Environmental Remediation Applications Research Articles

Synthesis of Ag−Cu−MnO Triple‐Metal Composite And Evaluation of its Antimicrobial Activity and Dye Removal Efficacy

AbstractThe synthesis of triple metal oxide nanocomposites has revolutionized materials science due to their unique properties resulting from the interaction of multiple oxide components. This study aimed to synthesize mixed metal oxide nanocomposites using a co‐precipitation method with copper sulfate, silver nitrate, and potassium permanganate as precursor salts and sodium hydroxide as the precipitating agent. The resulting Ag−Cu−MnO triple metal composite was extensively characterized using X‐ray diffraction (XRD), scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM‐EDS), and Fourier transform infrared (FT‐IR). The composite exhibited effective bactericidal efficacy against various bacterial strains, including Enterobacter bugandensis, Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa. Moreover, the composite demonstrated notable photocatalytic activity, degrading 87.26 % of 50 ppm Eosin Yellow within 140 minutes under sunlight irradiation, as monitored by a UV‐vis spectrophotometer. This study highlights the dual functionality of the synthesized composite as both a photocatalyst and an antibacterial agent. These findings underscore its potential for diverse applications in environmental remediation and healthcare, marking a significant advancement in materials science.

Bilayer-favored intercalation induced low-voltage electrochemical production of nano-graphene oxide in neutral phosphate

Graphene oxide (GO) exhibits great potential in various fields such as catalysis, wastewater treatment, and energy storage. However, traditional top-down GO preparation methods based on graphite exfoliation often suffer from high energy consumption and inevitably environmental pollution. In this work, an environmentally benign and low-voltage electrochemical exfoliation approach to fabricate nanoscale GO employing carbon fiber-based materials as the precursor using phosphate was proposed. Under neutral phosphate electrolyte, bilayer graphene oxide with a lateral size of ∼500 nm, thickness of ∼1.5 nm, and C/O ratio of 2.96 could be obtained via a constant potential process. By adjusting the pH to 12 to intensify the exfoliation reaction, the lateral size of the graphene oxide was controllable, decreasing to ∼50 nm, while the C/O ratio decreased to 0.9. Due to the further decrease in C/O ratio, the thickness increased slightly to 2–3 nm. The exfoliation potential (1.6–2.5 V vs. Ag/AgCl) and electrolyte concentration (50–500 mM) had an obvious impact on the yield of graphene oxide. Through electrochemical analysis such as linear sweep voltammetry, as well as density functional theory calculations, the exfoliation mechanism of phosphate is elucidated in detail, demonstrating that the stepwise ionized phosphate anions possess more robust intercalation capability than sulfate, thus enabling efficient exfoliation to the intertwined nanocrystalline graphite structure of carbon fibers. The DFT results revealed the bilayer-favored intercalation of phosphate, which accords well with experiments. This work provides a new controllable and green approach for GO synthesis, demonstrated by life cycle assessment. It could assist subsequent studies exploring the size effects of GO and its applications in environmental remediation and energy storage.

Preparation of novel ACMO-AA/PVDF composite membrane by one-step process and its application in removal of heavy metal ions from aqueous solutions

In this study, a simple one-step process was used to fabricate a high-efficiency 4-acryloylmorpholine-acrylic acid/polyvinylidene fluoride (ACMO-AA/PVDF) composite membrane for the adsorption of heavy metal ions. The initiation phase involved the use of the strong organic base tetramethylammonium hydroxide (TMAH) to facilitate the partial dehydrofluorination of PVDF, thereby yielding a reactive CC bond. Following this, undesirable residuals and by-products of TMAH were removed through a thermal treatment process. Subsequently, an ACMO and AA, both possessing distinctive functional groups, onto the active CC bond took place in-situ. The use of a suitable initiator (AIBN) and crosslinking agent (MBA) facilitated the copolymerization process, culminating in the production of the ACMO-AA/PVDF composite membrane with excellent capability for the adsorption of heavy metal ions. Performance evaluations confirmed the membrane high efficiency in Pb2+ removal with complete removal realized at initial Pb2+ concentrations of ≤50 mg·L–1 and presenting a maximum adsorption capacity of 1214.75 mg·g–1, as described by the Langmuir model. In complex environments with co-existing metal ions such as Cu2+, Hg2+, and Cd2+, at an each initial concentration of up to 50 mg·L–1, the membrane exhibited a Pb2+ removal rate of 93.81 %, and Hg2+ and Cu2+ removal rates of 93.75 % and 92.93 %, respectively. The results of surface morphological and microstructural analyses showed that the principal adsorption mechanism is chemical chelation. Furthermore, the membrane exhibited sustainable usability, retaining its structural integrity and adsorption efficacy over multiple regeneration cycles. This indicates that the ACMO-AA/PVDF composite membrane is a viable candidate for deep decontamination processes involving Pb2+, Hg2+, and Cu2+ in environmental remediation applications.

Attuned band structure in triple S-scheme heterojunctions for naproxen degradation under visible light

The limited charge carrier separation and transportation in single semiconductor photocatalysts has lobbied research and development in rational design and fabrication of heterojunction photocatalysts which has become a hot topic in the last decade. In-depth investigation of a four-component semiconductors interfacial charge transfer analysis considering the contribution of all components was done for the first time to deduce triple S-scheme heterojunction. This work investigated four-component semiconductors (Cu3(PO4)2, BaWO4, C-MgO and LDH) heterojunction photocatalyst formation by the solvothermal method for visible light degradation of NPX. The degradation rate of CBLM-B (0.0429 min−1) with high BaWO4 content was two times the degradation rate of CBLM-A (0.0203 min−1) with high LDH/C-MgO content. XPS, electrochemistry, and band structure analysis were used to propose a triple S-scheme heterojunction with high electron mobility and charge separation that enhanced the formation of OH• >•O2− > h+ species as supported by radical trapping experiments due to presence of two oxidative and two reductive sites for stable generation of ROSs. Internal electric field (IEF) and band bending modulated an S-S interfacial strategy at the three junctions. Cu leaching affected the catalyst stability, and NPX degradation pathways were investigated with QTOF-HPLC-MS. This work demonstrated band structure adjustment for design of highly efficient triple S-Scheme heterojunctions application in environmental pollution remediation as a new development to advance scientific knowledge on four-component heterojunctions which may also be described using the Z-scheme charge transfer model.

Removal of quinoline in aqueous solutions using chemically modified and unmodified hydrochars from lotus seedpods: A comprehensive experimental study

In this study, a novel hydrochar adsorbent derived from lotus seedpods was synthesized and subsequently modified to enhance its adsorption efficiency for quinoline contaminated wastewater. Using lotus seedpods as biomass raw material, lotus seedpod hydrochar (LSH) was prepared by hydrothermal carbonization method, and it was modified with hydrochloric acid (HA) and phosphoric acid (PA) as modifiers to improve adsorption efficiency. The adsorption kinetics and isotherms of quinoline on both the unmodified and modified hydrochars were studied in detail to elucidate the underlying adsorption mechanisms. Furthermore, the effect of coexisting organic pollutants, i.e. phenol and pyridine, commonly found in coking effluents, on the quinoline adsorption efficiency of hydrochar was investigated. The regenerative potential of the adsorbent was explored through desorption studies to assess the reusability and practicality of hydrochar post-adsorption. The optimal conditions for modified LSH were determined as follows: an adsorbent dosage of 3 g/L, pH of 3, an initial quinoline concentration of 200 mg/L, and a contact time of 90 minutes. The maximum adsorption capacities for PA-LSH and HA-LSH were 48.59 mg/g and 49.12 mg/g, respectively. Among the types of modification agents, acid modifiers, particularly 20 % phosphoric acid and 20 % hydrochloric acid, significantly enhanced the adsorption efficiency, increasing the adsorption rates by 24.24 % and 14.56 %, respectively, compared to unmodified hydrochar (64.06 %). Coexisting pollutants minimally affected quinoline adsorption, with phosphoric acid-modified hydrochar maintaining 80.33 % removal in simulated coking wastewater. Regeneration with hydrochloric acid showed improved utility, with modified hydrochar sustaining over 80 % adsorption after three cycles. This research not only presents an innovative approach to the development of efficient adsorbents for quinoline removal, but also provides insight into the adsorption behavior of hydrochar in the complex wastewater systems. The findings contribute to both the advancement of sustainable water treatment technologies and the use of biomass-derived materials for environmental remediation. As such, this work holds promise for applications in wastewater treatment and environmental remediation.

Facile synthesis, morphological, optical, catalytic and photocatalytic properties of Ag nanoparticles decorated Ce doped ZnO hybrid plasmonic nanorods

Designing plasmonic metal–semiconductor hybrid nanostructures for photodecomposition of industrial textile effluent has been considered as a great way to boost the catalytic and photocatalytic capability by promoting effective separation of photoexcited charge carriers. Herein, fabrication of Ag nanoparticles decorated Ce doped ZnO nanostructures were demonstrated via facile wet chemical method. The morphology and structure of the fabricated photocatalysts were analysed using FESEM, XRD and Raman spectroscopy whereas PL, TRPL and UV–vis absorption spectroscopy were employed to examine their optical behaviour. Catalytic response of the synthesized catalysts was studied for 4-NP to 4-AP reduction and the results are more favourable for Ag loaded Ce doped ZnO catalysts and achieved 96.4 % reduction of 4-NP in only 4 min. Photocatalytic measurements showed that higher Ag NP loading onto Ce doped ZnO nanostructures led to superior photodegradation ability over other photocatalysts for the degradation of synthetic dyes and levofloxacin antibiotic. The sunlight driven photodecolorization of harmful synthetic dyes and levofloxacin were studied and efficacy of 97.5, 97.1, 85.1, and 70.9 % were achieved for MG, MB, RhB and MO dyes, respectively in 12 min and 97.2 % efficiency for degradation of levofloxacin was achieved in 20 min of sunlight exposure. Furthermore, the key reactive species was identified and tentative photodegradation process was explained. This work provides an excellent plasmonic-semiconductor catalyst and photocatalyst with good photostability and practical applicability indicating its enormous potential for application in environmental remediation.

The Construction of Iodine-Doped Carbon Nitride as a Metal-Free Nanozyme for Antibacterial and Water Treatment.

Metal-free photocatalysis that produces reactive oxygen species (ROS) shows significant promising applications for environmental remediation. Herein, we constructed iodine-doped carbon nitride (I-CN) for applications in the photocatalytic inactivation of bacteria and the heterogeneous Fenton reaction. Our findings revealed that I-CN demonstrates superior photocatalytic activity compared to pure CN, due to enhanced light adsorption and a narrowed band gap. Antibacterial tests confirmed that I-CN exhibits exceptional antibacterial activity against both Escherichia coli and Staphylococcus aureus. The results showed that I-CN effectively generates superoxide radicals and hydroxyl radicals under light irradiation, resulting in enhanced antibacterial activity. In addition, I-CN can also be applied for a heterogeneous photo-Fenton-like reaction, achieving a high performance for the degradation of sulfamethoxazole (SMX), a typical antibiotic, via the photocatalytic activation of peroxymonosulfate (PMS). These results shed new light on the fabrication of metal-free nanozymes and their applications for disinfection and water decontamination.

Fabrication of a novel tin disulfide/vanadium carbide MXene (SnS2/V2CTx) photocatalytic heterojunction with the potential application for environmental remediation

Lately, researchers have been striving to develop efficient and economically viable multifunctional photocatalysts. This is in effort to address the currently faced energy and water crises. Herein, tin disulfide/vanadium carbide MXene (SnS2/V2CTx) heterojunction was prepared through facile self-assembly approach, followed by calcination for strong integration of the two materials (SnS2 and V2CTx). The prepared pristine and composite materials' structural characteristics, chemical composition, morphology, and charge transfer kinetics were studied using spectroscopic, microscopic techniques, and electrochemical impedance spectroscopy (EIS). The prepared SnS2/V2CTx composites exhibited improved optical and photoelectrochemical properties compared to the pristine materials. In particular, the energy bandgap (Eg) was reduced from 1.30 eV (SnS2) to 0.81 eV (SnS2/V2CTx). Additionally, the calculated band alignments exhibited superior redox potentials towards the generation of useful reactive oxygen species. Moreover, the formation of a heterostructure between SnS2 and V2CTx MXene presents a reproducible approach towards fabrication of efficient photocatalyst with combined synergistic catalytic attributes.

Polychloride and benzene ring synergistically boosting photocatalytic degradation and nitrogen fixation performances of carbon nitride

The limited active site exposure, insufficient light absorption and poor charge behavior of carbon nitride (CN) limit its application in environmental remediation and clean energy production. In this study, ultrathin porous CN with enhanced photocatalytic activity was constructed by doping 2,2′,5,5′-Tetrachlorobenzidine (TB) into CN framework. The synergistic effect of polychloride and benzene rings on CN leads to the significant enhancement of range/intensity of visible-light harvest and charge behavior, as well as specific surface area. The optimal sample achieves 100% tetracycline photodegradation efficiency with a rate constant approximately 9 times of pristine CN, and total organic carbon removal efficiency reaches 78.2%. Moreover, photocatalytic ammonia production rate is 7 times of pristine CN. Through active species trapping experiments, ESR, LC-MS, toxicity prediction and DFT calculations, the main active species, degradation pathway, intermediates toxicity and enhanced mechanism of photocatalytic activity are investigated. This work provides a reference for simultaneously regulating the morphology, light absorption and charge behavior of CN-based photocatalyst for addressing environmental and energy concerns.

Enhanced removal of hazardous organic contaminants with advanced visible light-active F-doped TiO2/rGO/PVDF photocatalytic membranes

Polyvinylidene fluoride (PVDF) membranes and composite variants with x% FGT/PVDF photocatalytic membranes were prepared at different concentrations (x = 1 %, 5 %, and 10 %) using the phase inversion technique. The synthesized photocatalysts and the membrane materials were thoroughly characterized using different analytical methods. The focus was on determining the photocatalytic efficiency of these materials in degrading two important harmful dyes, namely methylene blue (MB) and crystal violet (CV), under visible light irradiation. High degradation percentages of MB (96 %) and CV (92 %) at 90 minutes were observed with 5 % F-TiO2/rGO (named as 5 %FGT). Similarly, the 5 % F-TiO2/rGO/PVDF (5 %FGT/PVDF) photocatalytic membranes showed 98 % and 93 % degradation of MB and CV, respectively. Kinetic studies revealed that the photocatalytic degradation reaction followed a pseudo-first-order mechanism. The total organic carbon (TOC) analysis of the treated MB and CV dyes showed a degradation of 78 % and 71 %, respectively. Recycling of the most active 5 % FGT/PVDF composite membrane exhibited very high stability of 800 min. The composite material utilizes the photocatalytic properties of TiO2 and the stimulating transport properties of rGO. Additionally, fluorine doping enhances charge carrier separation, tunes the bandgap for visible light response, and increases surface activity, thereby improving the overall degradation of organic pollutants. These properties make the composite material promising for various applications in environmental remediation and wastewater treatment.

Self-assembly preparation of 3D nanorestricted domain catalysts based on carbon nanotube wires and in-depth analysis of tetracycline degradation performance, mechanism, and toxicology

In this study, the 3D intertwined tubular structure of carbon nanotube sponge (CNTS) was utilized to intersperse MIL-53(Fe) onto the nanofragments of CNTS. For the preparation of a novel composite catalyst, MIL-53(Fe)@CNTS, nanorestricted domain growth was combined with self-assembly regulation to realize the ordered growth of MIL-53(Fe) in the space of CNTS. The catalyst exhibited excellent activation performance for PMS within a wide pH range. The maximum removal of tetracycline (TC, 20 mg/L) was as high as 96.7 % within 90 min, and the maximum degradation rate constant (K) was as high as 0.1648 min−1. The performance of the catalyst was directly correlated with the number of domain-limited assemblies. Synchrotron radiation results and DFT theoretical calculations confirmed that the overall catalytic performance of MIL-53(Fe) was greatly improved after the nanorestricted domain assembly in CNTS. The TC degradation system involved radical–oxidative and nonradical pathways. The intermediates of the reaction system were identified by HPLC-MS, and several possible degradation pathways during the TC reaction were proposed. The toxicity degree of the intermediate monomers was analyzed in conjunction with the TEST program, and their effects on the biological environment were predicted. Combined with the toxicity prediction of the TC degradation pathways, the post-reaction degradation solution was used for practical biotoxicity assessment. The effects of the real solution before and after degradation on the ecotoxicity of different organisms were also determined. In conclusion, the composite catalyst MIL-53(Fe)@CNTS synthesized by precise assembly using the nanorestricted domain strategy has promising applications in pollutant degradation and environmental remediation.

Multiplicative rGO/Cu-BDC MOF for 4-nitrophenol reduction and supercapacitor applications

Two-dimensional nanosheets, with their distinct characteristics, are widely used in various applications such as water splitting, supercapacitors, catalysis etc. In this research, we produced Cu-BDC MOF nanosheets by using Cu2O nanotubes for metal ions and H2BDC as the organic linker. We combined these Cu-BDC MOF nanosheets with reduced graphene oxide (rGO) to form a nanocomposite. The collaboration between Cu-BDC MOF and rGO boosts both the catalytic reduction of 4-nitrophenol and the electrochemical capabilities. The conversion of 4-nitrophenol to 4-aminophenol is achieved using sodium borohydride as both a reducing agent and a catalyst. The study explores the impact of different concentrations of 4-nitrophenol and sodium borohydride on catalytic efficiency. The increase in sodium borohydride concentration enhances catalytic efficiency by providing more BH4− ions and electrons for the reduction process. The catalytic reduction process adheres to the Langmuir–Hinshelwood mechanism with apparent pseudo-first-order kinetics. Specifically, Cu-BDC MOF and rGO/Cu-BDC MOF exhibit specific capacities of 468.4 mA h/g and 656.4 mA h/g at a current density of 2 A/g, respectively, while also enhancing the operating voltage window. Therefore, electrodes based on rGO/Cu-BDC MOF nanosheets present a novel approach for environmental remediation and energy storage applications across various fields.

Probing the Photocatalytic Pathways of Iron (III) Protoporphyrin IX-Functionalized TiO2: A Study on Oxo-Iron(IV) Porphyrin π-Cation Radical Formation

The presence of phenolic compounds in aquatic environments, resulting from industrial activities such as coal processing and petroleum refining, poses significant concerns due to their adverse effects on water safety, even at minimal concentrations. These compounds present challenges during remediation using traditional techniques such as solvent extraction, biological treatments or chemical oxidations. In response to these challenges, Advanced Oxidation Processes have emerged as a promising solution, with methods like heterogeneous photocatalysis, ozonation, sonification and so on, showing potential for degrading persistent organic molecules[1] [2].Titanium dioxide (TiO2) has gained importance in environmental remediation due to its ease of synthesis, cost-effectiveness, and versatility. Its unique properties, including exceptional chemical stability and non-toxic nature, make it suitable for water purification among other applications. Several studies aim to extend responsiveness of TiO2 beyond UV-A radiation, seeking to harness the wider and more prevalent visible light spectrum. This endeavor is driven by the desire to optimize the utilization of solar energy in various applications. To enhance TiO2 absorption of visible light, alternative chromophores, particularly porphyrins, are employed. Porphyrins, known for their extended lifespan in the excited state and efficient photoabsorption in the visible region, serve as excellent sensitizers when combined with TiO2, enabling effective charge separation[3].This study explores the activity enhancement of TiO2 catalyst by incorporating iron (III) protoporphyrin IX (FePPIX). The objective is to understand how hydrogen peroxide (H2O2), generated through photocatalysis on the TiO2 surface, influences the formation of oxo-iron(IV) porphyrin π-cation radicals. These radicals specifically form through the interaction with iron porphyrin attached to TiO2, offering a unique pathway for efficiently degrading phenolic compounds, as is proposed in Figure 1. The investigation underscores the significance of TiO2 surface sensitization and the simultaneous emergence of porphyrin radicals in shaping the dynamics of the photocatalytic process.We fabricated TiO2 nanotube sheets (TiO2-NTs) by anodizing metallic titanium sheets and then functionalized them with FePPIX. The process involved degreasing, chemical cleaning, anodization, exfoliation, and thermal treatment for anatase phase formation. Additionally, we utilized anatase-TiO2 nanoparticles. We carried out functionalization, which included ozone exposure, UV-C light treatment, and immersion in an acidic FePPIX solution in methanol, reacting with the hydroxylated surface induced by ozone treatment. After functionalization, we carefully washed away the excess iron protoporphyrin with methanol, and we air-dried the materials at room temperature. We comprehensively characterized the nanomaterials using diverse analytical techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), Raman and UV-Vis spectroscopies, and ESR analyses. We further investigated the photogeneration of hydroxyl radicals (•OH) on FePPIX-functionalized and non-functionalized TiO2 nanotube arrays through the photobleaching of N-N-dimethyl-4-nitrosoaniline. Additionally, we studied phenol degradation under UV irradiation. Our findings provide detailed insights into the physical and chemical properties, morphology, and composition of the fabricated nanomaterials.The SEM images reveal well-defined nanotube arrays, underscoring the efficacy of the fabrication technique. Energy-Dispersive X-ray Spectroscopy mapping further solidifies this observation, confirming a uniform distribution of iron in functionalized nanoparticles and supporting the success of functionalization. FTIR and Raman spectroscopy provide detailed insights into the presence of functional groups and vibrational modes, establishing the success of the functionalization process as well. Tauc plots show a narrowed energy gap in functionalized nanotubes, hinting at their potential for visible light activity.Photocatalytic assessments uncover diminished behavior, with lower •OH generation rates observed under UV-A light for functionalized nanotubes but notable activity under visible light, aligning with the reduced band gap energy. Furthermore, enhanced phenol degradation on functionalized nanotubes under UV-A light, potentially associated with compound I, introduces complexity to the photocatalytic pathways. The application of ESR study confirms the presence of paramagnetic species, such as [PPFeIV=O]+•, thereby highlighting the influence of protoporphyrin on the TiO2 surface and its integral role in photocatalysis.In summary, the study confirms successful TiO2 nanomaterial functionalization with FePPIX, promising applications in environmental remediation. Analyses validate binding with hydroxyl groups, Tauc plots indicate enhanced photocatalytic activity under visible light, and ESR analysis suggests the presence of paramagnetic species that could improved phenol degradation. Further investigation is needed for a comprehensive understanding. Overall, these findings hold potential for efficient and sustainable wastewater treatment.[1] S. Rasalingam, R. Peng, R. T. Koodali, J. Nanomater. 2014, 617405.[2] Y. Deng, R. Zhao, Curr Pollut. Rep 2015, 1, 167.[3] C. C. Huang, P.S. Parasuraman, H. C. Tsai, J. J. Jhu, T. Imae, RSC Adv. 2014, 4, 6540. Figure 1

MFe2O4 (M: Cu, Ni)/SnS2magnetic Core-Shell Heterostructure for Photocatalytic H2 Generation and Environmental Remediation

Overgrowing demand for sustainable energy sources and environmental remediation has driven extensive research in the field of photocatalysis. This study presents a hydrothermal synthesis of a novel MFe2O4 (M: Cu, Ni)/SnS2 magnetic core-shell heterostructure. The engineered heterostructure combines the unique properties of MFe2O4 (M: Cu, Ni) magnetic crystal as a core with SnS2 nanosheets as a shell, aiming to exploit type-2 heterojunction properties to improve effects for improved photocatalytic performance. The structural chemistry, phase formation, and crystal orientation of the prepared material are investigated using various analytical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, and FTIR Spectroscopy. FE-SEM analysis reveals a well-defined core-shell morphology with intimate interfaces between MFe2O4 (M: Cu, Ni) crystals and SnS2 nanosheets. Photocatalytic efficiency is assessed through the industrial dye degradation process. The influence of the heterostructure's structural features on the photocatalytic activity is explored through density function theory, emphasizing the role of the core-shell interface and the magnetic properties of MFe2O4 (M: Cu, Ni) cores. The chemistry between the magnetic core and the shell in the heterostructure is demonstrated to be crucial for optimizing charge carrier dynamics and promoting surface reactions. Photocatalytic H2 generation under artificial simulated sunlight irradiation in the presence of MFe2O4 (M: Cu, Ni)/SnS2 core-shell heterostructure is demonstrated. This study not only presents a novel MFe2O4 (M: Cu, Ni)/SnS2 heterostructure for photocatalytic H2 generation but also provides valuable insights into the intricate relationship between structural chemistry and photocatalytic efficiency. The engineered heterostructure shows promising potential for applications in sustainable energy production and environmental remediation, contributing to the ongoing efforts towards a cleaner and more sustainable future.

Bioinspired copper oxide nanocomposites: harnessing plant extracts for enhanced photocatalytic performance.

This study focuses on developing copper oxide-based nanocomposites using plant extracts for photocatalytic applications. Curcuma amada leaf and Alysicarpus vaginalis leaf extracts were utilized alongside recycled copper precursors to synthesize photocatalysts via a green synthesis approach. Structural characterization through X-ray diffraction confirmed the formation of monoclinic CuO with reduced crystallite sizes due to plant extract incorporation. Fourier-transform infrared spectroscopy identified additional functional groups from the plant extracts, enhancing the material's properties. UV-Vis spectroscopy demonstrated increased light absorption and narrowed bandgaps in the nanocomposites, crucial for efficient photocatalysis under visible light. Morphological studies using FESEM revealed unique leaf-like structures in nanocomposites, indicative of the plant extract's influence on morphology. Photocatalytic degradation of methylene blue, rhodamine B, Congo red, and reactive blue 171 dyes showed enhanced performance of plant extract-modified CuO compared to without plant extract mediated CuO, attributed to improved charge carrier separation and extended lifetime. The effects of pH, catalyst dosage, and dye concentration on degradation efficiency were systematically investigated, highlighting optimal conditions for each dye type. Radical scavenger studies confirmed the roles of holes and hydroxyl radicals in the degradation process. Kinetic analysis revealed pseudo-second-order kinetics for dye degradation, underscoring the effectiveness of the nanocomposites. Overall, this research provides insights into sustainable photocatalytic materials using plant extracts and recycled copper, showcasing their potential for environmental remediation applications.

Influence of Hydrothermal Temperature on the Physical Characteristics and Photocatalytics Activity of TiO2 for Degradation of Amoxicillin

Titanium dioxide (TiO2) is a photocatalyst material widely used for environmental remediation applications. In this research, TiO2 material was synthesized using the hydrothermal method at various temperatures (150°C, 180°C, and 200°C). Based on the Fourier-transform infrared (FTIR) data, it was found that all the synthesized materials showed similar absorption peaks, and Ti-O-Ti bonds were detected, which is a characteristic of TiO2. X-ray diffraction (XRD) analysis showed that all the synthesized materials were TiO2 anatase with different crystalline sizes. The synthesized TiO2 using the hydrothermal temperature of 180°C showed the smallest crystalline size of 86.81 nm. Based on the analysis of the band gap energy, it was found that wider band gap energy was obtained at higher hydrothermal temperatures. The band gap energies of the synthesized materials are 3.18 eV, 3.19 eV, and 3.21 eV for hydrothermal temperatures of 150°C, 180°C, and 200°C, respectively. The photocatalytic activity of the three synthesized materials was tested in the photodegradation experiment of amoxicillin under ultraviolet (UV) irradiation. As a result, it was found that TiO2 synthesized at 180°C has the highest photocatalytic activity by degrading 100% of amoxicillin compounds within 120 minutes.

Hydroxyapatite derived from eggshell embedded on functionalized g-C3N4 for synergistic extraction of U(VI) from aqueous solution

In this paper, we report hydroxyapatite derived from egg-shell biowaste embedded on diglycolamic acid functionalized graphitic carbon nitride nanocomposite (abbreviated as HAp@D-gCN). The compositional and morphological characteristics of HAp@D-gCN were evaluated using scanning electron microscope, X-ray diffraction, BET, FTIR techniques and surface charge using zeta potential measurement. The sorption of U(VI) species on HAp@D-gCN was investigated through batch studies as a function of pH, contact time, initial U(VI) concentration, adsorbent dosage and ionic strength. The adsorption of U(VI) onto HAp@D-gCN was confirmed by FTIR, XRD and EDS elemental mapping. Adsorption kinetics follow pseudo second order model and it attains equilibrium within 20 min. Adsorption isotherm data correlates well with Langmuir isotherm model with a maximum sorption capacity of 993.6 mg of U(VI) per gram of HAp@D-gCN at 298K. U(VI) can be leached from the loaded adsorbent using 0.01 M Na2CO3 as desorbing agent and its sorption capacity remains unaffected even after 4 adsorption-desorption cycles. Hence, the present study reveals that HAp@D-gCN nanocomposite could serve as an environmental friendly material with potential application in environmental remediation.

Removal of crocein orange G from water solutions by trimetallic nanoparticles [Co/Cu/M (M=Ni, Zn)] prepared by chemical reduction method

Co-Cu-Ni and Co-Cu-Zn trimetallic nanoparticles (NPs) were prepared by chemical reduction method which were then used as adsorbent to remove Crocein Orange G dye from solution. The elemental composition of the fabricated NPs was determined by EDX analysis, surface morphology was assessed by SEM, and its crystalline nature was confirmed by XRD analysis. The functional groups on nanoparticles were confirmed by FT-IR analysis. The optimum dosage was found to be 0.01 g. Langmuir model as well as linear pseudo 2nd order kinetics models best explained the obtained data. The maximum adsorption capabilities were found to be around 497.618 mg/g and 683.093 mg/g, respectively for Co-Cu-Ni and Co-Cu-Zn trimetallic NPs. The adsorption process was exothermic, as evidenced from the positive ΔH° values. The negative values of ΔG° at the corresponding temperatures support the spontaneous nature of the adsorption processes. The positive entropy changes (ΔS°) suggested that there is more disorderness at the interface between the solid and the solution during the adsorption. The fabricated trimetallic nanoparticles have effectively adsorbed Crocein Orange G, which may be considered as an attractive option in wastewater treatment and environmental remediation applications due to diversity of metal ions on surface offering differential attractive forces for pollutant.

A Green Approach to Oil Spill Mitigation: New Hybrid Materials for Wastewater Treatment.

This study focuses on the development of adsorptive materials to retain degraded 5w40 motor oil. The materials were prepared using xanthan (XG) and XG esterified with acrylic acid (XGAC) as the polymeric matrix. LignoBoost lignin (LB), LB esterified with oleic (LBOL), stearic acid (LBST) and montmorillonite (CL) were added into XG and XGAC matrices to obtain the adsorbents. Adsorption experiments revealed that XG/CL/LBOL had the highest adsorption capacity at 46.80 g/g, followed by XGAC/CL at 45.73 g/g, and XG/CL at 37.58 g/g. The kinetic studies, employing the pseudo-second-order (PSO) model, indicated rapid sorption rates with a good correlation to experimental data. FTIR spectra analysis have evidenced the physical nature of adsorption process, involving interactions such as hydrogen bonding, van der Waals forces, and π-π interactions. Equilibrium data fitting to the Henry, Freundlich, and Temkin isotherm models showed that the adsorption occurs within materials diverse pore structures, enhancing oil retention. Structural parameters like density, porosity, and surface area were pivotal, with XG/CL/LBOL showing the most favorable properties for high oil adsorption. Additionally, it was found that the adsorption efficiency was influenced by the material's morphology and the presence of chemical modifications. This comprehensive evaluation highlights the potential of these novel adsorptive materials for environmental remediation applications, offering an efficient and sustainable approach to reducing degraded motor oil pollution.

2-Methylbenzimidazole-copper nanozyme with high laccase activity for colorimetric differentiation and detection of aminophenol isomers

Laccase is well-known for its eco-friendly applications in environmental remediation and biotechnology, but its high cost and low stability have limited its practical use. Therefore, there is an urgent need to develop efficient laccase mimetics. In this study, a novel laccase-mimicking nanozyme (MBI-Cu) was successfully synthesized using 2-methylbenzimidazole (MBI) coordinated with Cu2+ by mimicking the copper active site and electron transfer pathway of natural laccase. MBI-Cu nanozyme exhibited excellent catalytic activity and higher stability than laccase, and was utilized to oxidize a series of phenolic compounds. Environmental pollutant aminophenol isomers were found to display different color in solution when catalytically oxidized by MBI-Cu, which provided a simple and feasible method to identify them by the naked eye. Based on the distinct absorption spectra of the oxidized aminophenol isomers, a colorimetric method for quantitatively detecting o-AP, m-AP, and p-AP was established, with detection limits of 0.06 μM, 0.27 μM, and 0.18 μM, respectively. Furthermore, by integrating MBI-Cu-based cotton pad colorimetric strips with smartphone and utilizing color recognition software to identify and analyze the RGB values of the images, a portable colorimetric sensing platform was designed for rapid detection of aminophenol isomers without the need for any analytical instrument. This work provides an effective reference for the design of laccase nanozymes and holds significant potential for applications in the field of environmental pollutant monitoring.