Volume 58, Issue 6

The coronavirus disease 2019 (COVID-19) has led to serious health and economic damage to all over the world, and it still remains unstoppable. The SARS-CoV-2, by using its S-glycoprotein, binds with an angiotensin-converting enzyme 2 receptor, mostly present in alveolar epithelial type II cells. Eventually pulmonary surfactant depletion occurs. The pulmonary surfactant is necessary for maintaining the natural immunity as well as the surface tension reduction within the lung alveoli during the expiration. Its insufficiency results in the reduction of blood oxygenation, poor pulmonary regeneration, lung fibrosis, and finally the respiratory system collapses. Exogenous surfactants have previously shown great promise in the treatment of infant respiratory distress syndrome, and they may also aid in the healing of damaged alveolar cells and the prevention of respiratory failure. Surfactant based therapy has been advised for the prevention of COVID-19, and the trials have begun around the world. Furthermore, greater research on the timing, dose, and the distribution of surfactant to the COVID-19 patients is required before this technique can be implemented in clinical practice.

The global community is struggling with the highly contagious COVID-19. Returning to \normal life" now poses risks, and the use of appropriate protective measures has become necessary to continue daily life and protect public health. The main protective measures to prevent transmission of COVID-19 are masks, soaps and disinfectants. Because coronavirus is a \lipid-enveloped virus", it is very sensitive to lipid-dissolving chemicals and can therefore be effectively removed by washing hands sufficiently with soap and water. However, using an alcohol-based disinfectant is a more viable option for outdoor use. Alcohol-based disinfectants are inexpensive, immediately effective, easy to use and better tolerated by the skin compared to other disinfectants. WHO recommends disinfectants containing 75% isopropanol or 80% ethanol as highly effective in inactivating the SARS-CoV-2-virus. The current review discusses the role of alcohol-based hand sanitizers (ABHS) in preventing the spread of viruses, their side effects on human health, and suggests the use of alcohol-based sanitizers as potentially effective in combating the current epidemic.

A rapid, simple and economical spectrofluorimetric method for the determination of diclofenac potassium in pure form, in pharmaceutical preparations and in human plasma has been developed. The method is based on the enhancement of the fluorescence signal of diclofenac potassium by the addition of sodium dodecyl sulphate in McIvaine buffer with a pH of 5. Different experimental conditions such as buffer type, pH, type and concentration of surfactants were investigated. The fluorescence intensity of the solution was recorded at 361 nm after excitation at 243 nm. The method shows linearity in the concentration range of 0.2 μg mL –1 –10 μg mL –1 with a good correlation coefficient of 0.997. The relative standard deviation value was 3.62 (n = 7). The limit of detection and limit of quantification were calculated to be 2.84 × 10 –3 μg mL –1 and 9.47 × 10 –3 μg mL-1, respectively. The effect of excipients and co-administrated drugs was investigated and no interference was observed. The method was successfully applied for the determination of diclofenac potassium in pure form, in pharmaceutical products and in human plasma. The percentage recoveries obtained ranged from 100.25% to 102.16% for pure form and 97.50% to 102.00% for pharmaceutical products and from 98.50% to 101.67% for human plasma.

In the present study, three potentially Pb(II)-resistant and biosurfactant-producing bacterial strains were isolated from a total of 23 strains using various screening methods, investigated for their biosorption of Pb(II) and used for the biodegradation of used motor oil. The results show that strain E1 (Bacillus haynesii) has significantly high efficiency in biodegradation of used motor oil, up to 82 % in the first three days. Maximum Pb(II) biosorption capacities of 238.09 mg/g and 99.01 mg/g were determined for strains E1 and F5 (Pseudomonas aeruginosa), respectively. The biosorption process was found to be in good agreement with the Langmuir isotherm for both E1 (R 2 = 0.9614) and F5 (R 2 = 0.9646), suggesting monolayer biosorption. The four common screening methods, namely the haemolytic assay, the determination of surface tension, the emulsifying activity and the foam test, were also correlated with the Pearson correlation method.

In the present study, the lipase from Aspergillus fumigatus was purified which was found to be stable to commercial detergents and oxidising agents. A purification fold of 6.96 and yield of 11.03% were achieved when the enzyme was purified using Octyl Sepharose column chromatography. In presence of various oxidizing agents, the highest activity of lipase was 15.56 U/mg with hydrogen peroxide. Among various surfactants used, the maximum activity exhibited by lipase was with Tween 80. While studying the effect of various detergents, the highest activity of 9.3 U/mg was achieved with "Vanish" detergent. Wash performance was studied with various detergents out of which "Vanish" showed highest oil removal of 79%. Lipase from Aspergillus fumigatus possessed better stability with various surfactants and oxidizing agents. The results of this study have shown that the lipase from Aspergillus fumigatus along with detergent "Vanish" (0.7%) under optimized conditions (5 μg/ml lipase, 40°C wash temperature and 40 min wash duration) improved oil removal from cotton fabric stained with mustard oil by 84%.

In this work, a series of emulsifiers were prepared by changing the molar ratio of polyvinyl alcohol (PVA) to the long chain quaternary ammonium salt (A 0 ). The emulsifiers were characterised by FTIR and 1 HNMR. The stability of the emulsions was checked and evaluated by determining the phase separation and by UV-Vis spectrophotometry. The emulsion stability increased with increasing emulsifier concentration, which was mainly due to the reduced droplet size and increased viscosity of the emulsions. Stability was also dependent on pH. At pH values between 5 to 3, stability was increased, but at further decreasing pH values, the emulsion became unstable or the emulsion separated. This could be mainly because the excess of positive ions compresses the double electron layer. The experimental results showed that PVA as a macromolecular matrix material has a great application potential for the emulsification process.

A novel amphoteric asphalt emulsifier of octadecylbis(propanamide)-(3’-sodium phosphate-2’-hydroxypropyl)ammonium chloride was synthesised from the raw materials octadecylamine, acrylamide, epichlorohydrin and sodium dihydrogen phosphate. The tertiary amine octadecyl-bis(propanamide) was synthesised from octadecylamine and acrylamide (step 1). Sodium 3-chloro-2-hydroxypropyl phosphate (intermediate) was obtained from epichlorohydrin and sodium dihydrogen phosphate (step 2). The asphalt emulsifier was obtained from octadecyl-bis(propanamide)-tertiary amine and the intermediate by quaternisation reaction (step 3). The yield of the final product reached 94.90%. The structure was identified by FTIR, 1 H-NMR and elemental analysis. The critical micelle concentration of the product is 1.46 × 10 –5 mol L –1 . The surface tension at CMC is 37.78 mN ν –1 . The saturated adsorption amount of asphalt emulsifier is 2.72 × 10 –3 mmol ν –2 . The occupied area per asphalt emulsifier molecule at CMC is 0.611 nm 2 mol –1 . The surfactant is a fast-setting asphalt emulsifier.

Surfactants are very often used in tertiary oil production. However, the conventional surfactants cannot be used in high salinity reservoirs of tertiary oil production because the high salinity leads to the deactivation of the surfactants. Gemini sulpho-betaine surfactants have been developed to meet the requirements of tertiary oil production in such reservoirs. In this study, the Gemini sulphobetaine surfactant (bis{[(N-methyl-N-(3-alkoxy-2-hydroxy)propyl-N-(3-sulfonate)propyl]methylene}) was prepared by etherification, ring opening reaction and sulfonation reaction with decyl alcohol, epichlorohydrin, N,N’-dimethyl ethylene diamine and 1,3-propanesultone. The experimental conditions obtained are: the ratio of 1,3-propanesulfonic acid lactone to tertiary amine intermediate = 2.3 : 1, reaction temperature = 70°C and reaction time = 11 h. The analysis of the infrared spectrum showed that the structure of the synthesised substance corresponds to that of a Gemini sulphobetaine surfactant. The chemical shifts of the groups were determined by 1 HNMR structural characterisation of the products. The surface tension, emulsifying properties, foaming properties and wetting properties were investigated. The results showed that the surfactant has good foaming properties and good compatibility in a high salt environment.

In this study, a magnetic carbon nanocomposite (MCNC) was prepared using peanut shell biomass as carbon source. The prepared adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analysis (TGA/DTA) and BET surface analysis. Batch experiments were carried out to determine the adsorption parameters of cetyl dimethylethyl ammonium bromide (CDEAB) on MCNC. Of the isotherm and kinetics models used, the Langmuir model fitted the equilibrium adsorption data best, while the kinetics data were best explained by the second-order kinetic pseudo-equation. The numerical values of enthalpy change (ΔH8 = 38 kJ mol –1 ) and Gibb free energy (ΔG8 = 70.95 kJ mol –1 , 72.19 kJ mol –1 and 73.32 kJ mol –1 corresponding to 20°C, 30°C and 40 °C, respectively) were positive, while the value of entropy change (ΔS8 = –0.11 kJ mol –1 K –1 ) indicated an endothermic and non-spontaneous process. After determining the optimal adsorption parameters, the adsorbent was used in a hybrid plant with a membrane pilot plant equipped with ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes. In MCNC/membrane operation, an improvement in permeate flux was observed for the three selected membranes. The percentage retention of UF and NF membranes was also improved by MCNC pre-treatments in hybrid mode.

Pollution by heavy metals has become a problem that needs to be solved urgently. Therefore, the development of new efficient adsorbents to treat this pollution is of great importance. Due to their excellent adsorption properties and good biodegradability, natural polymeric materials are potential problem solvers. This study reports on the production and application of polypropylene glycol modified chitosan composites (PMC). The PMC composite material has many functional groups (–OH and –NH 2 ). Its maximum adsorption capacity for Cu(II) is 661.8 mg g –1 . The corresponding adsorption studies, including the effects of pH, contact time and amount of adsorbent, showed that the PMC composite has potential application value.