Journal of Water and Environmental Nanotechnology
Volume:7 Issue: 4, Autumn 2022

Dyes are produced as water pollutants in the textile, plastic, and dye industries. Many efforts have been made to remove dyes from industrial wastewater. In this area, Photocatalytic performance under Vis-lights is a useful and effective method. In this study, a series of highly efficient Sn-doped TiO2 photocatalysts were successfully developed using a simple heat treatment process. Three concentrations of SnCl2 powder (3%, 5%, and 7 %) were used for the preparation of materials.  The characterizations of resulting materials were distinguished by scanning electron microscopy (SEM), diffusion reflection spectroscopy (DRS), and X-ray diffraction spectroscopy (EDX). Also, methyl orange dye was served to indicate the photocatalytic activity of Sn-doped material under visible light irradiation. The results indicated that both doped and also pure TiO2 have a uniform size. Anatase was the only identified phase in all the products, whether doped or un-doped. The resulting Sn-doped materials have demonstrated a band gap value range of 3.14 to 2.68 eV in comparison with pure TiO2 which shows a value of 3.2 eV. The photocatalytic evaluations indicated that the samples prepared in the presence of 3, 5, and 7% SnCl2 have degradation efficiencies of 85%, 85%, and 90%, respectively within 120 min, which are much higher than that of un-doped TiO2. The enhancement in the efficiency was attributed to the gap changes in anatase by the incorporation of Sn ions into the TiO2 lattice structure. Compared to pure TiO2, which has a band gap of 3.2 eV, the band gap values for doped TiO2 ranged from 3.14 to 2.68 eV.

Pure and copper-doped Zirconium oxide nanoparticles were synthesized using a co-precipitation process and investigated the effect of doping on photocatalytic and anti-microbial activities. The prepared samples are pure tetragonal phase, as shown by the X-ray diffraction pattern, and the crystallite size decreases as the dopant concentration increases. Higher dopant concentrations resulted in needle-shaped morphology, as seen in the SEM image. The presence of Zr, Cu, and O in the sample is confirmed by EDS analysis. According to UV-VIS analysis, when the Cu content is increased, a more significant wavelength absorption band edge is formed, and the band gap reduces with the increase in dopant concentration. All samples have magnetic hysteresis loops with diamagnetic background effects, according to VSM tests. A prominent and influential peak at 485nm in the PL spectra suggests that ZrO2 nanoparticles emit blue light. The produced nanoparticles were utilized as a photocatalyst to degrade Methylene Blue (MB) dye, and the results indicate that a high dopant concentration (0.08wt percent) outperforms pure and other dopant concentrations. Copper-doped ZrO2 has moderate anti-bacterial and anti-fungal activities.

The present study explores the green approach for the preparation of silver nanoparticles (AgNPs) through the reduction of silver nitrate by the cell-free stem and leaf aqueous extracts of Litsea glutinosa (L.glutinosa) and its potential antibacterial activity. The analytical instruments include scanning electron microscopy, Fourier transforms infrared spectroscopy, UV-visible spectroscopy, and X-ray diffraction spectroscopy confirmed the synthesis of smaller, uniformly spherical AgNPs (10-40 nm). The average crystalline size of prepared AgNPs produced by L. glutinosa leaf extract was found to be 19 mm. From UV-visible spectral analysis, the maximum absorbance peak appeared at 444 nm for leaf extract AgNPs different from stem extract AgNPs (422 nm), which are found to be specific for AgNPs. The L.glutinosa stem extract-assisted AgNPs have shown significant antibacterial activity against Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) in comparison to Gentamycin. Hence, the AgNPs obtained by green synthesis can be therapeutically explored against bacterial infections.

The key to simple and rapid detection of a large volume of samples lies in the hands of solution-based nanomaterial sensors. Quantification of mercury in the river and coastal water is analytically challenging due to the potential interference of the matrix. In this endeavor, lysine-capped gold nanoparticles (Lys-AuNPs) based colorimetric sensors are demonstrated here towards efficient detection of trace amounts of mercury ions (Hg2+) in coastal and estuarine water. The colorimetric behavior of Lys-AuNPs is related to surface plasmon resonance (SPR)During analysis, interestingly a decrease in the intensity of the original SPR peak at 530 nm was observed, with the concomitant appearance of a new peak at a longer wavelength due to agglomerated Lys- AuNPs. Developed sensors exhibit excellent performance in different environmental samples with high selectivity towards Hg2+ ions in the presence of other metal ions. For the analysis of coastal water samples, a low value of regression coefficient was observed due to the potential interference of salt in the sample. To overcome this, matrix-matching experiments were carried out. Developed Lys- AuNPs show good selectivity towards Hg2+ in matrixed matched diluted coastal water samples. With a sensitivity of 0.02 ppm, the sensor can be utilized to screen large numbers of coastal water samples for their Hg2+ content to satisfy coastal regulation norms. As a whole, this method is simple, sensitive, selective, cost-effective and can be used to screen large numbers of samples across the coastal area for monitoring Hg2+ concentration.

The bioactive compounds in extracts are prone to degradation by oxidation, heat, or light. Nanoencapsulation is one of the best techniques to keep the properties of these chemical compounds. The aim of this study was the extraction of Melissa officinalis (MO) and nanoencapsulation of the extract via chitosan as a biodegradable polymer. In this research, extraction of MO was investigated using various extraction methods and nanoencapsulation with MO extract was carried out via ionic gelation technique. The effectiveness of the extracts was evaluated by measuring the total phenolic content (TPC), antioxidant activity, and extraction efficiency of the solid contents. The highest efficiency was achieved for microwave-assisted extraction with the utmost values in each parameter. (TSC) was 22.81% and amounts of the TPC and antioxidant activity were 311.94 mg Gallic acid and 36 mg diphenyl picryl hydrazyl (DPPH) per 1g of the plant, respectively.  Morphology study by field emission scanning electron microscopy (FE-SEM) indicated spherical shape nanoparticles with a diameter of 25nm. The size of the nanoparticles was evaluated by the Dynamic Light Scattering (DLS) technique for various concentrations of the used extracts in the encapsulation process. For 1.0, 3.0, and 5.0 mg /mL concentration, mean diameters were 24, 118, and 145 nm, respectively. Results indicated that microwave-assisted extraction was the best extraction method for MO and the encapsulation of MO extract could be created successfully with different particle sizes for the protection of bioactive compounds. Since MO is a beneficial herbal plant, the development of this research is recommended.

Nanoscale materials are widely used in many fields including medicine, engineering, and the environment that focuses on the synthesis of nano dimensional particles is a timely topic. Nanomaterials synthesized by chemical approaches have intended effects on the environment and human health. In response to these challenges, plant-mediated synthesis of inorganic nanoparticles has been a highly innovative research area over the last decade. Aqueous and solvent extracts have been employed as efficient resources in synthesis-controlled nanostructures and the fabrication of various nanomaterials. The present article unveils the possible role of plant biomolecules including amino acids, aldehydes, terpenoids, ketones, tannins, and phenolics in the reduction and stabilization of various metal and metal oxide nanoparticles. The green synthesized nanoparticles evolved as efficient alternative agents in solving the serious threats faced in the field of biomedical, energy conversion, environment, automobiles, electronics, and optical. Moreover, catalytic, and antimicrobial applications of green nanoparticles are also critically discussed.

Recently, there has been an increase in research interest in metal nanoparticles and their synthesis because of their various applications in different industrial areas. The current study deals with the Actinomycetes-mediated synthesis of copper nanoparticles (CuNPs) isolated from mangrove soil and to further access its application in different fields. Eight different soil samples were collected from three different mangrove sites located in Mumbai. A total of 15 different Actinomycetes isolates were obtained from soil samples and studied in the present investigation and were screened for metal tolerance. It was found that out of 15 isolates, only 3 were able to tolerate the highest metal salt concentration i.e. 10-1M. The synthesized CuNPs were further investigated with various characterizations such as UV-Vis spectroscopy, FTIR, and XRD. The identification of isolate GRC1 was done as per Bergey’s Manual of Systematic Bacteriology Volume 5 for preliminary identification of Actinomycetes and was identified as Streptomyces sp. This isolate was further characterized by Vitek MS and it was identified as Streptomyces verticillus. The inhibition zone by biosynthesized CuNPs was significantly greater when compared with standard antibiotics and CuSO4. The calculated degradation efficiency after 5hrs of incubation was 59.67% and 96.26% for Red M8B and Reactive green, respectively. Prevention of biofilm formation by CuNPs was confirmed by microscopic technique and significant inhibition of biofilm was observed. Thus, the mangrove Actinomycetes mediated bio-fabrication of CuNPs should gain much attention because of their unique properties like antimicrobial, anticancer, catalytic activity, wound healing, and antifouling.

Water is, indisputably, the most vital component of life on earth. Water is a life elixir and its hardness is defined by the high concentration of magnesium, calcium, lead, chromium, iron, and mercury. The hardness of water limits its domestic and industrial usage severely. Therefore it is essential to suggest a simple, low-cost, and robust method for hard water treatment by evaluating the results in terms of Physicochemical parameters.  In this paper, an efficient approach for hard water treatment by using synthesized carbon nanoparticles (C NPs) of Phyllanthus Emblica wood barks. The water samples are collected from the towns and villages located in Virudhunagar and Tuticorin District. For hardness treatment, in this work the physicochemical parameters considered are pH, TDS, dissolved Oxygen, Ca, Mg, Chloride, Alkalinity, and hardness levels. The experimental analysis, cleared that the proposed carbon nanoparticles synthesized from Phyllanthus Emblica wood barks are a very efficient and cost-effective solution.