Nickel oxide (NiO) nanostructures were synthesized by thermally oxidizing thin nickel (Ni) films deposited on glass substrates via electron beam evaporation under a controlled vacuum environment. Thermal oxidation was performed at 400 °C, 500 °C, and 600 °C in ambient air. X-ray diffraction (XRD) confirmed mixed phases of Ni and NiO at 400 °C and 500 °C, whereas a single-phase NiO with improved crystallinity was obtained at 600 °C. XRD data were analyzed using Rietveld refinement to confirm phase composition and structural evolution. Field emission scanning electron microscopy (FESEM) revealed that higher oxidation temperatures promote grain growth and induce a porous morphology. Energy-dispersive X-ray spectroscopy (EDX) confirmed the chemical purity of the oxidized films, showing only nickel and oxygen. Optical absorption analysis demonstrated a redshift in the bandgap with increasing temperature, consistent with defect-mediated electronic transitions. X-ray photoelectron spectroscopy (XPS) of the Ni 2p core level exhibited characteristic Ni 2p₃/₂ and Ni 2p₁/₂ peaks along with satellite features, evidencing the coexistence of Ni2+ and Ni3+ oxidation states. Nonlinear optical behavior was probed using the Z-scan technique at 532 nm, yielding third order nonlinear susceptibility (χ3) values in the range of 3.64 × 10–4–1.67 × 10–4 esu. The films displayed strong nonlinear absorption and thermal lensing effects, with an optical limiting threshold as low as 0.26 kJ/cm2. These findings highlight the potential of NiO thin films as efficient candidates for nonlinear optical limiting applications, where structural tuning via oxidation temperature plays a critical role in enhancing performance.

The present work focuses on the preparation of films via Sol–gel method and to study their nonlinear optical properties. Optical systems are always under a threat of attack from high intensity laser radiations, under the exposure of which any optical detector or any optical system may be damaged. Optical Limiters have been designed to protect such devices from high intensity Laser attacks. The study is dedicated to optical limiting properties of Scandium Doped Zinc Oxide (SZO) thin films for various doping concentrations. Films with doping concentration 0.2 wt, 0.4 wt, 0.6 wt and 0.8 wt

This work focuses on the synthesizing of g-C3N4/CuO nanocomposites by thermal decomposition and their nonlinear optical characterization. The XRD pattern shows that the crystalline peaks of copper oxide increase with the increase in concentration of copper acetate hydrate. The existence of vibrational modes was studied using FTIR. The vibrational peak at 812 cm−1 is due to the triazine ring and the Cu–O stretching vibration is represented by the peak at about 529 cm−1. With the increase in concentration, there is a red shift in the curves due to the effective interaction between g-C3N4 and CuO. The nanostructures were confirmed using FESEM. Raman spectroscopy confirms the Ag and 2Bg phonon modes of CuO. The G mode around 1586 cm−1 and the D mode around 1350 cm−1 is due to g-C3N4. The nonlinear optical properties, including the nonlinear coefficient of absorption (β), nonlinear coefficient of refraction (n2) and third-order nonlinear susceptibility (χ^3 ) were investigated using the Z-scan technique at a wavelength of 532 nm. The Nonlinear coefficient of absorption was found to be increase from 1.35×10^-4 to 1.18×10^-5 cm/W and negative nonlinear refraction due to self-defocusing varies from 2.019×10^-9 cm2/W to 0.897×10^-9 cm2/W. The estimated value of third-order susceptibility is found to be increased from 2.71×10^-7 to 1.23×10^-6 e.s.u., respectively. The limiting threshold was decreased from 5.07 to 0.074 kJ/cm2 with the increase in wt

The present study was focused on the fabrication of a device to remove fluoride using capacitive deionization (CDI). The conventional CDI device was modified such that electrodes coated on both sides could be used. The electrodes were prepared by mixing activated carbon (AC), graphite powder (GP), polyvinylidene fluoride (PVDF), and N, N-dimethylacetamide (NDMAc). The proportion of the constituents was varied to obtain the optimum composition for the most efficient electrodes. Electrodes with composition of AC:GP:PVDF=70:16:14 wt% were found to have sufficient mechanical strength and favorable capacitive characteristics for the electrosorption of fluoride ions. The maximum removal efficiency obtained with single-side coated electrodes was 90.38%+/- 1.33% under 45 min, whereas for electrodes coated on both sides, the maximum efficiency achieved was 97.38%+/- 0.44% under 25 min. The study was performed using a batch-type CDI device. The device could operate effectively at a low voltage of 1.5 V, making it an environment-friendly and efficient technology. The cost involved for the treatment of water was USD 0.039/L. (c) 2024 American Society of Civil Engineers.

In this study, polypyrrole (Ppy) and polypyrrole/multi-walled carbon nanotube (Ppy/MWCNT) composites were synthesized using a chemical oxidation polymerization process, with methyl orange acting as a surfactant. X-ray diffraction (XRD) confirmed the amorphous structure of the Ppy/MWCNT composites, while Raman spectroscopy provided insights into molecular interactions. Fourier transform infrared spectroscopy (FTIR) verified the presence of C–H and C–C bonds in the nanocomposites. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the cylindrical shape and chemical composition of the composite particles. The electrical conductivities of Ppy and Ppy/MWCNT(20wt

Arsenic contamination in natural waters is one of the biggest threats to human health, mainly due to its carcinogenic potential. Given its toxicity, nearly all organisms have evolved to develop an arsenic resistance mechanism. Conventional techniques of arsenic remediation suffer from various limitations of their applicability, cost and/or chemical intensive nature. In past few decades, bioremediation has emerged as a potential alternative to the conventional techniques. Microbial bioremediation, bacteria in particular, offers an eco-friendly and sustainable alternative, owing to its inherent metabolic capabilities to transform, immobilize or volatilize arsenic. Diverse biochemical pathways involving oxidation of As(III) to As(V), reduction of As(V) under anaerobic respiration or detoxification, methylation and demethylation, bioleaching and biomineralization into insoluble forms are essential mechanisms for arsenic remediation. These transformations, detoxification and resistance are regulated by specific genetic systems, including the ars operon, aio, arr and arsM, accessory genes such as arsR, arsB, acr3, arsC and arsP. The metabolic regulation of arsenic detoxification involves complex cofactor-dependent enzyme systems and environmental signal-responsive transcriptional control. Integrated approaches such as immobilization of bacteria on biochar or their encapsulation have also been known to enhance stability, reusability and stress tolerance. However, bioremediation is a very complex process due to the interrelationship of various influences such as, presence of specific microorganisms, nutrients and environmental factors. Therefore, it is of utmost importance to understand the bacterial interactions with arsenic for the development of bioremediation technologies. This review article tries to discuss the current status of arsenic bioremediation using bacteria, its field applications, challenges and future perspectives. It also includes the strengths, weaknesses, opportunities, threats (SWOT) analysis to assess the merits and demerits of using bacteria for bioremediation of arsenic.

Arsenic contamination in groundwater is a cause of global concern. Bioremediation presents a viable alternative to conventional methods employed for arsenic treatment. This study investigated the use of bacteria immobilized on polyurethane foam (PUF) for arsenic remediation in a recirculating packed bed bioreactor. The effectiveness of Proteus alimentorum strain TY6 and Pseudomonas aeruginosa strain K7Pb for removal of As(III) and As(V) was evaluated. Concentrations of arsenic ranged from 250 mu g/L to 50 mg/L at varying flow rates. The removal efficiency of TY6 varied from 0.45 % to 99.50 % for As(III) and 0.75 % to 98.40 % for As(V). For K7Pb, the efficiency ranged from 0.79% to 99.30% for As(III) and 0.80% to 99.40% for As(V). Bacteria immobilized on PUF were found to be highly efficient in arsenic removal. The removal efficacy was found to be above 65 % even at a concentration of 50 mg/L for both bacteria. Both bacterial strains also demonstrated significant potential for arsenic biotransformation. TY6 only oxidized As(III) to As(V), whereas K7Pb only reduced As(V) to As(III). The outcomes indicated that both strains possessed substantial potential for arsenic remediation.

Groundwater, constituting 97 % of global freshwater, is essential for domestic water supply. As the global population grows, securing safe drinking water remains a critical challenge. Therefore, it is essential to develop advanced technology for the effective reduction of arsenic (As) concentration from the environment. This study investigates the applicability of biochar derived from tea waste for As(V) ions adsorption from synthetic wastewater. The pristine biochar (tea waste biochar) was subsequently modified by H3PO4 (to produce acidic functional groups) via the wet impregnation method. X-ray diffraction (XRD) analysis revealed that acidic functional groups had been assimilated into the biochar's crystalline area. Brunauer-Emmett-Teller (BET) analysis exhibited a specific surface area of 6.85 m2/g of biochar, giving a maximum adsorption capacity of 33 mg/g for As(V) ions in solution. The adsorption equilibrium exhibited multi-layer adsorption, fitting well with the Freundlich isotherm model. Furthermore, an Artificial Neural Network (ANN) model was developed using an experimental dataset, achieving an optimal network topology with seven hidden neurons, demonstrating low mean squared error (MSE: 0.002287) and high correlation coefficient (R: 0.95869). The adsorption was feasible at all temperatures (based on Delta H ), with maximum uptake capacity at 40 degrees C (based on Delta G degrees ). Van der Waals forces, specifically weak molecular attraction forces, account for the adsorption of As(V). The modified biochar exhibited remarkable reusability (over 6 adsorption/desorption cycles) compared to TWB. This study confirms that tea waste biochar is a cost-effective, environment-friendly, and efficient adsorbent for removing arsenic from water.

During the present work, thin films of Copper (Cu) were deposited onto glass substrates using the electron beam deposition technique. The thin films were exposed to heat treatments at varying temperatures of 400 degrees C, 500 degrees C, and 600 degrees C. The films were analyzed to determine their structural, morphological, and optical characteristics using different techniques such as x-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and UV-visible spectroscopy respectively. FESEM revealed an increase in particle agglomeration with higher temperatures. EDX(Energy dispersive x-ray spectroscopy) confirmed the presence of only copper (Cu) and oxygen (O), indicating impurity-free films. The absorbance properties were analyzed using UV-visible spectroscopy. As the oxidation temperature increases, the optical energy bandgap of prepared thin films changes. The nonlinear optical properties of deposited thin films, such as non-linear third-order susceptibility (chi 3), nonlinear refractive index(n2), and absorption coefficient(alpha) were analyzed using the Z-scan method at 532 nm. The chi 3 values ranged from 2.71x10-5 e.s.u. to 1.19x10-5 e.s.u. The prepared thin films exhibited a reduced optical limiting threshold of 1.3 KJ cm-2, demonstrating their strong potential for optical limiting applications

The current study focuses on the synthesis of Zinc Oxide nanoparticles (ZnO NPs) and their impact on Graphitic Carbon Nitride and its nonlinear optical properties. The prepared samples were synthesized using thermal decomposition method. As the concentration of zinc acetate hydrate increases also the crystalline peaks of ZnO are identified in the XRD pattern. The UV-Visible spectrum of each sample reveals that absorption peaks at 450 nm. The curves exhibit a blue shift as the concentration rises due to the efficient interaction between ZnO and g-C3N4. FTIR reveals the peak at 500 cm− 1 as the stretching of the oxygen metal (Zn–O) and triazine rings at 812 cm− 1. The FESEM, surface morphology of the samples confirmed the nanostructures. At a wavelength of around 532 nm, the Z-scan approach was used to analyze the nonlinear optical properties, including the nonlinear index of refraction (n2), nonlinear absorption coefficient (β), and third-order nonlinear susceptibility\(\:\:\left({\chi\:}^{3}\right)\). The value of \(\:{\chi\:}^{3}\) varies from \(\:2.71\times\:{10}^{-7}\) e.s.u. to \(\:{2.46\times\:10}^{-6}\) e.s.u. for the synthesized nanostructures. The limiting threshold decreased from 5.078 kJ/cm2 to 2.178 kJ/cm2 as the weight percentage of ZnO increased. Due to their low limiting threshold value, these optoelectronic materials show great potential for optical sensors.

This study investigates the gas-sensing properties of acetone using two materials: polypyrrole (Ppy) and polypyrrole/silver nitrate (Ppy/AgNO3) nanocomposites. These materials were synthesized through a simple, cost-effective, and eco-friendly chemical oxidation polymerization process. Methyl orange was used as a surfactant during the synthesis. The Ppy/AgNO3 nanocomposites were prepared by incorporating silver nitrate in varying concentrations of 10

Aerosol optical depth (AOD) and Ångström exponent (AE) are the major environmental indicators to perceive air quality and the impact of aerosol on climate change and health as well as the global atmospheric conditions. In the present study, an average of AOD and AE data from Tera and Aqua satellites of MODIS sensors has been investigated over 7 years i.e., from 2016 to 2022, at four locations over Northern Great Plains. Both temporal and seasonal variations over the study periods have been investigated to understand the behavior of AOD and AE. Over the years, the highest AOD and AE were observed in winter season, varying from 0.75 to 1.17 and 1.30 to 1.63, respectively. During pre-monsoon season, increasing trend of AOD varying from 0.65 to 0.95 was observed from upper (New Delhi) to lower (Kolkata) Gangetic plain, however, during monsoon and post-monsoon a reverse trend varying from 0.85 to 0.65 has been observed. Seasonal and temporal aerosol characteristics have also been analyzed and it has been assessed that biomass burning was found to be the major contributor, followed by desert dust at all the locations except in Lucknow, where the second largest contributor was dust instead of desert dust. During season-wise analysis, biomass burning was also found to be as the major contributor at all the places in all the seasons except New Delhi and Lucknow, where dust was the major contributor during pre-monsoon. A boosting regression algorithm was done using machine learning to explore the relative influence of different atmospheric parameters and pollutants with PM2.5. Water vapor was assessed to have the maximum relative influence i.e., 51.66 % followed by CO (21.81 %). This study aims to help policy makers and decision makers better understand the correlation between different atmospheric components and pollutants and the contribution of different types of aerosols.

The study aims to evaluate the third-order optical nonlinearity caused by laser irradiation in transition metal oxide incorporated into graphitic carbon nitrides. The work describes the synthesis of nano-sized hybrid g-C3N4/ZnO (14%) and g-C3N4/CdO (14%). Nano-sized transition metal oxides: ZnO and CdO, have been prepared by thermally decomposing the organic precursors; Zinc Acetate Dihydrate, Cadmium Acetate Dihydrate, and Urea at 873 K. Graphitic carbon nitrides are synthesized from urea, which also functions as a reducing agent. The synthesized sample's structural and morphological characterization are investigated using x-ray diffraction (XRD), Fourier transforms infrared (FTIR), UV-vis. spectra, field emission scanning electron microscopy (FESEM), and energy dispersive x-ray spectroscopy (EDX). The grain size of the ZnO and CdO nanoparticles is observed to be similar to 21 nm and similar to 28 nm, respectively. The absorption in the samples is found to be 250-450 nm and transmit the light in the visible spectrum as observed in UV-vis. spectra. The bandgap values calculated from Tauc ' s plot for the hybrid structure of g-C3N4/ZnO and g-C3N4/CdO are found to be 2.97 eV and 2.30 eV.The z-scan method is adopted to evaluate the nonlinear susceptibility (chi 3), intensity-dependent absorption coefficient (beta), and nonlinear index of refraction (n(2)) using a pulsed Nd:YAG laser (similar to 532 nm). The results of the composite of g-C3N4/ZnO and g-C3N4/CdO show good third-order susceptibility and hence are useful for use as an optical limiter.

This study reports the Acetone gas sensing behavior of Polypyrrole (Ppy) and Polypyrrole/Zinc Oxide (Ppy/ZnO) nanocomposites synthesized by a simple, inexpensive, and eco-friendly chemical oxidation polymerization method using methyl orange as a surfactant. The Ppy/ZnO nanocomposites were synthesized by adding Zinc Oxide with different weight percentages of 10, 15, and 20 wt

The pharmaceutical business is one of the fastest emerging sectors in the global as well as in the Indian scenario. Due to the rapid growth of the pharmaceutical industry, its wastes have become a source of emerging pollutants of concern especially in water. In the past decades, pharmaceutical traces in small quantities have been observed even in the hydrological cycle. Considering the various impacts of pharmaceutical wastes on human and environmental health, their presence in water even in trace amounts can become a grave area of concern. In the present chapter, different compositions of pharmaceutical wastes along with their impacts on the environment and human health are elaborated. It also examines different remediation techniques for pharmaceutical wastes as well as foreseeable challenges in the near future. It has been observed that no technology can be adequate for the treatment of all such effluents. In this direction, employing green synthesis and environment-friendly treatment methodologies has the potential to reach an enhanced level of sustainability in this sector. The principles of green chemistry imply that synthesized chemicals must not only serve the targeted purposes but also be fast, effective, and easily degradable, and thus, this approach must provide both ecological and economic benefits.

Several adsorbents were prepared employing co‐precipitation, urea, ascorbic acid, and natural plant extracts and evaluated for the removal of arsenic from groundwater. Several parameters affecting adsorption, namely, initial arsenic concentration, pH, adsorbent dose, and contact time were studied in batch experiments. pH was found to be one of the most important parameters which affected adsorption, and it was most effective in the acidic pH range of 2–6. The optimum adsorbent dose varied from 0.24 g/L to 1.0 g/L for various methods and a contact time of 120 min. Maximum removal efficiency varied from 92% to 98% for various methods. Isotherms and kinetics studies were performed to determine the adsorption capacity and rate of reaction, respectively. The maximum adsorption capacities of 79.36 μg/g, 69.44 μg/g, 243.90 μg/g, and 101.01 μg/g could be obtained by the adsorbents produced through co‐precipitation, urea, ascorbic acid and natural plant extracts, respectively. The adsorbents prepared through co‐precipitation, urea and ascorbic acid followed Langmuir isotherm and adsorbents prepared using plant extracts followed Freundlich isotherm. Various characterization techniques, including XRD, BET, and SEM were employed for analysis of the adsorbents.

Arsenic ranks first on the Substance Priority List of the Agency for Toxic Substances and Disease Registry and causes a wide range of health problems, including cancer and even death. The present work was focused on the removal of arsenic using bacteria, Proteus alimentorum strain TY6 and Pseudomonas aeruginosa strain K7Pb, immobilized on peanut shell biochar [0.05 % (w/v)] and encapsulated in polyvinyl alcohol (PVA) - sodium alginate (SA) beads crosslinked with calcium chloride (CaCl2). The maximum removal efficiency obtained was 92.29 +/- 0.51 % and 93.63 +/- 0.09 % for As(V), using beads of K7Pb and K7Pb + TY6 respectively, whereas for As (III), it was 91.71 +/- 0.51 % with TY6 and 93.35 +/- 0.05 % for KP7b + TY6, at pH 7 at 30 degrees C. Surface morphology was characterized by scanning electron microscopy and energy-dispersive x-ray analysis. This study revealed that the encapsulated bacteria immobilized on biochar were more effective than the free-cell and bacteria immobilized on biochar. It was also found that the beads could be reused effectively for five cycles (for K7Pb and TY6) and eight cycles (for K7Pb + TY6) before their removal efficiency reduced to below 80 %.

This article investigates the effect of morphology on the thermoelectric properties of nanostructured zinc oxide. Three different samples of nanostructured zinc oxide, named ZnO, ZnO triethanol amine (TEA) and ZnO Calc., were synthesized. ZnO and ZnO TEA samples were synthesized by the chemical precipitation method, while ZnO Calc. sample was prepared by the direct calcination method. The FESEM analysis revealed that ZnO and ZnO Calc. samples have flakes and nanorod-like morphology, respectively, while ZnO TEA has a mixed hexagonal and irregularly shaped morphology. The Rietveld refinement of X-ray diffraction data confirmed that all the prepared samples have a hexagonal wurtzite phase of ZnO with space group P63mc. The energy-dispersive X-ray spectroscopy confirmed the presence of zinc and oxygen in all the synthesized samples. The electrical resistivity and Seebeck coefficient were recorded in the temperature range of 300–950 K. The negative values of the Seebeck coefficient revealed the n-type nature of all the samples. The increase in electrical resistivity with the increase in temperature confirmed that all three prepared ZnO samples show metallic behaviour. The highest Seebeck coefficient of –245 μV K–1 was attained by ZnO nanorods at 950 K, while the lowest Seebeck coefficient of –212 μV K–1 was obtained for ZnO TEA at 950 K. The highest thermoelectric power factor of 2.11 × 10^-3 W m–1 K–2 was attained by the ZnO Calc. sample at 950 K. The results indicate that the synthesized ZnO Calc. sample with nanorod-like morphology has better thermoelectric performance as compared to flakes and platelets-like morphology.

Copper nanoparticles embedded in polystyrene (PS) nanocomposite foils were prepared via the solution casting method to study their optical characteristics and antimicrobial activities. Structural and surface morphology of the prepared nanocomposite foils were carried out by FTIR and FESEM. UV–vis spectra reveal that the nanocomposite foils are optically transparent in the visible region, with a strong absorbance peak at 264 nm. Optical parameters such as optical band gap (Eg), refractive index (n), extinction coefficient (k), and dielectric constants (ε1, ε2, tanδ) were calculated using UV–vis spectroscopy. The Single Oscillator Wemple DiDomenico model was employed to determine the dispersion energy characteristics (E0, Ed), optical moments (M-1, M-3), and dispersion of refractive index (n0). The nonlinear index of refraction (n2) and third-order optical nonlinear susceptibility (χ3) were calculated using Miller’s expression. In-vitro antimicrobial activity was tested against Gram-negative bacterial species isolated from a hospital wastewater treatment plant, showing multiple drug resistance activity. The study revealed that PS/Cu nanocomposite foils exhibit promising results as optical limiters with significant antibacterial activity.

Groundwater contamination with fluoride is a cause of concern worldwide. This study was aimed to explore the feasibility of activated red mud (ARM) for adsorption of fluoride from aqueous solutions. The morphology of the adsorbent was characterized using scanning electron microscope and elemental composition was analyzed using X-ray fluorescence. Parameters such as pH and adsorbent dose were optimized to achieve maximum removal efficiency. Maximum removal efficiency of 96% was obtained at pH 7 with an adsorbent dose of 20 g/L. The isotherm and kinetic studies revealed that Langmuir isotherm and pseudo-second-order kinetic models best explained the adsorption process. The study established that ARM could be an environment-friendly and efficient adsorbent for the removal of fluoride from water.