Sunlight mediated enhanced photocatalytic activity of TiO2 nanoparticles functionalized CuO-Cu2O nanorods for removal of methylene blue and oxytetracycline hydrochloride

Design and preparation of a novel Mg-Al LDH@EDTA-Melamine nanocomposite for effective adsorptive removal of methylene blue and rhodamine B dyes from water

This paper deals with the preparation of a novel nanocomposite consisted of magnesium-aluminum layered double hydroxide (Mg-Al LDH) and ethylenediaminetetraacetic acid (EDTA) as well as melamine (MA) as an adsorbent. This nanocomposite was utilized to adsorb different dyes such as rhodamine B (RhB) and methylene blue (MB) from water. The prepared adsorbent was characterized using FT-IR, EDS, XRD, TGA, and FE-SEM analyses. The effects of various parameters such as concentration, time, adsorbent dosage, temperature, and pH were tested to investigate their influence on adsorption conditions. Both methylene blue and rhodamine B dyes showed pseudo-second-order adsorption kinetics, and their adsorption followed the Langmuir isotherm. Moreover, the maximum adsorption capacities for methylene blue and rhodamine B were found to be 1111.103 mg/g at 45 °C and 232.558 mg/g at 60 °C, respectively. Additionally, the adsorption processes were found to be spontaneous (ΔG°< 0, for both dyes) and exothermic (ΔH° = -12.42 kJ/mol for methylene blue and ΔH° = -25.84 kJ/mol for rhodamine B) for both dyes. Hydrogen bonding and electrostatic forces are responsible for the interactions occur between the nanocomposite and the functional groups in the dyes. The experimental findings demonstrated a greater adsorption rate of MB than RhB, suggesting the adsorbent's stronger affinity for MB. This preference is likely due to MB's size, specific functional groups, and smaller molecule size, enabling stronger interactions and more efficient access to adsorption sites compared to RhB. Even after recycling 4 times, the dye adsorption percentages of the adsorbent for MB and RhB dyes were 90 % and 87 %, but the desorption percentages of the adsorbate dyes were 85 % and 80 %, respectively. The prepared adsorbent boasts several unique properties, such as the swift and effortless adsorption of MB and RhB dyes, straightforward synthesis, mild adsorption conditions, remarkable efficiency, and the ability to be recycled up to 4 times without a significant decrease in activity.

Gas-Phase Fabrication and Photocatalytic Activity of TiO2 and TiO2-CuO Nanoparticulate Thin Films

CuO-loaded TiO2 nanomaterials have applications in pollutant degradation via photocatalysis. However, the existing methods of fabricating these nanomaterials involve liquid-phase processes, which require several steps and typically generate liquid waste. In this study, TiO2 and TiO2-CuO nanoparticulate thin films were successfully fabricated through a one-step gas-phase approach involving a combination of plasma-enhanced chemical vapor deposition and physical vapor deposition. The resulting films consisted of small, spherical TiO2 nanoparticles with observable CuO on the TiO2 surface. Upon annealing in air, the TiO2 nanoparticles were crystallized, and CuO was completely oxidized. The photocatalytic activity of TiO2-CuO/H2O2, when introduced into the rhodamine 6G degradation system, was substantially enhanced under both ultraviolet and visible light irradiation. Moreover, this study highlights the influence of pH on the photocatalytic activity; TiO2-CuO/H2O2 exhibited the highest photocatalytic activity at pH 13, with a reaction rate constant of 0.99 h-1 cm-2 after 180 min of visible light irradiation. These findings could facilitate the development of nanoparticulate thin films for enhanced pollutant degradation in wastewater treatment.

Domain-limited thermal transformation preparation of novel graphitized carbon-supported layered double oxides for efficient tetracycline degradation

The resource utilization of industrial lignin to construct high-performance catalysts for wastewater treatment field is pioneering research. Herein, the novel graphitized carbon-supported CuCoAl-layered double oxides (LDOs-GC) were successfully designed by the domain-limited thermal transformation technology using sodium lignosulfonate (LS) self-assembled CuCoAl-layered double hydroxides as the precursor. The optimized LDOs-GC catalyst owned the excellent tetracycline (TC) degradation of 98.0% within 15 min by activated peroxymonosulfate (PMS) under optimal conditions (20 mg/L catalyst, 1.5 mM PMS, 30 mg/L TC). The density of metal ions in the catalyst and the synergistic interaction between graphitized carbon (GC) and metal ions played a major role in TC degradation. Based on a comprehensive analysis, the TC degradation in LDOs-GC/PMS system was proved to be accomplished by a combination of free radicals (SO4·- and HO·) and non-radicals (1O2). Meanwhile, the possible degradation pathways of TC were proposed by the analysis of TC degradation intermediates and a comprehensive analysis of the rational reaction mechanism for TC degradation by LDOs-GC/PMS system was also performed. This work provides a new strategy for developing novel high-performance catalysts from industrial waste, while offering a green, cheap and sustainable approach to antibiotic degradation.

E-beam irradiation-induced synthesis of hydroxyethyl cellulose/(Cu2O-rGO)/BiVO4-based nanocomposite for photocatalytic remediation of wastewater under visible light

Using E-beam irradiation as an eco-friendly technique for initiation and crosslinking, a series of Hydroxyethyl Cellulose-poly vinyl alcohol copolymer hydrogels were synthesized as templates for cuprous oxide (Cu2O), reduced graphene oxide (rGO) and bismuth vanadate (BiVO4) nanoparticles to be used as nanocomposites photocatalysts for methylene blue (MB) dye decolorization using visible light. Preparation conditions were optimized to ensure the construction of a good network architecture and therefore the highest gelation degree. For the preparation of (Cu2O@rGO)/BiVO4 nanocomposites, a series of rGO was decorated by Cu2O using the precipitation method, followed by mixing with BiVO4 which was synthesized hydrothermally. (EDX), (XRD), (TEM), and (SEM) were used for nanoparticle characterization. The thermal characteristics of the fabricated nanocomposites were evaluated using thermal gravimetric analysis. The presence of rGO enhanced the decolorization efficiency of MB about 20 % higher than that of (HEC-PVA)/Cu2O which achieves only (59 %) decolorization efficiency. After the addition of BiVO4 NPs, the decolorization efficiency increased to reach 90 % after 150 min at pH 11 using a 10 ppm MB solution. The developed (HEC-PVA)/(Cu2O@rGO)/BiVO4 photocatalyst exhibits efficient reusability for 5 cycles. Treated dyed water shows a germination index (GI) of 82 % suggesting its suitability for irrigation of playgrounds and gardens.

The prospect of CuxO-based catalysts in photocatalysis: From pollutant degradation, CO2 reduction, and H2 production to N2 fixation

The topic of photocatalysis and CuxO-based materials has been intertwined for quite a long time. Its relatively high abundance in the earth's crust makes it an important target for researchers around the globe. One of the properties exploited by researchers is its ability to exist in different oxidation states (Cu0, Cu+, Cu2+, and Cu3+) and its implications on photocatalytic efficiency improvement. Recently, they have been extensively used as photocatalytic materials for dye and pollutant degradation. However, it has almost reached saturation levels, therefore, currently, they are being mostly utilized for CO2 reduction and H2 evolution. Hence, this review will discuss the evolution (in application) of CuxO-based photocatalysts, relating to their past, present, and future. Moreover, photocatalytic efficiency improvement strategies such as doping, heterojunction formation, and carbonaceous construction with other materials will also be touched upon. Finally, the prospect of Cu2O-based photocatalysts will be discussed in the field of photocatalytic N2 fixation to ammonia. The significance of N2 chemisorption on photocatalysts to maximize ammonia production will also be given importance.

Formation of Self-Assembled Nanowires from Copper Nanoparticles Synthesized by the Electro-Explosion of Wires Technique-Study of the Time-Dependent Structural and Functional Evolution

We report here the formation of Cu nanowires (CuNWs) from Cu nanoparticles (CuNPs) by a self-assembly process. The CuNPs were synthesized by the electro-explosion of wire (EEW) technique that included nonequilibrium processes for the synthesis. Structural evolution in terms of aggregation or nanowire formation in the samples was observed when the CuNPs were kept for a month after synthesis in a glass vial without the application of any external driving force. The emergence of tangled CuNWs was noticed at the bottom of the vials only when no agitation or aeration was allowed. The nanowires were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Thermal oxidation of the nanowire samples implied that they could convert into rod-shaped structures. Loss of functionality was also observed in the hemoglobin precipitation study conducted to compare the activity of freshly prepared CuNPs and CuNWs. From the above observations, we conclude that the CuNP, after synthesis, possesses a huge amount of energy, and attainment of equilibrium occurs through either aggregation (clustering) or ordered self-assembly, depending on the conditions applied.

Emerging micropollutants in aquatic ecosystems and nanotechnology-based removal alternatives: A review

There is a significant concern about the accessibility of uncontaminated and safe drinking water, a fundamental necessity for human beings. This concern is attributed to the toxic micropollutants from several emission sources, including industrial toxins, agricultural runoff, wastewater discharges, sewer overflows, landfills, algal blooms and microbiota. Emerging micropollutants (EMs) encompass a broad spectrum of compounds, including pharmaceutically active chemicals, personal care products, pesticides, industrial chemicals, steroid hormones, toxic nanomaterials, microplastics, heavy metals, and microorganisms. The pervasive and enduring nature of EMs has resulted in a detrimental impact on global urban water systems. Of late, these contaminants are receiving more attention due to their inherent potential to generate environmental toxicity and adverse health effects on humans and aquatic life. Although little progress has been made in discovering removal methodologies for EMs, a basic categorization procedure is required to identify and restrict the EMs to tackle the problem of these emerging contaminants. The present review paper provides a crude classification of EMs and their associated negative impact on aquatic life. Furthermore, it delves into various nanotechnology-based approaches as effective solutions to address the challenge of removing EMs from water, thereby ensuring potable drinking water. To conclude, this review paper addresses the challenges associated with the commercialization of nanomaterial, such as toxicity, high cost, inadequate government policies, and incompatibility with the present water purification system and recommends crucial directions for further research that should be pursued.

Enhanced photocatalytic reduction of Cr(VI) from aqueous solution using Fe0/TiO2-based polymeric nanocomposites

The combination of zerovalent iron (Fe0) and titanium dioxide (TiO2) has been investigated as a promising method for environmental remediation. However, it is a challenge to prepare conveniently desirable Fe0/TiO2 nanocomposites with excellent efficiency and reusability. Here, a novel nanocomposite material, Fe0/TiO2@D201, was synthesized to enhance the removal of Cr(VI) from an aqueous system by impregnating Fe0 and TiO2 inside a commercial anion exchanger (D201). The proposed structure and Cr(VI) removal mechanism of Fe0/TiO2@D201 were confirmed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. Compared to the monometallic samples (Fe0-D201 and TiO2-D201), Fe0/TiO2@D201 showed outstanding Cr(VI) removal and the removal ratio reached up to 97.30% after 120 min of UV light irradiation. The removal of Cr(VI) by Fe0/TiO2@D201 remained high (91.70%) even after four cycles, indicating the stability of the nanocomposites toward Cr(VI) removal and their strong potential for practical applications. The addition of ethylenediaminetetraacetic acid (EDTA) positively affected the Cr(VI) reduction process, whereas the addition of Na2S2O8 negatively affected the Cr(VI) process. The XPS results revealed that the photocatalytic reduction of Cr(VI) by Fe0/TiO2@D201 involved the capture of photoexcited electrons and Fe0 reduction. A path for the photogenerated electrons engaging in the reduction reaction to improve the utilization of Fe0 was proposed. These results demonstrate that Fe0/TiO2@D201 is a promising alternative composite catalyst for the efficient Cr(VI) removal from contaminated water.

Enhanced photocatalytic and SERS performance of Ag nanoparticles functionalized MoS2 nanoflakes

We report the preparation of Ag nanoparticles functionalized MoS2 nanoflakes by using the chemical reduction method followed by the hydrothermal method. Field emission scanning electron microscopy and elemental mapping reveals the uniform functionalization of Ag nanoparticles with MoS2 nanoflakes. High density of Ag plasmonic nanoparticles onto MoS2 nanoflakes demonstrates tremendously improved charge separation behavior in Ag-MoS2 nanohybrids. Photodecomposition capability of plasmonic Ag-MoS2 nanohybrids was explored by the decomposition of industrial pollutant molecules, showing a direct correlation between the Ag content over the MoS2 surface with their photodecomposition ability. The SERS-based detection profiles of the plasmonic were investigated by the ultra-low detection of MB molecules. The Ag-MoS2 nanohybrids SERS substrate manifests the detection of MB molecules solution up to a concentration of 10-9 M with an enhancement factor of 107. In the current study, we proposed and elucidated the probable efficient charge transfer mechanism for improved photocatalytic behavior and SERS-based sensing performance.

Fe3O4@ABA-aniline-CuI nanocomposite as a highly efficient and reusable nanocatalyst for the synthesis of benzothiazole-sulfide aryls and heteroaryls

Studying diaryl sulfides and benzothiazoles is important in organic synthesis because numerous natural and medicinal products contain these scaffolds. Over the past few years, research on the synthesis of compounds containing benzothiazole-sulfide aryls, as important biological molecules, has received significant attention. Multicomponent reactions are the most popular strategy for performing difficult reactions and the synthesis of complexed molecules such as benzothiazole-sulfide aryls. In this work, CuI was successfully immobilized on the surface of magnetic Fe₃O₄ nanoparticles modified with aniline and 4-aminobenzoic acid [Fe₃O₄@ABA-Aniline-CuI nanocomposite] and its catalytic activity was investigated in the preparation of a broad range of benzothiazole-sulfide aryls and heteroaryls through the one-pot three-component reactions of 2-iodoaniline with carbon disulfide and aryl or heteroaryl iodides in the presence of KOAc as base in PEG-400 as solvent. TEM and SEM images revealed that the shape of the Fe₃O₄@ABA-Aniline-CuI particles is spherical and the size of the particles is approximately between 12-25 nanometers.

Emerging 2D Copper-Based Materials for Energy Storage and Conversion: A Review and Perspective

2D materials have shown great potential as electrode materials that determine the performance of a range of electrochemical energy technologies. Among these, 2D copper-based materials, such as Cu-O, Cu-S, Cu-Se, Cu-N, and Cu-P, have attracted tremendous research interest, because of the combination of remarkable properties, such as low cost, excellent chemical stability, facile fabrication, and significant electrochemical properties. Herein, the recent advances in the emerging 2D copper-based materials are summarized. A brief summary of the crystal structures and synthetic methods is started, and innovative strategies for improving electrochemical performances of 2D copper-based materials are described in detail through defect engineering, heterostructure construction, and surface functionalization. Furthermore, their state-of-the-art applications in electrochemical energy storage including supercapacitors (SCs), alkali (Li, Na, and K)-ion batteries, multivalent metal (Mg and Al)-ion batteries, and hybrid Mg/Li-ion batteries are described. In addition, the electrocatalysis applications of 2D copper-based materials in metal-air batteries, water-splitting, and CO₂ reduction reaction (CO₂ RR) are also discussed. This review also discusses the charge storage mechanisms of 2D copper-based materials by various advanced characterization techniques. The review with a perspective of the current challenges and research outlook of such 2D copper-based materials for high-performance energy storage and conversion applications is concluded.

Fabrication of Ni/TiO2 visible light responsive photocatalyst for decomposition of oxytetracycline

Nickel-impregnated TiO₂ photocatalyst (NiTP) responding to visible light was prepared by the liquid phase plasma (LPP) method, and its photoactivity was evaluated in degrading an antibiotic (oxytetracycline, OTC). For preparing the photocatalyst, nickel was uniformly impregnated onto TiO₂ (P-25) powder, and the nickel content increased as the number of LPP reactions increased. In addition, the morphology and lattice of NiTP were observed through various instrumental analyses, and it was confirmed that NiO-type nanoparticles were impregnated in NiTP. Fundamentally, as the amount of impregnated nickel in the TiO₂ powder increased sufficiently, the band gap energy of TiO₂ decreased, and eventually, the NiTP excited by visible light was synthesized. Further, OTC had a decomposition reaction pathway in which active radicals generated in OTC photocatalytic reaction under NiTP were finally mineralized through reactions such as decarboxamidation, hydration, deamination, demethylation, and dehydroxylation. In effect, we succeeded in synthesizing a photocatalyst useable under visible light by performing only the LPP single process and developed a new advanced oxidation process (AOP) that can remove toxic antibiotics.

Removal of oxytetracycline from water by liquid-phase plasma process with an iron precipitated TiO2 photocatalyst

This study developed a new water treatment method using liquid-phase plasma (LPP) process that can decompose oxytetracycline (OTC) remaining in the aquatic environment. Relatedly, the OTC causes damage to the human body and cannot be removed by traditional water treatment methods. The study also prepared Fe/TiO₂ photocatalyst responding to visible light using the LPP process. In particular, the OTC decomposition efficiency of the LPP process improved by more than 10% with the use of the Fe/TiO₂ photocatalyst as compared to that of the one with the use of bare TiO₂ photocatalyst. Further, the optimal LPP process parameters and Fe/TiO₂ photocatalyst amount in the LPP process for OTC decomposition were established in the study. Finally, the degradation pathway of the OTC in the LPP process was found based on the five intermediates of the LPP reaction that were detected by the liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis. In particular, the decomposition pathway was estimated to be involving the mineralization of the OTC through demethylation, deamination, dehydration, and ring cleavage.

Natural Cotton Cellulose-Supported TiO2 Quantum Dots for the Highly Efficient Photocatalytic Degradation of Dyes

The artificial photocatalytic degradation of organic pollutants has emerged as a promising approach to purifying the water environment. The core issue of this ongoing research is to construct efficient but easily recyclable photocatalysts without quadratic harm. Here, we report an eco-friendly photocatalyst with in situ generated TiO₂ quantum dots (TQDs) on natural cotton cellulose (CC) by a simple one-step hydrothermal method. The porous fine structure and abundant hydroxyl groups control the shape growth and improve the stability of nanoparticles, making natural CC suitable for TQDs. The TQDs/CC photocatalyst was synthesized without the chemical modification of the TQDs. FE-SEM and TEM results showed that 5-6 nm TQDs are uniformly decorated on the CC surface. The long-term stability in photocatalytic activity and structure of more than ten cycles directly demonstrates the stability of CC on TQDs. With larger CC sizes, TQDs are easier to recycle. The TQDs/CC photocatalysts show impressive potential in the photocatalytic degradation of anionic methyl orange (MO) dyes and cationic rhodamine B (RhB) dyes.

Laser induced plant leaf extract mediated synthesis of CuO nanoparticles and its photocatalytic activity

Metal nanoparticles furnished by the green synthesis approach have exhibited fascinating attributes owing to their biocompatibility with biomolecules, and their rapid environmentally friendly synthesis. On copper oxide (CuO) nanoparticles, a laser induced bio reduction work has been accomplish using Centella asiatica aqueous extract at room temperature is the pioneer in the field. This synthesis technique is easy, fruitful, eco-friendly, and counterfeit for the size-tunable synthesis of diverse shapes of stable copper nanoparticles. UV-visible spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy - Dispersive X-ray Spectroscopy (EDX), X-ray diffraction (XRD) and photodegradation study have astounding properties of regulating the formation, crystalline nature, and morphology of an integrated specimen. Moreover, the obtained copper oxide nanoparticle has the tendency to decrease the absorbance maximum value of methylene blue because of the catalytic activity posed by these nanoparticles on the reduction of methylene blue by Centella asiatica. It has been studied and confirmed by UV-visible spectrophotometer, and it has been recognised as an electron relay effect.

Layered Molybdenum (Meta)phosphate for Photoreduction of Hexavalent Chromium and Degradation of Methylene Blue under Sunlight Radiance

Noble metal, semiconductor, or metal-free nanomaterials have shown promising applicability as potential photocatalyst materials. A one-step process has been established for the synthesis of layered molybdenum (meta)phosphate [MoO₂(PO₃)₂] using a solvothermal method. The nanopowders were characterized by X-ray diffraction (XRD), UV-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), surface area analysis (Brunauer-Emmett-Teller (BET)), electron spin resonance (ESR), and high-resolution transmission electron microscopy (HRTEM). Through this study, we demonstrate the use of MoO₂(PO₃)₂ as a photocatalyst for wastewater treatment. The photoreduction of toxic Cr⁶⁺ to Cr³⁺ by layered molybdenum (meta)phosphate is investigated using formic acid as a scavenger. This catalyst has also been used for photodegrading organic dyes like methylene blue. MoO₂(PO₃)₂ has been shown to complete photoreduction of toxic Cr⁶⁺ to Cr³⁺ in 6 min and achieved 78% degradation efficiency for methylene blue in 36 min. The reactive species trapping experiments revealed that the key active species like O₂ ^•-, ^•OH, and h⁺ can exist and play an important role in methylene blue photodegradation.

N-TiO2-δ/g-C3N4 Dual Photocatalysts for Efficient Oxytetracycline Hydrochloride Photodegradation and CO2 Photoreduction

A series of $x\%$ (wt) N-TiO2-δ/g-C3N4 composites was synthesized by calcination and hydrothermal methods (labeled $x$ TiCN, $x$ : 5, 10, and 15). All composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The photocatalytic activity of these composites was evaluated through oxytetracycline hydrochloride (denoted as OTC) photodegradation and CO2 photoreduction. The $x$ TiCN composites exhibited higher OTC photodegradation than bulk g-C3N4. 10TiCN was slightly more active than 5TiCN and 15TiCN, with a photodegradation yield of 97% after 5 h of light irradiation and constant rate of 0.647 h-1. For CO2 photoreduction, it was observed that 5TiCN exhibited the highest activity among the synthesized composites, with 7.0 ppm CH4 formed. This CH4 concentration was 7.8 times higher than the concentration formed by bulk g-C3N4 (0.9 ppm). A $Z$ -scheme mechanism was proposed to explain the enhanced photocatalysis by $x\%$ (wt) N-TiO2-δ/g-C3N4 composites. The $Z$ -scheme structure increased redox ability, caused better separation of photogenerated electron-hole pairs, and broadened the light absorption zone of the photocatalysts.

Bioremediation and decontamination potentials of metallic nanoparticles loaded nanohybrid matrices - A review

The current nanotechnological advancements provide an astonishing insight to fabricate nanomaterials for nano-bioremediation purposes. Exciting characteristics possessed by hybrid matrices at the nanoscale knock endless opportunities to nano-remediate environmentally-related pollunanomaterials tants of emerging concern. Nanometals are considered among the oldest generation of the world has ever noticed. These tiny nanometals and nanometal oxides showed enormous potential in almost every extent of industrial and biotechnological domains, including their potential multipurpose approach to deal with water impurities. In this manuscript, we discussed their role in the diversity of water treatment technologies used to remove bacteria, viruses, heavy metals, pesticides, and organic impurities, providing an ample perspective on their recent advances in terms of their characteristics, attachment strategies, performance, and their scale-up challenges. Finally, we tried to explore their futuristic contribution to nano-remediate environmentally-related pollutants of emerging concern aiming to collect treated yet safe water that can be reused for multipurpose.

Sustainable nanotechnology based wastewater treatment strategies: achievements, challenges and future perspectives

Nanotechnology is being an emerging science for wastewater treatment requires more research emphasis and depth knowledge. For wastewater treatment, different forms of nanomaterials are used based on the type of contaminants and treatment efficiency desired. With the development in the field of nanomaterials, novel and emerging nanomaterials are coming into existence. The nanomaterials used for wastewater treatment can be carbon, single-walled carbon nanotubes, multiple walled carbon nanotubes, covalent organic frameworks, metal and metal oxide- based nanoparticles. Graphene based nanoparticles, their oxides (GO) and reduced graphene oxide (rGO) find tremendous applicability to be used in wastewater treatment purposes. Due to the introduction of graphene oxide nanoparticles in the adsorbent materials, their adsorption capacities have get enhanced and such materials have also improved the mechanical stability of the adsorbent. Ferric oxide shows greater adsorption capacities for organic pollutants. Furthermore, magnetic nano-powder confers a low adsorption capacity for phenols. Pyrrolidone reduced graphene oxide (PVP-RGO) nanoparticles have been used as adsorbents for the elimination of inorganic target contaminant copper, with great adsorption (1698 mg/g). The present study comprehensively reviews nanotechnology as a wastewater treatment strategy besides enlightening its safety issues and efficiency. The novelty of this article is that it highlights the overview of recent applications of various types of nanomaterials and research works releated to it. Such an approach will be helpful to get insights into technological advances, applications and future challenges of nanotechnology implementation for wastewater treatment.

Chemical Vapor Deposition and Thermal Oxidation of Cuprous Phosphide Nanofilm

Inorganic semiconductors usually show n-type characterization; the development of p-type inorganic semiconductor material will provide more opportunities for novel devices. In this paper, we investigated the chemical vapor deposition (CVD) of p-type cuprous phosphide (Cu3P) nanofilm and studied its thermal oxidation behavior. Cu3P film was characterized by optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), laser Raman spectroscopy (Raman), and fluorescence spectroscopy (PL). We found that the thickness of film ranged from 4 to 10 nm, and the film is unstable at temperatures higher than room temperature in air. We provide a way to prepare inorganic phosphide nanofilms. In addition, the possible thermal oxidation should be taken into consideration for practical application.

Photocatalytic effect of CuO nanoparticles flower-like 3D nanostructures under visible light irradiation with the degradation of methylene blue (MB) dye for environmental application

The present research work focuses on preparing 3D transition metal doped copper oxide nanostructures through sonication method and to investigate the effect of doping different transition metal into copper oxide (CuO) on the basic properties of CuO nanoparticles and, to study the photocatalytic behaviour of the doped CuO samples. The morphological studies performed with the help of SEM revealed the formation of flower like CuO 3D nanostructures for all the doped samples. The slight shift in the position of peaks in the x-ray diffraction (XRD) pattern confirms that doping has been successfully done into CuO. Also, the sharp diffraction peaks suggest the polycrystalline nature of the sample with monoclinic structure. The UV-vis absorption analysis reveals a bandgap of 2.26, 2.12 and 2.15 eV for the CuO samples doped with nickel, zinc, and iron respectively via Tauc plot. The photocatalytic performance of the samples tested through the degradation of methylene blue (MB) dye suggests that samples doped with Zn shows better degradation. Thus, it is evident that the morphology and the optical properties of the CuO can be tailored by doping transition metal into it.

Photoluminescence properties of cuprous phosphide prepared through phosphating copper with a native oxide layer

Although cuprous phosphide (Cu₃P) has been widely studied and applied in other fields, its photoluminescence (PL) properties are rarely investigated. Herein, we report that Cu₃P can emit near-infrared light at 750 nm. We show that the annealing and the presence of cuprous oxide can enhance the PL emission. The mechanism of the PL enhancement is the improvement of crystal quality and the formation of a space charge region. Our results provide a reference for improving the PL properties of p-type semiconductors.

Selective biosorption mechanism of methylene blue by a novel and reusable sugar beet pulp cellulose/sodium alginate/iron hydroxide composite hydrogel

A cellulose-based sodium alginate/iron hydroxide (C/SA/Fe) composite hydrogel was fabricated by using epichlorohydrin as cross-linking agent as an effective adsorbent for dye. The physicochemical structure of the C/SA/Fe hydrogel was characterized by SEM, FTIR, XRD and TG. The adsorption performance for the removal of methylene blue (MB) was investigated. In addition, the selective adsorption of cationic dye was also studied. The FTIR analysis revealed that the Fe(OH)₃ colloidal particles was successfully combined in the cellulose/sodium alginate hydrogel. The modified hydrogel had better adsorption performance, and the maximum adsorption capacity of C/SA/Fe0.5 for MB was 105.93 mg/g according to the fitting results of adsorption isotherm. The kinetic study showed that MB adsorption of C/SA/Fe was more consistent with the pseudo-second-order model, and the adsorption of MB in C/SA/Fe was dominated by chemisorption mechanism such as ion exchange or electron sharing. The adsorption data fits well with the Langmuir model. Thermodynamics analysis showed that the MB adsorption by C/SA/Fe was exothermic, spontaneous, favorable and feasible. After five adsorption-desorption cycles, the adsorption capacity was almost unchanged. So, the C/SA/Fe hydrogel is a potential material in the field of the recovery of agricultural by-products or other bio-based cellulose, or environmental protection, etc.

Inlaying metal-organic framework derived pancake-like TiO2 into three-dimensional BiOI for visible-light-driven generation of vanillin from sodium lignosulfonate

Pancake-like TiO₂ (M-TiO₂) derived from the metal-organic framework was inlaid into three-dimensional flower-like BiOI through a facile solvothermal method. M-TiO₂ supplies large surface area and mesoporous structure for attachment and transfer of the substrates and products, while BiOI acts as a photosensitizer to absorb visible light and generates electrons and holes. The distinct structure of M-TiO₂/BiOI gives a favorable contact between the two monomers, and promotes the transfer of charge carriers. In conjunction with the proper band positions of M-TiO₂ and BiOI, the efficient separation of electron-hole pairs is attained. Benefiting from the above cooperative effects of M-TiO₂ and BiOI, the performance for the vanillin generation from sodium lignosulfonate (SLS) over M-TiO₂/BiOI composites has a prominent improvement under visible light. Specifically, the yield over optimal M-TiO₂/BiOI sample is about 5.8 mg/g_SLS, obviously superior to that over pristine M-TiO₂ (~1 mg/g_SLS) and BiOI (~1.1 mg/g_SLS). It is found that h⁺ and O₂^- play the key role for vanillin generation from sodium lignosulfonate, and the low vanillin generation under UV-vis light sheds light on that OH is an adverse factor. We hoped that this work could inspire the studies on the photocatalytic valorization of biomass using noble metal-free catalysts.

Enhanced sunlight driven photocatalytic activity of In2S3 nanosheets functionalized MoS2 nanoflowers heterostructures

Visible light-sensitive 2D-layered based photocatalytic systems have been proven one of the effective recent trends. We report the preparation of a 2D-layered based In₂S₃-MoS₂ nanohybrid system through a facile hydrothermal method, capable of efficiently degrading of organic contaminants with remarkable efficiency. Transmission electron microscopy (TEM) results inferred the attachment of 2D-layered In₂S₃ sheets with the MoS₂ nanoflakes. Field emission SEM studies with chemical mapping confirm the uniform distribution of Mo, In, and S atoms in the heterostructure, affirming sample uniformity. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy results confirm the appearance of 2H-MoS₂ and β-In₂S₃ in the grown heterostructures. UV-DRS results reveal a significant improvement in the optical absorbance and significant bandgap narrowing (0.43 eV) in In₂S₃-MoS₂ nanohybrid compared to pristine In₂S₃ nanosheets in the visible region. The effective bandgap narrowing facilitates the charge transfer between MoS₂ and In₂S₃ and remarkably improves the synergistic effect. Effective bandgap engineering and improved optical absorption of In₂S₃-MoS₂ nanohybrids are favorable for enhancing their charge separation and photocatalytic ability. The photocatalytic decomposition efficiency of the pristine In₂S₃ nanosheets and In₂S₃-MoS₂ nanohybrids sample is determined by the decomposing of methylene blue and oxytetracycline molecules under natural sunlight. The optimized In₂S₃-MoS₂ nanohybrids can decompose 97.67% of MB and 76.3% of OTC-HCl molecules solution in 8 min and 40 min of exposure of sunlight respectively. 2D-layered In₂S₃-MoS₂ nanohybrids reveal the tremendous remediation performance towards chemical contaminations and pharmaceutical waste, which indicates their applicability in industrial and practical applications.

Neural network-crow search model for the prediction of functional properties of nano TiO2 coated cotton composites

This paper presents a new hybrid approach for the prediction of functional properties i.e., self-cleaning efficiency, antimicrobial efficiency and ultraviolet protection factor (UPF), of titanium dioxide nanoparticles (TiO₂ NPs) coated cotton fabric. The proposed approach is based on feedforward artificial neural network (ANN) model called a multilayer perceptron (MLP), trained by an optimized algorithm known as crow search algorithm (CSA). ANN is an effective and widely used approach for the prediction of extremely complex problems. Various studies have been proposed to improve the weight training of ANN using metaheuristic algorithms. CSA is a latest and an effective metaheuristic method relies on the intelligent behavior of crows. CSA has been never proposed to improve the weight training of ANN. Therefore, CSA is adopted to optimize the initial weights and thresholds of the ANN model, in order to improve the training accuracy and prediction performance of functional properties of TiO₂ NPs coated cotton composites. Furthermore, our proposed algorithm i.e., multilayer perceptron with crow search algorithm (MLP-CSA) was applied to map out the complex input–output conditions to predict the optimal results. The amount of chemicals and reaction time were selected as input variables and the amount of titanium dioxide coated on cotton, self-cleaning efficiency, antimicrobial efficiency and UPF were evaluated as output results. A sensitivity analysis was carried out to assess the performance of CSA in prediction process. MLP-CSA provided excellent result that were statistically significant and highly accurate as compared to standard MLP model and other metaheuristic algorithms used in the training of ANN reported in the literature.

CeO2/CuO/TiO2heterojunction photocatalysts for conversion of CO2to ethanol

An attempt to reduce CO₂emissions has led to the development of CeO₂/CuO/TiO₂heterojunction photocatalysts for photoconversion of CO₂to useful products, e.g. ethanol. Composite photocatalysts were simply prepared by mixing TiO₂(P25) with different mass ratios of CeO₂(1 wt%) and CuO (2 or 3 wt%) by ball milling. The prepared photocatalysts had uniformly distributed CeO₂and CuO phases, throughout the TiO₂phase. The integration of CeO₂and CuO into TiO₂at 1 wt% CeO₂and 3 wt% CuO produced a composite, with a reduced band gap of 2.88 eV, allowing absorption of lower energy light and a lower electron-hole recombination rate. The 1%CeO₂/3%CuO/TiO₂photocatalysts yielded ethanol at 30.5μmol g_cat^-1h^-1, almost three times higher than the yield from pure TiO₂. This improved CO₂conversion efficiency was due to contributions from properties of both additives: CeO₂increased light absorption, while CuO acted as an electron trap and enhanced CO₂adsorption. In addition, the heterojunction at the interfaces facilitated the photogenerated charge separation, which, in turn, increased the charge participation in the catalyzed conversion reactions.

Enhanced photocatalytic degradation of tetracycline by constructing a controllable Cu2O–TiO2 heterojunction with specific crystal facets

Type II heterojunction of 100Cu2O–TiO2 exhibits enhanced photodegradation rate of TC at the sacrifice of absolute decomposition, while 111Cu2O–TiO2 Z-scheme heterojunction displays simultaneous increased degradation rate and profound decomposition.