhalide (BiOBr zI (1-z)) (0 ≤ z ≤ 1) materials were successfully prepared through the hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) were used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBr zI (1-z) materials was examined through methylene blue (MB) degradation under UV light and solar irradiation. Results: The XRD showed that BiOBr zI (1-z) materials crystallized into a tetragonal crystal structure with (102) peak slightly shifting to lower diffraction angle with an increase in the amount of iodide (I -). BiOBr 0.6I 0.4 materials showed a point of zero charge of 5.29 and presented the highest photocatalytic activity in the removal of MB with 99% and 88% efficiency under solar and UV irradiation, respectively. The kinetics studies of MB removal by BiOBr zI (1-z) materials showed that the degradation process followed nonlinear pseudo-first-order model indicating that the removal of MB depends on the population of the adsorption sites. Trapping experiments confirmed that photogenerated holes (h +) and superoxide radicals ( •O 2 -) are the key species responsible for the degradation of MB. Conclusions : This study shows that bismuth oxyhalide materials are very active in the degradation of methylene blue dye using sunlight and thus they have great potential in safeguarding public health and the environment from the dye's degradation standpoint. Moreover, the experimental results agree with nonlinear fitting.

Recycled and desalinated water: Consumers' associations, and the influence of affect and disgust on willingness to use.

Traditional water sources are increasingly coming under pressure from urbanization, population and industrial growth as well as climate variability and alternatives such as desalinated and recycled water will need to be considered in the future. However, available data indicate that consumers are apprehensive about these alternative water sources, with many reactions centered on disgust. It is not clear though, whether trait or state disgust is responsible for these disgust reactions. Secondly, the associations the public has with desalinated and recycled water are not well described, even though knowledge of these associations would provide the holistic understanding required for addressing perceptions. Using respondents from Australia and South Africa, therefore, this study investigated the associations people have with recycled and desalinated water, as well as the influence of affect, institutional trust, cultural/religious beliefs, water scarcity, and demographic variables, on willingness to use (WTU) these waters. The results show that whereas recycled water is associated with negative affect from notions of disgust, desalinated water is often thought of in terms of minerals, or as "simply water". We also found that affect was the most significant predictor, and that state disgust as well as trait disgust influenced WTU. Together these data suggest that disgust-related rejection of is likely due to the disgust elicited by the waters rather than disgust-proneness of individuals. It is plausible, therefore, that efforts to induce positive affect through making salient positive associations e.g. NEWater in Singapore, may increase WTU.

Cross-cultural validation of the short version of the Food Disgust Scale in ten countries.

The cross-cultural testing of scales represents an important step in the scale validation process. The present study evaluated whether the eight-item short version of the recently developed Food Disgust Scale (FDS-short) is a reliable and valid tool for measuring food disgust sensitivity in ten countries: Australia, China, England, France, Germany, Mexico, South Africa, Spain, Sweden, and the USA. In an online survey, the participants (N = 6128) answered items from the FDS-short and other scales related to (food) disgust sensitivity so as to test the construct and criterion validity of the FDS-short. Confirmatory factor analysis of the one-factor structure of the FDS-short revealed an adequate to good model fit in all the countries except for China. Multiple group analysis to test measurement invariance showed the FDS-short to be metrically invariant in all the tested countries (except for China) relative to Australia. With regard to the construct validity, significant positive correlations were observed in all the countries between the FDS-short and pathogen disgust sensitivity, sexual disgust sensitivity, moral disgust sensitivity, germ aversion, and food neophobia. Criterion validity of the FDS-short in all the tested countries was confirmed by the positive correlations between it and having a sensitive stomach, experiencing gastrointestinal complaints after eating animal-based foods (except for France and Germany), and the perceived infection risk of food-borne diseases in one's country. The direction of the correlations indicated that for each country, those with higher FDS-short scores also scored higher on all the tested constructs than those with lower FDS-short scores. Taken together, the present results indicate that the FDS-short is a reliable and valid tool for assessing food disgust sensitivity across countries.

Tap versus bottled water consumption: The influence of social norms, affect and image on consumer choice.

What drives consumers to choose bottled water instead of tap water where the latter is safe, accessible, costs far less, and in spite of its environmental impacts? This research investigates the influence of hitherto unexplored psychological drivers in an attempt to generate a more holistic understanding of the phenomenon, and strategies for designing more effective consumption reduction campaigns. Using data from an internet survey of Swiss and German respondents (N = 849) we investigated the role of, social norms, affect and image on water consumption. Results suggest that these psychological factors play a role in water consumption choice. Convenience was the only contextual predictor - the inconvenience of transporting bottled water has a negative effect on its consumption, and a positive effect on tap water consumption. Although concern about the effect of bottled water on the environment was not a significant predictor of tap water consumption, we found that for some people, a link exists between environmental concern and consumption choice. Ways through which consumers may be more effectively influenced towards environmentally-friendly consumption are discussed.