Water scarcity and strict legislation make water reuse in dye related industries like textile and leather become more important. Among the different types of dyes, soluble dyes are the most problematic. Nanofiltration was vital for the treatment of dye wastewater but the major limitation is fouling. Coagulation/flocculation can be effective to enhance nanofiltration performance towards water reuse and minimisation of fouling. The selection of the coagulant type (metal or polymer) and dosages are very critical in this technique. Factors that improved the coagulation were studied in detail and suitable metal coagulants were presented. Cationic, anionic and natural polymers as flocculant aids were also reported for successfully enhancing dye removal. Adding a suitable type of metal coagulant-polymer at an optimum dosage and mixing conditions increases the dye removal at a wider range of operating pH and reduces the production of sludge. In-depth studies on the effect of metal coagulant-polymer on membrane fouling are still lacking and visualisation techniques might be helpful in this regard.
Currently, no medicine has demonstrated efficacy in treating the ongoing pandemic COVID-19 caused by SARS-CoV-2 virus. Being a potent oxidant, ozone is lethal against most bacteria and viruses found in water, or on surfaces and aerosols. Ozone has also been successfully used to treat several viral diseases such as Ebola and HIV Hepatitis B and C. Using molecular modeling, this study evaluated the reactivity of ozone toward representative key molecules in the structure of SARS-CoV-2. The results show that ozone is able to attack the proteins and lipids of the virus's spikes and envelope, particularly the amino acids tryptophan, methionine and cysteine, and the fatty acids, arachidonic acid, linoleic acid, and oleic acid. Ozone also attacks the N-glycopeptides of the spike protein subunits 1 and 2, though at lower reactivity. Disruption of the structure of SARS-CoV-2 could inactivate the virus, suggesting that ozone could be an effective oxidant against COVID-19 virus. If incorrectly applied, ozone is toxic and contact with the respiratory tract must be avoided.
A simplified model that considered the oil constituents as one constituent, anethole, the major component, was used to describe the mass transfer of steam extraction of aniseed essential oil. The model can be used to optimise and control the process. Depending on the oil content, two mass transfer regimes were identified (i) the first one corresponds to an unsaturated surface extraction and (ii) the second corresponds to the slower transfer of oil from the deeper parts of the material to the surface, which may be due to concentration gradients and chemical bonding. The model was validated by experimental data obtained from a pilot-plant system. Solid-steam mass transfer coefficients were determined and a critical oil content was found to limit the two mass transfer regimes. The value for this critical oil concentration (x B ) was found to be 0.011 (g oil g −1 solid). In addition, an optimal operating pressure of 200 kPa was found to give maximum extraction yield.
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