Tuning of metal oxides photocatalytic performance using Ag nanoparticles integration

Edge-oriented growth of cadmium sulfide nanoparticles on nickel metal-organic framework nanosheets for photocatalytic hydrogen evolution

In this study, a directional loading of cadmium sulfide (CdS) nanoparticles (NPs) was achieved on the opposite edges of nickel metal-organic framework (Ni-MOF) nanosheets (NSs) by adjusting the weight ratio of CdS NPs in the reaction process to produce effective visible light photocatalysts. The close contact between the zero-dimensional (0D) and two-dimensional (2D) regions and the matching positions of the bands promoted charge separation and heterojunction formation. The optimal CdS NPs loading of composite material was 40 wt%. At this ratio, CdS NPs grew primarily at the opposite edges of the Ni-MOF NSs rather than on their surfaces. When lactic acid was used as the sacrificial agent, the hydrogen production rate of the 40 %-CdS/Ni-MOF heterojunction under visible light irradiation was 19.6 mmol h-1 g-1, making a 20-fold enhancement compared to the original CdS NPs sample (1.0 mmol h-1 g-1). The charge carriers generated in CdS NPs were transferred to Ni-MOF NSs through heterojunctions, where Ni-MOF NSs also served as cocatalysts to improve hydrogen production. The combination of the two materials improved the light absorption ability. In particular, the 40 %-CdS/Ni-MOF heterojunction exhibited good photostability, effectively preventing the photocorrosion of CdS NPs. This study introduces an approach for constructing efficient and stable photocatalysts for visible light-driven photocatalytic hydrogen production.

Exploring the diverse performance of nickel and cobalt spinel ferrite nanoparticles in hazardous pollutant removal and gas sensing performance

A simple sol-gel combustion process was employed for the creation of MFe2O4 (M=Ni, Co) nanoparticles. The synthesized nanoparticles, acting as both photocatalysts and gas sensors, were analyzed using various analytical techniques. MFe2O4 (M=Ni, Co) material improved the degradation of methylene blue (MB) under UV-light irradiation, serving as an enhanced electron transport medium. UV-vis studies demonstrated that NiFe2O4 achieved a 60% degradation, while CoFe2O4 nanostructure exhibited a 76% degradation efficacy in the MB dye removal process. Furthermore, MFe2O4 (M=Ni, Co) demonstrated chemosensitive-type sensor capabilities at ambient temperature. The sensor response and recovery times for CoFe2O4 at a concentration of 100 ppm were 15 and 20, respectively. Overall, the synthesis of MFe2O4 (M=Ni, Co) holds the potential to significantly improve the photocatalytic and gas sensing properties, particularly enhancing the performance of CoFe2O4. The observed enhancements make honey MFe2O4 (M=Ni, Co) a preferable choice for environmental remediation applications.

FeOCl/MOF-derived In2S3 photocatalysts with high H2O2 adsorption: Degradation mechanism, H2O2 activation process

The FeOCl-based photo-Fenton heterojunction catalyst holds great promise for effective water pollution treatment. A novel heterojunction FeOCl/MOF-In2S3 (F/M-I) was fabricated by coating hollow MOF-In2S3 nanoflowers onto the surface of FeOCl. Under the optimal conditions, the maximum photo-Fenton degradation rate constants of FeOCl/MOF-In2S3 for oxytetracycline (OTC) within 20 min is 0.88192 L mg-1·min-1, which are 3.2 and 2.5 times that of pure FeOCl (0.27357 L mg-1·min-1) and MOF-In2S3 (0.35222 L mg-1·min-1). Density functional theory (DFT) results confirm that the electron-rich nature of MOF-In2S3 accelerates the cycle between Fe (III)/Fe (II)of FeOCl, promoting H2O2 adsorption by FeOCl/MOF-In2S3 and generating more hydroxyl radicals (·OH) for pollutant degradation. Based on the results of DFT, combined with the results of the reactive oxidation species scavenger (ROSs), electron paramagnetic resonance (EPR) and Mott-Schottky curves, the separation and transfer behavior of photoexcited charges in FeOCl/MOF-In2S3 heterojunction and the possible photocatalytic degradation mechanism were investigated. Finally, a Z-scheme heterostructure is proposed to elucidate the catalytic mechanism. This study provides a new perspective on designing and synthesizing semiconductor materials for water treatment by photo-Fenton catalysis.

Graphene oxide as an emerging sole adsorbent and photocatalyst: Chemistry of synthesis and tailoring properties for removal of emerging contaminants

Contaminants of emerging concern (CEC) contain a wide range of compounds, such as pharmaceutical waste, pesticides, herbicides, industrial chemicals, organic dyes, etc. Their presence in the surrounding has extensive and multifaceted effects on human health as they have the potential to persist in the environment, accumulate in biota, and disrupt ecosystems. In this regard, various remediation methods involving different kind of functional nanomaterials with unique properties have been developed. The functional nanomaterials can provide several mechanisms for water pollutant removal, such as adsorption, catalysis, and disinfection, in a single platform. Graphene oxide (GO) is a two-dimensional carbon-based material that has an extremely large surface area and a large number of active sites. Recent advances in synthesising GO have shown great progress in tailoring its various physiochemical, optical, surface, structural properties etc., making it better adsorbent and photocatalysts. In this review, sole adsorbent and standalone photocatalytic performances of GO for the removal of CEC have been discussed in light of tailoring its adsorption and photocatalytic properties through novel synthesis routes and optimizing synthesis parameters. This review also examines various models describing the structure of GO and its surface/structural modifications for improved adsorption and photocatalytic properties. The article provides valuable information for the production of efficient and cost-effective GO-based sole adsorbents and photocatalysts as compared to the traditional materials. Furthermore, future prospective and challenges for sole GO nanostructures to compete with traditional adsorbents and photocatalysts have been discussed providing interesting avenues for future research.

Adsorption Efficiency of Carbon Materials for the Removal of Organic Pollutants: DDT from Aqueous Solution

Carbon nanotubes (CNTs) are widely used to adsorb organic pollutants from wastewater due to their porous structure, large specific surface area, and unique physical and chemical properties. Examining the interactions between pollutant molecules and carbon nanotubes is an important topic in the applications of nanotubes for the removal of pollutants. In this study, molecular dynamics (MD) and metadynamics simulations were used to investigate the adsorption mechanism of Dichlorodiphenyltrichloroethane (DDT) pollutants on carbon nanotubes. Obtained results revealed that functionalized CNTs (f-CNTs) with active groups exhibited significantly enhanced performance compared to pristine CNTs. The adsorption isotherms were analyzed at different DDT concentrations, and it was found that increasing the concentration of DDT molecules led to a decrease in system energy and increased stability. The presence of biosurfactants as functional groups on the CNTs enhanced the interaction between DDT molecules and the nanotubes. In CNT, the addition of DDT increases the van der Waals energy from -176.83 kJ/mol for 3 DDT molecules to -2237.88 kJ/mol for 50 DDT molecules. In the case of f-CNT, the van der Waals energy in the system with 50 DDT molecules is about 2061.05 kJ/mol more negative than the system with 3 DDT molecules. The number of contacts between the adsorbent and DDT molecules increased over time, indicating increased adsorption interaction. The radial distribution functions (RDF) of DDT molecules around CNTs and f-CNTs showed the highest probability of finding DDT molecules at a distance of about 0.5 nm from the adsorbent surface. The study provided valuable insights into the adsorption process and can guide future experimental studies.

Structural, electronic, optical and thermodynamic properties of AlAuO2 and AlAu094Fe006O2 compounds scrutinized by density functional theory (DFT)

In this study, density functional theory (DFT) simulations have been used to study the structural, electrical and optical properties of AlAuO2 and AlAu094Fe006O2. Initially, the estimated bandgap of AlAuO2 0.45, 0.486, 0.419 and 2.49 eV in Perdew-Burke-Ernzerhof (PBE), Revised Perdew-Burke-Ernzerhof (RPBE), PBE for solids (PBE sol) and Becke three-parameter Lee-Yang-Parr (B3LYP) method respectively while AlAu094Fe006O2 has a zero-band gap after 6 % Fe doping. Then, density of state (DOS) and partial density of state (PDOS) were studied to determine the characteristics of the various orbitals of AlAuO2. The bonding characteristics and thermal stability of this crystal are determined by the Mulliken population charge and thermos physical parameters. Band edge of AlAuO2 was calculated which revealed that the AlAuO2 has suitable oxidation and reduction potential to degrade the contamination. A remarkable absorption has recorded for both AlAuO2 and AlAu094Fe006O2 in visible and ultraviolet region and capability to utilize photocatalytic dye degradation and hydrogen production through water splitting.

Visible Light Photocatalytic Degradation of Methylene Blue Dye and Pharmaceutical Wastes over Ternary NiO/Ag/TiO2 Heterojunction

Ternary NiO/Ag/TiO2 heterojunction photocatalyst was prepared by deposition coprecipitation for visible light photocatalytic applications. Physicochemical properties of the synthesized NiO/Ag/TiO2 composite were characterized by X-ray diffraction, Brunauer-Emmett-Teller surface area measurement method, transmission electron microscopy, energy-dispersive X-ray spectroscopy techniques, X-ray photoelectron spectroscopy technique, and ultraviolet-visible absorption spectroscopy. The results suggest that the well-dispersed small metallic silver nanoparticles (<3 nm) facilitate electron transfer and bridge nickel oxide and titanium oxide. The photocatalytic degradation and the methylene blue (MB) dye kinetics were carried out on a ternary NiO/Ag/TiO2 composite and compared to bare TiO2 under visible light irradiation. The results indicate that NiO/Ag/TiO2 has superior MB photodegradation efficiency with a high reaction rate constant and low degradation time (93.15% within 60 min) compared to Ag/TiO2, NiO/TiO2, and bare TiO2. NiO/Ag/TiO2 nanocomposite was also investigated for the most common pharmaceutical waste degradation and exhibited excellent degradation efficiency. The enhancement of the composite's performance could be attributed to the surface plasmonic resonance of the Ag nanoparticles, the formation of Schottky junctions at the Ag-TiO2 and Ag-NiO interface, and the p-n heterojunction between NiO and TiO2. Ag NPs act as a photosynthesizer and a photocatalyst, facilitate electron transfer, shift the absorption to the visible light region, reduce the band gap of TiO2, suppress the electron-hole recombination, and enhance the photocatalytic activity and stability as a result.

Mesoporous Cu-Doped Manganese Oxide Nano Straws for Photocatalytic Degradation of Hazardous Alizarin Red Dye

The present work reports the photocatalytic degradation of alizarin red (AR) using Cu-doped manganese oxide (MH16-MH20) nanomaterials as catalysts under UV light irradiation. Cu-doped manganese oxides were synthesized by a very facile hydrothermal approach and characterized by energy dispersive X-ray spectroscopy, powder X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller analysis, UV-vis spectroscopy, and photoluminescence techniques. The structural, morphological, and optical characterization revealed that the synthesized compounds are nanoparticles (38.20-54.10 nm), grown in high mesoporous density (constant C > 100), possessing a tetragonal phase, and exhibiting 2.98-3.02 eV band gap energies. Synthesized materials were utilized for photocatalytic AR dye degradation under UV light which was monitored by UV-visible spectroscopy and % AR degradation was calculated at various time intervals from absorption spectra. More than 60% AR degradation at various time intervals was obtained for MH16-MH20 indicating their good catalytic efficiencies for AR removal. However, MH20 was found to be the most efficient catalyst showing more than 84% degradation, hence MH20 was used to investigate the effect of various catalytic doses, AR concentrations, and pH of the medium on degradation. More than 50% AR degradation was obtained for all studied parameters with MH20 whereas the pseudo-first-order kinetic model was found to be the best-fitted kinetic model for AR degradation with k = 0.0015 and R2 = 0.99 indicating a significant correlation between experimental data.

Gamma irradiation effect on photocatalytic properties of Cu and Sr ions codoped PbS

Gamma-irradiation effects on photocatalytic action of PbS nanocrystallites codoped with Cu and Sr ions were performed for organic dye degradation. The physical and chemical characterizations of these nanocrystallites were examined employing X-ray diffraction, Raman, and field emission electron microscopic analysis. The optical bandgaps of gamma-irradiated PbS with co-dopants have shifted from 1.95 eV (pristine PbS) to 2.45 eV in the visible spectrum. Under direct sunlight, the photocatalytic action of these compounds against methylene blue (MB) was investigated. Observations indicated that gamma-irradiated Pb_(0.98)Cu_0.01Sr_0.01S nanocrystallite sample exhibits a higher photocatalytic degradation activity of 74.02% in 160 min and stability of 69.4% after three cycles, suggesting that gamma irradiation could potentially influence organic MB degradation. This is due to combined action of high-energy gamma irradiation (at an optimzed dose), which causes sulphur vacancies, and defects created by dopant ions, which alter the crystal structure by inducing strain in the crystal lattice, hence altering the crystallinity of PbS.

A Review on Photocatalysis Used For Wastewater Treatment: Dye Degradation

Water pollution is a global issue as a consequence of rapid industrialization and urbanization. Organic compounds which are generated from various industries produce problematic pollutants in water. Recently, metal oxide (TiO2, SnO2, CeO2, ZrO2, WO3, and ZnO)-based semiconductors have been explored as excellent photocatalysts in order to degrade organic pollutants in wastewater. However, their photocatalytic performance is limited due to their high band gap (UV range) and recombination time of photogenerated electron-hole pairs. Strategies for improving the performance of these metal oxides in the fields of photocatalysis are discussed. To improve their photocatalytic activity, researchers have investigated the concept of doping, formation of nanocomposites and core-shell nanostructures of metal oxides. Rare-earth doped metal oxides have the advantage of interacting with functional groups quickly because of the 4f empty orbitals. More precisely, in this review, in-depth procedures for synthesizing rare earth doped metal oxides and nonocomposites, their efficiency towards organic pollutants degradation and sources have been discussed. The major goal of this review article is to propose high-performing, cost-effective combined tactics with prospective benefits for future industrial applications solutions.

CaTiO3/g-C3N4 heterojunction-based composite photocatalyst: Part I: Experimental design, kinetics, and scavenging agents' effects in photocatalytic degradation of gemifloxacin

A critical, challenging environmental issue is explored pollution of water supplies by discharging industrial/pharmaceutical/hospital/urban wastewaters into the aquatic environment. These needs introducing/developing novel photocatalysts/adsorbents/procedures for removing or mineralizing various pollutants in wastewater before discharging them into marine environments. Further, optimizing conditions to achieve the highest removal efficiency is an important issue. In this study, CaTiO₃/g-C₃N₄ (CTCN) heterostructure was synthesized and characterized by some identification techniques. The simultaneous interaction effects of the experimental variables on the boosted photocatalytic activity of CTCN in the degradation of gemifloxcacin (GMF) were studied in RSM design. The optimal values for four parameters were: catalyst dosage: 0.63 g L^-1, pH: 6.7, C_GMF: 1 mg L^-1, and irradiation time: 27.5 min, with approximately 78.2% of degradation efficiency. The quenching effects of the scavenging agents were studied to show the reactive species' relative importance in GMF photodegradation. The results illustrate that the reactive ^•OH plays a significant role, and the electron plays a minor role in the degradation process. The direct Z-scheme mechanism better described the photodegradation mechanism due to the great oxidative and reductive abilities of prepared composite photocatalysts. This mechanism is an approach to efficiently separating photogenerated charge carriers and improving the CaTiO₃/g-C₃N₄ composite photocatalyst activity. The COD has been performed to study the details of the mineralization of GMF. The pseudo-first-order rat (from the Hinshelwood model) constants of 0.046 min^-1 (t_1/2 = 15.1 min) and 0.048 min^-1 (t_1/2 = 14.4 min) were respectively obtained from the GMF photodegradation data and COD results. The prepared photocatalyst retained its activity after five reusing runs.

Highly dispersed g-C3N4 on well-designed three-dimensional porous nanostructured ZrO2 for high-performance photocatalytic degradation and H2 production

A novel polymer-assisted freeze-drying method was adopted for preparing three-dimensional porous nanostructured ZrO₂ (3DPZ) with macro self-supporting properties. Then, g-C₃N₄ was in-situ grown uniformly on the 3DPZ through a gas-solid reaction, forming 3D nanoporous ZrO₂/g-C₃N₄ heterojunctions (3DP/ZC) with different g-C₃N₄ loadings that retained self-supporting characteristics. The k_app value of Rhodamine B (RhB) degradation and H₂ evolution rate of the 3DP/ZC-2 under visible light reached 0.035 min^-1 and 1013.1 μmol h^-1 g^-1, which were 19.6 and 6.6 times higher than pure g-C₃N₄, respectively. The ZrO₂ nanoparticles (ZNps) prepared via freeze-drying, but without polymer precursor, were used as support to form ZrO₂/g-C₃N₄ nanoparticles (ZCNps-2) for comparison study. The RhB degradation rate and H₂ evolution rate of the 3DP/ZC-2 under visible light were about 3.7 and 5.3 times higher than ZCNps-2. Their enhanced photocatalytic activity could be attributed to their unique 3D heterointerface with matched energy bands for rapid charge separation and transfer and a hierarchical porous structure for mass transfer and surface reaction processes. The scavenger trapping and ESR measurements confirmed that the primary reactive radicals for degradation were superoxide radical ions (^⋅O₂^-), hydroxyl radicals (^⋅OH), and photogenerated holes (h⁺). The pH-dependent photocatalytic degradation activity originated from the H⁺-related ^⋅OH conversion reaction. Besides, the macro self-supporting nature could provide excellent separability and recyclability, and self-supporting membranes were also constructed and demonstrated as stable and recyclable photocatalysts. This work provides a new routine for designing 3D-heterojunctions as new kinds of functional materials for applications in environmental remediation and green energy production.

Current research trends on emerging contaminants pharmaceutical and personal care products (PPCPs): A comprehensive review

Pharmaceutical and personnel care products (PPCPs) from wastewater are a potential hazard to the human health and wildlife, and their occurrence in wastewater has caught the concern of researchers recently. To deal with PPCPs, various treatment technologies have been evolved such as physical, biological, and chemical methods. Nevertheless, modern and efficient techniques such as advance oxidation processes (AOPs) demand expensive chemicals and energy, which ultimately leads to a high treatment cost. Therefore, integration of chemical techniques with biological processes has been recently suggested to decrease the expenses. Furthermore, combining ozonation with activated carbon (AC) can significantly enhance the removal efficiency. There are some other emerging technologies of lower operational cost like photo-Fenton method and solar radiation-based methods as well as constructed wetland, which are promising. However, feasibility and practicality in pilot-scale have not been estimated for most of these advanced treatment technologies. In this context, the present review work explores the treatment of emerging PPCPs in wastewater, via available conventional, non-conventional, and integrated technologies. Furthermore, this work focused on the state-of-art technologies via an extensive literature search, highlights the limitations and challenges of the prevailing commercial technologies. Finally, this work provides a brief discussion and offers future research directions on technologies needed for treatment of wastewater containing PPCPs, accompanied by techno-economic feasibility assessment.

Functionalized MOF-Based Photocatalysts for CO2 Reduction

Metal-organic frameworks (MOFs) materials have become a research forefront in the field of photocatalytic CO₂ reduction attributed to their ultra-high specific surface area, adjustable structure, and abundant catalytic active sites. Particularly, MOFs can be facilely tuned to match CO₂ photoreduction by utilizing post-modification of metal nodes, functionalization of organic linkers, and combination with other active materials. Herein, the recent advances in the construction strategy of MOF-based photocatalysts materials for CO₂ reduction are highlighted. Some systematic modification strategies on MOF-based photocatalysts are also discussed, such as modification of metal sites and organic ligands, construction of heterojunction, introduction of single/dual-atom, and strain engineering. Finally, the future development directions of MOF-based photocatalysts in the field of CO₂ reduction are presented.

The Ultrahigh Adsorption Capacity and Excellent Photocatalytic Degradation Activity of Mesoporous CuO with Novel Architecture

In this paper, mesoporous CuO with a novel architecture was synthesized through a conventional hydrothermal approach followed by a facile sintering procedure. HR-TEM analysis found that mesoporous CuO with an interconnected pore structure has exposed high-energy crystal planes of (002) and (200). Theoretical calculations indicated that the high-energy crystal planes have superior adsorption capacity for H⁺ ions, which is critical for the excellent adsorption and remarkable photocatalytic activity of the anionic dye. The adsorption capacity of CuO to methyl orange (MO) at 0.4 g/L was approximately 30% under adsorption equilibrium conditions. We propose a state-changing mechanism to analyze the synergy and mutual restraint relation among the catalyst CuO, H⁺ ions, dye and H₂O₂. According to this mechanism, the degradation rate of MO can be elevated 3.5 times only by regulating the MO ratio in three states.

A censorious review on the role of natural lignocellulosic fiber waste as a low-cost adsorbent for removal of diverse textile industrial pollutants

BACKGROUND

Textile industries produce fabricated colored products using toxic dyes and other harsh chemicals. It is the responsibility of the textile industries to treat and eliminate these hazardous pollutants. However, due to the growing population demand, the treatment of these hazardous effluents is ineffective and imposes the treatment cost over the end users. The release of partially treated effluents in the environment may cause a severe threat to the ecology and its biota. The critical objective is to treat textile effluents efficiently using agricultural natural fiber waste. Generation of agricultural lignocellulosic fibrous waste increases every year due to growing population demand. Its use in the modern world is limited due to synthetic products. An alternative has enumerated to avoid wastage of fibrous resources and its clean disposal.

OBJECTIVE

The main objective of this review paper discussed the feasibility of lignocellulosic fibers and other lignocellulosic materials as natural low-cost adsorbent.

METHODS

The literature study was performed using Web of Science and Scopus indexed journals. The main factors considered to increase the adsorption ability, including the types of lignocellulosic surface modification techniques were searched with utmost importance for quality results. Intending to summarize the literature survey and provide persuasive content, systematic review process was considered for this novel article.

RESULTS

Out of 230 valuable publications, 159 published articles were considered for the present study until March 2022. The articles surplus with factors affecting adsorption (pH, adsorption dosage, surface area, temperature, initial concentration, contact time, physical and chemical properties of pollutants) and surface modification techniques (physical, chemical, and biological) were considered for this manuscript.

CONCLUSION

Overall, the physical and chemical modification methods are widely used instead of biological methods due to various factors as discussed briefly. Furthermore, the finding of this article supports the fact that the fibrous by-product resources are wasted in various occasions due to the modern lifestyle. Even though there is evidential possibility to implement the low-cost adsorbents, the industries limit their application prospects due to existing technology and financial compromises.

Heterogeneous Cu2O-Au nanocatalyst anchored on wood and its insight for synergistic photodegradation of organic pollutants

In this study, a Cu₂O-Au nanoparticles (NPs) heterojunction catalyst anchored on wood was developed by in situ reduction and hydrothermal treatment, and the properties of the catalyst were systematically characterized. The catalyst exhibited prominent photocatalysis of methyl orange (MO, 0.169 min^{- 1}), and tetracycline (TC, 0.122 min^-1) which were degraded completely within 20 min. Even after four recyclings, the efficiency of MO degradation by the catalyst remained at 80%. The natural wood with three-dimensional porous structures acted as a reducing agent and a stabilizer for Au NPs and Cu₂O, which helped to maintain high performance and reusability. The presence of Au NPs mediated the light-induced electron transfer and enhanced the absorption of visible light for promoting photocatalytic activity. The intermediates of contaminants within the degradation process were characterized by liquid chromatography-mass spectrometry. Additionally, the photogenerated superoxide radicals and holes were identified by electron spin resonance. Thus, the potential degradation mechanism catalyzed by the Cu₂O-Au NPs-wood was proposed. This findings of this study valorizes biomass as a photocatalyst for wastewater remediation.

Electrospun composite nanofibers as novel high-performance and visible-light photocatalysts for removal of environmental pollutants: A review

Environmental pollution caused by industries and human manipulations is coming a serious global challenge. On the other hand, the world is facing an energy crisis caused by population growth. Designing solar-driven photocatalysts which are inspired by the photosynthesis of plant leaves is a fantastic solution to use solar energy as green, available, and unlimited energy containing ∼50% visible light for the removal of environmental pollutants. The polymeric and non-polymeric-based electrospun composite nanofibers (NFs) are as innovative photocatalytic candidates which increase photocatalytic activity and transition from UV light to visible light and overcome the aggregation, photocorrosion, toxicity, and hard recycling and separation of the nanosized powder form of photocatalysts. The composite NFs are fabricated easily by either embedding the photocatalytic agents into the NFs during electrospinning or via their decorating on the surface of NFs post-electrospinning. Polyacrylonitrile-based, tungsten trioxide-based, zinc oxide-based, and titanium dioxide-based composite NFs were revealed as the most reported composite NFs. All the lately investigated electrospun composite NFs indicated long-term stability, high photocatalytic efficiency (∼> 80%) within a short time of light radiation (10-430 min), and high stability after several cycles of use. They were applied in various applications including degradation of dyes/antibiotics, water splitting, wastewater treatment, antibacterial usage, etc. The photogenerated species especially holes, O₂^∙-, and ^.OH were mostly responsible for the photocatalytic mechanism and pathway. The electrospun composite NFs have the potential to use in large-scale productions in condition that their thickness and recycling conditions are optimized, and their toxicity and detaching are resolved.

Photocatalytic assessed adsorptive removal of tinidazole from aqueous environment using reduced magnetic graphene oxide-bismuth oxychloride and its silver composite

Antibiotics (tinidazole (TNZ)) in wastewater, exhibit adverse effects on humans and ecosystem. The current study was aimed to synthesize photocatalysts mrGO/BiOCl and mrGO/BiOCl/Ag. mrGO was coupled with BiOCl by hydrothermal method and Ag was deposited over it. The synthesized mrGO/BiOCl and mrGO/BiOCl/Ag were confirmed by Pzc analysis (5.5 and 4.4 for mrGO/BiOCl and mrGO/BiOCl/Ag, respectively), surface area analysis (380 m² g^-1, 227.7 m² g^-1, 220 m² g^-1 for mrGO, mrGO/BiOCl and mrGO/BiOCl/Ag respectively), elemental analysis (Ag, O, Bi, Fe), surface morphology (rough ball like sphere of mrGO/BiOCl and cubic Ag nanoparticles in mrGO/BiOCl/Ag), functional groups and band gap (Eg) determination. The Eg was determined using Kubelka-Munk equation as 3.5 and 2.8 eV for mrGO/BiOCl and mrGO/BiOCl/Ag respectively. During the adsorption study, the best experimental conditions for various operating parameters such as pH (2), contact time (5 min for mrGO/BiOCl and 10 min for mrGO/BiOCl/Ag under UV irradiation), TNZ concentration (18 μgL^-1) and catalyst dosage (0.001 g) were achieved. Kinetic study revealed that both composites followed pseudo second order kinetics (R² = 0.9979 and 0.9986, respectively). Data of rGO/BiOCl was fitted to Freundlich adsorption model (R² = 0.9687) and rGO/BiOCl/Ag fitted to Langmuir adsorption model (R² = 0.9994). Moreover, thermodynamic parameters confirmed that a photodegradation phenomenon was spontaneous and exothermic. The results confirmed that rGO/BiOCl and rGO/BiOCl/Ag are appropriate composites for TNZ removal from the aqueous environment with removal efficiency of 97 and 24%, respectively.

A Comprehensive Study on Starch Nanoparticle Potential as a Reinforcing Material in Bioplastic

Starch can be found in the stems, roots, fruits, and seeds of plants such as sweet potato, cassava, corn, potato, and many more. In addition to its original form, starch can be modified by reducing its size. Starch nanoparticles have a small size and large active surface area, making them suitable for use as fillers or as a reinforcing material in bioplastics. The aim of reinforcing material is to improve the characteristics of bioplastics. This literature study aims to provide in-depth information on the potential use of starch nanoparticles as a reinforcing material in bioplastic packaging. This study also reviews starch size reduction methods including acid hydrolysis, nanoprecipitation, milling, and others; characteristics of the nano-starch particle; and methods to produce bioplastic and its characteristics. The use of starch nanoparticles as a reinforcing material can increase tensile strength, reduce water vapor and oxygen permeability, and increase the biodegradability of bioplastics. However, the use of starch nanoparticles as a reinforcing material for bioplastic packaging still encounters obstacles in its commercialization efforts, due to high production costs and ineffectiveness.

Fabrication of different adsorbents based on zirconium oxide, graphene oxide, and dextrin for removal of green malachite dye from aqueous solutions

In this study, graphene oxide and amine graphene were studied by binding to dextrin and zirconium oxide nanoparticles as adsorbent nanocomposites to the removal of dye. Identification and characterization of the synthesized materials were examined using FTIR, XRD, SEM, and BET analyses. Adsorption tests between adsorbents and green malachite (MG) dye solution for the synthesized nanocomposites were performed by considering parameters such as contact time, solution pH, and adsorbent dosage. The data indicated that dye removal increased with increasing the amount of adsorbent dosage. Increased dye removal by increasing the adsorbent dosage can be attributed to the increase of availability of the number of active sites. The active adsorption sites are saturated during the adsorption process, by the molecules of the adsorbate and filled over time. The results showed that the synthesized bio-composite had malachite green removal ability from aqueous media.

Separation of organic contaminant (dye) using the modified porous metal-organic framework (MIL)

Herein, the porous metal-organic framework (MIL-88B: Materials Institute Lavoisier) was synthesized and identified by FT-IR (Fourier transform infrared), SEM (Scanning Electron Microscopy), EDS (Energy Dispersive X-Ray Spectroscopy), and XRD (X-ray powder diffraction) analyses. Then MIL-88B was modified using 3-aminopropyl trimethoxy silane and presented as NH₂-MIL-88B. The synthesized materials were used to separate direct red dye 23 (DR23) as an organic contaminant from water. The effect of various important factors such as the amount of adsorbent, initial concentration of contaminants, and pH was investigated. The results showed that the modified adsorbent (NH₂-MIL-88B) had a higher adsorption capacity than the row adsorbent (MIL-88B). The amount of dye adsorption is high at lower pH values. The percentage of DR23 dye removal was complete under optimal conditions. Increasing the amount of adsorbent (0.001-0.003 g) and decreasing the pH (2.1-8.1) increases the percentage of dye removal and increasing the concentration of contaminant (50-125 mg/L) reduces the dye removal in the process. Isotherm data showed that the adsorption process followed the Langmuir model. Also, pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models were used to investigate the adsorption kinetics. Dye adsorption followed pseudo-second-order kinetics with correlation coefficient (0.99 <). The results showed that the modified adsorbent could be used as a suitable adsorbent with a high adsorption capacity for dye removal from water.

Engineering microbes for enhancing the degradation of environmental pollutants: A detailed review on synthetic biology

Anthropogenic activities resulted in the deposition of huge quantities of contaminants such as heavy metals, dyes, hydrocarbons, etc into an ecosystem. The serious ill effects caused by these pollutants to all living organisms forced in advancement of technology for degrading or removing these pollutants. This degrading activity is mostly depending on microorganisms owing to their ability to survive in harsh adverse conditions. Though native strains possess the capability to degrade these pollutants the development of genetic engineering and molecular biology resulted in engineering approaches that enhanced the efficiency of microbes in degrading pollutants at faster rate. Many bioinformatics tools have been developed for altering/modifying genetic content in microbes to increase their degrading potency. This review provides a detailed note on engineered microbes - their significant importance in degrading environmental contaminants and the approaches utilized for modifying microbes. The genes responsible for degrading the pollutants have been identified and modified fir increasing the potential for quick degradation. The methods for increasing the tolerance in engineered microbes have also been discussed. Thus engineered microbes prove to be effective alternate compared to native strains for degrading pollutants.

Polyol-assisted hydrothermal synthesis of Mn-doped α - Fe2O3(MFO) nanostructures: Spin disorder-induced magnetism and photocatalytic properties

Hierarchical nanostructures play an important role in environmental clean-up and sustainability applications. The magnetic and photocatalytic characteristics of flower-like Mn-doped α-Fe₂O₃ nanostructures were prepared by using a polyol-assisted hydrothermal method. Crystallite sizes are in the range of 35-42 nm, and the existence of 3D hierarchical nanostructures was observed in FESEM pictures. The optical band gap energy varies between 2.08 and 2.16 eV, while XPS examination exposes the ions' charge states and validates Mn³⁺ inclusion in the Fe³⁺ lattice. At room temperature, the addition of Mn to α-Fe₂O₃ results in a spin disorder ferromagnetism and coercivity of about 600 Oe was achieved. Methylene blue (MB) dye solution degraded by 92% when 2.5% Mn doped with α-Fe₂O₃ under visible conditions for 120 min irradiation time.

Existence of Ti3+ and dislocation on nanoporous CdO-TiO2 heterostructure applicable for degrading chlorophenol pollutant

This study addresses the significance of wastewater recuperation by a simple and facile treatment process known as photocatalyst technology using visible light. Titanium di-oxide (TiO₂) is the most promising photocatalyst ever since longing decades, has good activity under UV light, owing to its small band gap. Hence, TiO₂ has been modified with metal oxides for the positive response against visible light. Since this is an efficient process, the novelty has been made on nanometal oxide CdO (cadmium oxide) combined with TiO₂ to acquire the best efficiency of degrading organic chlorophenol contaminant. Initially, the composites were synthesized by sol-gel and thermal decomposition methods and investigated for their various outstanding properties. The characterized outcomes have exhibited heterostructures with reduced crystallite size from the X-ray diffraction studies. Then, the determination of nanoporous feature was recognized through HR-TEM analysis which was also detected with some dislocations. The EDX spectrum was identified the perfect elemental composition. The nitrogen adsorption-desorption equilibrium was attained that offers many pores measured with high surface area. The XPS result convinced that Ti³⁺ was accessible along with TIO₂/CdO composite. Further the absorption towards higher wavelength was obtained from UV-vis spectra. Finally, for the photocatalytic application of chlorophenol, the composite shows higher percentage of degrading efficiencies than the pristine TiO₂. The photocatalytic mechanism was discussed in detail.

Visible-light-driven photodegradation of organic pollutants by simply exfoliated kaolinite nanolayers with enhanced activity and recyclability

The need for abundant photocatalyst in wastewater treatment is currently a must. A simple intercalation process was utilized to exfoliate Kaolinite clay mineral structure Al₂Si₂O₅(OH)₄ into two-dimensional nanostructured separated layers operated in visible light range. The intercalating agents were hydrazine hydrate and urea. Detailed characterization confirmed the nanolayered structures of kaolinite hexagonal nanosheets (NK). In addition, Bandgap energy was reduced based on intercalating agents from 3.45 to 2.48 eV as revealed by light absorption spectra. The quenching of PL spectra for the nK has also been ascribed to the suppression of charge carrier recombination. The exfoliated nK was utilized to photodegrade Rhodamine B dye (RhB) and P-nitrophenol (PNP) as industrial pollutants in wastewater. The results showed 92.3% and 99.7% photodegradation of RhB and PNP within 180 min of visible-light irradiation utilizing the exfoliated NK by urea. We denote the boosted photocatalytic performance of this NK to the uncovered, low bandgap metal oxide inclusions on the exterior of NK besides the nitrogen doping due to exfoliation with urea. This simple exfoliation has modified abundant and stable clay nanolayers that are a promising alternative for the eminent nanostructured oxide photocatalysts to overcome the organic pollutants in wastewater at a high scale.

Coimmobilized enzymes as versatile biocatalytic tools for biomass valorization and remediation of environmental contaminants - A review

Due to stringent regulatory norms, waste processing faces confrontations and challenges in adapting technology for effective management through a convenient and economical system. At the global level, attempts are underway to achieve a green and sustainable treatment for the valorization of lignocellulosic biomass as well as organic contaminants in wastewater. Enzymatic treatment in the environmental aspect thrived on being the promising rapid strategy that appeased the aforementioned predicament. On that account, coimmobilization of various enzymes on single support enhances the catalytic activity ensuing operational stability with industrial applications. This review pivoted towards the coimmobilization of enzymes on diverse supports and their applications in biomass conversion to industrial value-added products and removal of contaminants in wastewater. The limelight of this study chronicles the unique breakthroughs in biotechnology for the production of reusable biocatalysts, which inculcating various enzymes towards the scope of environment application.

Lignosulfonate valorization into a Cu-containing magnetically recyclable photocatalyst for treating wastewater pollutants in aqueous media

This study presents an eco-friendly and economical process for preparing a magnetic copper complex conjugated to modified calcium lignosulfonate (LS) through a diamine (Fe₃O₄@LS@naphthalene-1,5-diamine@copper complex; FLN-Cu) as a green and novel catalyst. The prepared catalyst was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET), energy-dispersive X-ray spectroscopy (EDS), elemental mapping, inductively coupled plasma-optical emission spectrometry (ICP-OES) and field emission scanning electron microscopy (FESEM) techniques. The photocatalytic performance of the synthesized FLN-Cu catalyst was investigated by the degradation of aqueous solutions of dyes such as Rhodamine B (RhB), methylene blue (MB), and Congo red (CR) under UV irradiation. The dye degradation was followed by UV-Vis (ultraviolet-visible) spectrophotometry by measuring the changes in absorbance. The effects of different factors such as pH, contact time, photocatalyst dosage, and initial concentration of dye on the adsorption percentage were also investigated. Moreover, the catalyst showed high stability and could be readily separated from the reaction media using a magnet and reused five times without a remarkable loss of catalytic ability.

Comparative Study of SnO2 and ZnO Semiconductor Nanoparticles (Synthesized Using Randia echinocarpa) in the Photocatalytic Degradation of Organic Dyes

Symmetry in nanomaterials is essential to know the behavior of their properties. In the present research, the photocatalytic properties of SnO2 and ZnO nanoparticles were compared for the degradation of the cationic dyes Methylene Blue (MB) and Rhodamine B (RB). The nanoparticles were obtained through a green synthesis process assisted by Randia echinocarpa extracts; they were then analyzed through Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) to characterize their structure. Transmission electron microscopy (TEM) was used to identify the morphology and disclose nanoparticle size, and the optical properties were studied through Ultraviolet–visible spectroscopy (UV–Vis). The results show that the synthesized SnO2 and ZnO nanomaterials have quasispherical morphologies with average sizes of 8–12 and 4–6 nm, cassiterite and wurtzite crystal phases, and band gap values of 3.5 and 3.8 eV, respectively. The photocatalytic activity yielded 100% degradation of the MB and RB dyes in 210 and 150 min, respectively. ZnO performed higher photocatalytic degradation of the cationic dyes than SnO2 due to a higher content of Randia echinocarpa extracts remaining after the green synthesis process.

Efficient green photocatalyst of silver-based palladium nanoparticles for methyle orange photodegradation, investigation of lipid peroxidation inhibition, antimicrobial, and antioxidant activity

Nanotechnology is an interdisciplinary study that has been developing worldwide in recent years and has a serious impact on human life. The fact that the nanoparticles of plant origin are clean, non-toxic, and biocompatible has enabled new fields of study. The Hibiscus sabdariffa (H. sabdariffa) plant has been attracted by scientists because of its impact on health and many other areas. The lipid peroxidation inhibiting activity, antioxidant properties, and antimicrobial properties of H. sabdariffa plant with Ag-Pd metal was ditermined. For the total phenolic component, gallic acid was used as the standard and quarcetin was used for the total flavonoid. The lipid peroxidation inhibition activity of Ag-Pd NPs in ethanol extract was found to be very well compared to the positive control (BHA). The lowest and highest concentrations of DPPH radical scavenging activity were 82.178-97.357%, whereas for BHA these values were found to be 84.142-94.142%. The highest concentration of Ag-Pd NPs at 200 μg/mL the DPPH radical quenching activity was higher than BHA. Ag-Pd NPs showed a good antimicrobial activity against certain pathogenic microorganisms such as Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, which are the causative agents of various diseases in humans. The photodegradation activity of Ag-Pd NPs also investigated against Methyl orange dye (MO) under sunlight irradiation for 120 min and was found to be as 67.88.

Nano-architectural design of TiO2 for high performance photocatalytic degradation of organic pollutant: A review

In the past several decades, significant efforts have been paid toward photocatalytic degradation of organic pollutants in environmental research. During the past years, titanium dioxide nano-architectures (TiO₂ NAs) have been widely used in water purification applications with photocatalytic degradation processes under Uv/Vis light illumination. Photocatalysis process with nano-architectural design of TiO₂ is viewed as an efficient procedure for directly channeling solar energy into water treatment reactions. The considerable band-gap values and the subsequent short life time of photo-generated charge carriers are showed among the limitations of this approach. One of these effective efforts is the using of oxidation processes with advance semiconductor photocatalyst NAs for degradation the organic pollutants under UV/Vis irradiation. Among them, nano-architectural design of TiO₂ photocatalyst (such as Janus, yolk-shell (Y@S), hollow microspheres (HMSs) and nano-belt) is an effective way to improve oxidation processes for increasing photocatalytic activity in water treatment applications. In the light of the above issues, this study tends to provide a critical overview of the used strategies for preparing TiO₂ photocatalysts with desirable physicochemical properties like enhanced absorption of light, low density, high surface area, photo-stability, and charge-carrier behavior. Among the various nanoarchitectural design of TiO₂, the Y@S and HMSs have created a great appeal given their considerable large surface area, low density, homogeneous catalytic environment, favorable light harvesting properties, and enhanced molecular diffusion kinetics of the particles. In this review was summarized the developments that have been made for nano-architectural design of TiO2 photocatalyst. Additional focus is placed on the realization of interfacial charge and the possibility of achieving charge carriers separation for these NAs as electron migration is the extremely important factor for increasing the photocatalytic activity.

TiO2 nanoflower photocatalysts: Synthesis, modifications and applications in wastewater treatment for removal of emerging organic pollutants

Titanium dioxide (TiO₂) has been considered as one of the most promising photocatalysts nanomaterials and is being used in a variety of fields of energy and environment under sunlight irradiation via photocatalysis. Highly efficient photocatalytic materials require the design of the proper structure with excellent morphology, interfacial structures, optical and surface properties, etc. Which are the key points to realize effective light-harvesting for photocatalytic applications. Hierarchical TiO₂ based nanoflower structures (i.e., 3D nanostructures) possess such characteristics and have attracted much attention in recent years. The uniqueness of TiO₂ nanoflowers (NFs) with a coarse texture and arranged structures demonstrates higher photocatalytic activity. This review deals with the hydrothermal synthesis of 3D TiO₂ NFs and effect of shape/size as well as various key synthesis parameters to improve their optoelectronic and photocatalytic properties. Furthermore, to improve their photocatalytic properties, various strategies such as doping engineering and heterojunction/nanocomposite formation with other functional nanomaterials have been discussed followed by their potential applications in photocatalytic degradation of various emerging pollutants discharged into the wastewater from various sources. Importance of such 3D nanoarchitecutres and future research in other fields of current interest in environments are discussed.

Natural and anthropogenic origin of metallic contamination and health risk assessment: A hydro-geochemical study of Sehwan Sharif, Pakistan

Heavy metal contamination in groundwater is a serious threat to the environment and therefore its proper monitoring is a matter of great concern these days. In the present research, groundwater samples from Sehwan Sharif district Jamshoro, Pakistan were collected to estimate the concentration of various elements including potentially hazardous metals. Statistical analysis of the collected data based on Pearson co-relation metal clustering and Principal Component Analysis (PCA) divides the elements into three groups; Group I contains As, Cu, Ni, and Cd, Group II contains Mn, Fe, B, and Cr and Group III contains Pb and Zn. The elements Cu, Ni, As, Pb, Cd, and Zn found with higher RSD values demonstrate their anthropogenic origin whereas the lower concentration of Mn, Fe, B, and Cr indicate their natural origin (Tepanosyan et al., 2016). The histograms and box-plots of Mn, Fe, B and Cr were found normally distributed while abnormal for Cu, Ni, Pb, As, Cd and Zn. The HQs of these elements indicate their non-carcinogenic risks. However, results of individual metallic behavior indicate the highest HQ measured for B followed by HQs for Cu, and As. The toxic effects of investigated metal (loid)s calculated using HI were found to be 1.58 for adults and 1.35 for the child which is considered the medium chromic risk and cancer risk. About the toxicity of these heavy metals, their cancer risk was assessed on the levels of Cd, As, and Cr in groundwater. The carcinogenic risk of As was found to be 2.78 × 10^-4 and 1.62 × 10^-3 for child and adult, respectively. Furthermore, the values of this carcinogenic risk are 2.64 × 10^-6 and 1.54 × 10^-5 for Cd while 4.24 × 10^-3 and 2.48 × 10^-2 for Cr in child and adult, respectively. Since cancer risk exceeded the target risk of 1 × 10^-4 for As and Cr in adults and children, it can thus be considered 'non-acceptable'. The Geographic Information System (GIS) based maps were prepared using Inverse Distance Weighted (IDW) interpolation which showed the Spatial distribution of all elements throughout Sehwan Sharif from different sources of environment. Spatial maps of elements produced by ArcGIS show the hotspots of potentially hazardous elements such as the highest concentration of Pb, As, Zn, Cu, Ni, and Cd were found in urban areas of Sehwan Sharif district Jamshoro, Pakistan.

Direct observation of carrier migration in heterojunctions to discuss the p-n and direct Z-scheme heterojunctions

Type II p-n heterojunction and direct Z-scheme heterojunction are identical staggered band alignments, but were reported ambiguously in many composite photocatalysts because their carriers migrate in opposite directions. In this research, metal oxides CuO, NiO and Co₃O₄-based heterojunctions with Na_0.9Mg_0.45Ti_3.55O₈(NMTO) were synthesized via a simple hydrothermal method. The CuO/NMTO heterojunction was demonstrated as a direct Z-scheme heterojunction, whereas the NiO/NMTO and Co₃O₄/NMTO heterojunctions showed type II p-n band alignment, distinguished by the direct observation of carrier migration under light illumination, and confirmed by the x-ray photoelectron spectroscopy, Mott-Schottky measurements, ultraviolet photoelectron spectra and capture experiments. These all heterojunctions enjoyed better photocatalytic performance to degrade methylene blue and antibiotics (Enrofloxacin, Metronidazole and tetracycline) than the pure NMTO, attributed to their effective separation of the photoinduced electron-hole pairs owing to the staggered band alignment. Prominently, the NiO/NMTO and Co₃O₄/NMTO p-n heterojunctions exhibited superior degradation ability to the CuO/NMTO Z-scheme heterojunction. The initial relative Fermi position of two semiconductors is the prerequisite to determine whether the p-n heterojunction or direct Z-scheme heterojunction is built because the electrons diffuse from one semiconductor with a higher Fermi level to another with a lower Fermi level while the holes diffuse reversely until a united Fermi level when they combine. The built-in electric field at the heterojunction interface is determined by the difference in the initial Fermi levels or work functions of two semiconductors, regulating the separation ability of photogenerated electrons and holes to affect the photocatalytic performance. Thus, the high difference in the initial Fermi levels of semiconductors is crucial in the development of heterojunctions with staggered band alignment to obtain high performance in photocatalytic reactions.

Nano-Ag: Environmental applications and perspectives

Silver nanoparticles (AgNPs) are promising bactericidal agents and plasmonic NPs for environmental applications, owing to their various favorable properties. For example, AgNPs enables reactive oxygen species (ROS) generation, surface plasmon resonance (SPR), and specific reaction selectivities. In fact, AgNPs-based materials and their antimicrobial, optical, and electrical effects are at the forefront of nanotechnology, having applications in environmental disinfection, elimination of environmental pollutants, environmental detection, and energy conversions. This review aims to comprehensively summarize the advanced applications and fundamental mechanisms to provide the guidelines for future work in the field of AgNPs implanted functional materials. The state-of-art terms including (photo)(electro)catalytic reactions, heterojunction formation, the generation and attacking of ROS, genetic damage, hot electron generation and transfer, localized surface plasmon resonance (LSPR), plasmon resonance energy transfer (PERT), near field electromagnetic enhancement, structure-function relationship, and reaction selectivities have been covered in this review. It is expected that this review may provide insights into the rational development in the next generation of AgNPs-based nanomaterials with excellent performances.

Sulfonated calixarene modified Poly(methyl methacrylate) nanoparticles:A promising adsorbent for Removal of Vanadium Ions from aqueous media

The poly (methyl methacrylate) (PMMA)-based nanoparticle was synthesized by surfactant-free emulsion polymerization method and then post modified with Calixarene using (3-Aminopropyl)triethoxysilane organo-silane as a linker after OH-treatment. The prepared structure was applied for efficient adsorption of Vanadium ions in the aqueous solution after characterization by FT-IR, SEM, TEM, DLS, and EDX. Additional investigations discovered that the prepared adsorbent has a good capacity to adsorb vanadium ions. The effect of key experimental factors was studied to find the optimal point of adsorbent efficiency including the initial concentration of analyte, sorbent dosage, pH of the solution, contact time, and type/quantity of the eluents. It was specified, the maximum adsorption capacity for the synthesized nanoparticles was obtained about 322 mg g^-1. The adsorption mechanism was revealed that the model of Langmuir isotherm well-matched compared to the others due to the calculated equilibrium data. Besides, the kinetics of the adsorption process was fitted with pseudo-second-order. Eventually, the prepared adsorbent was successfully applied in vanadium adsorption from real water media.

Removal of pharmaceuticals (diclofenac and amoxicillin) by maltodextrin/reduced graphene and maltodextrin/reduced graphene/copper oxide nanocomposites

Due to the scarcity of water and the growing industrialization, pharmaceutical wastewater treatment is of particular importance. For this reason, it is necessary to achieve an efficient method to eliminate all types of pharmaceutical pollutants. Herein, synthetic nano-composite is proposed to take a step towards improving the operation of removing pharmaceutical contaminants from the environment and aquatic and industrial effluents. Binary (maltodextrin/reconstituted graphene nanocomposite) and ternary (maltodextrin/reconstituted graphene nanocomposite/copper oxide) nanocomposites were prepared and characterized using, FT-IR, FESEM-EDS, TEM, DLS, and XRD. The nanocomposites were used to eliminate diclofenac and amoxicillin as Pharmaceuticals. The removal of amoxicillin at a concentration of 30 mg/L with an adsorbent dose of 0.05 g and a pH of 7.4 and an optimal temperature of 20 °C in 10 min has the highest removal rate of 86%. In addition, diclofenac with nano-adsorbents prepared under optimal conditions, including an initial concentration of 20 mg/L, adsorbent dose of 0.05 g, adsorption time of 7 min, a temperature of 20 °C and a pH of 7, has the highest removal efficiency of 94%. The results indicated that the prepared nanocomposites are alternative adsorbents to remove Pharmaceuticals from water.

A review on magnetic sensors for monitoring of hazardous pollutants in water resources

Water resources have long been of interest to humans and have become a serious issue in all aspects of human life. The disposal of hazardous pollutants in water resources is one of the biggest global concerns and poses many risks to human health and aquatic life. Therefore, the control of hazardous pollutants in water resources plays an important role, when it comes to evaluating water quality. Due to low toxicity, good electrical conductivity, facile functionalization, and easy preparation, magnetic materials have become a good alternative in recent years to control hazardous pollutants in water resources. In the present study, the idea of using magnetic sensors in controlling and monitoring of pharmaceuticals, pesticides, heavy metals, and organic pollutants have been reviewed. The water pollutants in drinking water, groundwater, surface water, and seawater have been discussed. The toxicology of water hazardous pollutants has also been reviewed. Then, the magnetic materials were discussed as sensors for controlling and monitoring pollutants. Finally, future remarks and perspectives on magnetic nanosensors for controlling hazardous pollutants in water resources and environmental applications were explained.

Nanomaterials with Excellent Adsorption Characteristics for Sample Pretreatment: A Review

Sample pretreatment in analytical chemistry is critical, and the selection of materials for sample pretreatment is a key factor for high enrichment ability, good practicality, and satisfactory recoveries. In this review, the recent progress of the sample pretreatment methods based on various nanomaterials (i.e., carbon nanomaterials, porous nanomaterials, and magnetic nanomaterials) with excellent adsorption efficiency, selectivity, and reproducibility, as well as their applications, are presented. Due to the unique nanoscale physical–chemical properties, magnetic nanomaterials have been used for the extraction of target analytes by easy-to-handle magnetic separation under a magnetic field, which can avoid cumbersome centrifugation and filtration steps. This review also highlights the preparation process and reaction mechanism of nanomaterials used in the sample pretreatment methods, which have been applied for the extraction organophosphorus pesticides, fluoroquinolone antibiotics, phenoxy carboxylic acids, tetracycline antibiotics, hazardous metal ions, and rosmarinic acid. In addition, the remaining challenges and future directions for nanomaterials used as sorbents in the sample pretreatment are discussed.

Functionalization of MXene-based nanomaterials for the treatment of micropollutants in aquatic system: A review

The increased industrialization and urbanization generate a larger quantity of effluent that is discharged into the environment regularly. Based on the effluent composition produced from various industries, the number of hazardous substances such as heavy metals, hydrocarbons, volatile organic compounds, organic chemicals, microorganisms introduced into the aquatic systems vary. The conventional wastewater treatment systems do not meet the effluent standards before discharge and require a different treatment system before reuse. Adsorption is an eco-friendly technique that uses selective adsorbents to remove hazardous pollutants even at microscale levels. MXene, a 2-Dimensional nanomaterial with resplendent properties like conductivity, hydrophilicity, stability, and functionalized surface characteristics, is found as a potential candidate for pollutant removal systems. This review discusses the fabrication, characterization, and application of MXene based nanoparticles to remove many pollutants in water treatment systems. The improvement in surface properties and adsorption capacity of MXene based NPs, when modified using different modification agents, has also been discussed. Their feasibility in terms of economic and environmental aspects has been evaluated to understand their scope for practical application in large-scale industries. The challenges towards the synthesis and toxicity's importance have been discussed, with the appropriate recommendations.

Improving photocatalytic activity of the ZnS QDs via lanthanide doping and photosensitizing with GO and g-C3N4 for degradation of an azo dye and bisphenol-A under visible light irradiation

In this research, insertion of Gd ions (2 wt%) into the crystalline lattice of the ZnS QDs enhanced the photocatalytic activity of the QDs. In addition, the influence of graphene oxide (GO) and graphitic carbon nitride (g-C₃N₄) was assessed on the photocatalytic activity of the ZnS QDs through degradation of acid red 14 (AR14) and bisphenol-A (BA) under visible light. Higher photocatalytic degradation efficiency (97.1% for AR14 and 67.4% for BA within 180 min) and higher total organic carbon (TOC) removal (67.1% for AR14 and 59.2% for BA within 5 h) was achieved in the presence of ZnS QDs/g-C₃N₄ compared with ZnS QDs/GO nanocomposite. Finally, the Gd-doped ZnS QDs were hybridized with g-C₃N₄ as optimal support to fabricate a potent visible-light-driven photocatalyst for the decomposition of organic contaminants. The maximum photocatalytic degradation of 99.1% and 80.5% were achieved for AR14 and BA, respectively, in the presence of Gd-doped ZnS QDs/g-C₃N₄ nanocomposite. The photosensitization mechanism was suggested for the improved photocatalytic activity of the ZnS QDs/GO, ZnS QDs/g-C₃N₄, and Gd-doped ZnS QDs/g-C₃N₄ nanocomposites under visible light.