Recyclability Research Articles

Construction of MoO3 nanopaticles /g-C3N4 nanosheets 0D/2D heterojuntion photocatalysts for enhanced photocatalytic degradation of antibiotic pollutant

A new type of 0D-2D Z-scheme heterojunction photocatalyst (MoO3/g-C3N4) was successfully prepared via simple hydrothermal calcination method. The catalytic activities of MoO3/g-C3N4 was evaluated by the degradation effect of tetracycline. The results indicated that the 0D-2D MoO3/g-C3N4 Z-scheme heterojunction was significantly better than that of original g-C3N4. Especially, the optimal 0.5 wt% MoO3/g-C3N4 could reach 85.9% removal efficiency within 100 min under visible light irradiation (λ > 420 nm), and its degradation rate constant was 2.3 times higher than that of g-C3N4·In addition, the effects of real water matrix, natural sunlight irradiation on tetracycline removal were examined. Reactive-species-trapping experiments show that both photo-generated •O2− and h+ are the main active species in the photocatalytic process. Besides, the results of •O2− and •OH detection further indicated that the yield amount of •O2− and •OH in MoO3/g-C3N4 case showed enhancement when compared with g-C3N4. Moreover, the quite stable crystal structure and excellent recycling ability endowed the MoO3/g-C3N4 composite with a great potential for applying in photocatalytic fields.

Interface and defect engineering enable fast and high-efficiency Li extraction of metatitanic acid adsorbent

Considering the striking theoretical Lithium (Li) uptake capacity, environmental benignity and low cost, metatitanic acid (H2TiO3, abbreviated to HTO) is considered to be one of the most promising lithium ion sieve (LIS) adsorbent for liquid-phase Li extraction technology. However, the discouraging adsorption kinetics seriously hampers its industrial application. Herein, the traditional HTO-LIS is promoted by the combined strategies of pore-structure construction, surface heteroatom modification and alien Zn ion bulk doping, which ameliorates the surface characterization of the HTO adsorbent towards fast Li+ capturing from the solution, facilitating the activation and replacement of Li+ on the interface. Further, the oxygen bulk defect originated from Zn doping accelerates the Li+ transfer in solid-phase via the depressed diffusion energy barrier. The interfacial modification and defect engineering synergistically cooperate to extremely speed up the Li extraction process that the Li uptake rate of the optimized sample (PN-HZTO-0.04) increases to 457% compared to the pristine HTO-0 adsorbent. Remarkably, in the optimized Solid/Liquid ratio adsorption test, the adsorption efficiency of above 96% are achieved in 2 h, without obvious capacity degradation and Ti dissolution loss during adsorption/desorption cycles, representing excellent recycling ability.

Highly Emissive Metal-Organic Frameworks for Sensitive and Selective Detection of Nitrofuran and Quinolone Antibiotics.

The overuse of antibiotics makes its detection very significant for human health. New facile methods and high-performance sensory materials will be urgently needed for detection of antibiotics. Unfortunately, there are few reports on fluorescence enhancement of antibiotics detection. Herein, based on the modulability of the coordination mode, we proposed two MOFs with different coordination modes based on different metal ions: Zn-MOF (1) and Cd-MOF (2). The fluorescence of 1 and 2 can be efficiently and selectively quenched by nitrofuran antibiotics (nitrofurazone, NFZ and furazolidone, FZD) and chloramphenicol (CAP), respectively. Particularly, the matched energy levels between 2 and enrofloxacin (ENR) enables 2 with turn-on sensing for ENR. Moreover, apart from the sensitivity and selectivity, 1 and 2 also have strong recyclable ability, fast response time and anti-interference ability, which make them great potential sensory materials to detect antibiotics.

Keggin-type polyoxometalates molecularly loaded in Zr-ferrocene metal organic framework nanosheets for solar-driven CO2 cycloaddition

Although Keggin-type polyoxometalates (POMs) have shown nice catalytic efficiency for CO2 cycloaddition reaction, they suppressed by their low recycling ability and energy costing of direct heating. Decorated POMs into solid porous support with photothermal property is an alternative but promising way for solar-driven reaction. Herein, phosphomolybdate molecularly decorated ferrocene-based Zr-Fc (PMo12@Zr-Fc) metal organic frameworks (MOFs) nanosheet, which has outstanding photothermal conversion ability, are synthesized and used to catalyze cycloaddition reaction with styrene oxide and CO2 under simulated sunlight. At light intensity of 0.4 W/cm2, the temperature of reactor with PMo12@Zr-Fc MOFs rapidly rises and up to 80 ℃, and 88.05 % yield of product is achieved. This PMo12@Zr-Fc catalyst also demonstrates nice recycling stability. The solar-driven cycloaddition process may exploit a new avenue for reusing CO2.

Fast electron transfer and enhanced visible light photocatalytic activity of silver and Ag2O co-doped titanium dioxide with the doping of electron mediator for removing gaseous toluene

Volatile organic compounds (VOCs) can influence air quality and threaten human health; however, the development of an effective method to remediate toxic VOCs is still remain challenge. Herein, a novel silver and Ag2O co-doped TiO2 with fast electron transfer modified by nitrogen doping carbon dots was prepared via a facile chemical precipitation-reduction method. Under 50 min of visible light irradiation, the novel photocatalyst exhibited approximately 50% gaseous toluene degradation efficiency, which was ca. 9.7 times and 2.2 times higher than that of bare TiO2 and silver and Ag2O co-doped TiO2, respectively. Importantly, the photocatalyst also showed a stable structure and good recycling ability after 400 min of photocatalytic degradation with little amount of NCDs. Besides, the up-conversion effect of NCDs could emit high-energetic light and thus generate more e−-h+ pairs, which could facilitate the SPR effect of Ag and thus showed strong visible light response because of the localized surface plasmon resonance (LSPR) excitation. Thus, the excellent photocatalytic performance could attribute to the synergetic effect of up-conversion effect of NCDs and SPR effect of silver which could both facilitate charge carriers separation and improve visible-light response. Finally, a possible mechanism for the excellent photocatalytic activity was proposed, in which the active species including ·O2−, ·OH and h+ were generated and contributed to photocatalytic process. The successful fabrication of DACT provides a potential strategy for the treatment of VOCs in practical applications.

An excellent sulfonated hydrothermal carbon catalyst from Mangifera indica L. (mango peels) for biodiesel production: preparation, characterization, optimization, and kinetic study

The current study describes the preparation and catalytic activity evaluation of newly synthesized hydrothermal carbon catalysts for biodiesel production. The catalysts (HTCC-M2-10h) were prepared through the sulfonation of mango peels (Mangifera indica L.) using concentrated sulfuric acid at various time intervals from 2- to 10-h process. The catalysts were characterized via sophisticated analytical techniques to analyze surface area, functional groups, morphology, and acid density sites. The catalyst prepared at a 6-h time interval shows a high density of proton switchable/acidic sites attached to the carbon surface (i.e., SO3H, COOH, and OH). The catalyst was found to exhibit a large surface area (42.13 m2/g), well-ordered porosity, and large pore volume. The catalytic activity was determined by examining the catalyst performance for fatty acid esterification to produce the methyl ester (i.e., biodiesel). Thus, HTCC-M6h (prepared at 6 h) gives the maximum catalytic activity due to its high acid density (3.46 mmol/g) and large surface area. The maximum 98.6% oleic acid conversion into methyl oleate was obtained at 65 °C by using 10:1 v/v methanol:oil and 5 wt% of catalyst within 4 h. The kinetic study for oleic acid esterification by HTCC-M6h performed at temperatures between 40 and 70 °C confirmed the first-order reaction as is the case for homogeneous esterification reaction. The recyclable ability of catalyst was also determined and found that the catalyst has enough potential to recycle up to four times without any reactivation step and any activity loss after that catalyst can be regenerated. The results revealed that the HTCC-M6h exhibits high stability, high catalytic activity, and reusability. It could be concluded that the prepared HTCC-M6h will prove itself an innovation in heterogeneous catalysis.

A pretreatment method for effective utilization of copper product manufacturing waste

In South Korea, the manufacturing system from chalcopyrite (CuFeS2) to Cu products is divided into two parts: electrolytic Cu manufacturing and Cu product manufacturing (CPM). Most of the CPM waste is deposited in landfills unlike the waste generated in electrolytic Cu manufacturing that has a good recycling ability. Therefore, in this study, a method to improve the utilization of CPM waste was proposed as a case study for South Korea. Furthermore, the CPM was investigated and classified into five types in terms of the raw materials, major products, additives, main processes, and characteristics of the CPM waste (waste type, particle size, and chemical composition). Next, the CPM waste was environmentally assessed via leaching toxicity tests using the Korean standard official method, ES 06150. In addition, the amount of specific heavy metals (Pb, Cu, Cd, As, Hg, and Cr6+) was determined to confirm the presence of substances labeled as hazardous waste. Based on these results, a pretreatment method with grinding (under 0.1 mm), screening (0.15 mm grid), magnetic separation (1.0 T), and alkali leaching (30–90 °C and 1–5 mol/dm3) was proposed. The final materials can be categorized into groups, such as fine-particle groups with high Zn and Fe contents, leachate groups with high Cu and Zn concentrations, and metal-scrap groups. Moreover, material flow analysis of all CPM waste streams in the designed pretreatment method was conducted in South Korea in 2019.

Fabrication of cylindrical 3D cellulose nanofibril(CNF) aerogel for continuous removal of copper(Cu2+) from wastewater

Heavy metal contamination in wastewater is a serious problem due to its high toxicity. In this study, three-dimensional porous and flexible polyethylene imine grafted cellulose nanofibril aerogel (PEI@CNF aerogel) is synthesized as a highly efficient biosorbent for continuous treatment of wastewater containing copper (Cu2+). The synthesized PEI@CNF aerogel efficiently separates Cu2+ from wastewater and exhibits outstanding selectivity for Cu2+ in the presence of other metal ions. The amine groups in polyethylene imine (PEI) grafted onto the porous cellulose nanofibrils (CNFs) scaffold form chelates with Cu2+ thereby effectively adsorbing Cu2+. The combination of a flexible CNF scaffold and rigid PEI results in a durable elastic matrix of the aerogel providing excellent wet stability, shape recovery property and recycle ability of PEI@CNF aerogel. Finally, in the column test, the PEI@CNF aerogel treats 88 bed volumes of wastewater containing Cu2+(∼20 mg/L). This result demonstrates that PEI@CNF aerogels are practically viable and highly efficient bio-sorbents for the treatment of wastewater containing Cu2+.

Covalent immobilization of molecular complexes on metal-organic frameworks towards robust and highly efficient heterogeneous water oxidation catalysts

The major challenges to practical implementation of efficient noble metal based molecular water oxidation catalysts are their stability and recycle ability. Herein, noble metal Ru based molecular water oxidation catalysts were covalently anchored in MOFs through “amide bond” as bridges, which leads to the formation of high-efficiency and robust heterogeneous catalysts for water oxidation reaction. We show that the efficiency for CeIV-driven water oxidation was significantly enhanced by 120 times when the Ru molecules were immobilized on the frameworks of MIL-101(Cr). The relationship between recycle stability and the structure of the Ru complexes covalently anchored in MOFs was carefully studied by recycle tests and various characterization methods. [Ru(terpy)(pic)2(H2O)]2+ was directly certified as real catalytic species instead of the original complex [Ru(terpy)(pic)2Cl]+ by the X-ray absorption spectroscopy and control experiments. The synthetic method of hybrid catalysts offers a good strategy for enhancing water oxidation activity and stability of molecular catalysts.

Construction of a novel electron transfer pathway by modifying ZnIn2S4 with α-MnO2 and Ag for promoting solar H2 generation

Using photocatalysts to split water by solar energy for sustainable H2 generation has aroused researchers' wide concern. In this study, we chose α-MnO2 as the electron storage and transfer medium, and introduced the surface plasma resonance effect of Ag into the composite material to successfully prepare novel ternary Ag/α-MnO2/ZnIn2S4 (Ag/α-MnO2/ZIS) photocatalysts. Various technologies such as photoluminescence (PL), Photocurrent-Time (PC), Linear sweep voltammetry (LSV), Mott–Schottky measurement (M–S) and electrochemical impedance spectra (EIS) were used to characterize the ternary Ag/α-MnO2/ZnIn2S4 photocatalysts. Noteworthy, due to the synergistic effect of the three materials, the composite catalysts have the characteristics of excellent optical properties, more active sites, greater carrier density, and stronger carrier separation and transfer ability. This structural design can remarkably improve photocatalytic performance driven by visible light. As expected, the Ag/α-MnO2/ZnIn2S4 photocatalysts exhibit excellent photocatalytic activity with a maximum H2-production rate of 3.65 mmol g-1 h−1, and it is about 14.9 times higher than that of pure ZnIn2S4. Furthermore, the ternary Ag/α-MnO2/ZnIn2S4 photocatalysts show recycle ability and good stability, and a photogenerated electron transfer mechanism has been put forward and detailly analyzed. The work offers a novel strategy to design highly active visible light photocatalysts for clean energy.

Removal of Cu(II) Contamination from Aqueous Solution by Ethylenediamine@β-Zeolite Composite.

The low cost β-zeolite and ethylenediamine modified β-zeolite (EDA@β-zeolite) were prepared by self-assembly method and used for Cu(II) removal from contaminated aqueous solution. Removal ability of β-zeolite toward Cu(II) was greatly improved after ethylenediamine (EDA) modification, the removal performance was greatly affected by environmental conditions. XPS results illustrated that the amide group played important role in the removal process by forming complexes with Cu(II). The EDA@β-zeolite showed desirable recycling ability. The finding herein suggested that the proposed composite is a promising and suitable candidate for the removal of Cu(II) from contaminated natural wastewater and aquifer.

Waste minimisation of ceramic wall tiles

Many wastes are commonly produced during the ceramic tiles manufacturing process such as: Roller kiln grinding waste, cyclone dust waste, and ceramic sludge. Those wastes are landfilled because they have been predictable to be less conducive to recycling. In this study, the recyclability of the mentioned wastes is enhanced to minimize natural resource consumption, save energy, reduce cost and decrease hazards to the surrounding environment. Three types of collected wastes were added in different ratios to a standard wall tile mix and factorial 23 design techniques was used to investigate the effect of adding these wastes in different ratios on the properties of unfired and fired bodies. Suggested recipes were shaped in standard tile form, dried and fired at 1,160 oC for 15 min. Tests performed on these tiles revealed that they abide by standard requirements for ceramic wall tiles.

Recyclable Iron Oxide Loaded Poly (Methyl Methacrylate) Core/Polyethyleneimine Shell Nanoparticle as Antimicrobial Nanomaterial for Zoonotic Pathogen Controls

In this study, a recyclable antimicrobial agent against infectious pathogens in contaminated water was proposed. Iron oxide (IO) loaded poly (methyl methacrylate) (PMMA) core/polyethyleneimine (PEI) shell nanoparticles (PMMA/PEI-IO) was fabricated. The PMMA/PEI-IO showed a cationic surface charge property which is reflected by the protonation behavior of PEI. IO content in PMMA/PEI was evaluated by TGA and indicated that the residue incorporation of IO was 50% by dried weight. The existing of IO in PMMA/PEI was confirmed by the vibrating-sample magnetometer (VSM) showing a superparamagnetic property. The antibacterial ability was confirmed in waterborne bacteria, Escherichia coli and Staphylococcus aureus. The disturbance of the cell membrane integrity occurred after 20 min post-incubation of PMMA/PEI-IO with bacteria. Antimicrobial activity and recycling ability was further confirmed in an infectious, zoonotic and waterborne pathogen, Streptococcus agalactiae. Antiviral activity of PMMA/PEI-IO was observed and proved in an avian flu virus H3N2, a virus that has the potential to contaminate water reservoirs. The result showed that PMMA/PEI-IO nanoparticles were effective in killing H3N2. This study proposes a novel nanoparticle-based antimicrobial agents with recycle ability. Moreover, PMMA/PEI-IO nanoparticle is a potent bactericidal and virucidal agents when tested with waterborn zoonotic pathogens.

Thermally and light‐triggered reconfigurable shape memory polydopamine/epoxy composite with self‐healing and recyclable ability

AbstractShape memory epoxy with self‐healing ability has received much more academia and industry attention. In this work, 4‐aminophenyl disulfide containing disulfide bonds was used to replace the traditional epoxy resin‐curing agent, and the waterborne epoxy resin (sWEP) was composited with the polydopamine (PDA) nanoparticles with photothermal conversion effect through the melt mixing and hot‐press molding. As revealed, the addition of 1 wt% PDA increases the tensile strength of sWEP from 36.1 to 50.3 MPa. Specifically, the shape memory properties of the PDA/sWEP composite as manifested by a ca. 97.4% shape memory fixing ratio and ca. 67.8% shape memory recovery ratio. Moreover, the PDA/sWEP composite had the temperature‐dependent thermosetting and thermoplastic conversion capabilities, which can be programmed to a new permanent shape via a photothermal‐induced plasticity process.

Exploring Rapid Photocatalytic Degradation of Organic Pollutants with Porous CuO Nanosheets: Synthesis, Dye Removal, and Kinetic Studies at Room Temperature

In this work, we report the facile, environmentally friendly, room-temperature (RT) synthesis of porous CuO nanosheets and their application as a photocatalyst to degrade an organic pollutant/food dye using NaBH4 as the reducing agent in an aqueous medium. Ultrahigh-resolution field effect scanning electron microscopy images of CuO displayed a broken nanosheet-like (a length of ∼160 nm, a width of ∼65 nm) morphology, and the lattice strain was estimated to be ∼1.24 × 10–3 using the Williamson–Hall analysis of X-ray diffraction plots. Owing to the strong quantum size confinement effect, CuO nanosheets resulted in an optical energy band gap of ∼1.92 eV, measured using Tauc plots of the ultraviolet–visible (UV–vis) spectrum, resulting in excellent photocatalytic efficiency. The RT synthesized CuO catalyst showed a high Brunauer–Emmet–Teller surface area of 30.88 ± 0.2313 m2/g (a correlation coefficient of 0.99972) with an average Barrett–Joyner–Halenda pore size of ∼20.385 nm. The obtained porous CuO nanosheets exhibited a high crystallinity of 73.5% with a crystallite size of ∼12 nm and was applied as an efficient photocatalyst for degradation of the organic pollutant/food dye, Allura Red AC (AR) dye, as monitored by UV–vis spectrophotometric analysis and evidenced by a color change from red to colorless. From UV–vis spectra, CuO nanosheets exhibited an efficient and ultrafast photocatalytic degradation efficiency of ∼96.99% for the AR dye in an aqueous medium within 6 min at RT. According to the Langmuir–Hinshelwood model, photodegradation reaction kinetics followed a pseudo-first-order reaction with a rate constant of k = 0.524 min–1 and a half-life (t1/2) of 2.5 min for AR dye degradation in the aqueous medium. The CuO nanosheets showed an outstanding recycling ability for AR degradation and would be highly favorable and an efficient catalyst due to the synergistic effect of high adsorption capability and photodegradation of the food dye.

Highly Active and Stable Palladium Single-Atom Catalyst Achieved by a Thermal Atomization Strategy on an SBA-15 Molecular Sieve for Semi-Hydrogenation Reactions.

Single-atom catalysts (SACs) have great potential to revolutionize heterogeneous catalysis, enabling fast and direct construction of desired products. Given their notable promise, a general and scalable strategy to access these catalyst systems is highly desirable. Herein, we describe a straightforward and efficient thermal atomization strategy to create atomically dispersed palladium atoms anchored on a nitrogen-doped carbon shell over an SBA-15 support. Their presence was confirmed by spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurement. The nitrogen-containing carbon shells provide atomic diffusion sites for anchoring palladium atoms emitted from palladium nanoparticles. This catalyst showed exceptional efficiency in selective hydrogenation of phenylacetylene and other types of alkynes. Importantly, it showed excellent stability, recyclability, and sintering-resistant ability. This approach can be scaled up with comparable catalytic activity. We anticipate that this work may lay the foundation for rapid access to high-quality SACs that are amenable to large-scale production for industrial applications.

Single-atom-nickel photocatalytic site-selective sulfonation of enamides to access amidosulfones

A single-atom photocatalyst Ni/TiO2 was developed for the visible-light-induced site-selective sulfonation of enamides to give amidosulfones with 36 examples up to 99% yield.

Nanocatalytic Medicine of Iron-Based Nanocatalysts

Iron can be found in all mammalian cells and is of critical significance to diverse cellular activities within human bodies. Widespread applications and the underlying chemical and biological funda...

MYCELIUM-BASED MATERIALS FOR THE ECODESIGN OF BIOECONOMY

The exceptional organic recycling ability of fungi is attracting attention in the bioeconomy, being exploited in industrial processes. Mushroom mycelium has been classified as the largest living organism on earth, being capable of growth through its symbiotic relationship with the substrate components. The ability of fungal mycelium to decompose lignocellulosic materials makes it usable for the fabrication of packaging materials, as isolation material or for bio-textile products. This paper presents an up-todate overview of the current state of the art regarding mycelium biostructures. Thus, we described the development of research over the years, the most tested fungal species, the most used substrates and the up-to-date findings regarding technological challenges.

Construction of Fe3O4@MXene composite nanofiltration membrane for heavy metal ions removal from wastewater

Nanofiltration (NF) with adsorptive membrane technologies are one of the most promising methods for the efficient treatment of industrial wastewater having toxic heavy metal ions. The present investigation deals with the fabrication of nanocomposite Fe3O4@MXene membranes by self‐assembly of Fe3O4 nanoparticles (NPs) and two‐dimensional (2D) MXene nanosheets on the surface of cellulose acetate (CA) base membrane. The Fe3O4 NPs were found to be uniformly dispersed on the MXene sheet structure and thus expanded the 2D nanochannel of MXene. The water flux and the removal ratio of heavy metal ions by this nanocomposite membrane were found to improve significantly, compared to the virgin MXene membrane. Under the synergistic effect of layer sieving and the adsorption ability, the composite NF membrane was found to achieve a maximum of 63.2% for Cu2+, 64.1% for Cd2+ and 70.2% for Cr6+ removal from wastewater, respectively. Moreover, Fe3O4@MXene membrane also exhibited good recycling ability after washing by HCl solution.