Reusability Performance Research Articles

Hierarchical micro-meso-macroporous xAIL@HP UIO-66-NH2 catalysts used for efficient biodiesel production from low-grade acidic oils

The utilization of hierarchical porous supports to fabricate an efficient solid catalyst is a feasible strategy due to their remarkable merit in ameliorating the diffusion of reactants on the catalyst surface and increasing the exposure of active species in particular for the bulky molecule-involving reactions. In this research, to abatement the mass transfer resistance of large triglycerides, the hierarchical porous solid catalyst (xAIL@HP UIO-66-NH2) was prepared by grafting acidic ionic liquid (AIL) with double acidic sites of -SO3H and HSO4- onto micro-meso-macroporous metal-organic gels (HP UIO-66-NH2) through acid-base interactions between -NH2 moiety of HP UIO-66-NH2 and acidic moiety of AILs. The catalyst characterization results showed that the xAIL@HP UIO-66-NH2 catalyst owned the hierarchical porous structure and double Brønsted-Lewis acid centers with large BET surface area and pore volume. This catalyst was adopted for efficient biodiesel production from low-grade acidic oils, exhibiting high catalytic activities for triglyceride transesterification and free fatty acid (FFA) esterification reactions. By using acidic oils as feedstocks, the oil transesterification conversion could reach 91.3 % and the FFAs were completely converted to biodiesel under the conditions of 130 °C for 8 h at methanol-to-oil molar ratio of 35: 1 and catalyst dosage of 8 wt%. Based on the kinetic study, the activation energy Ea of this catalyst was 56.6 kJ/ mol, and the reaction complied with pseudo-first-order kinetics. This solid catalyst demonstrated satisfactory acid and water resistance, with good reusable performance, posing great potential in the efficient biodiesel preparation by the one-pot method using the low-grade acidic oils.

Synthesis of some anion exchange resins for selective separation of 99Mo and 131I: A comparative study

ABSTRACT Amination of styrene-divinylbenzene (SDVB) copolymers is a traditional process for preparing strong anion exchange resins that can greatly improve their performance and applications. In the present investigation, poly(styrene-co-divinyl benzene) copolymers functionalized by various amino groups were synthesized by the amination route. The performance of synthesized exchange resins for the separation and recovery of active Mo(VI) and I(I) isotopes from their aqueous solutions was compared to that of three commercial ion exchange resins, used in the actual production of these radioisotopes in the Radioisotopes Production Facility. The morphology and structural properties of the synthesized copolymers as well as the commercial reference resins were characterized using FT−IR, SEM, TG, and XPS. The results demonstrate that the copolymer was successfully functionalized with amino groups, where trimethylamine produced amination greater than triethylamine. Furthermore, the thermal stability of synthesized anion exchanges was significantly higher than that of commercial beads. The synthesized polymer networks presented excellent radiation stability under applied experimental conditions. Compared to the reference resins, the synthesized co-polymeric beads showed enhanced adsorption capability for MoO4 2− and I− ions from an aqueous solution. Further, the uptake affinity of the networks aminated with trimethylamine for both radioisotopes, in optimal conditions, was greater than that of triethylamine aminated beads. The sorption mechanism was inferred through FT−IR and XPS analysis, and the results clarified that the separation of both radioisotopes was substantially related to the amine functional groups on the resin framework. The spectroscopic analysis illustrated that one molybdenum ion (in the form of MoO4 2−) was subjected to an ion-exchange interaction and two Cl− ions in the amine resin. A similar exchange mechanism was predicted for I− with Cl− ions. Further, the enhanced sorption of Mo(VI) could be additionally attained through coordination interactions with N atoms in the amine groups that have good chelating capability toward metal ions. The reusability performance of the synthesized exchange resins is better than that of the commercial reference resins, where they could be effectively regenerated for up to five cycles. Finally, this study presents a new technique for the separation and recovery of Mo(VI) and I(I) from irradiated low-enriched U-targets by employing highly promising amino-modified polystyrene-divinyl benzene microspheres.

Enhanced photo-assisted thermal catalytic oxidation of formaldehyde via abundant surface adsorbed oxygen in Co3O4 with the assistance of natural zeolite

Photo-assisted catalytic oxidation is a promising and sustainable method for the formaldehyde (HCHO) degradation. Catalyst loading and surface adsorbed oxygen species are common strategies to enhance the efficiency of photo-assisted catalytic oxidation. In this work, acid-treated zeolite-based natural zeolites (mordenite and stellerite) were used as supports, to obtain Co3O4-natural zeolite composites by impregnation and MOF-templated methods. Under the combined action of visible light irradiation and heat condition, the photo-assisted thermal catalytic performance of different composites was determined. Among these composites, the Co-AS (Co3O4-acid-treated stellerite) composite exhibited the best HCHO mineralization performance. The use of acid-treated stellerite as a catalyst carrier effectively reduced the crystallite size of Co3O4, improved its dispersibility, and increased the surface adsorbed oxygen species, contributing to enhanced catalytic efficiency. The in-situ DRIFTs results showed that the main intermediates of photo-assisted thermal catalysis degradation were dioxymethylene (DOM) and HCOO−. Additionally, the reusability performance of the composites was also investigated. Experimental results showed that the composite had good photo-assisted thermal catalytic performance and durability, making it a promising catalyst for indoor air purification.

Evaluation of a novel activated carbon/graphene oxide as an efficient composite adsorbent for the removal of herbicide 2,4-Dichlorophenoxyacetic acid: Adsorption isotherm and kinetics study

Thysanolaena maxima-derived activated carbon/graphene oxide (TMAC/GO) composite was synthesized through a one-step mixing process via ultrasonication and used as an adsorbent for the removal of 2,4-Dichlorophenoxyacetic acid (2,4-D) herbicide from solution. Various analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FESEM-EDX), X-ray diffractometer (XRD), Brunauer, Emmett, and Teller (BET) surface area analyzer, and Transmission electron microscopy (TEM) were employed to characterize the synthesized composite. Results showed that the TMAC/GO had a porous structure with a large surface area of 960 m2/g, an average pore diameter of 2.658 nm, and a total pore volume of 0.6372 cm3/g. A series of batch experiments were conducted for different adsorption parameters, which include TMAC/GO dosage (0.05–0.25 g/L), initial concentration (50–300 mg/L), pH (2–12), contact time (20–140 mins), and temperature (298–398 K). Adsorption thermodynamics, isotherm models, and kinetics were employed to understand the adsorption mechanism. The composite showed good adsorption ability with the Langmuir maximum adsorption capacity of 98.469 mg/g. When compared with TMAC, the composite exhibited higher removal efficiency under the same dosage, concentration, and temperature with variations in pH and time. The pseudo-second-order kinetics model justified the experimental results with an R2 value of 0.997. Furthermore, the composite displayed good reusability performance up to 5 cycles. These findings, along with the cost-effectiveness of the material and its selectivity towards the herbicide, suggest its practical importance for water decontamination.

The facile preparation of polydopamine-modified sepiolite and its adsorption properties and microscopic mechanism for cadmium ion

Natural sepiolite (SEP) has the characteristics of cation exchange, abundant reserves, low cost, and environmental friendliness, but its adsorption capacity for heavy metal pollutants is limited. Because polydopamine (PDA) molecules contain rich functional groups such as phenolic and amino groups, in the present work, dopamine and natural sepiolite were utilized as raw materials to prepare polydopamine-modified sepiolite composite (SEP/PDA) by simple co-precipitation method. According to Langmuir isotherm model, the maximum adsorption capacity of SEP/PDA for Cd2+ can reach 203.21 mg/g at 298 K. At the initial concentration of 100 mg/L, the adsorption capacity was 2.9 times that of natural sepiolite. The composite material has good reusability and anti-cationic interference performance and has 100 % removal ability of low concentration Cd2+ in actual electroplating wastewater. Density Functional Theory (DFT) calculations were performed to obtain the electronic structure information. To elucidate the microscopic mechanism, molecular surface analyses, Interaction Region Indicator (IRI), Atom In Molecules (AIM) theory, Bond Order Density (BOD), and Electron Localization Function (ELF) were conducted. These analyses revealed that the amino nitrogen and phenolic oxygen atoms in the dopamine molecules donate lone pair electrons to coordinate with cadmium ions. Polydopamine, which possesses multiple oxidation states, contains catechol, quinone, and indole or a lesser extend pyrrole groups that can complex with cadmium ions, resulting in the formation of a surface complex. This coordination significantly enhances the adsorption properties of the SEP/PDA composite.

Remarkable adsorptive capacity and reusability performance of magnetic magnetite@silica@L-histidine nanocomposite towards gaseous benzene pollutant

Herein, magnetic magnetite@silica@L-histidine (Fe3O4@SiO2@L-Hist) core-shell nanoparticles (NPs) were prepared as novel adsorbents via chemical co-precipitation and sol-gel technology for the adsorption of gaseous benzene pollutant. The Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs were characterized using a combination of scanning electron microscopy (SEM), SEM - energy dispersive X-ray (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Brunauer-Emmett-Teller analysis (BET), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). The adsorption capacities of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs for benzene were found to be 188, 279 and 481 mg g−1, respectively, with Fe3O4@SiO2@L-Hist NPs demonstrating the highest capacity. Kinetic and isotherm studies indicated that the pseudo-2nd-order kinetic model and the Langmuir isotherm model provided the best fit to the experimental data, suggesting favorable physical adsorption. In addition, Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs exhibited remarkable reusability, with reuse efficiencies of 85.67, 89.65 and 91.73 %, respectively, after five recycle cycles, demonstrating their potential for practical benzene remediation applications. Overall, this study offers valuable insights into creating effective and sustainable adsorbents for eliminating volatile organic compounds (VOCs). This contributes to mitigating air pollution and safeguarding both human health and the environment.

Corn stalk decorated with magnetic graphene oxide as an efficient adsorbent for the removal of cationic dye from wastewater

In this study, an in situ immersion loading method is employed to introduce graphene oxide (GO) nanosheets and hollow copper ferrite nanospheres into the ordered porous structure of alkali-activated corn stalk (CS). This approach facilitates the construction of a novel magnetic three-dimensional composite sponge (GO/CS/CuFe2O4) utilized for the efficient removal of methylene blue (MB) and malachite green (MG) dyes from wastewater samples. In this hybrid adsorbent, the stacking of GO nanosheets is inhibited due to the ordered porous structure of CS, based on which GO nanosheets are well immobilized and dispersed. In addition, the hollow CuFe2O4 nanospheres and GO nanosheets support each other, further reducing the accumulation of GO, and increasing the specific surface area of the adsorbent. The engineered morphology of GO/CS/CuFe2O4 sponges supports the maximum exposure of the active adsorption sites to the dye solution, promoting the adsorption process. Microscopy and surface analyses show that GO/CS/CuFe2O4 sponges have a rich pore structure with the specific surface area of 289.85 m2·g−1, more than 17 times higher than that of CS, significantly improving their adsorption performance for MB and MG. The maximum adsorption capacity of GO/CS/CuFe2O4 for MB and MG is as high as 243.65 and 231.53 mg/g, respectively, superior to those of many other biomass-based adsorbents. The dye adsorption performance of GO/CS/CuFe2O4 can be well described by the Langmuir adsorption isotherm and pseudo-second-order kinetic model, suggesting the existence of strong monolayer chemisorption. The FTIR and X-ray photoelectron spectroscopy (XPS) analyses show that the dye removal mechanisms observed mainly includ π-π interactions, hydrogen bonding, electrostatic interactions and pore filling. In addition, GO/CS/CuFe2O4 sponges exhibit an excellent magnetic behavior (Ms = 49.52 emu/g), enabling the adsorbent to be recycled by the application of a magnetic field. The adsorption capacities of the adsorbent for MB and MG remain 88.6 % and 90.2 % of the initial adsorption capacity, respectively, even after 10 regeneration cycles, showing its excellent reusability performance. Finally, GO/CS/CuFe2O4 is applied for the removal of MB and MG from real aqueous environments comprising the seawater, tap water and wastewater treatment plant effluent, and the removal rates are observed to be over 90 % of that achieved in deionized water. This study provides new concepts for the sustainable utilization of agricultural waste and natural structure of plants to purify dye containing wastewater.

Easily reusable g-C3N4/NiFe2O4 magnetic heterojunction material for tetracycline degradation by visible light

To efficiently degrade tetracycline (TC) in water, magnetic reusable g-C3N4/NiFe2O4 heterojunction photocatalyst was synthesized by thermal polymerization and hydrothermal method. The obtained heterojunction photocatalyst achieved efficient degradation by degrading 86 % of TC in 2 h under visible light irradiation. and showed excellent magnetic reusable performance. The heterostructure formed between g-C3N4 and NiFe2O4 improved the separation efficiency and photoresponse range of photogenerated electrons and holes, and thus improved the photocatalytic degradation performance of the material. This study provides a new strategy for the efficient degradation of TC in water under visible light.

Thermo-mechanical coupling failure mechanisms of reusable SiCf/SiC composites with PyC interphase

The extreme and repeated aerothermal environments working on reusable launch vehicles bring challenges for the design of hot structure. Due to the outstanding high-temperature resistant, SiCf/SiC composite is an excellent candidate material for hot structures in re-entry vehicles. In this paper, the thermo-mechanical coupling failure mechanisms of SiCf/SiC composite are investigated comprehensively. Experimental results reveal different failure mechanisms of SiCf/SiC composites subjected to monotonic quasi-static tension at room temperature and high temperature, cyclic thermal fatigue and thermo-mechanical coupling fatigue. Cyclic thermal environment causing oxidation of interphase layer and embrittlement of fiber plays a significant role in decrease of load bearing capacity of SiCf/SiC composites. The long-term periodic fatigue load that is superimposed on the cyclic thermal condition would further deteriorate the performance of materials. To better understand the damage evolution process, a thermo-mechanical coupling fatigue model is proposed to describe the degradation of SiCf/SiC composites for different stress levels. The service life of SiCf/SiC composites is obtained, which could be used to evaluate the reusable performance of SiCf/SiC hot structure. The results of this study provide novel insights into the design of SiCf/SiC composites for reusable launch vehicles under prolonged and repeated service environment.

Solvent-free oxidation of alcohols by a heterogeneous Fe3O4@SiO2-DTPA-Ru nanocatalyst

A novel magnetic heterogeneous ruthenium catalyst (Fe3O4@SiO2-DTPA-Ru) was prepared by using magnetic silicon spheres as support, ethylenediaminepentaacetic acid (DTPA) as functional ligands, ruthenium chloride as catalyst precursor. The results obtained after a series of characterizations showed that the catalyst Fe3O4@SiO2-DTPA-Ru was 5–15 nm in size with a 0.205 nm lattice and contained 0.31 mmol Ru/g catalyst. It also had a good thermal stability under 232°C which was verified by thermal filtration method. Besides, the saturation magnetic intensity was as high as 20.54 emu/g. The catalyst Fe3O4@SiO2-DTPA-Ru was applied for the first time into thirteen oxidation reactions of aromatic alcohols and showed good catalytic activity even the yields of eleven aromatic alcohols were all over 90%. In catalyzing 1-phenylethanol to acetophenone, its TOF and TON were 9677 h−1 and 6991, respectively. The Fe3O4@SiO2-DTPA-Ru catalyst could still maintain good reusability and catalytic performance after 15 cycles of 1-phenylethanol oxidation, which was superior to many reported catalysts and had great potential in future industrial production.

CuMn2O4 anchored on mesoporous yttrium orthovanadate for the visible-light removal of hexavalent chromium ions in water

Recently, there has been significant interest in using one-dimensional nanomaterials for environmental cleanup in water sources, particularly for breaking down and eliminating harmful pollutants. Creating a reusable and effective photocatalyst poses a challenge in addressing semiconductor flaws such as instability and rapid recombination. This work discusses developing a highly responding photocatalyst by introducing varying quantities of CuMn2O4 (CMO) onto the surface of yttrium vanadate (YVO4) nanoparticles using the surfactant sol-gel method. The structures and morphology of these developed nanocomposites were verified using many characterization methods. The findings reveal that CMO is an electron trap within the dual system, which impedes charge carrier recombination and ameliorates photocatalytic performance. Their photocatalytic efficacy was evaluated through the photoreduction of Cr(VI) ions under visible illumination, revealing that adding CMO nanoparticles significantly boosts YVO4's photocatalytic activity. The Cr(VI) photoreduction follows a first-order reaction model. Among the tested photocatalysts, the 2.0 g/L dose of 9.0 % CMO-YVO4 demonstrated the most effective and reusable performance within 45 min. This sustained photocatalytic performance is credited to improved capture of light and effective transfer of charges resulting from the combination of CMO and YVO4.

β-Ketoenamine-linked covalent organic framework for efficient iodine capture.

Exploring the materials that effectively capture radioactive iodine is crucial in managing nuclear waste produced from nuclear power plants. In this study, a β-ketoenamine-linked covalent organic framework (bCOF) is reported as an effective adsorbent to capture iodine from both vapor and solution. The bCOF's high porosity and heteroatom-rich skeleton offer notable iodine vapor uptake capacity of up to 2.51 g g-1 at 75 °C under ambient pressure. Furthermore, after five consecutive adsorption-desorption cycles, the bCOF demonstrates high reusability performance with significant iodine vapor capacity retention. The adsorption mechanism was also investigated using various ex situ structural characterization techniques, and these mechanistic studies revealed the existence of a strong chemical interaction between the bCOF and iodine. The bCOF also showed good iodine uptake performance of up to 512 mg g-1 in cyclohexane with high removal efficiencies. The bCOF's performance in adsorbing iodine from both vapor and solution makes it a promising material to be used as an effective adsorbent in capturing radioactive iodine emissions from nuclear power plants.

Adsorption of Sudan II dye onto fly ash/polyacrylic acid/melamine composite: Factorial design optimization, reusability performance and removal mechanism

This study aims to develop fly ash (FA) modified with melamine (M) and polyacrylic acid (PAA) for strong adsorption of Sudan II dye from aquatic media. Surface functionality and morphological characteristics of the prepared FA/PAA/M composite were characterized using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) techniques. A factorial design model was applied to estimate the influence of adsorption and interactions of adsorption parameters such as contact time, pH, adsorbent dose, and initial dye solution. The significant interactions among these factors were investigated by analysis of variance (ANOVA). The isotherm modeling data indicated the Langmuir adsorption capacity for raw FA and FA/PAA/M composite as 57.4 and 142.3 mg/ g, respectively. This means that the Sudan II dye adsorption capacity of FA was boosted more than one time after modification with PAA/M polymer due to increased affinity towards the dye molecules by amide and hydroxyl groups onto the surface of the composite adsorbent. The adsorption kinetic evaluation revealed that the Sudan II dye adsorption by the composite was well-defined by the pseudo-second-order model. The produced FA/PAA/M showed a reasonable regeneration performance of 72/66 % after the adsorption/desorption processes were repeated four times. The adsorption mechanism between dye molecules and surface functional groups of the composite was described by hydrogen bonding interactions, π- π interactions, metal-π interaction and electrostatic attractions. The results indicated that the composite could be a promising adsorbent for dye removal from industrial wastewater due to its strong adsorption capacity, easy preparation, and good reusability performance.

Enhanced photocatalytic performance of CuS/O,N-CNT composite for solar-driven organic contaminant degradation

Herein, a hydrothermal etching approach was used to generate an innovative CuS/O,N-CNT composite. The hydrothermal etching of g-C3N4 led to the creation of O,N-CNT, with ethanol as the oxygen source. The SEM and TEM characterizations confirmed the formation of CNT, whereas the XPS analysis proved the doping of oxygen and nitrogen in the CNT matrix along with the incorporation of CuS. Under sun irradiation, the produced CuS/O,N-CNT showed outstanding photocatalytic efficiency, eliminating methyl orange and methylene blue dyes with 97.21% and 98.11% efficacy, respectively. Adding hydrothermally etched O,N-CNT increased light absorption and charge migration kinetics, as can be studied from the UV-DRS and PL analysis; hence, the observed improvements in light absorption and charge transfer pathways contributed to the CuS/O,N-CNT composite's enhanced photocatalytic activity, indicating its potential for efficient elimination of organic contaminants under solar irradiation. The catalyst demonstrated high reusability performance up to six cycles and significantly degraded other dyes. Scavenger analysis, along with VB-XPS and UV-DRS analysis, aid in developing a photocatalytic mechanism that confirms the participation of hydroxyl and superoxide radicals in the degradation process.

Pentahomoserine functionalized graphene oxide decorated polyamide thin film for enhanced separation of green tea polyphenols

The isolation of valuable compounds from the byproducts of food processing industries presents a significant contemporary challenge. Thin film nanocomposite (TFN) membranes have been identified as potential media for separating bioactive compounds. In this work, pentahomoserine functionalized graphene oxide (FGO) based TFN membranes were prepared for the effective separation of tea polyphenols epigallocatechin (EGC) and epigallocatechin gallate (EGCG). The nanocomposite selective polyamide (PA) layer was prepared through the dispersion of FGO in an aqueous monomer solution. The prepared membranes possess high average surface roughness with improved hydrophilicity and thermal stability. Additionally, FGO membranes contain more hydroxyl or carboxyl groups with cross-linked PA layer through interfacial polymerization (IP) process. Moreover, FGO membranes featured increased hydroxyl or carboxyl groups, facilitating cross-linking with the PA layer via intermolecular forces. The effects of amine functionality on the membrane characteristics such as surface morphology, roughness and hydrophilicity were also investigated. Remarkably, the membranes demonstrated rejection efficiency of 96.3% towards polyphenols. Furthermore, comprehensive assessments of reusability performance of the membrane highlighted their potential for industrial applications. This study provides valuable insights into the fabrication of highly efficient TFN membranes for biomolecule separation across diverse technological domains.

One pot synthesis of novel C3N4/C nanosheet composites under environmental benign molten salts for peroxymonosulfate activation with enhanced efficiency and reusability

The application of g-C3N4 based carbon materials in peroxymonosulfate (PMS) activation has faced challenges due to the electrochemically inert nature of nitrogen without light irradiation. In this study, two types of crystalline C3N4/C nanosheet composite catalysts were synthesized from glucose and dicyandiamide (DCD) via molten salt-assisted pyrolysis, denoted as M-GD and M-GD2. Both the composite catalysts showed significant improvement in the degradation of acid orange 7 amid PMS activation, taking the advantages of high graphitic N content and defect degree. Specifically, M-GD2 with excessive dosage of DCD exhibited a record catalyst specific activity value (0.0925 L min−1 m−2) in comparison with conventional C3N4 based carbon catalysts. The study also examined the effects of catalyst and PMS concentrations, temperatures, initial pH, and impurity ions on catalytic activity, as well as the catalytic performance in actual sludge wastewater cases. Notably, the M-GD2 catalyst exhibited exceptional regeneration capacity after four consecutive tests, attributed to its unique 3D structure comprising g-C3N4 nanoparticles loaded on crystalline C3N4/C nanosheets. Mechanism analysis revealed that a non-radical mechanism predominantly drove the PMS activation reaction, primarily involving catalyst-mediated electron transfer and surface-bound radicals due to the formation of catalyst-PMS* complexes. This work presents a facile and economical method for preparing defect-rich crystalline C3N4/C nanosheet composite with high graphitic N content, highlighting its catalytic activity, reusability, and regeneration performance synchronously. These findings contribute to advancing the field of PMS activation and offer promising applications in water environment remediation.

K+ promoted fabrication of nanoneedle low-silicon ZSM-48 mesocrystal

Owing to their distinct structural properties, low-dimensional zeolites are rising stars in the field of catalysis. However, shortening their size while maintaining the acidity continues to be challenging. In addition, simplified synthesis methods to efficiently prepare low-dimensional zeolites with more skeleton types and extended frame components are also of great interest. Herein, a facile strategy is developed for fabricating ultrathin nanoneedle (ca. 6-8 nm in diameter of each needle) ZSM-48 mesocrystals with a low Si/Al ratio (ca. 27, close to the lowest synthesized so far). This is achieved by adding potassium ions in a ZSM-12 synthetic system. The promoting effect of appropriate K+ ions was confirmed by adjusting the gel composition and tracking the crystallization process. Moreover, a superior conversion, reusability and regeneration performance for xylose to furfural is achieved with more accessible acidity and a more suitable Lewis/Brønsted acid ratio, which further expands the development of ZSM-48 zeolite.

Interfacial engineering and vacancy design of quasi-2D NiCoAl-LDH/Kaolin hybrid for activating peroxymonosulfate to boost degradation of antibiotics

Oxygen vacancies are prevalent in metal compounds and play a significant role in the activation of peroxomonosulfate (PMS) to mitigate water pollution. However, how to easily construct these oxygen vacancies and elucidate the mechanism of PMS activation by oxygen vacancies are still pending research and solution. This study presents the synthesis of a NiCoAl-LDH/Kaolin (NiCoAl-LDH/Kao) hybrid catalyst with quasi-2D layer structures morphology and abundant oxygen vacancies (OVs) for activating peroxymonosulfate (PMS). We proposed an intriguing phase transformation from NiCo-carbonate hydroxide (CH) to NiCoAl-layered double hydroxide (LDH), and elucidated the morphological evolution mechanism from nanorod to nanosheet structures through alkaline etching. The NiCoAl-LDH/Kao-PMS system exhibited excellent rapid kinetics and removal efficiency of norfloxacin (NOR), degrading 92.0 % of NOR within 10 min and achieving a final degradation rate of 97.2 %, along with remarkable reusability performance of the NiCoAl-LDH/Kao catalyst. Furthermore, reactive oxygen species including sulfate radical (SO4−), hydroxyl radical (OH), superoxide anion (O2−) and singlet oxygen (1O2) were found to be involved in the degradation process of NOR, and the degree of activity of the active groups from strong to weak is 1O2, SO4−, O2− and OH. The activation mechanism and conceivable degradation pathways of NOR were experimentally studied and proposed, and the toxicity of degradation intermediates was evaluated. The facile preparation method for NiCoAl-LDH/Kao nanocomposite holds potential for large-scale manufacturing in organic pollutant remediation, while also providing new insights on the indispensable role of OVs in heterogeneous catalysis.

Nanoarchitectonics of bamboo-based heterojunction photocatalyst for effective removal of organic pollutants

A high-performance photocatalyst with both efficient and reusable performance is essentially demanded for the purification of organic wastewater and the removal of indoor formaldehyde. However, recovery of photocatalyst particles from the reaction system remains a challenge. Herein, based on the abundant pore structure of natural bamboo and the outstanding photocatalytic activity of ZnO/WO3, we fabricated an efficient bamboo-based photocatalyst (ZnO/WO3@bamboo) for the efficient photocatalytic degradation of formaldehyde and organic dyes. The pretreatment of bamboo substrates with NaOH solution resulted in the formation of nucleation sites for ZnO/WO3 growth within bamboo cellulose channels. Subsequently, the as-prepared ZnO and WO3 were mixed in different mass ratios, and loaded on the pretreated bamboo substrates using the hydrothermal method. The results showed that the ZnO/WO3@bamboo had the effective function of photocatalytic degradation of formaldehyde gas and organic dyes. Moreover, the as-prepared ZnO/WO3@bamboo photocatalyst demonstrated superior recycling ability toward organic pollutants, which was described by photocatalytic degradation efficiency of formaldehyde gas more than 89% after 10 cycles, and organic dyes over 93% after 20 cycles. The coupling of ZnO and WO3 leads to electron delocalization, which caused the electron holes generated in the valence band (VB) of ZnO to delocalize to the VB of WO3, and reduced the recombination of electron-hole. Therefore, the photocatalytic degradation performance of the ZnO/WO3@bamboo was enhanced. The proposed ZnO/WO3@bamboo photocatalyst holds great promise in the field of air pollution and wastewater remediation.

Preparation of a novel LC@MWCNTs membrane and its application for enhanced phosphate removal and fouling control

To control the eutrophication originating from phosphate discharge, a novel adsorptive membrane was prepared by vacuum filtrating lanthanum carbonate modified multi-walled carbon nanotubes (LC@MWCNTs) on the UF membrane. The LC@MWCNTs were firstly made using an in-situ method by adding MWCNTs to LaCl3·7H2O solution and forming lanthanum carbonate under alkaline conditions. The adsorption experiments exhibited that the maximum adsorption capacity of LC@MWCNTs was 77.58 mg P/g at pH 5. And the phosphate adsorption by LC@MWCNTs was not predominantly reliant on electrostatic interaction, but rather achieved through chemical interactions. Then, the prepared LC@MWCNTs membrane was systematically evaluated for its phosphate removal efficiency and anti-fouling performance during filtration. With the initial phosphate concentration of 1 mg P/L and membrane flux of 378 L·m−2 h−1, the phosphate removal by LC@MWCNTs membrane approached almost 100 %. Moreover, the LC@MWCNTs membrane exhibited higher permeability (281.6 L·m−2h−1bar−1) and effectiveness for humic acid (HA) removal (75 %), and LC@MWCNTs membrane mitigated the fouling caused by HA. XPS, FTIR and XRD elucidated that phosphate removal by LC@MWCNTs membrane primarily through the formation of La-O-P inner-sphere complexes via ligand exchange, resulting in the formation of adsorption product LaPO4·0.5H2O. Under strong alkaline conditions, the LC@MWCNTs membrane rapidly restored its phosphate removal performance (30 min) with no significant detachment of the LC@MWCNTs layer, indicating its good recovery and reusability performance. Additionally, the LC@MWCNTs membrane could continuously remove phosphate from actual water, confirming its potential for future practical applications.