Journal of Water and Environmental Nanotechnology
Volume:5 Issue: 4, Autumn 2020

Photocatalysis mediated by metal nanoparticles is emerging as an effective method for removal of hazardous dye pollutants in natural aquatic bodies. Nanoparticles of Cu, Ni and Ag were synthesized by chemical method using PEG and PVP polymers as capping agents. Experimental photocatalyis was carried out in a one pot batch reactor using metal nanoparticle catalysts for degradation of crystal violet (CV), bromocresol green (BCG) and methylene blue (MB) in aqueous solution in the presence of NaBH4 reductant independently under solar and UV irradiations at 25oC. Metal nanoparticles caused the removal of BCG and CV in 90-120 min and MB in 30-60 min. Linear relationship between the irradiation time and the absorbance were recorded and the kinetic plots exhibited pseudo-first order kinetic. The trend of dye degradation among the nanoparticles based on the catalytic efficiency (c) and rate coefficient (k) values was Cu>Ag>Ni. Mineralization experiment indicated 94, 91 and 90% of TOC removal ratio (R) respectively for CV, MB and BCG dyes. Nanoparticles stabilized using PEG demonstrated better catalytic efficiency than those with PVP. Solar irradiation showed superior augmenting effect on the nanoparticle catalysts than the UV irradiation. The electron-hole pair mediated reduction mechanism was proposed as a basis for photocatalytic degradation of dyes.

Silver and zinc oxide are well known for both antimicrobial and pro-healing properties. ZnO is a biocompatible and bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. ZnO nanomaterials can interact chemically as well as physically to exhibit antibacterial activities. Chemical interactions of the ZnO nanomaterials with bacterial cells lead to the photo-induced production of reactive oxygenated species (ROS), formation of H2O2, and release of Zn2+ ions. In contrast, physical interaction can show biocidal effects through cell envelope rupturing, cellular internalization or mechanical damage. Here, we present a green method using Tridax Procumbens leaf extract to synthesize Ag doped ZnO nanoparticles (NPs) to explore the synergistic antibacterial properties of Ag and ZnO nanoparticles against certain gram positive and gram negative bacterial strains. The newly synthesized Ag doped ZnO NPs were characterized by X-ray diffraction (XRD) to study the crystalline structure, composition and purity. Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and Dynamic Light Scattering (DLS) technique was used to study particle size, shape, and morphology. The XRD and UV studies confirmed the ZnO phase. The absorbance peak around 618 cm-1 - 749 cm-1 in the FTIR spectrum referred presence of silver. The surface morphological studies also supported the FTIR result. The synthesized sample exhibited enhanced antibacterial activity irrespective of all tested microorganisms than the standard antibiotic used. The maximum size distribution of particle is found to be around 60 nm from the DLS technique.

In this study, thiol-functionalized nanostructure silica type MCM-41 was successfully prepared via the facile one-pot hydrothermal method with low amounts of the directing agent. The mesoporous silica indicated a remarkable adsorption behavior toward Pb(II) ions without any interference of the competing ions. The main experimental variables affecting removal efficiency of the adsorbent were examined, and the optimized conditions were achieved as to be 6, 50 mg, and 30 min for solution pH, the adsorbent dosage, and contact time, respectively. The adsorbent was triumphantly used for the removal of Pb (II) ion from real water samples with a notable removal efficiency as 95%. The concentrations of the competitive ions in the solution were about 10 to 100 times more than Pb (II) ions. The results show that other ions had no interfering effect on the removal efficiency of Pb (II) ions. It means that SH-SiO2 has excellent selectivity for Pb (II) ions and is an appropriate candidate for removing Pb (II) ions from the real samples.

The MoS2/S-doped graphitic carbon nitride (MoS2/S-g-C3N4) was synthesized by a simple method and applied for methylene blue (MB) removal as an organic pollutant. The structure of MoS2/S-doped graphitic carbon nitride was characterized using FTIR, XRD, SEM, TGA and BET techniques. The accomplishment of MoS2/S-doped graphitic carbon nitride as an adsorbent was investigated to removal of MB from aqueous solution. The various parameters were studied such as: pH, initial MB concentration, adsorbent dose, temperature and time. The best findings were obtained at pH=8, 8 ppm MB concentration, 0.05 g MoS2/S-g-C3N4, 30 min and 22 ˚C. The Langmuir isotherm model was adopted with the obtained data. The kinetic studies were showed that the adsorption of methylene blue can be well described by the second-order equation. Maximum adsorption was calculated as 166 mg/g. The degradation of MB was studied by MoS2/S-doped graphitic carbon nitride under Light Emmition Diode (LED). Results showed that the MoS2/S-doped graphitic carbon nitride can enhance photocatalytic activity compared to pure g-C3N4 and MoS2/g-C3N4. The findings confirmed that the MoS2/S-doped graphitic carbon nitride can be applied as an efficient, low-cost adsorbent, and photocatalyst to remove of cationic dyes such as methylene blue.

Cobalamins are one of the most complicated cofactors produced by the microorganisms. Propionibacterium freudenreichii has to follow the anaerobic and aerobic conditions respectively during a course of batch fermentation, for the production of the biologically active form of cobalamins. Magnetite (Fe3O4) nanoparticles can modify gas-liquid volumetric mass transfer coefficient in the fermentation system to create more efficient aeration step. Initially, the modified production of Fe3O4 nanoparticle through coprecipitation method was investigated, and the smallest size of nanoparticles optimized to 13.86 nm via Box-Behnken design of response to surface methodology (RSM). The optimum condition was at the synthesis temperature of 60 °C, reaction duration of 10 minutes, and the medium agitation speed of 700 rpm. Synthesized nanoparticles characterized by SEM images, PXRD and EDS analysis while EDS spectrum reflects 39.33% of Fe and 51.8% of oxygen atomic distribution, which confirms Fe3O4 nanoparticles synthesis. Magnetite nanoparticle suspension added to the fermentation medium to compare the effect of nanoparticles incorporation and dimethylbenzimidazole addition on the cobalamin production via Propionibacterium freudenreichii. NPs incorporation in the fermentation broth was able to increase cyanocobalamin production by 20%, while there was no incorporation of external DMBI in the medium. Finally, by the central composite design analysis, cyanocobalamin production from Propionibacterium freudenreichii fermentation was optimized to 1.548 mg.L-1. Oily sludge (as a new carbon source) of 4 %w/v, magnetite nanoparticles suspension of 7.5 %v/v, and the fermentation temperature of 37 °C caused to CCD optimum condition.

Homogenous catalysis which the catalyst operates in the same phase as the reactants is definitely efficient in catalysis processes while it suffers from the impossibility or inconvenience of the removal of the catalyst from the reaction media. In this research, In2S3 nanoparticles were synthesized by a simple precipitation method and then immobilized and stabilized in the porous structure as a substrate. The properties of pure hydrogel and In2S3 in hydrogel were characterized by FTIR, DRS, XRD, BET, BJH, FESEM, and EDX. The DRS results confirmed that the stabilization of nanoparticles in hydrogel led to redshift of bandgap. The hydrogel with In2S3 showed a more porous structure in comparison with pure hydrogel. Because of the decrease of bandgap and increase of specific surface area, In2S3 nanoparticles stabilized in hydrogel removed Rhodamine B (RhB) as a model pollutant very well. The performance of catalyst in the removal of RhB under dark condition (adsorption) and visible light irradiation (photocatalysis) was investigated and 77.7% and 95.2% of dye removal percentage were obtained in 120 min under dark and light irradiation, respectively. In conclusion, immobilization In2S3 as a high-efficiency visible light photocatalyst in hydrogel provided promising heterogeneous and reusable catalyst for water treatment

Notwithstanding the enormous benefit of crizotinib, as anti lung cancer, severe toxicity as side effects are the main problem for this drug. In this research, the interaction of crizotinib over NH2 agent with C60 fullerene, boron-doped fullerene (C59B), and carboxylated fullerenes (C60COOH) using density functional theory at B3LYP/6-311G(d) theoretical level in the gaseous phase and the water solvent were evaluated. Comparison of the drug-fullerenes complex in terms of structure, energy, type of interaction was performed through optimization, frequency, natural bond orbital, and atoms in molecules calculations. The results showed that the interaction of the drug with fullerenes due to the positive interaction energy and the unstable complexation could not be proper interaction between the drug and the nanoparticle. Binding between crizotinib and C59B is covalent, and the drug absorption is chemical. The interaction between crizotinib with C60COOH has been recognized as appropriate due to some properties such as higher solubility in water, relative stability, hydrogen bonding, and physical absorption of the drug. The result of this research can be counted as a promising strategy to reduce the toxicity and develop the anti lung cancer activity of crizotinib.

Reducing the entry of heavy metals into the food chain in plant cultivated in the areas contaminated with heavy compounds or petroleum compounds is one of the main environmental issues. This research was conducted to evaluate the role of co-inoculation of wheat with piriformospora indica and pseudomonas putida on plant Cd concentration which has been planted in the Cd and petroleum hydrocarbon -polluted soil and treated with Zn oxide nanoparticles and agricultural steel slag. Treatments consisted of Cd-polluted soil (0, 10 and 20 mg kg-1 soil) that was amended with 0 and 2 % (W/W) Zn oxide nanoparticles and agricultural steel slag and the wheat plant that was co-inoculated with P.indica and P.putida that which was cultivated in a soil that was naturally polluted with petroleum hydrocarbon. After 90 days, plants were harvested and the Cd concentration was measured using atomic absorption spectroscopy. In addition the degradation rate of petroleum hydrocarbon in the soil was determined. Plant co-inoculation with P.indica and P.putida significantly decreased and increased the plant Cd concentration and degradation rate of petroleum hydrocarbon in the soil by 13.1 and 14.9%, respectively. In addition, using 2 % (W/W) Zn oxide nanoparticles and agricultural steel slag significantly decresed the plant Cd concentration by 18.2 and 15.4%, respectively. It can be concluded that plant co-inoculation with P.indica and P.putida had additive effect on degradation of petroleum hydrocarbon in the soil that was amended with Zn oxide nanoparticles and agricultural steel slag.