Reusability Properties Research Articles

Sandwich-likely structured, magnetically-driven recovery, biomimetic composite penicillin G acylase-based biocatalyst with excellent operation stability

Immobilization of penicillin G acylase (PGA) on carrier was an established approach to improve the stability and reusable property of it. Herein, Magnetic Fe3O4 nanoparticles (Fe3O4 NPs) that coated by poly (tannic acid), named as Fe3O4 @PTA nanoparticles (Fe3O4 @PTA NPs), had been used as carrier for immobilizing of PGA by physical adsorption effect to produce Fe3O4 @PTA-PGA NPs. Then Fe3O4 @PTA-PGA NPs was post-modified by spontaneous in-situ self-polymerization of dopamine to prepare polydopamine (PDA) coated Fe3O4 @PTA-PGA/PDA nanocapsule. Fe3O4 @PTA-PGA/PDA nanocapsule with sandwich-like structure was a biomimetic composite penicillin G acylase-based biocatalyst, having excellent operational stability. The response rate of Fe3O4 @PTA-PGA/PDA nanocapsule decreased with the extension of polymerization time, whereas the storage stability, thermal stability and pH stability increased with the extension of polymerization time. The EAR of Fe3O4 @PTA-PGA/PDA nanocapsule was 76.4 % with PDA coating time of 4 h. The relative activity (Rt) of Fe3O4 @PTA-PGA/PDA magnetic nanocapsule was 87.1 %, while that of free PGA was 12.5 % after 90 days of storage. Moreover, the Fe3O4 @PTA-PGA/PDA nanocapsule still had 94.1 % of its initial enzyme activity retained and with a enzyme recovery ratio (Re) of 98.0 % after 12 cycles of repeated usage. All those results indicated that the Fe3O4 @PTA-PGA/PDA nanocapsule had excellent operation stability and reusable property, which was very promising for being used as biocatalyst in industrial applications.

Zinc oxide nanoparticles functionalized with chelating nitrogenous groups for the adsorption of methyl violet in aqueous solutions

In this study, a potent material for adsorption of methyl violet (MV) in water was developed. This material was synthesized from silica coated zinc oxide nanoparticles. The material was obtained after functionalization of silica coated zinc oxide nanoparticles with pyrene ligand. Fourier transform infrared spectrometer (FTIR), Brunauer–Emmett–Teller analyzer, energy dispersive X-ray spectrometer, scanning electron microscope (SEM), X-ray diffratometer, transmission electron microscope (TEM) and thermogravimetric analyser were used for characterization of the synthesized materials. Moreover, the ligand was initially characterized with proton and carbon 13 nuclear magnetic resonance spectroscope and FTIR. The results showed characteristic Zn-O stretch in all synthesized nanoparticles’ FTIR spectra. Also, the nanoparticles showed crystalline morphology and spherical geometry in the SEM and TEM analyses respectively. The potent adsorbent showed a reasonable adsorption maximum capacity (qmax) (31.5 mg/g) in comparison with other MV adsorbents. Efficiency test of the adsorbent for MV was carried via batch adsorption experiments. The highest adsorption efficiency and adsorption capacity were found to be 87.7 % and 57.4 mg/g respectively. Kinetic and isotherm studies showed applicability of pseudo-first order and Langmuir isotherm models respectively. These result showed that this special adsorbent can serve as another high efficient adsorbent for MV in wastewater. Further, these results also implied that this adsorbent could be considered for other toxic contaminants in wastewater and can be considered for industrial usage. This is due to its high efficiency and capacity as observed in the study and its reusability and recyclability properties for cost effectiveness.

RSC: Optically stimulated emission of LiF:Mg, Cu, P - towards 3D optically stimulated luminescence dosimetry

With the introduction of highly conformal treatment modalities, dose verification in 3D is becoming more important than ever for patient-specific quality assurance of radiotherapy. Reusability of 3D dosimeters may be the path to cope with the cost-benefit issues caused by batch-to-batch fluctuations and intense calibration protocols in existing 3D systems. We present the idea of an envisioned (optically stimulated luminescence) OSL-based 3D readout system, which exploits the inherently reusable dosimetry properties of OSL. We provide the emission spectra of the OSL active material LiF:Mg, Cu, P (MCP) for three stimulation wavelengths (460 nm, 532 nm, and 664 nm), and summarize recently published optical characterization results to highlight the requirements of a readout system for an MCP-based dosimeter.

Determinants of sustainable building materials (SBM) selection on construction projects

The complexity and fragmented nature and the multiple stakeholders in the construction industry often make it difficult to come up with a firm decision regarding sustainable building materials selection. The wrong choice could negatively impact the project objective and performance outcome. This study assessed the critical factor influencing the choice of sustainable building materials (SBM) selection on construction projects in the Southeast geopolitical zone of Nigeria. Data were collected using a well-structured questionnaire, non-probability (purposive and snowball) sampling techniques, and an internet-mediated survey. Data analyses were carried out using the appropriate descriptive and inferential statistical tools and exploratory factor analysis (EFA). The study revealed recycled plastic, natural clay and mud, stone, bricks and tile, cellulose, stray bales, grasses, limestone, and wood timber, are the commonly used sustainable building materials. Also, their level of awareness is high while their adoption is moderate. EFA revealed that the major clusters of determinants of the choice of green building materials are: emissions minimisation, low running cost and reusability, low thermal and energy consumption efficiency, low cost and high health and safety consideration and waste minimisation. The key factors influencing the choice of sustainable building materials selection in construction are: reducing greenhouse gas emissions from buildings, materially embodied energy cost, operating and maintenance costs, non-toxic or low toxic emissions generated by the products/materials, recyclability of the building materials, availability of the technical skills, renewable (reusable) properties, inhibiting the impact of buildings on the environment, safety and health of the occupants, and appearance and aesthetic. It is recommended that consideration be given to these factors in selecting sustainable/green building materials in the designs and specifications of construction projects.

Synthesis of Ce-doped magnetic NaY zeolite for effective Sb removal: Study of its performance and mechanism

A Ce-doped magnetic NaY zeolite adsorbent (NaY@Ce−Fe) was synthesized by co-precipitation method for efficient Sb removal. NaY@Ce−Fe exhibited considerable maximum adsorption capacities of Sb (11.56 ± 0.58 mg/g for Sb(III) and 5.36 ± 0.43 mg/g for Sb(V)) and reusability property and excellent saturated magnetization of 71.1 emu/g. The adsorption data of Sb(III) and Sb(V) were well fitted with the Langmuir isotherm model and Freundlich isotherm model, respectively. Kinetic studies showed that the adsorption processes of Sb(III) and Sb(V) followed the pseudo-second-order kinetic model. The excellent adsorption performance of NaY@Ce−Fe maintained over a wide pH range of 4–9 without the release of Ce and Fe, or in the presence of coexisting anions of Cl−, SO42− and NO3−. The combined results of scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), X-ray Powder Diffraction (XRD), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) further confirmed the successful doping of Ce and Fe3O4 on NaY. Based on the results of batch experiments and physiochemical analyses, the mechanisms controlling Sb adsorption on NaY@Ce−Fe involved the electrostatic attraction, hydrogen bonding, ligand exchange and surface complexation. The abundant number of surface hydroxyl groups promoted the formation of the Ce−O−Sb inner-sphere surface complexes, which was the major contribution to the adsorption of Sb. All the results suggested that NaY@Ce−Fe could be applied as a promising adsorbent for Sb pollution reduction.

Simultaneous extraction of multi-antibiotic residues in environmental water by DTPA-modified polyaniline nanofibers membrane

In this study, novel diethylenetriaminepentaacetic acidmodified polyaniline nanofibers membrane (DTPA-PANI NFsM) was designed and fabricated. By the synergistic effect of PANI and DTPA, the DTPA-PANI NFsM demonstrated superior sorption performance towards three classes of antibiotics with very different properties: phenicols, tetracyclines and sulfonamides. The mass transfer efficiency of DTPA-PANI NFsM was particularly high. From the isotherm and thermodynamic studies, favorable and spontaneous adsorption processes were confirmed. The potential adsorption mechanisms were investigated by FT-IR analysis. Under the optimized conditions, an efficient, fast, sensitive and economical method for the high-throughput detection of antibiotic residues in environmental water was developed. Low detection limits (1.6–28.6 ng/L for phenicols, 10–34.3 ng/L for tetracyclines, 0.46–15 ng/L for sulfonamides), broad linear range (1.5 ng/L-5 µg/L) as well as satisfactory recoveries and precisions were obtained. In addition, DTPA-PANI NFsM exhibited excellent regeneration and reusability properties, which could be reused for at least 12 times. Also, the practical application feasibility of the method was confirmed by the test of actual samples.

A novel biocomposite based on peanut husk with antibacterial properties for the efficient sequestration of trimethoprim in solution: Batch and column adsorption studies

The adverse impact of emerging pollutants (such as antibiotics) on water quality and subsequently on the ecosystem makes their removal very important. Herein, peanut husk (a low-cost material) was modified with betaine via a simple synthetic route to form a novel adsorbent (PN-Bet). The efficiency of PN-Bet for the removal of trimethoprim in solution was carried out via the batch and column method. Results from the batch studies indicated that factors such as initial concentration, solution pH and temperature had an influence on the uptake of TMP onto PN-Bet. A maximum monolayer adsorption capacity of 37.6 ± 1.5 mg g–1 (at 293 K) according to the Langmuir model was recorded with the process being exothermic in nature. Kinetic studies showed that both pseudo-first kinetic model and pseudo-second order kinetic model could describe the adsorption process indicating the complexity of the process. PN-Bet also showed some removal efficiency towards TMP in real water samples. The feasibility of PN-Bet for industrial applications was confirmed via the fixed-bed adsorption studies with the Clark model best describing the adsorption process. The facile synthetic route employed in this study involving the use of a low-cost material under benign environmental condition can help address some of the challenges associated with some reported adsorbents for the removal of TMP. Also, the development of this adsorbent with antibacterial and good reusability properties as well as high removal efficiency for TMP can serve as a model for the development of other novel adsorbents for the sequestration of both chemical and biological pollutants in wastewater.

A sugarcane bagasse carbon-based composite material to decolor and reduce bacterial loads in waste water from textile industry

In present study, H3PO4–activated sugarcane bagasse carbon-based composite with Al(OH)3, was prepared and characterized by Brunauer-Emmett-Teller (BET), Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. The adsorptive decolorization of methylene blue (MB) and methyl violet (MV) contaminated water employing sugarcane (Saccharum officinarum L.) bagasse carbon/Al(OH)3 {SBC/Al(OH)3} composite was explored under varying operational conditions. The equilibrium data for MB and MV adsorption was best appropriated by Langmuir and Freundlich isotherm models, respectively with the maximum Langmuir adsorption capacity of 261 mg/g for MB and 125 mg/g for MV illustrating the monolayer adsorption of MB onto energetically homogeneous sites and multilayer adsorption of MV onto heterogeneous surface sites. The kinetics of both MB and MV adsorption process onto SBC/Al(OH)3 composite was consistent with pseudo-second order model. The thermodynamic parameters such as ∆H° (5–17 kJ/mol for MB; 20–17 kJ/mol for MV) and ∆S° (0.063–0.1 kJ/mol.K for MB; 0.095 −0.21 kJ/mol.K for MV), and –∆G° (6.1–11.3 kJ/mol for MB; 12.4–30.0 kJ/mol for MV) advocated respectively the endothermic, increased randomness at the SBC/Al(OH)3–MB or MV interface, and spontaneous and feasible adsorption process. The adsorbent was efficiently regenerated and had the potential to be used for five recycles with limited loss in efficacy. The SBC/Al(OH)3 exhibited consistently good antibacterial activity against gram–negative (K. pneumonia; E. coli; P. aeruginosa) bacterial strains with zone of inhibition between 8 and 18 mm compared to gram–positive, B. cereus (6–13 mm). The apparent superiority of SBC/Al(OH)3 over other adsorbents in terms of adsorption capacity, promising reusability, and potent antibacterial properties demonstrated that SBC/Al(OH)3 composite could be a sustainable, remarkably efficient and cost-effective adsorbent for aquatic pollution abatement.

Fast decolorization of rhodamine-B dye using novel V2O5-rGO photocatalyst under solar irradiation

Degradation of dyes through Metal-oxide semiconductors using Advanced Oxidation Process (AOP) presents a unique opportunity for the development of advanced treatment techniques for effective removal of dyes from industrial wastewater. In this paper, an experimental study is being carried out by synthesizing the vanadium pentoxide–reduced graphene oxide (V2O5-rGO) nanocomposite for effective dye-degradation through photocatalysis under solar irradiation. V2O5-rGO nanocomposite is obtained by using an easy and efficient procedure of V2O5 nanowire in an rGO solution. V2O5 nanowires when bonded to rGO sheets (2D), serves as an excellent catalyst for the degradation of Rhodamine-B (RhB) dye. V2O5-rGO nanocomposites has been characterized using FESEM (Field Emission Scanning Electron Microscope), XRD (X-Ray Diffraction), and FTIR (Fourier Transform Infrared spectroscopy) techniques. V2O5-rGO is primarily used as a photocatalyst which utilizes sunlight for degradation of aqueous Rhodamine-B (RhB) dye through the principle of photoreaction. The nanocomposite shows ̴ 97% dye removal efficiency of RhB (20 mg/L) solution for a short processing time of 50 min. The study shows an increased generation of hydroxyl radicals (∙OH) in the presence of rGO sheets in the catalyst, which supports the photocatalytic process through suppression of electron (e-) and hole (h+) recombination causing the degradation of RhB dyes. Adding rGO shows ~84% faster decolorization in comparison to pure V2O5. The catalyst efficacy is further evaluated through varying pH of the RhB solution medium. A pH dependency of the reaction rate is observed with the fastest degradation time in the presence of V2O5-rGO nanocomposite being achieved at a pH of 9. Reusable catalytic properties for the suspended V2O5-rGO nanocomposite are studied for 6 cycles and the degradation efficiency of more than 90% is observed in 50 min. A brief study is performed to determine the decreased photocatalytic performance, which is fully reverted using simple chemical treatment by H2O2 and UV irradiation for further usage of the photocatalyst.

Protective Face Masks: Current Status and Future Trends.

Management of the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has relied in part on the use of personal protective equipment (PPE). Face masks, as a representative example of PPE, have made a particularly significant contribution. However, most commonly used face masks are made of materials lacking inactivation properties against either SARS-CoV-2 or multidrug-resistant bacteria. Therefore, symptomatic and asymptomatic individuals wearing masks can still infect others due to viable microbial loads escaping from the masks. Moreover, microbial contact transmission can occur by touching the mask, and the discarded masks are an increasing source of contaminated biological waste and a serious environmental threat. For this reason, during the current pandemic, many researchers have worked to develop face masks made of advanced materials with intrinsic antimicrobial, self-cleaning, reusable, and/or biodegradable properties, thereby providing extra protection against pathogens in a sustainable manner. To overview this segment of the remarkable efforts against COVID-19, this review describes the different types of commercialized face masks, their main fabrication methods and treatments, and the progress achieved in face mask development.

Effective desalination of brackish groundwater using zeolitized diatomite/kaolinite geopolymer as low-cost inorganic membrane; Siwa Oasis in Egypt as a realistic case study

The salinization of the groundwater wells in Siwa oasis, Egypt represents a critical environmental and economic issue. Developing low-cost, effective, and self-supported inorganic membranes were suggested as suitable desalination techniques. Zeolite/geopolymer (Z/GP) membrane was synthesized as a potential low-cost membrane for effective desalination of brackish groundwater in Siwa Oasis, Egypt. The membrane was synthesized by simple geopolymerization for natural kaolinite and diatomite at room temperature. This was followed by hydrothermal growth of zeolite at 100 °C for 24 h to produce zeolitized geopolymer as potential inorganic membrane. After that, the prepared membrane was incorporated in the pervaporation desalination system considering the effect of the membrane thickness and the temperature. The results demonstrated water flux values of 8.34 kg.m−2.h−1, 7.63 kg.m−2.h−1, and 7.05 kg.m−2.h−1 for the tested membrane at thicknesses of 1 mm, 2 mm, and 3 mm, respectively. This associated with significant salt rejection prearranges 95.8% (1 mm), 97.6% (2 mm), and 99.4% (3 mm). Moreover, the high-temperature value (90 °C) is of strong positive impact on the water flux (7.82 kg.m−2.h−1) and a slight impact on the salt rejection (99.6%). The membrane is of significant stability considering the obtained water flux (7.51 kg.m−2.h−1) and salt rejection (99.57%) after 130 h. The reusability properties of the Z/GP membrane demonstrated its suitability to be used in the desalination process for five runs. Therefore, the synthetic Z/GP membrane is a highly recommended product for simple, effective, low cost, and available desalination technique brackish groundwater in Siwa Oasis.

Structural, optical and photocatalytic properties of magnetic recoverable Mn0.6Zn0.4Fe2O4@Zn0.9Mn0.1O heterojunction prepared from waste Mn–Zn batteries

Green, simple and high value-adding technology is crucial for realizing waste batteries recycling. In this work, the magnetically recyclable Mn0.6Zn0.4Fe2O4@Zn0.9Mn0.1O (MZFO@ZMO) heterojunctions are prepared from waste Mn–Zn batteries via a green bioleaching and sample co-precipitation method. The as-prepared catalysts with different Zn0.9Mn0.1O weight percentage (25%, 50% and 75%) have been comprehensively characterized in structure, optics, photoelectrochemistry and photocatalytic activity. Characterization results indicate that MZFO@ZMO heterojunctions with the core-shell structure, demonstrates excellent absorption intensity in the visible light region, outperforming that of individual ZnO and Zn0.9Mn0.1O. Especially, the staggered bandgap alignment of Mn0.6Zn0.4Fe2O4 and Zn0.9Mn0.1O greatly enhances electron transfer and charge separation in the binary heterojunction system. The optimized MZFO@50%-ZMO shows the highest photodegradation performance toward methylene blue (MB) under the visible light irradiation, with a 99.7% of photodegradation efficiency of 20 mg L−1 of MB within 90 min, and its reactive kinetic constants is about 7.2, 10.8 and 21.7 times higher than that of Zn0.9Mn0.1O, P25 TiO2 and Mn0.6Zn0.4Fe2O4, respectively. The MB photocatalytic mechanism is investigated in the scavenger and 5,5-dimethylpyrroline-N-oxide (DMPO) spin-trapping electron spin resonance (ESR) experiments, and h+ and *O2− are identified as the major active species for MB degradation. In addition, MZFO@50%-ZMO also exhibits a good reusability and high magnetic separation properties after six successive cycles. This new material indicates the advantages of low costs, simple reuse and great potential in application.

2D MoO2/N-Doped-Carbon Nanosheets as SERS Tweezers: A Non-Noble Metal Reusable Substrate for Selective Organic Dye Detection

The design and synthesis of a highly sensitive and exceptionally selective surface-enhanced Raman scattering (SERS) substrate with an excellent reusable property are of significant interest because...

Facile fabrication of magnetically recyclable Fe3O4/BiVO4/CuS heterojunction photocatalyst for boosting simultaneous Cr(VI) reduction and methylene blue degradation under visible light

It is a challenging problem that develops a low-cost, efficient and sustainable technology in order to remove heavy metals and organic contaminants in the practical wastewater. Herein, a novel recyclable Fe3O4/BiVO4/CuS (FBCu) heterojunction photocatalyst was facilely fabricated by a method, coating CuS nanoparticles on the surface of Fe3O4 and BiVO4 simultaneously. FBCu composite not only has the ability to degrade Cr(VI) or methylene blue (MB) alone under visible light irradiation, but also exhibits higher photocatalytic ability in simultaneously removing Cr(VI) and MB mixed pollutants. The superior photocatalytic performance of FBCu is related to the formation of p-n heterojunction, which extends the spectral response and facilitates the efficiency of charge carriers separation and utilization. Moreover, FBCu exhibits satisfactory properties of reusability and stability after five cycling experiments in the Cr(VI)-MB coexistence system. Furthermore, the detailed mechanism for simultaneous removal of mixed pollutants was proposed and verified by DRS results, photoelectrochemical analysis, scavenger experiments and electron spin resonance determination. This work provides a recyclable photocatalyst with eco-friendliness and multifunctional applications in water pollution.

Amino acid-assisted ferrite/MOF composite formation for visible-light induced photocatalytic cascade C=C aerobic oxidative cleavage functionalization

Due to their high variability and extraordinary features, the MOF-based nanomaterials are regarded as promising photocatalysts in organic reactions. In this study, the magnetic Co-MOF-based nanocomposite (denoted by Cys-CoFe/HK) was prepared through a facile sonochemical method. The composite design was based on the integration and synergy of the desired properties of the components, i.e., optical properties of the magnetic substrate and its separation capability, desirability of metal-organic framework to promote A3-coupling reaction, and use of cysteine ​​amino acid as a natural modifier to modify nanoparticles and make an efficient charge transfer. The information about their structural features was obtained using various characterization methods. In addition to the high photocatalytic activity of the developed composite in the aerobic oxidative propargylic functionalization of styrene under visible light illumination, the composite showed a high capability to interact with a wide range of amines, styrene, and terminal alkynes as participants in A3-coupling reaction. Furthermore, the developed catalyst demonstrated high accessibility of active sites, reusability, and magnetic properties, which accelerated the efficiency of the A3-coupling reaction. Moreover, the mechanistic investigations, including trapping experiments, confirmed the presence of superoxide radical (O2●) and holes (h+) as essential species to perform the considered reaction. Our methodical approach to the fabrication of Cys-CoFe/HK composite provided optimal conditions for improving previous studies and thus the industrial processes in environmentally sensitive areas.

Preparation of molecularly imprinted resin/polydopamine nanofibers mat for the highly efficient extraction and determination of sulfonamides in environmental water.

With polyacrylonitrile nanofibers mat (PAN NFsM) as a template, molecularly imprinted resin/polydopamine nanofibers mat (MIR/PDA NFsM) was synthesized for the extraction of sulfonamides (SAs) in water. The specific surface area and pore volume were increased obviously due to the functionalization of MIR. The adsorption efficiencies of MIR/PDA NFsM under optimized conditions for SAs were92.3-99.3%. Possible adsorption mechanisms of imprinting recognition and hydrogen bond interactions were also put forward. Compared with MIR particles, the MIR/PDA NFsM exhibited much superior adsorption performance. Particularly, the outstanding mass transfer efficiency of MIR/PDA NFsM was much higher than the other reported adsorbents for SAs. Finally, a new method based on the solid-phase extraction (SPE) of MIR/PDA NFsM was successfully developed for the detection of five SAs in environmental water with HPLC-MS/MS and applied to the analysis of actual samples. Under the selected conditions, the enrichment factors of MIR/PDA NFsM of SCP, SMT, SMZ, SMR, and SMX were between 23.0 and 25.0. Low detection limits (0.26-0.76ng L-1), broad linear range (1.0ng L-1 to 10.0μg L-1), and satisfactory recoveries (82.8-115.6%) and precisions (RSDs < 7.2%) were obtained. Moreover, the excellent reusability properties and storage stability endowed MIR/PDA NFsM with great value forpractical applications.

A Data Mining Technique to Improve Configuration Prioritization Framework for Component-Based Systems: An Empirical Study

Department of Software Engineering, In the current application development strategies, families of productsare developed with personalized configurations to increase stakeholders’ satisfaction. Product lines have theability to address several requirements due to their reusability and configuration properties. The structuringand prioritizing of configuration requirements facilitate the development processes, whereas it increases theconflicts and inadequacies. This increases human effort, reducing user satisfaction, and failing to accommodatea continuous evolution in configuration requirements. To address these challenges, we propose a framework formanaging the prioritization process considering heterogeneous stakeholders priority semantically. Featuresare analyzed, and mined configuration priority using the data mining method based on frequently accessed andchanged configurations. Firstly, priority is identified based on heterogeneous stakeholder’s perspectives usingthree factors functional, experiential, and expressive values. Secondly, the mined configuration is based on frequentlyaccessed or changed configuration frequency to identify the new priority for reducing failures or errorsamong configuration interaction. We evaluated the performance of the proposed framework with the help ofan experimental study and by comparing it with analytical hierarchical prioritization (AHP) and Clustering.The results indicate a significant increase (more than 90 percent) in the precision and the recall value of theproposed framework, for all selected cases.

Photocatalytic studies of copper oxide nanostructures for the degradation of methylene blue under visible light

As a well-known global fact, the presence of toxic, non-biodegradable and harmful organic pollutants in soils, wastewater, and atmosphere has become an indisputable significant environmental problem. The present study reports the photocatalytic properties of the cubic-shaped Cu/Cu2O/CuO and bud-shaped CuO nanoparticles for methylene blue (MB) removal from the synthetic dye solution. Nanocrystalline copper oxide particles are synthesized by a simple solvothermal method followed by an annealing process at 400 °C in an open atmosphere. The crystalline structure and morphology of the nanoparticles are characterized by X-ray diffraction and field emission-scanning electron microscopy. The optical band gap energies of the prepared powders are estimated using the UV–vis spectrometer. Interestingly, cubic shaped Cu/Cu2O/CuO nanoparticles shows a photo-degradation efficiency of about 78% after 120 mins whereas bud-shaped CuO shows 61% in the presence of H2O2. Further, Cu/Cu2O/CuO nanoparticles show good recyclability of up to three cycles. The excellent photocatalytic performance and reusability properties of Cu/Cu2O/CuO heterojunctions also synergistically lowers the electron–hole recombination rate, promotes the utilization of light and photo-generation of charge carriers. All these combined effects result in the enhanced photocatalytic degradation and mineralization of the MB dye.

Green synthesis of magnetically recyclable Mn0.6Zn0.4Fe2O4@Zn1-xMnxS composites from spent batteries for visible light photocatalytic degradation of phenol

Magnetic binary heterojunctions are a kind of promising photocatalysts due to their high catalytic activity and easy magnetic separation; however, their synthesis may involve high costs or secondary environmental impacts. In this work, the magnetically recyclable Mn0.6Zn0.4Fe2O4@Zn1-xMnxS (MZFO@Zn1-xMnxS, x = 0.00–0.07) photocatalysts are synthesized from spent batteries via a green biocheaching and egg white-assisted hydrothermal method. The as-synthesized photocatalysts have been comprehensively characterized in phase, morphology, texture, optics, photoelectrochemistry and photocatalytic activity. Characterization results indicate that the desired core-shell structure MZFO@Zn1-xMnxS composites are successfully synthesized, theirs absorption intensity in the visible light region is greatly enhanced compared to Zn1-xMnxS. In addition, doped Mn2+ in ZnS host lattice and the staggered bandgap alignment of MZFO and Zn1-xMnxS greatly enhances electron transfer and charge separation in the binary heterojunction system. The optimized MZFO@Zn0.95Mn0.05S shows the highest photodegradation performance toward phenol under the visible light irradiation, with a complete degradation of 25 mg L−1 of phenol within 120 min, and its reactive kinetic constants is about 5.2 and 13.3 times higher than that of pure Zn0.95Mn0.05S and MZFO, respectively. Furthermore, the mechanism and pathways for the degradation of phenol are proposed. In addition, MZFO@Zn0.95Mn0.05S also exhibits a good reusability and high magnetic separation properties after 5 successive cycles. This new material has the advantages of low costs, simple reuse and great potential in application.

In-situ catalytic upgrading of bio-oil from rapid pyrolysis of biomass over hollow HZSM-5 with mesoporous shell

To solve the issue of narrow micropores in traditional protonic type Zeolite Socony Mobil-5 (HZSM-5) catalysts in the restricting of large-molecular reactants/products diffusion, hollow HZSM-5 with a mesoporous shell was prepared using a hydrothermal method combined with a tetrapropylammonium hydroxide (TPAOH) treatment process. Applying for in-situ catalyst upgrading of bio-oil from rapid pyrolysis of biomass, the obtained most efficient catalyst of Hollow(30)-TP resulted in aromatic hydrocarbon yields in the range of 78.49–78.67% for cellulose and hemicellulose, which is much greater than those using the traditional HZSM-5 (61.06–68.26%). Furthermore, in the case using real biomass (cedar) with an optimal biomass/catalyst weight ratio of 1:2, the aromatic hydrocarbon yield reached up to 80.16%. In addition, this catalyst exhibited excellent reusability and regeneration property due to the increased accessibility to the acid sites in the hollow HZSM-5 for the improving of the reaction rate as well as the reducing of coking.