Leaching Of Metal Ions Research Articles

Ascorbic acid enhanced CuFe2O4-catalyzed heterogeneous photo-Fenton-like degradation of phenol

CuFe2O4 particles were synthesized using the sol-gel self-combustion method and characterized for their compositional surface morphology and crystal structure. When compared to the photo-Fenton system without ascorbic acid (AA), the presence of AA significantly enhanced the catalytic degradation of phenol using CuFe2O4. The highest catalytic degradation efficiency was achieved at an AA concentration of 1 mmol/L, resulting in up to 98.6 % elimination of phenol in just 40 min. The reaction rate was found to be 31.7 times higher than that of the system without AA. The mechanism of AA enhancement in the CuFe2O4 photo-Fenton system was further investigated. Two key factors were found to contribute to the enhancing mechanism of AA introduction in the CuFe2O4 photo-Fenton system. Firstly, AA promoted the Cu/Fe redox cycle on the catalyst surface, leading to a more efficient generation of reactive species that are responsible for phenol degradation. Secondly, AA accelerated the leaching of metal ions from the catalyst surface, facilitating the homogenous Fenton effect. The Cu/Fe bimetallic cycle system offers new perspectives on effective Fenton catalyst design and provides crucial insights for reductant-enhanced photo-Fenton activation.

A functionalized waste tire rubber powders for mitigating leaching of heavy metal ions and enhancing photocatalytic properties of rubberized cement mortar

In this study, waste tire rubber powder (R) was subjected to modification using tannic acid (TA) and ZnO to produce R-TA-ZnO composites, aiming to enhance the immobilization of heavy metal ions and improve the photocatalytic properties of rubberized cement-based materials. The characterization of R-TA-ZnO was conducted using a comprehensive range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible-diffuse reflectance spectroscopy (UV–Vis-DRS), and other relevant methods. The findings of the study revealed that R-TA-ZnO exhibited notable hydrophilicity, surface activity, and photocatalytic properties, resulting in effective containment of the leaching of heavy metal ions. FTIR and XRD analyses confirmed the retardation of R and R-TA-ZnO. Nevertheless, the strength of the rubberized cement mortar with 5% R-TA-ZnO exceeds that of the rubberized cement mortar with 5% R (28 days) due to the interfacial bonding. The SEM and X-ray Computed Tomography (XCT) results of the rubberized cement mortar indicated that R-TA-ZnO exhibited strong binding to the cement paste, reducing both the number and size of pores. However, a high concentration of R-TA-ZnO led to the formation of larger pores, which did not contribute to the reduction of porosity. Furthermore, the rubberized mortar incorporating R-TA-ZnO displayed remarkable photocatalytic capabilities. The results of the 5-cycle degradation experiments and microscopic characterization confirmed its exceptional structural stability and reusability.

Efficient sulfamethoxazole degradation via boosting nonradical-based peroxymonosulfate activation by biochar supported Co-Ni bimetal oxide

Nonradical-based peroxymonosulfate (PMS) activation has recently caught increasing attention due to its less susceptible to environmental interference in the complex water matrix, but the performance of activators still requires further development for efficient pollutants degradation in wastewater treatment. Herein, a novel Co-Ni bimetal oxide loaded biochar was fabricated to boost nonradical PMS activation for enhancing sulfamethoxazole (SMX) degradation. According to the results, the as-obtained catalyst exhibited excellent SMX degradation efficiency of 96.2% within 30 min through complete nonradical oxidation pathway (including both 1O2 and mediated electron transfer). Co was confirmed to be the active sites to generate 1O2 dominated nonradical pathway. The biochar acted as the porous material to achieve the electron transfer oxidation process, as well as Ni ensured sufficient electron transfer rate and bound Co active sites to prevent the leaching of metal ions. Meanwhile, the prepared Co-Ni bimetal oxide loaded biochar possessed a remarkable catalytic degradation durability in the complex water environment conditions and showed universality for various organic contaminants. This study offers a valuable clue on the rational design of novel catalyst to induce the nonradical pathway-based persulfate activation.

Enhanced tetracycline degradation efficiency by CoFe2O4 decorated TA-ZIF-8 catalyst via activating peroxymonosulfate under confinement effect

Spinel oxides can be considered effective heterogeneous catalysts in activating peroxymonosulfate (PMS) for wastewater decontamination. However, the intrinsic characteristics of agglomeration and metal ion leaching impede its further application. In this work, to further improve the catalytic efficiency and stability of the catalyst, ZIF-8 was employed as the candidate and further etched by tannic acid (TA) to obtain a core-shell structure with less mass transfer resistance. Following this, CoFe2O4 was anchored on TA-ZIF-8 matrix via a hydrothermal method. Benefiting from the tailored core-shell structure and high activity of CoFe2O4, the as-prepared CoFe2O4 @TA-ZIF-8 catalyst shortened the mass transfer distance of radical to target pollutant, thus realizing high radical utilization efficiency. Accordingly, 98.1% of tetracycline (TC) can be eliminated in 30 min with kinetic constants 3.15 times higher than pristine CoFe2O4. Besides, the TC degradation efficiency can still maintain 84.1% after five consecutive cycles with cobalt leaching lower than 0.306 mg/L, showing favorable stability compared with pristine CoFe2O4. Furthermore, electron paramagnetic resonance (EPR) and quenching experiments exhibited that singlet oxygen and sulfate radicals play dominant roles in TC degradation processes. This work fabricates an efficient CoFe2O4 @TA-ZIF-8 heterogeneous catalyst for degrading refractory TC, which may possess potential applications in wastewater treatment.

A novel 3-dimensional graphene-based cobalt-manganese bimetallic layered double hydroxide:Formation mechanism and performance in photo-assisted permonosulfate-activated degradation of sulfamethoxazole in aqueous solution

Sulfamethoxazole (SMX) is a common antibiotic used mainly for bacterial treatment. In this study, a novel three-dimensional cobalt-manganese bimetallic layered double hydroxide graphene hydrogel (CoMn-LDHs/rGO) has been prepared for photo-assisted permonosulfate (PMS)-activated degradation of SMX in water. Compared with the CoMn-LDHs/rGO + PMS and CoMn-LDHs/rGO + Vis systems, the degradation effect of CoMn-LDHs/rGO + PMS + Vis system is the best, and the degradation effect of CoMn-LDHs/rGO system could reach more than 98% under the optimal conditions. After 10 cycles, the catalytic degradation performance of CoMn-LDHs/rGO system remained good, while effectively preventing the leaching of metal ions. Based on the synergistic effect of photocatalysis and PMS oxidation, electron spin resonance spectroscopy and quenching experiments showed that three active substances (•OH, •SO4− and O2•−) were involved in the degradation of SMX. Density functional theory and liquid chromatography-mass spectrometry (LC-MS) results further proposed the SMX degradation transformation calculation. As expected, the study of the reaction mechanism of 3D CoMn-LDHs/rGO assisted PMS activation under visible light provides an efficient and rapid method for the sustainable degradation of pollutants in water system.

Activation of ozone by CoFe-LDO-BC heterogeneous catalyst for efficient mineralization of methylene blue: The role of oxygen vacancies and acidic sites

CoFe-layered double oxide derived from Hydrotalcite-like combining biochar (CoFe-LDO-BC) was prepared and applied to catalytic ozonation process for removing methylene blue (MB). The catalyst has not only greater specific surface area (about 26 times and 2 times more than that of BC and LDO respectively) and more abundant oxygen vacancies, but inhibited metal agglomeration and accelerated the electron transfer between Co (III)/Co (II) effectively. TOC analysis revealed mineralization rate of methylene blue was 3.7 × 10−2 min−1 (R2 = 0.996, pH = 9, catalyst dosage = 10 mg, ozone = 0.35 mg/min) in the catalytic ozonation system, much higher than that of single ozone (1.5 ×10−2 min−1, R2 = 0.907). Accordingly, the TOC degradation efficiency increased from 31.6% to 68.25%. Moreover, the lower metal ion leaching made the catalyst still maintain higher mineralization ability, and its mineralization efficiency decreased at only 7.9% point after five cycles. The results from XPS, EPR, NH3-TPD and Py-IR confirmed the oxygen vacancies and metal acid sites on catalyst surface could synergistically activate ozone to produce·OH, O2·- and 1O2, and·OH was dominating in mineralization process. The degradation pathway of MB in CoFe-LDO-BC+O3 catalytic system was proposed. This work is helpful for exploring and preparing stable and efficient ozone catalysts.

High efficient manganese‑nitrogen co-doped lignin-based carbon catalysts to activate peroxymonosulfate for the degradation of bisphenol A

Mn-based catalysts have attracted widespread attention because of their low price, sufficient source and effective activation of peroxymonosulfate (PMS) to generate free radicals for rapid degradation of organic pollutants. In most pulp and paper industries, lignin sulfonates are usually the waste streams or serve as low-value fuels. However, lignin sulfonates due to its abundant aromatic structure and sulfur functional groups, is regarded as an excellent carbon resource. The stability of supported Mn-based catalyst can be improved by doping nitrogen atoms through the formation of covalent bonds. In this work, Mn, N co-doped carbon composites were prepared by one-step carbonization, and the catalysts were characterized by TEM, XRD, XPS, etc. and the results show that the catalysts with low Mn content mainly contain highly dispersed Mn species such as MnNx species, while high Mn loading catalyst includes some MnOx species. The catalytic performances of the catalysts were evaluated by the degradation of bisphenol A (BPA) by activating PMS, which can reach >95 % in 8 min. Catalyst recyclability experiments demonstrate that carbon-based materials have good stability without the remarkable leaching of metal ions during the degradation reaction. The results of radical capture experiments and radical-assisted ESR show that the active species of the reaction is non-free radical singlet oxygen (1O2), which can effectively degrade BPA. This study provides a facile and efficient method to prepare high-efficient Mn-N-C catalysts in the catalytic decomposition of BPA.

Controllable synthesis of nanorod nickel doped cobalt molybdate as an efficient heterogeneous catalyst of peroxymonosulfate for degradation of chloroquine phosphate

This study reports the preparation of an affordable Ni-doped CoMoO4 catalyst (NiXCo1−XMoO4 (X = 0–1)) via a hydrothermal method by substituting Co with Ni and investigated the performance and mechanism of NiXCo1−XMoO4 catalyzing peroxymonosulfate (PMS) to degrade organic pollutants for the first time. Based on characterization, it can be observed that the synthesized Ni0.5Co0.5MoO4 catalyst exhibited excellent surface properties and structural stability. Under optimal conditions, Ni0.5Co0.5MoO4 and PMS synergistically achieved over 95% degradation of chloroquine phosphate (CQP) within 20 min, demonstrating superior performance. The degradation system maintained high efficiency under interference different interfering substances in aqueous media, exhibiting excellent tolerance and practicality. Elemental analysis and mechanistic studies of the catalyst showed that Ni doping promoted the reduction between Co2+/Co3+ and Mo4+/Mo6+, which is critical for catalyst durability and reusability. The quenching experiment and electron paramagnetic resonance (EPR) show that the 1O2 generated through non-free radical pathways represented the predominant reactive species. A total of 19 intermediates were detected by LC-MS during degradation and possible pathways for CQP degradation were proposed and toxicity evaluation. After 5 cycles, the catalyst still showed good stability. Ni0.5Co0.5MoO4 challenges including poor activation, metal ion leaching and low recovery of transition metal catalysts were addressed. This work offers new insights for the design of atom-doped spinel catalysts for catalytic oxidation and mechanism research. The Ni0.5Co0.5MoO4/PMS catalytic system can be extended to the treatment of other organic pollutants and even applied in the processing of high-concentration organic wastewater that requires rapid treatment, offering broader prospects for practical applications.

Highly efficient removal of Cr(VI) from wastewater using electronegative SA/EGCG@Ti/SA/PVDF sandwich membrane

The use of green, non-toxic raw materials is of great significance to the sustainable development of the environment, among which epigallocatechin gallate (EGCG) is a renewable carbon source from plants. At present, there is a lack of research on the metal-polyphenol nanomaterials their use in water decontamination. In this study, a novel SA/EGCG@Ti/SA/PVDF (SESP) sandwich membrane was prepared to effectively solve the problems of difficult recovery of nanomaterials and the leaching of metal ions. The membrane was made by scraping SA on the surface of the PVDF substrate as the bottom protective layer, depositing EGCG@Ti NPs as the functional layer, then coating SA as the surface isolation layer, and finally cross-linking with anhydrous calcium chloride. Results showed that EGCG@Ti NPs dispersed well on the surface of the SA/PVDF basement membrane. SESP sandwich membrane had good hydrothermal and acid-base stability, and it can be applied to wastewater with multiple co-existing heavy metals (e.g., Cu, Pb, Cd, and Ni). The contact angle and pure water flux of the SESP sandwich membrane with a negatively charged surface were 14.0–15.6° and 171.40 L/m2 h, respectively. The pure water flux of the regenerated membrane after BSA pollution recovered to 98.68 L/m2 h, and the interception efficiency and the interception flux of Cr(VI) were 100 % and 72.92 L/m2 h at 40 min of interception, respectively. Additionally, the removal efficiency of Cr(VI) by SESP sandwich membrane was maintained above 83 % for simulated wastewater and 100 % for actual wastewater after five adsorption-desorption cycles. Cr(VI) and Cr(III) can be removed simultaneously with the negatively charged SESP sandwich membrane. EDS and XPS analysis showed that the removal of Cr(VI) was controlled by the Donnan effect, anion exchange, chelation/complexation, and reduction mechanism. In contrast, Cr(III) was mainly influenced by electrostatic attraction and chelation/complexation mechanisms. In conclusion, the newly prepared sandwich membrane has good application potential in treating Cr(VI) wastewater.

Orange peels biochar doping with Fe-Cu bimetal for PMS activation on the degradation of bisphenol A: A synergy of SO4[rad]−, [rad]OH, 1O2 and electron transfer

Recently, the usage of biomass wastes has attracted considerable attention, especially in water purification. Herein, the modified orange peels biochar with Fe-Cu bimetal (FeCu/OPB-1) was prepared by one-step carbonization for activating peroxymonosulfate (PMS) to remove bisphenol A (BPA). The prepared FeCu/OPB-1 could degrade 90% of BPA by activating PMS at pH 5.2–9.0. HCO3− could significantly enhance BPA degradation and reduce the amount of leached metal ions. SO4− and OH were produced on the surface of FeCu/OPB-1, and the catalytic process was demonstrated to take place primarily on the catalyst surface. One of the main reactive oxygen species (ROSs) identified was 1O2. Moreover, Fe-Cu bimetal and the C = O functional group on FeCu/OPB-1 accelerated the electronic migration in the activation process. Relying on the produced intermediates, three feasible degradation pathways were suggested. Besides, further insight into the use of OPB-based catalysts for the degradation of organic pollutants was hereby provided through the activation of PMS.

Simplified solvent extraction process for high-purity Ni/Co mixed solution for lithium–ion batteries

ABSTRACT The demands for Ni-based raw materials increase as Ni–Co–Mn ternary cathode materials become the main axis of the battery industry. Conventional hydrometallurgical process to produce raw materials from Ni ore for battery application is as follows: (i) leaching of metal ions by acid, (ii) solvent extraction process to extract target metals, and (iii) crystallization process to produce final single-metal compound as powder products. The conventional solvent extraction process is a three-circuit process comprising impurity removal, Co extraction, and Ni extraction circuits. Unlike conventional process, in this work, we suggest a simplified two-circuit process to simultaneously extract Ni and Co to produce Ni/Co mixed solution for cathode material precursor production. Accordingly, the efficiency of site utilization can be maximized by reducing the investment cost for the manufacturing process and downsizing mixer-settler facilities. Further, eco-friendly effects such as reducing the consumption of titrants and cutting down the process costs and wastewater discharge can be realized.

Natural clay membranes: A sustainable and affordable solution for treating dye solutions, coal mine washery waste, and aquaculture wastewater

In this study, we fabricated low-cost, sustainable inorganic membranes using a one-step dry compaction process that incorporates natural clay and edible glycerin, followed by sintering at low temperatures. Open porosity and permeability of the membranes were in the 33.6–45.2 % and 621.74–864.7 l/m2.h.bar range, respectively. Regarding molecular weight cut-off (MWCO) and mercury porosity of membranes with 33.6 % and 45.2 % porosity, the average pore size of the former was ~10 nm, while it was increased up to 10–70 nm, 0.9–3 μm, and ~ 10 μm for the latter. The membranes were subjected to filtration for dye solutions, coal mine washery waste, and aquaculture wastewater, resulting in remarkable removal efficiencies. Specifically, the membranes achieved removal rates of 99.8 % for direct blue 71, 92.44 % for disperse red 74, and 99.1 % for red 2G in dye solutions. Furthermore, they demonstrated removal efficiencies of 99.19 % for turbidity and 94.2 % for chemical oxygen demand (COD) in coal mine washery waste. The membranes removed 98.5 % of total suspended solids from the fish farm effluent. During extended periods of operation, the clay membrane exhibited remarkable stability and minimal leaching of metal ions. Superior properties, including low-cost, nontoxic, and accessible precursors, one-step uni-axial fabrication process without the need for lubricant and plasticizer, low sintering temperature compared to commercial ceramic membranes, promising long-term chemical stability in highly acidic and alkaline media, recyclability, and reproducibility, make the as-prepared membranes an affordable and sustainable solution for treating wastewater in various industries, including textile, mining, and aquaculture, thereby mitigating the environmental impact of these industries.

A Phosphorofluoridate-Based Multifunctional Electrolyte Additive Enables Long Cycling of High-Energy Lithium-Ion Batteries.

Ni-rich layered oxides are regarded as key components for realizing post Li-ion batteries (LIBs). However, high-valence Ni, which acts as an oxidant in deeply delithiated states, aggravates the oxidation of the electrolyte at the cathode, causing cell impedance to increase. Additionally, the leaching of transition metal (TM) ions from Ni-rich cathodes by acidic compounds such as Brønsted-acidic HF produced through LiPF6 hydrolysis aggravates the structural instability of the cathode and renders the electrode-electrolyte interface unstable. Herein, we present a multifunctional electrolyte additive, bis(trimethylsilyl) phosphorofluoridate (BTSPFA), to attain enhanced interfacial stability of graphite anodes and Ni-rich cathodes in Li-ion cells. BTSPFA eliminates the corrosive HF molecules by cleaving silyl ether bonds and enables the formation of a polar P-O- and P-F-enriched cathode electrolyte interface (CEI) on the Ni-rich cathode. It also promotes the creation of a solid electrolyte interphase composed of inorganic-rich species, which suppresses the reduction of the electrolyte during battery operation. The synergistic effect of the HF scavenging ability of BTSPFA and the stable BTSPFA-promoted CEI effectively suppresses the TM leaching from the Ni-rich cathode while also preventing unwanted TM deposition on the anode. LiNi0.8Co0.1Mn0.1O2/graphite full cells with 1 wt % BTSPFA exhibited an enhanced discharge capacity retention of 79.8% after 500 cycles at 1C and 45 °C. These unique features of BTSPFA are useful for resolving the interfacial deterioration issue of high-capacity Ni-rich cathodes paired with graphite anodes.

Synergistic enhancement of redox pairs and functional groups for the removal of phenolic organic pollutants by activated PMS using silica-composited biochar: Mechanism and environmental toxicity assessment

In present work, a novel catalyst of cobalt supported on silica-composited biochar (Co@ACFA-BC) derived from fly ash and agricultural waste was synthesized. A series of characterizations confirmed that Co3O4 and Al/Si–O compounds were successfully embedded on the surface of biochar, which triggered superior catalytic activity for PMS activation towards phenol degradation. Particularly, the Co@ACFA-BC/PMS system could completely degrade phenol in the wide pH range, and was almost unaffected by environmental factors including humic acid (HA), H2PO4−, HCO3−, Cl−, and NO3−. Further quenching experiment and EPR analysis proved that both radical (SO4·-, ·OH, O2·-) and non-radical (1O2) pathways were involved in the catalytic reaction system, and the excellent PMS activation was attributed to the electron pair cycling of Co2+/Co3+ and the active sites provided by Si–O–O and Si/Al–O bonds on the catalyst surface. Meanwhile, the carbon shell effectively inhibited the leaching of metal ions, enabling the Co@ACFA-BC catalyst to maintain excellent catalytic activity after four cycles. Finally, biological acute toxicity assay demonstrated that the toxicity of phenol could be significantly reduced after being treated by Co@ACFA-BC/PMS. Overall, this work provides a promising strategy for solid waste valorization and a feasible methodology for green and efficient treatment of refractory organic pollutants in water environment.

Impact of nitrogen and sulfur fertilizers on leaching behavior of heavy metals from aquifer sediments to groundwater

BackgroundThe groundwater of the Bathinda district of Punjab is contaminated with heavy metals, nitrate (NO3), and sulfate (SO4) exceeding the BIS limits for drinking water in many areas. The article attempts to understand the role of fertilizers, nitrate and sulfate, in the mobilization of heavy metals from the aquifer minerals. MethodHeavy metal mobilization from aquifer sediments was studied through batch experiments using artificial groundwater (AGW) with varying concentrations of NO3 and SO4. For actual field conditions, column experiments were conducted with artificial groundwater containing 50 ppm NO3 as mobile phase and 1 ml/minute flow rate. The leached metal ions from the sediments were analyzed with ICP-MS. Significant findingsIt was found that compared to the AGW without NO3 and SO4, the heavy metal mobilization potential of AGW with NO3 and SO4 was significantly enhanced. The presence of nitrate significantly influenced the leaching of Cr, Co, Ni, Zn, and Hg, moderately affected the mobilization of As, and least impacted the mobilization of Fe, Mn, Cu, Cd, Pb, and U. An increase in leaching of Cr, Mn, Ni, Zn, As, and U was observed with the increase in SO4 concentration from 0 to 400 ppm, however, drastic reduction was observed with SO4 concentration of 500 ppm indicating high concentration of SO4 is posing an inhibitory action. The concentration of Cr, Fe, Co, Ni, Cu, Zn, Se, and Pb were significantly positively correlated indicating similar processes driving the mobilization of these metals. To reduce the mobilization of toxic heavy metals from the aquifer sediments, the NO3 and SO4 from the wastewater and agricultural run-off should be removed/reduced to the extent possible through optimized fertilizer usage, use of organic fertilizers, and treating the wastewater before discharging in the environment.

Fluorine and nitrogen dual-doped carbon material as metal-free peroxymonosulfate activator for efficient tetracycline degradation: Radical-free mechanism

Persulfate-based advanced oxidation technology holds great potential for antibiotic treatment. However, its low activity, metal ion leaching, and poor stability mainly limit the practical application. Fluorine-nitrogen heteroatomic dual-doping carbon material (F, N-CM) was successfully prepared using ZIF-8 metal–organic frameworks as a precursor. F, N-CM exhibited high peroxymonosulfate (PMS) activation capability for tetracycline (TC) degradation. The incorporation of F and N dopants in F, N-CM created abundant defects and active sites, facilitating the activation of PMS. Notably, the presence of fluorine atomic lone electron pairs significantly enhanced electron transfer from PMS to TC. The high degradation performance of the F, N-CM/PMS system was primarily attributed to radical-free pathways involving singlet oxygen and electron transfer. Furthermore, F, N-CM demonstrated good stability for PMS activation and could be regenerated through simple calcination. This research provides a novel strategy for developing metal-free carbon materials with dual-doped heteroatoms as effective catalyst for PMS activation and degradation of refractory organic pollutants.

Biocrystal-encased manganese ferrite coupling with peroxydisulfate: Synergistic mechanism of adsorption and catalysis towards tetracycline removal

Biocrystal-encased manganese ferrite (BC@MnFe2O4), an adsorption/catalytic bifunctional catalyst, was synthesized for peroxydisulfate (PDS) activation and tetracycline (TC) removal. Under the optimal conditions (PDS 6.0 mM, pH 7.0, dosage 0.30 g L−1, and TC content 20.0 mg L−1), the TC removal efficiency reached 85.11% and maintained 79.07% after four cycles. Furthermore, inorganic anions (H2PO4− > HCO3− > NO3− > SO42− > Cl−) and natural organic matter (HA) inhibited TC elimination to varying degrees. Compared with the MnFe2O4 nanorods, BC@MnFe2O4 effectively alleviated the side effects caused by particle aggregation and reduced metal ion leaching. Adsorption kinetic and isotherm results exhibited that the adsorption process of TC on MnFe2O4 and BC@MnFe2O4 were better fitted with the pseudo-second-order and Langmuir models. The analyses of quenching experiment, electron paramagnetic resonance, and X-ray photoelectron spectroscopy demonstrated that Fe and Mn sites exposed on the BC@MnFe2O4 served as the catalytic centers for PDS activation, and OH, SO4−, and 1O2 were crucial reactive oxidant species contributing to the rapid TC degradation. Based on the determination of TC degradation intermediates, three possible degradation pathways were proposed, and TC was converted to small molecules via hydroxylation, demethylation, deamidation, dehydration, and other reactions. This study offers novel insights into the synergistic effect of adsorption and catalysis by inorganic-biological hybrid design, and gives inspiration for the construction of high-performance catalysts in organic wastewater treatment.

Low bandgap high entropy alloy for visible light-assisted photocatalytic degradation of pharmaceutically active compounds: Performance assessment and mechanistic insights

The incessant accumulation of pharmaceutically active compounds (PhACs) in various environmental compartments represents a global menace. Herein, an equimolar high entropy alloy (HEA), i.e., FeCoNiCuZn, is synthesized via a facile and scalable method, and its effectiveness in eliminating four different PhACs from aqueous matrices is rigorously examined. Attributing to its relatively low bandgap and multielement active sites, the as-synthesized quinary HEA demonstrates more pronounced photocatalytic decomposition efficiency, towards tetracycline (86%), sulfamethoxazole (94%), ibuprofen (80%), and diclofenac (99%), than conventional semiconductor-based photocatalysts, under visible light irradiation. Additionally, radical trapping assays are conducted, and the dissociation intermediates are identified, to probe the plausible photocatalytic degradation pathways. Further, the end-products of FeCoNiCuZn-mediated photocatalysis are apparently non-toxic, and the HEA can be successfully recycled repeatedly, with no obvious leaching of heavy metal ions. Overall, the findings of this study testify the applicability of FeCoNiCuZn as a visible light-active photocatalyst, for treating wastewaters contaminated with PhACs.

The reuse potential of spent ZIF-8@GO-COOH nano adsorption materials: Study on their impact on the hydration mechanism and mechanical properties of cement-based composites

Spent adsorbents often contain harmful substances, which may have an impact on the ecological environment if these substances enter the environment. This study mainly introduces a safe treatment method for solid waste formed after heavy metal ions are adsorbed by an efficient adsorbent, ZIF-8@GO-COOH. This work mainly discusses the impact of solidifying the spent adsorbent in the cement system on the cement mechanical properties and hydration process. The experimental results showed that when the dosage of the spent adsorbent was 0.01%, 0.02%, 0.03%, and 0.04%, respectively, the compressive strength of 28 d was increased by 4.24%, 6.16%, 7.19%, and 8.87%, respectively, compared with the cement without spent adsorbent. Introducing spent ZIF-8@GO-COOH in the cement production process does not have a negative impact on the cement mechanical properties, and can refine the cement pore structure and dense microstructure, thereby improving the compressive strength. The Toxicity Characteristic Leaching Procedure (TCLP) results showed that solidifying the spent adsorbent with cement can effectively reduce the leaching of heavy metal ions in the spent adsorbent. This study solidifies the spent ZIF-8@GO-COOH nanoadsorbent material into the cement system as a sustainable alternative to landfilling. This treatment method has certain economic benefits and safety, and has some reference significance for promoting the development and improvement of spent adsorbents and improving their safe treatment and reuse.

Tannic Acid-Mediated Layered Double Hydroxide Hybridizing PVDF Superwetting Catalytic Membranes Constructed via Ion Diffusion-Induced Interfacial Self-Assembly for Boosting Water Purification

It is a great challenge to fabricate superwetting catalytic membranes with intrinsic self-cleaning capacity for highly stable and effective water purification by simple, mild and energy-efficient manufacturing technologies. Herein, diffusion-induced interfacial self-assembly and polyphenol-mediated strengthening strategies were employed to fabricate tannic acid -mediated layered double hydroxide hybridizing PVDF superwetting catalytic membranes (named as TA@CoFe-LDH@PVDF). The simultaneous phase transformation/in-situ synthesis of CoFe-LDH nanosheets and subsequent coordination assembly with tannic acid (TA) was implemented. Superhydrophilic and underwater-superoleophobic properties were achieved through the cooperation effect of the rough microstructures of CoFe-LDH nanosheets and the strong hydration ability of TA molecules. This enabled efficient separation of various oil-in-water emulsions with more than 99 % separation efficiency and permeation flux up to 593.9 L m-2h−1 bar−1 in cross-flow filtration. Furthermore, due to the reducibility of TA molecules that promoted the Mn+1/Mn+ cycle, TA@CoFe-LDH@PVDF membrane exhibited high static degradation efficiency and kinetics (nearly 100 % in 5.0 min) toward methylene blue by PMS activation. The degradation rate constant (1.04 min−1) was 2.67 times compared to that of CoFe-LDH@PVDF. Surprisingly, it was found that the dynamic mass transfer process in the membrane significantly accelerated the catalytic kinetics, resulting in a degradation rate in dead-end filtration was 23.89 times higher than that under static conditions. Additionally, it was proved that assembled TA could inhibit and reduce metal ion leaching during the catalytic and separation process. This simple manufacturing process of multifunctional membranes with superior performances offers a high application potential in wastewater treatment.