Sustainable and energy-efficient photocatalytic degradation of textile dye assisted by ecofriendly synthesized silver nanoparticles

Laser-induced optical and structural modification in AgI thin films loaded with silver nanoparticles

Silver-silver iodide (Ag-AgI) films are photosensitive materials in the visible light region. In this work, the colour change in Ag-AgI films under low-power monochromatic laser irradiation is shown, which is due to the size variation of silver nanoparticles (AgNPs) on the AgI thin films. This colour variation depends on the wavelength of the laser beam. In contrast, it is independent of the silver iodide thickness. Laser irradiation is employed not only for the colouration of Ag-AgI films but also for promoting the crystallinity of Ag and AgI in these films. At room temperature and atmospheric pressure, the β-phase and the γ-phase of AgI crystals are formed. The optical and structural changes of the Ag-AgI films with two different thicknesses of silver iodide, before and after laser irradiation, are characterized by synchrotron X-ray diffraction, UV-vis spectrophotometry, and X-ray photoelectron spectroscopy. The growth of silver crystals after laser irradiation is significant, especially in the sample with a thinner AgI film under the irradiation of green and blue laser beams with an energy higher than the bandgap energy. However, in the sample with a thicker film of AgI, the size of the β-phase and the γ-phase of AgI crystals increases faster than that of silver crystals after laser irradiation. This study demonstrated that Ag-AgI films have antibacterial and photocatalytic activities.

Enhanced photocatalytic degradation of malachite green and trypan blue using 3-aminopropyl triethoxysilane (APTES) functionalized iron oxide nanocomposite

Biochar-capped iron oxide nanoparticle functionalized with 3-aminopropyl triethoxysilane (APTES) was synthesized and used as photocatalysts for the degradation of malachite green (MG) and trypan blue (TPB) dyes. Powder X-ray diffraction patterns confirmed the crystalline cubic spinel structure of Fe3O4. HRTEM image shows nanocomposites with an average particle size of 22.4 nm, interplanar spacings of 0.297 nm and 0.245 nm, which correspond to the (220) and (222) planes of Fe3O4. SAED patterns indicate that Fe3O4@BC/APTES nanocomposite is polycrystalline. The energy bandgap of the biochar-capped iron oxide nanoparticles was reduced from 3.47 to 2.85 eV after functionalization with APTES. Photocatalytic degradation potential of the nanocomposite was evaluated with malachite green (MG) and trypan blue (TPB) dyes using the response surface methodology based on the Box-Behnken design (RSM-BDD). The optimal degradation efficiency from RSM-BBD for MG was 99.94% with a catalyst dosage of 7.5 mg, dye concentration of 50 ppm, and pH of 9 for 105 min. The optimum parameters for TPB were found to be a concentration of 30 ppm, a catalyst dosage of 12 mg, a pH of 5, and 85.77% of degradation after 90 min. Reusability studies show that the nanocomposite can be reused five times without significant reduction in the photocatalytic degradation efficiency.

Spectroscopic approach to optimize the biogenic silver nanoparticles for photocatalytic removal of ternary dye mixture and ecotoxicological impact of treated wastewater

The fabricating of extremely effective, economical, ecologically safe, and reusable nanoparticle (NP) catalysts for the removal of water pollution is urgently needed. This study, spectroscopically optimizes the process parameters for the biogenic synthesis of AgNP catalysts using Cledrdendrum infortunatum leaf extract. The optimization of several synthesis parameters was systematically studied using UV-Vis spectroscopy to identify the ideal conditions for AgNPs formation. The AgNPs are spherical with a size of ~ 20 nm, pure and stable. Mechanistic insights into the biogenic synthesis process were explored. The photocatalytic performance of biogenic AgNPs was evaluated for the degradation of three common (crystal violet, thioflavin T, and methylene blue) dyes as models in ternary mixtures under the influence of sunlight. AgNPs show excellent photocatalytic efficiency in terms of degradation percentage (82.89-96.96% within 110 min), kinetics (0.0247-0.0331 min-1), half-life (20.96-28.11 min), and T80 (48.67-65.28 min) and also easily recovered and reused. Ecological safety assessment of the treated wastewater was assessed on the growths of rice, mustard, and lentil plants, and preliminary findings demonstrated that seedling growths for treated wastewater were nearly similar to the control sample but retarded in dye-contaminated wastewater suggesting potential use of treated wastewater for sustainable agriculture without compromising ecological balance. So, this study explores biogenic AgNPs as cost-effective, safe, and sustainable photocatalytic agents for the remediation of hazardous mix dyes and real-life applications of treated water for agricultural purposes.

Eco-Friendly Synthesis of ZnO for Efficient Photodegradation of Pharmaceutical Drug Removal by Photocatalysis

In the present work, a comparative study on eco-friendly synthesis of zinc oxide (ZnO) sample 1 and sample 2 with 3.17 and 4.17 M NaOH, respectively, is reported. Sample 2 with 4.17 M NaOH is applied in the photocatalytic degradation of paracetamol (pure and raw both) using the ultraviolet (UV, 280-400 nm) and UV/H2O2 reaction systems. Pure paracetamol (PCM1) and raw paracetamol (PCM2) from tablets are used for photocatalytic degradation by photocatalysis. Our experimental evidence show that ZnO sample 2 was more active in the UV/H2O2 reaction system than under ultraviolet (UV, 280-400 nm) irradiation only in the photocatalytic degradation process. Field emission scanning electron microscopy (FE-SEM) confirms the homogeneous growth of a rod-like structure for sample 1 and brittle and randomly aggregated rod-like and wire-like nanostructures for sample 2. The peaks observed in the region around 440 to 900 cm-1 in the FTIR spectra for sample 1 and sample 2 annealed at 250 °C confirms the presence of ZnO bonds. UV absorption spectroscopy indicates a red shift in the absorption spectra due to the increase in the molar concentration of NaOH to 4.17 M for sample 2. In this study, the band gap values are found to be 3.33 and 3.01 eV for the synthesized ZnO sample 1 and sample 2, respectively, which are 40 and 360 meV less as compared to that of bulk ZnO (3.37 eV). The oxidation rate is increased in the UV/H2O2 reaction system, producing the highest rate for PCM1 drug removal with rate constant 9.7 × 10-3 min-1 and half-life 71.5 min. The kinetic study results for the removal of PCM1 and PCM2 show good results and follow the pseudo-first-order kinetic model with correlation coefficients 0.69556 and 0.90851, respectively, whereas PCM2 follows the pseudo-second-order kinetic model with correlation coefficient 0.9993. The experimental and calculated values of removal capacity (q e) at equilibrium is found close to those of the pseudo-second order kinetic model for the removal of both the paracetamol forms PCM1 and PCM2 with the catalyst ZnO nanostructure. The photostability of ZnO sample 2 is also tested with a reusability test in photocatalytic degradation of paracetamol at least four times. The absence of a maxima peak at 243 of PCM1 in the UV/H2O2 reaction system indicates nearly 100% successful conversion of 20 ppm PCM1 by using synthesized catalyst ZnO sample 2. The comparative results of both reaction systems, i.e., UV and UV/H2O2, show that the hydroxyl radicals, as the active species, are responsible for major degradation of both paracetamol forms (PCM1 and PCM2).

Examining plasma-generated ozone and nitric oxide's role in synthetic textile dye water remediation and ecotoxicological analysis

Synthetic dyes produced by the textile dyeing industry and released into wastewater contribute significantly to water pollution. This study explores the efficacy and versatility of a novel multi-electrode dielectric barrier discharge (MEDBD) plasma system that mainly generates ozone (O3 generator) and nitric oxide (NO generator) selectively to degrade various synthetic textile dyes, namely Methylene Blue (MB), Congo Red (CR), Methyl Orange (MO), Crystal Violet (CV), and Evans Blue (EB). Plasma achieved selective enrichment of O3 and NO by utilizing optimized plasma generation duty cycles of 15% and 100%, respectively. The proposed O3 generator plasma involves plasma-generated aqua electron impact, excited species, and reactive oxygen species notably O3, which degrades synthetic textile dyes into simple forms such as CO2, H2O, and N2. This approach achieved over 95% degradation of the above synthetic textile dyes when employing the O3 enriched plasma with 2.44 ± 0.21 W of power. Ecotoxicological evaluation, including microbial, human cell, and phytotoxicity evaluations of the O3 generator plasma for MB and CR dye-contaminated water, underscored the potential of this plasma system for environmentally friendly dye degradation. Overall, this study promotes MEDBD plasma, particularly the O3 generator, as a sustainable and efficient solution for treating synthetic dye-contaminated water across industries.

Nanotechnology in action: silver nanoparticles for improved eco-friendly remediation

Nanotechnology is an exciting area with great potential for use in biotechnology due to the far-reaching effects of nanoscale materials and their size-dependent characteristics. Silver and other metal nanoparticles have attracted a lot of attention lately because of the exceptional optical, electrical, and antimicrobial characteristics they possess. Silver nanoparticles (AgNPs) stand out due to their cost-effectiveness and abundant presence in the earth's crust, making them a compelling subject for further exploration. The vital efficacy of silver nanoparticles in addressing environmental concerns is emphasized in this thorough overview that dives into their significance in environmental remediation. Leveraging the distinctive properties of AgNPs, such as their antibacterial and catalytic characteristics, innovative solutions for efficient treatment of pollutants are being developed. The review critically examines the transformative potential of silver nanoparticles, exploring their various applications and promising achievements in enhancing environmental remediation techniques. As environmental defenders, this study advocates for intensified investigation and application of silver nanoparticles. Furthermore, this review aims to assist future investigators in developing more cost-effective and efficient innovations involving AgNPs carrying nanoprobes. These nanoprobes have the potential to detect numerous groups of contaminants simultaneously, with a low limit of detection (LOD) and reliable reproducibility. The goal is to utilize these innovations for environmental remediation purposes.

Eco-synthesis of green silver nanoparticles using natural extracts and its application as co-catalyst in photocatalytic hydrogen production

Green silver nanoparticles (AgNPs) were synthesized using natural extracts as reducing agents and were firstly applied as co-catalysts in low-intensity-visible-light driven photocatalytic hydrogen production (PH2P), which a solution for green energy sources and independence from fossil fuels. The as-prepared AgNPs possessed size in a few tens nanometers and exhibited surface plasmon resonance (SPR) effects in the 310-560 nm region. Depositing AgNPs on g-C3N4 nanosheets broadened the visible absorption range, reduced electron-hole recombination, and increased electronic communication at the interface. g-C3N4/Ag demonstrated high PH2P efficiency, stability over three consecutive cycles, and a rapidly rising photocurrent under low-intensity visible light irradiation, although these features were not observed in g-C3N4 alone. The H2 evolution of g-C3N4/Ag_CC (CC: Cinnamomum camphora), g-C3N4/Ag_GT (GT: green tea), and g-C3N4/Ag_PP (PP: pomelo peels) reached 252.6, 125.3 and 92.0 μmol g-1 at 180 min at the first cycle, respectively. Among them, g-C3N4/Ag_CC showed the highest photocatalytic activity, which may be attributed to the superior morphology, optical properties of AgNPs_CC, and efficient electron transfer from g-C3N4 to AgNPs_CC. The SPR effect and Schottky barriers formed at the interface could contribute to enhancing the overall efficiency of the heterojunction photocatalysts. The results highlighted a crucial advancement toward H2 production under low-intensity visible-light irradiation.

Fabrication of multifunctional wool textile using the synthesis of silver-modified N-doped ZnO/TiO2 photocatalysts

Photocatalysts and noble metals have attracted considerable attention for their potential in addressing global environmental pollution through photochemical processes. At low temperatures, multifunctional self-cleanable wool fabric was developed through green photo-sonosynthesis of N-Ag/TiO2/ZnO. A narrower bandgap of the hybrid photocatalyst, the surface plasmonic resonance effect of silver nanostructures, and nitrogen doping resulted in synergistically enhanced self-cleaning activity. The self-cleaning activity was evaluated by monitoring the discoloration of methylene blue stains on the wool fabric exposed to natural sunlight, using CIELAB color space and ΔE measurements. The ΔE value of the N-Ag/TiO2/ZnO-sonicated wool was superior, showing a value of 45.9 compared to 15.7 for the control and 28.7 for the sample coated by the stirrer. Furthermore, the nanocomposite construction improved tensile strength, enhanced fabric hydrophilicity, and reduced the yellowness index. Additionally, the synthesis of TiO2 and silver particles on ZnO particles increased surface resistance to acid, reducing ZnO acid solubility. The reflectance of the non-treated wool ranged from 5 to 20 % within 200-380 nm, while the reflectance of the Ag/TiO2/ZnO-sonicated sample remained constant at 4 %, exhibiting protection against UV rays. AATCC test revealed 100 % bacteria reduction against E. coli and S. aureus and 99 % against C. albicans fungus for N-Ag/TiO2/ZnO-sonicated sample. Moreover, cell culture assays demonstrated a viability of over 70 %, indicating non-cytotoxicity.

Green Synthesis of Silver Nanoparticles Using Cashew Nutshell Liquid (CNSL): Characterization and Methylene Blue Removal Studies

In this work, silver nanoparticles (AgNPs) were synthesized from cashew nutshell liquid (CNSL) by varying the concentration of silver ions and the pH of the CNSL extract. The synthesized AgNPs were further characterized to study their surface, structural, and morphological properties and tested for the removal of methylene blue (MB) dye. The results of this study showed that depending on the conditions, particles of various sizes, ranging from 1 to 60 nm, and different degrees of stabilization and agglomeration were produced. The concentration of silver ions equal to 3 mM and the pH of the extract of ~4.5 (AgNP3) resulted in the most efficient synthesis, where particles appeared to be highly stabilized and homogeneously distributed on the surface, exhibiting a small average particle size and a narrow particle size distribution (6.7 ± 6.5 nm). Such particles further showed the highest percent removal of MB, where up to 80% removal was recorded within the first 20 min. Higher concentrations of silver ions and higher pH of the extract resulted in substantial particle agglomeration and particles being over-capped by the CNSL biomolecules, respectively, which further negatively affected the ability of particles to remove MB. Finally, the fact that visible light showed no significant effect on the removal of MB, with the average removal rates found to be about the same as in the dark, suggests the strong catalytic nature of AgNPs, which facilitates the electron transfer reactions leading to MB reduction.

Molecularly imprinted Ag2S quantum dots with high photocatalytic activity for dye removal: Experimental and DFT insights

Molecular imprinted polymers (MIPs) were developed by carrying out the cocktail solution of Template ((Salata, 2004)-Gingerol), monomer, crosslinker, and Ag2S Quantum Dots (QDs) by ex-situ dissolved in an appropriate solvent, resulting in an efficient crosslinked polymer composite. Degradation of Alizarin red S (ARS) dye and yellowish sunset (SY) azo dye under visible light irradiation was reported first time by the introduction of prepared MIPs composite. In this research, the result shows efficient photocatalyt activity of Ag2S-MIPs composite for the degradation of AR and SY dye with degradation% (80%) and (84%) in the aqueous wastewater. The degradation efficiency of the Ag2S-MIPs composite and the Ag2S QD associated with non-imprinted polymers (NIPs) (i.e.Ag2S-NIPs composite) were calculated by using different parameters such as catalyst dose, pH value, optimum time and concentration variation and the observations are evocative. Moreover, the density functional theory (DFT) approach was also used to analyze the structural, stability/energetics, and electronic features of the organic-inorganic hybrid composites of the Ag2S QD with the MIPs based on (Salata, 2004)-gingerol extract. The proposed QD and MIPs (EGDMA and (Salata, 2004)-Gingerol) composite model has been detected to be the most stable because it shows the largest binding energy (BE) among the three chosen composite models. It was found out that imprinted polymers were superior in enhancing the degradation of dyes when compared to non imprinted polymers. Introducing MIPs into the valence band accelerates the catalysis properties to stabilize newly fashioned excitons that are basically generated as a result of light excitation in presence of Ag2S Quantum Dots (QDs) and molecular imprinted polymer (MIPs). Motivation behind this work is to address the challenges related to environmental pollution causing by organic dyes. These toxins are known to cause diverse symptoms (e.g., skin irritation, eye infection, respiratory disorders, and even cancer) once exposed through ingestion and inhalation. Through incorporation of Ag2S QD into MIP,the purpose of this research is to enhance the selectivity, specificity and photocatalytic activity for dyes and that work holds a potential towards environmental remediation by developing a cost effective and sustainable method for controlling pollution in water.

Silver and carbon nitride-doped nickel selenide for effective dye decolorization and bactericidal activity: in silico docking study

In this study, nickel selenide (NiSe), Ag/C3N4-NiSe, and C3N4/Ag-NiSe nanowires (NWs) were synthesized via coprecipitation. The prepared NWs were employed for the degradation of the rhodamine B (RhB) dye in the absence of light using sodium borohydride (NaBH4), bactericidal activity against pathogenic Staphylococcus aureus (S. aureus) and in silico docking study to investigate the d-alanine ligase (DDl) and deoxyribonucleic acid (DNA) gyrase of S. aureus. NWs demonstrate a catalytic degradation efficiency of 69.58% toward RhB in a basic medium. The percentage efficacy of the synthesized materials was evaluated as 19.12-42.62% at low and 36.61-49.72% at high concentrations against pathogenic S. aureus. Molecular docking results suggest that both C3N4/Ag-doped NiSe and Ag/C3N4-doped NiSe possess inhibitory activities toward DDl and DNA gyrase of S. aureus, which coincides with the in vitro bactericidal activity. Based on the research outcomes, the synthesized NWs show potential as an effective agent for water purification and resistance to microbial contaminants.

Bio-fabrication of calcium oxide nanoparticles from Coccinia grandis as a potential photocatalyst for dye degradation with antimicrobial activity

In the current study, Coccinia grandis fruit extract was used to synthesize calcium oxide nanoparticles (CaO NPs) in an economical and environmentally friendly manner. UV-Vis spectroscopy and Fourier transform infrared spectroscopy revealed that the phytoconstituents found in Coccinia grandis fruit extract facilitated the production of CaO NPs by acting as better stabilizing, biodegradable, and reducing agents. The synthesized CG-CaO NPs were also tested for photocatalytic activity in the breakdown of selective dyes such as methyl red, methyl orange, and methylene blue in the presence of sunlight. The degradation percentage was determined by analyzing the color removal rates for all dye components. After 6 h of reaction, the IC50 values for methyl red, methyl orange, as well as methylene blue dyes were 73, 107, and 133, respectively. The CG-CaO NPs were further evaluated for their antimicrobial activity against specific bacteria and fungi using the agar-well diffusion method. 200 μg/mL CG-CaO NPs inhibited Aspergillus niger, Escherichia coli, Salmonella typhi, Streptococcus mutans, and Staphylococcus aureus at zones of 13, 14, 16, 14, and 15 mM, respectively. Further checkerboard assay confirmed the antagonism effect with gentamicin. Also, Artemia salina toxicity assay showed that the LD50 value of CaO NPs was 400 μg/mL of CaO NPs. The findings confirm that Coccinia grandis-mediated CG-CaO NPs can be used effectively in antimicrobial and environmental settings.

Amphi-Luminescent MoS2 nanostructure for photocatalytic splitting of water and removal of Methylene Blue

Chemical dyes used in the textile industries are one of the major pollutants in water. Methylene blue (MB) is a commonly seen dye that creates hazardous health problems. In this article the photocatalytic degradation of MB by the nanocatalyst MoS2 (Nano-MoS2) and carbon dot (C Dots) incorporated MoS2 (Nano-CD-MoS2) is reported. The photocatalytic degradation of MB is analyzed based on the electron-hole recombination rate of the catalyst. Photoluminescence emission exhibited by the catalyst is used as a key indicator to probe the electron-hole recombination rate. Nano-MoS2 was synthesized hydrothermally at 180 0C for 8 h from ammonium tetra thiomolybdate (ATTM). C Dot was prepared following a green root from ash guard extract which later mixed with Nano-MoS2 and kept in an autoclave at a temperature 140 °C for 4 h to get Nano-CD-MoS2. The photoluminescence (PL) and photocatalytic behavior of Nano-MoS2 and Nano-CD-MoS2 and their application for water splitting and water purification are reported. The incorporation of graphene and artificial C Dot into MoS2 nanostructures are reported to increase the conductivity and active edge sites of MoS2 that enhances the photocatalytic action. Since green C Dots are eco-friendly and easily synthesizable than artificial C Dots, as a novel study, this article investigated the influence of green C Dots on the PL and photocatalytic performance of nanosized MoS2. Nano-MoS2 and Nano-CD-MoS2 exhibited both upconversion and downconversion PL; accordingly the nanostructures were termed as amphi-luminescent. The amphi-luminescence property widens the photon absorption range and hence enhances the catalytic degradation of dyes. Nano-MoS2 which exhibited lesser intensity of amphi-luminescence emission compared to Nano-CD-MoS2 showed better results in degradation of MB. C Dots may bind with the valence band electrons of MoS2, resulting in the reduction of dangling bonds. Dangling bonds can trap photo-induced excitons to hinder the rate of electron-hole recombination. So, fast electron-hole recombination occurs in Nano-CD-MoS2 than Nano-MoS2. Fast electron-hole recombination supports radiative electron-hole recombination while suppresses the non-radiative energy transfer of electrons and causes high PL intensity. However, according to the energy level diagram, Nano-MoS2 with minimal electron-hole recombination rate is more favorable for O2/O2-,.OH/ OH- and.OH/H2O reactions that facilitate MB degradation. Photocatalytic activity of catalysts were confirmed by measuring the photocurrent from a simple custom-made two-electrode water photolysis cell where the nanocatalysts were dispersed in electrolyte. Lead and steel rods were used as electrodes. Multimeter was used to measure current. Nano-MoS2 exhibited better performance with a maximum photocurrent of 141 µA. Influence of green C Dots in energy levels, PL and photocatalysis of MoS2 and mechanisms of PL and degradation of MB are thoroughly investigated in this article.

Accelerated mineralization of textile wastewater under 222 nm irradiation from Kr/Cl2 excilamp: an environmentally friendly and energy efficient approach

The textile dyeing and manufacturing industry is the major producer of significant amounts of wastewater that contain persistent substances such as azo dyes that require adequate remediation measures. Far ultraviolet at 222 nm light may provide an advantage for contaminants degradation as compared to conventional UV sources (254 nm). In this paper, the degradation of reactive black 5 (RB5) in artificial wastewater has been performed using a 222 nm Kr/Cl2 excimer source under direct photolysis and an advanced oxidation process using TiO2/H2O2. The solution pH, catalyst concentration, 222 nm intensity, initial concentration of dye, and addition of H2O2 influence the degradation rate constant. The molar absorption coefficient, quantum yield of RB5 at 222 nm and the electrical energy per order (EEO) from different treatment methods have been reported. RB5 shows 1.26 times higher molar absorption at 222 nm than at 254 nm. The EEO for excimer-222/H2O2 ( ∼ 13 kWh/m3) is five times lower than that of the excimer-222/TiO2 process, which makes the process energy efficient. The degradation of wastewater has been carried out at three distinct pH values (2, 6, and 10), and the pH level of 10 exhibited the highest degree of degradation. The degradation rate in the alkaline medium is 8.27 and 2.05 times higher than in the acidic or ambient medium. Since textile effluent is highly alkaline, this result is significant, as no neutralization of the wastewater is required, and direct treatment is possible. A possible degradation pathway has been established based on Fourier transform infrared spectroscopy (FTIR) and high resolution mass spectroscopy (HRMS) analysis. The phytotoxicity of the treated wastewater has also been evaluated for its suitability for reuse in agriculture. The study reveals that the excimer-222/H2O2 treated wastewater significantly enhanced the germination percentage of Raphanus sativus seed (97%) compared to dye wastewater-grown seeds (75%). This work offers crucial information for future studies on the direct and indirect photolysis of azo dyes, as well as insight into the process of RB5 degradation under Kr/Cl2 excimer radiation.

Phytosynthesis and characterization of tin-oxide nanoparticles (SnO2-NPs) from Croton macrostachyus leaf extract and its application under visible light photocatalytic activities

Nanotechnology is rapidly becoming more and more important in today's technological world as the need for industry increases with human well-being. In this study, we synthesized SnO2 nanoparticles (NPs) using an environmentally friendly method or green method from Croton macrostachyus leaf extract, leading to the transformation of UV absorbance to visible absorbance by reducing the band gap energy. The products underwent UV, FTIR, XRD, SEM, EDX, XPS, BET, and DLS for characterization. Characterization via UV-Vis spectroscopy confirmed the shift in absorbance towards the visible spectrum, indicating the potential for enhanced photocatalytic activity under visible light irradiation. The energy band gap for as-synthesized nanoparticles was 3.03 eV, 2.71 eV, 2.61 eV, and 2.41 eV for the 1:1, 1:2, 1:3, and 1:4 sample ratios, respectively. The average crystal size of 32.18 nm and very fine flakes with tiny agglomerate structures of nanoparticles was obtained. The photocatalytic activity of the green-synthesized SnO2 nanoparticles was explored under visible light irradiation for the degradation of rhodamine B (RhB) and methylene blue (MB), which were widespread fabric pollutants. It was finally confirmed that the prepared NPs were actively used for photocatalytic degradation. Our results suggest the promising application of these green-synthesized SnO2 NPs as efficient photocatalysts for environmental remediation with low energy consumption compared to other light-driven processes. The radical scavenging experiment proved that hydroxyl radicals (_OH) are the predominant species in the reaction kinetics of both pollutant dyes under visible light degradation.

Synthesis characterization and application of butyl acrylate mediated eco-friendly silver nanoparticles using ultrasonic radiation

In the present investigation, with an effort to provide appropriate material for future applications, we have touched on two viable advancement targets: the production of silver nanoparticles (Ag-NPs) employing an ultrasonic approach and the use of Ag-NPs in environmental remediation. A green economical method was involved to prepare Ag-NPs using butyl acrylate as a stabilizer. The following techniques were used for analysing Ag-NPs: energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD), and Fourier transformed infrared (FT-IR) spectroscopy. X-ray diffraction (XRD) analysis for the lattice characteristics showed that Ag-NPs have a face-centered structure with an average crystallite size of 9.51-11.83 nm. FE-SEM and TEM analysis were used for morphological investigations, and revealed that Ag-NPs had a spherical shape with an average particle size of 16.27 nm. The EDX profile displayed a strong signal at ∼3.0 keV, which indicated that the samples comprised silver. UV-Visible spectrophotometer with the absorption maximum occurring between 401 and 411 nm further confirmed the formation of Ag-NPs. The dye degradation effect of synthesized Ag-NPs on methylene blue and Rhodamine B was analyzed to assess their ability for environmental remediation, and results showed that around 100% of the dye degradation effect. This study has provided a most plausible mechanism for the dye degradation.

Graphene oxide@Fe3O4-decorated iota-carrageenan composite for ultra-fast and highly efficient adsorption of lead (II) from water

The aggravated problem of lead pollution, especially in aquatic environments, necessitates the development of eminent adsorbents that could radically solve this environmental problem. Hence, a new composite was constructed based on iota carrageenan (i.Carr), graphene oxide (GO) and magnetite (Fe3O4) for removing noxious Pb2+ ions. The GO@Fe3O4-i.Carr composite was characterized by VSM, SEM, XPS, XRD, FTIR and Zeta potential. The removal of Pb2+ ions attained a quick equilibrium of almost 30 min with a removal efficiency reaching 93.68 %. The removal of Pb2+ was boosted significantly, in the order of GO@Fe3O4-i.Carr(1:1) > GO@Fe3O4-i.Carr(1:3) > GO@Fe3O4-i.Carr(3:1). Moreover, acquired experimental data fitted the pseudo 2nd order kinetic model and Freundlich isotherm model with a maximal monolayer adsorption capacity reached 440.05 mg/g. Notably, after five adsorption runs, the composite maintained its removal efficiency exceeding 74 %. The assumed adsorption mechanisms of Pb2+ onto GO@Fe3O4-i.Carr were complexation, precipitation, Lewis acid-base, and electrostatic attraction forces. Overall, the GO@Fe3O4-i.Carr composite elucidated the auspicious adsorbent criteria, comprising fast adsorption with high performance, ease-separation and tolerable recyclability, advising its feasible use to decontaminate water bodies from hazardous heavy metals.

Polyol synthesis of one-dimensional Ag nanowires for the photocatalytic degradation of textile dye and effective removal of microbes

Due to the excess release of hazardous pollutants to the environment, the quest for the synthesis of effective nanomaterials for wastewater treatment is never-ending. Present study reports the polyol synthesis of Ag NWs of ~ 85 nm diameter and average length of 4.08 µm using PVP and ethylene glycol. The experimental data on the methylene blue dye degradation substantiated the photocatalytic efficiency of Ag NWs (88% degradation in 120 min). Furthermore, the Ag NWs exhibited microbial load reducing property in air conditioner condensate water (ACW) within a time period of 60 min. Also, the anti-bacterial effect of Ag NWs was estimated using two human pathogenic bacterial strains, namely Staphylococcus aureus and Bacillus cereus. The antibacterial potential of Ag NWs against Staphylococcus aureus and Bacillus cereus was revealed significant with an inhibition zone size of 14 ± 0.1 mm and 9 ± 0.1 mm, respectively. Hence, the present work validates the potential efficiency of Ag NWs in the degradation of textile dyes and reduction of microbial population.

Exploring the viability of a floating photocatalyst in a continuous stirred tank reactor system for continuous water treatment

The use of photocatalysts in continuous stirred tank reactor (CSTR) systems allows for efficient and continuous water treatment, thus meeting the demand for scalable technology and comparative data in large-scale implementations. Hence, this study aims to explore the feasibility of a floating photocatalyst within a CSTR system for continuous water treatment. An expanded polystyrene (EPS)-TiO2 composite was synthesized following established methodologies, and their efficacy in removing the water pollutant methylene blue (MB) was compared for both batch and CSTR systems. A nonlinear first-order model was identified as the most suitable approach to accurately simulate MB degradation under experimental conditions, and the calculated pseudo-first-order degradation rate constant (k') for the CSTR system (0.0126-0.0172/min) was found to be superior to that observed for the batch system (0.0113/min). In addition, an increase in the flow rate reduced the retention time, leading to lower MB removal efficiency for the CSTR system. In addition, the EPS-TiO2/UV system with a CSTR configuration was found to efficiently use light and energy based on the calculated quantum yield (Φ = 2.86 × 10-4) and electrical energy per order (EEO = 857.46 kWh/m3/order). The findings of this study contribute to the development of sustainable and efficient water treatment strategies, offering valuable insight into the implementation of practical water treatment processes.

Barium Lanthanum Oxide Nanosheets in Photocatalytic and Forensic Applications: One-Pot Synthesis and Characterization

The present work elucidates the fabrication of Barium Lanthanum Oxide nanosheets (BaLa2O4 NSs) via a simple one-pot precipitation method. The acquired results show an orthorhombic crystal system with an average crystallite size of 27 nm. The morphological studies revealed irregular-shaped sheets stacked together in a layered structure, with the confirmation of the precursor elements. The diffused reflectance studies revealed a strong absorption between 200 nm and 350 nm, from which the band-gap energy was evaluated to be 4.03 eV. Furthermore, the fluorescence spectrum was recorded for the prepared samples; the excitation spectrum shows a strong peak at 397 nm, attributed to the 4F7/2→4G11/2 transition, while the emission shows two prominent peaks at 420 nm (4G7/2→4F7/2) and 440 nm (4G5/2→4F7/2). The acquired emission results were utilized to confirm the color emission using a chromaticity plot, which found the coordinates to be at (0.1529 0.1040), and the calculated temperature was 3171 K. The as-prepared nanosheets were utilized in detecting latent fingerprints (LFPs) on various non-porous surfaces. The powder-dusting method was used to develop latent fingerprints on various non-porous surfaces, which resulted in detecting all the three ridge patterns. Furthermore, the as-synthesized nanosheets were used to degrade methyl red (MR) dye, the results of which show more than 60% degradation at the 70th minute. It was also found that there was no further degradation after 70 min. All the acquired results suggest the clear potential of the prepared BaLa2O4 NSs for use in advanced forensic and photocatalytic applications.

Application of a novel composite of Fe3O4@SiO2/PAEDTC surrounded by MIL-101(Fe) for photocatalytic degradation of penicillin G under visible light

The novel photocatalyst of Fe3O4@SiO2/PAEDTC@MIL-101(Fe) was prepared based on the sol-gel method, and its structure and morphology were determined by SEM mapping, TEM, XRD, FTIR, and N2 adsorption-desorption analyses. The photocatalytic activity of nanocomposite was evaluated in comparison with other particles as well as adsorption and photolysis processes. The effect of operating parameters showed that the complete degradation of penicillin G (PNG) can be provided at a photocatalyst dosage of 0.6 g/L, radiation intensity of 36 W, pH of 5, and time of 60 min. In the optimum condition, 84% TOC removal was attained and the BOD5/COD rate for the treated effluent was above 0.4, which was representative of the high biodegradability of the treated effluent compared to the raw sample. The findings of energy consumption showed that PNG can be easily and effectively treated by the photocatalytic process based on magnetic MIL-101(Fe) with electrical energy per order between 10 and 20.87 kWh/m3. Due to the excellent interaction between the MIL-101(Fe) and Fe3O4@SiO2/PAEDTC, the photocatalyst stability test showed a recyclability of the particles for 5 consecutive reaction cycles with a minimum reduction of 7%. Solution treated with photocatalyst under UV and visible light sources explained that the toxicity of the effluent after treatment is significantly reduced with the growth of Escherichia coli. Scavenging experiments showed that •OH radical and hole (h+) are the main agents in degrading PNG to CO2, H2O, and biodegradable and low-toxicity products. Finally, the findings of the diagnostic analysis and comparative experiments proved that with the interaction of Fe3O4@SiO2, NH2, and MIL-101(Fe), a lower band gap can be prepared for more absorption of photons and pollutant and also more and faster production of active radicals.

Simultaneous photocatalytic removal of organic dye and heavy metal from textile wastewater over N-doped TiO2 on reduced graphene oxide

Methylene blue (MB) and hexavalent chromium Cr(VI) are hazardous pollutants in textile waste and cannot be completely removed using conventional methods. So far, there have been no specific studies examining the synthesis and activity of N-TiO₂/rGO as a photocatalyst for removing MB and Cr(VI) from textile wastewater. This work especially highlights the synthesis of N-TiO₂/rGO as a photocatalyst which exhibits a wider range of light absorption and is highly effective for simultaneous removal of MB-Cr(VI) under visible light. Titanium tetrachloride (TiCl₄) was used as the precursor for N-TiO₂ synthesis using the sol-gel method. Graphite was oxidized using Hummer's method and reduced with hydrazine to produce rGO. N-TiO₂/rGO was synthesized using a hydrothermal process and then analyzed using several characterization instruments. The X-ray diffraction pattern (XRD) showed that the anatase N-TiO₂/rGO phase was detected at the diffraction peak of 2θ = 25.60°. Scanning electron microscopy and transmission electron microscopy (SEM-EDS and TEM) dispersive X-ray spectrometry images show that N-TiO₂ particles adhere to the surface of rGO with uniform size and N and Ti elements are present in the N-TiO₂/rGO combined investigated. Gas absorption analysis data (GSA) shows that N-TiO₂/rGO had a surface area of 77.449 m²/g, a pore volume of 0.335 cc/g, and a pore size of 8.655 nm. The thermogravimetric differential thermal analysis (TG-DTA) curve showed the anatase phase at 500-780 °C with a weight loss of 0.85%. The N-TiO₂/rGO composite showed a good photocatalyst application. The photocatalytic activity of N-TiO₂/rGO for textile wastewater treatment under visible light showed higher effectiveness than ultraviolet light, with 97.92% for MB and 97.48% for Cr(VI). Combining N-TiO₂ with rGO is proven to increase the light coverage in the visible light region. Removal of MB and Cr(VI) can be carried out simultaneously and results in a removal efficiency of 95.96%.