Cycles Of Reuse Research Articles

Enzyme Immobilization On Polypropylene Film: A Role Model For Biocatalytic Polymer Membranes?

Polymer electrolyte membrane (PEM) technologies hold promise for sustainable energy solutions, yet pinhole-related challenges persist. Our research introduces a novel biohybrid approach to self-healing, enhancing multiple healing cycles with minimal membrane disruption. Initial steps involve immobilizing enzymes on a polymeric membrane. This study establishes the immobilization process and analytical framework through enzyme immobilization on polypropylene. Applicability and stability are investigated, laying groundwork for potential Nafion™ applications and advancing climate neutral energy. Qualitative analysis employs colorimetric p-NPA assay on polypropylene-immobilized lipase from Candida rugosa (CRL) and Lipase B from Candida antarctica (CALB). Both enzymes hold their temperature optimum at 50°C which is increased by 10°C via immobilization. Diisopropylcarbodiimide (DIC) is optimal for immobilization. Synchronous enzyme and DIC addition is advantageous. After 8 reuse cycles, immobilized enzymes retain 54.3% residual activity. Immobilizates exposed to PEM fuel cell conditions show better stability due to covalent immobilization than free CRL. Yet, declines occur under stressors like 60 °C and concentrated alcohol. Immobilizates remain resilient at pH 3 and under oxidizing as well as reducing conditions constituted by varied gas atmospheres. Considering PEM fuel cells' operational range, in-depth investigations across conditions are vital. Future studies target long-term PEM fuel cell lifespans, focusing on extremophilic enzymes or modifications for high-temperature stability. Subsequently, the transferability of the immobilization method to Nafion™ shall be deliberated based on the outcomes.

Enhancing the sustainable immobilization of laccase by amino-functionalized PMMA-reinforced graphene nanomaterial

Human health and the environment are negatively affected by endocrine-disrupting chemicals (EDCs), such as bisphenol A. Therefore, developing appropriate remediation methods is essential for efficiently removing phenolic compounds from aqueous solutions. Enzymatic biodegradation is a potential biotechnological approach for responsibly addressing water pollution. With its high catalytic efficiency and few by-products, laccase is an eco-friendly biocatalyst with significant promise for biodegradation. Herein, two novel supporting materials (NH2-PMMA and NH2-PMMA-Gr) were fabricated via the functionalization of poly(methylmethacrylate) (PMMA) polymer using ethylenediamine and reinforced with graphene followed by glutaraldehyde activation. NH2-PMMA and NH2-PMMA-Gr were utilized for laccase immobilization with an immobilization yield (IY%) of 78.3% and 82.5% and an activity yield (AY%) of 81.2% and 85.9%, respectively. Scanning electron microscope (SEM) and Fourier-transform infrared (FTIR) were used to study the characteristics of fabricated material supports. NH2-PMMA-Gr@laccase exhibited an optimal pH profile from 4.5 to 5.0, while NH2-PMMA@laccase exhibited optimum pH at 5.0 compared to a value of 4.0 for free form. A wider temperature ranges of 40–50 °C was noted for both immobilized laccases compared to a value of 40 °C for the free form. Additionally, it was reported that immobilized laccase outperformed free laccase in terms of substrate affinity and storage stability. NH2-PMMA@laccase and NH2-PMMA-Gr@laccase improved stability by up to 3.9 and 4.6-fold when stored for 30 days at 4 °C and preserved up to 80.5% and 86.7% of relative activity after ten cycles of reuse. Finally, the degradation of BPA was achieved using NH2-PMMA@laccase and NH2-PMMA-Gr@laccase. After five cycles, NH2-PMMA@laccase and NH2-PMMA-Gr@laccase showed that the residual degradation of BPA was 77% and 84.5% using 50 μm of BPA. This study introduces a novel, high-performance material for organic pollution remediation in wastewater that would inspire further progress.

Effect of Repeated Use of Different Types of Scan Bodies on Transfer Accuracy of Implant Position.

Some components of implant treatment are reusable. Therefore, possible changes during fixation, removal, and sterilization process should be tested. Many studies have examined the reuse of implant parts, but the impact of repeated use of scan bodies on the accuracy of implant position has not been well investigated. The aim of this in vitro study was to compare the effect of repeated use of two different types of scan bodies on the accuracy of implant position. In this in vitro experimental study, two acrylic resin maxillary models, each with two implant analogues inserted at the site of missing first and second molars were used. Two types of scan bodies including titanium and polyetheretherketone (PEEK) were used for digital impression. Then they were ten times removed and autoclaved for sterilization. The first scan was considered as a reference to be compared with the other next nine scans. Values of linear distance between two scan bodies, diameter changes of each scan body, and three-dimensional linear displacement (ΔR) were measured. These values were compared between the two types of scan bodies using t-test (α=.05). There was significant difference between titanium and PEEK scan bodies regarding inter-implant distance variation (p=.006) and diameter change (p< .001) in repeated use. However, for the ΔR, there was no significant difference between them (p= 0.759). The results demonstrated that type of scan body could affect the accuracy of implant position transfer after repeated use. PEEK scan body performed better after 9 cycles of reuse in comparison with titanium scan body.

Efficient activation of peroxydisulfate by modified red mud biochar derived from waste corn straw for levofloxacin degradation: Efficiencies and mechanisms

As using iron-based materials and biomass to prepare effective catalyst has emerged as a hit trend in persulfate-based advanced oxidation processes (PS-AOPs), the problems associated with excessive chemical consumption, costly expenses, and complex synthetic processes have become more urgent to be addressed. Therefore, by using red mud (RM) and corn straw (CS), a modified red mud biochar catalyst (MRBC) was synthesized through acid pretreatment and pyrolysis (700 °C). MRBC presented excellently in peroxydisulfate (PDS) activation to degrade levofloxacin (LFX). Under the experimental setup involving 8 mM PDS, 10 mg L−1 LFX, and 1.6 g L−1 MRBC, 88.59% of LFX was effectively eliminated within 30 min with an exceedingly low Fe leaching rate of 0.049 mg L−1. Furthermore, even after four cycles of reuse, it was able to sustain a remarkable 61.63% efficiency in LFX degradation. The characterization of catalysts demonstrated the synergistic effect of RM and biomass could be responsible for the excellent catalytic properties of MRBC. The results of quenching experiment and the presence of DMPOX in EPR demonstrated radical pathway mainly contributed to the LFX degradation in MRBC/PDS system. Overall, PDS was activated by the active sites of MRBC such as Fe (II) and persistent free radicals (PFRs) to generate a large amount of SO4•− and •OH to remove LFX. This work investigated the synergy of RM and biomass in catalyst preparation, deepened the insights into the application of RM catalysts in PS-AOPs to degrade antibiotic, and contributed greatly to the recovery of waste resources.

Visible-light photocatalytic degradation of two textile dyes by recyclable ZnO-Perlite: kinetic models and cost analysis

ABSTRACT Zinc oxide (ZnO), as an n-type semiconductor photocatalyst, is often selected due to its excellent photocatalytic performance and is supported on commercial expanded perlite (EP) to enhance interfacial charge separation efficiency under visible LED light. The structure and photocatalytic properties of the synthesised photocatalyst via the co-precipitation route were studied through XRD, FT-IR, SEM, EDX and pHpzc analyses. The photocatalytic response was evaluated by studying the degradation of two toxic and refractory azo dyes, reactive black 5 (RB5) and acid red 14 (AR14). Azo dyes (20 mg L−1) were completely degraded in the studied system, which occurred at pH 7 and 3, with catalyst amounts of 2 and 1 g L−1, and in the presence of H2O2 at 2 and 10 mM under LED light (15 W) within 2 h for RB5 and AR14, respectively. The degradation of RB5 and AR14 followed first-order kinetics with Kobs values of 0.0218 and 0.0169 min−1 and R2 values of 0.9271 and 0.8325, respectively. The assessment of energy consumption (EEO) and total operation cost (OC) confirmed that the supported ZnO offered the lowest power and cost requirements to transform selected pollutants into the acquired effluent, with values of 20.65 and 25.13 kWh m−3 and 3.11 and 3.205 USD kg−1 for RB5 and AR14, respectively, compared to using only VIS/ZnO, VIS/EP and VIS. Furthermore, the catalyst exhibited stability without the need for any additional chemicals for up to 10 h (5 reuse cycles). Additionally, the presence of major anions (sulphate, chloride and alkalinity) reduced the degradation efficiency in a real water matrix (1.74 and 1.47 times for RB5 and AR14, respectively) compared to that in distilled water.

Experimental and theoretical investigations on Hg(II) removal by recyclable composite sorbents comprised of polymers bearing thiourea or amidoxime functional groups and mesoporous silica

It is extremely desirable but still challenging to skilfully manufacture highly efficient sorbents to remmediate, in a reversible manner, the water pollution with mercury. Herein, new sorbents for Hg(II) ions have been designed by the initial synthesis of polyacrylonitrile networks inside mesoporous SiO2 microparticles, followed by the chemical modification of acrylonitrile groups with thiourea or amidoxime moieties. The Hg(II) ions sorption properties of the new composites were compared with respect of initial solution pH, contact time, equilibrium concentration and impact of interfering metal ions. It was demonstrated that the sorbents containing thiourea groups exhibited superior sorption capacities (1.76 mmol Hg(II) g−1) compared to the ones containing amidoxime groups (1.68 mmol Hg(II) g−1), and also higher selectivity for Hg(II) ions separation from binary mixtures with Cu(II), Cd(II) or Pb(II) ions. Kinetic study and DFT results supported a combined sorption mechanism, both physical sorption and chem-isorption being possible. Following the elution of Hg(II) ions with 1 M HNO3 and the regeneration with 0.1 M NaOH, all sorbents exhibited around 90 % sorption capacity recovery after 4 reuse cycles.

Layered Double Hydroxide Coated by Carbon-Based Material for Environmental Dye Pollutant

We conducted this research to modify NiAl layered double hydroxide with several carbon-based materials, including cellulose, biochar and graphite. This material was successfully prepared by coprecipitation methods and was proven by XRD, SEM and FTIR characterization. Furthermore, we conducted the adsorption process and reusability to investigate their ability as water treatments. The dose effect on M.G. removal was investigated by the highest M.G. removal capacity using the CBC-NiAl LDHs composite, which was 100 mg. M.G. removal capacity was increased with an increase in contact time, and the saturation point was reached after 60 min for CC-NiAl and CGF-NiAl LDHs, which CBC-NiAl LDH increased and saturated after 100 min with high adsorption capacity. CC-NiAl, CBC-NiAl and CGF-NiAl LDHs composite have proved efficient, sustainable materials that maintain adsorption capability in each reusable cycle.

Bioremoval and biodetoxification of ciprofloxacin from hospital wastewater effluent by the efficient and recyclable laccase@hercynite magnetic nanoparticles

Fluoroquinolones present in hospital wastewater potentially threaten human health security due to the development of antibiotic-resistant bacteria and genes. Today enzymatic treatments are known as a promising method for the removal of antibiotic residues from environmental waters. In the present study, laccase was adsorbed on the surface of hercynite (FeAl2O4) magnetic nanoparticles (MNPs) to remove ciprofloxacin from hospital wastewater (HWW) with high stability and efficiency. For this purpose, the hercynite MNPs were fabricated via the co-precipitation method, and their surface was subsequently modified by copper (II) ions to create coupling with the functional groups of the enzyme. The catalytic activity of laccase@Cu2+@hercynite•MNPs was preserved up to 50% of its initial activity after 13 cycles of reuse. The stability of the adsorbed enzyme was 2.2-fold and 4-fold higher than the free laccase after one month of storage at 4 °C and 25 °C, respectively. The immobilized laccase removed 85% of ciprofloxacin in HWW after 3 h incubation with 1 mM p-coumaric acid at 40 °C. The removal process involved defluorination, hydroxylation, and piperazine ring cleavage, which reduced the antibiotic toxicity against G+ and G– bacteria. Thus, laccase@Cu2+@hercynite•MNPs can be recommended for the bioremediation of micro-pollutants from hospital effluents.

Magnetic core-shell cellulose system for the oriented immobilization of a recombinant β-galactosidase with a protein tag

The objective of this study was to immobilize a recombinant β-galactosidase (Gal) tagged with a cellulose-binding domain (CBD) onto a magnetic core-shell (CS) cellulose system. After 30 min of reaction, 4 U/capsule were immobilized (CS@Gal), resulting in levels of yield and efficiency exceeding 80 %. The optimal temperature for β-galactosidase-CBD activity increased from 40 to 50 °C following oriented immobilization. The inhibitory effect of galactose decreased in the enzyme reactions catalyzed by CS@Gal, and Mg2+ increased the immobilized enzyme activity by 40 % in the magnetic CS cellulose system. The relative enzyme activity of the CS@Gal was 20 % higher than that of the soluble enzyme activity after 20 min at 50 °C. The CS support and CS@Gal capsules exhibited an average size of 8 ± 1 mm, with the structure of the shell (alginate-pectin-cellulose) enveloping and isolating the magnetic core. The immobilized β-galactosidase-CBD within the magnetic CS cellulose system retained ∼80 % of its capacity to hydrolyze lactose from skim milk after 10 reuse cycles. This study unveils a novel and promising support for the oriented immobilization of recombinant β-galactosidase using a magnetic CS system and a CBD tag. This support facilitates β-galactosidase reuse and efficient separation, consequently enhancing the catalytic properties of the enzyme.

Anti-abrasion collagen fiber-based membrane functionalized by UiO-66-NH2 with ultra-high efficiency and stability for oil-in-water emulsions separation

Membrane separation strategies offer promising platform for the emulsion separation. However, the low mechanical strength of membrane separation layers and the trade-off between separation flux and efficiency present significant challenges. In this study, we report a CFM@UiO-66-NH2 membrane with high separation flux, efficiency and stability, through utilizing a robust anti-abrasion collagen fiber membrane (CFM) as the multifunctional support and UiO-66-NH2 by an in-situ growth as the separation layer. The high mechanical strength of the CFM compensated for the weakness of the separation layer, while the charge-breaking effect of UiO-66-NH2, along with the size sieving of its constituent separating layers and the capillary effect of the collagen fibers, contributed to the potential for efficient separation. Additionally, the CFM@UiO-66-NH2 membrane exhibited superhydrophilic properties, making it suitable for separating oil-in-water microemulsions and nanoemulsions stabilized by anionic surfactants. The membrane demonstrated remarkable separation efficiencies of up to 99.960% and a separation flux of 370.05 L·m−2·h−1. Moreover, it exhibits stability, durability, and abrasion resistance, maintaining excellent separation performance even when exposed to strong acids and alkalis without any damage to its structure and performance. After six cycles of reuse, it achieved a separation flux of 417.97 L·m−2·h−1 and a separation efficiency of 99.747%. Furthermore, after undergoing 500 cycles of strong abrasion, the separation flux remained at 124.39 L·m−2·h−1, with a separation efficiency of 99.992%. These properties make it suitable for the long-term use in harsh operating environments. We attribute these properties to the electrostatic effect resulting from the amino group on UiO-66-NH2 and its in-situ growth on the CFM, which forms a size-screening separation layer. Our work highlights the potential of the CFM@UiO-66-NH2 membrane as an environmentally friendly size-screening material for the efficient emulsion wastewater separation.

Unraveling kinetic and synergistic effects during ultrasound-enhanced carbocatalysis for water remediation as a function of ultrasonic frequency

The ability of the ultrasound (US) combined with peroxymonosulfate (PMS), and a carbonaceous material (BC) was evaluated in the degradation of a model pollutant (acetaminophen, ACE). The US/BC/PMS system was compared with other possible systems (US, oxidation by PMS, BC adsorption, BC/PMS, US/PMS, and US/BC. The effect of the ultrasonic frequency (40, 375, and 1135 kHz) on the kinetics and synergy of the ACE removal was evaluated. In the US system, kinetics was favored at 375 kHz due to the increased production of hydroxyl radicals (HO•), but this did not improve in the US/PMS and US/BC systems. However, synergistic and antagonistic effects were observed at the low and high frequencies where the production of radicals is less efficient but there is an activation of PMS through mechanical effects. US/BC/PMS at 40 kHz was the most efficient system obtaining ∼95% ACE removal (40 μM) in the first 10 min of treatment, and high synergy (S = 10.30). This was promoted by disaggregation of the carbonaceous material, increasing the availability of catalytic sites where PMS is activated. The coexistence of free-radical and non-radical pathways was analyzed. Singlet oxygen (1O2) played the dominant role in degradation, while HO• and sulfate radicals (SO4•–), scarcely generated at low frequency, play a minimum role. Performance in hospital wastewater (HWW), urine, and seawater (SW) evidenced the competition of organic matter by BC active sites and reactive species and the removal enhancement when Cl− is present. Besides, toxicity decreased by ∼20% after treatment, being the system effective after three cycles of reuse.

Fabrication and performance of novel multifunctional sodium alginate/polyvinylpyrrolidone hydrogels

In this work, a novel alginate/polyvinylpyrrolidone (SA/PVP-Fe) hydrogel spheres were prepared by cross-linking with Fe2+ ions after blending sodium alginate with polyvinylpyrrolidone. The degradation performance of the hydrogels was assessed through the degradation of phenol, achieving 100% degradation and about 64% total organic carbon (TOC) mineralization within 60 min (initial concentration of phenol = 20 mg/L; H2O2 concentration = 5 mM; initial pH = 6.5; catalyst dosage = 1.0 g/L). Degradation kinetics were monitored using high-performance liquid chromatography (HPLC). The structural and chemical properties of the hydrogels were characterized using scanning electron microscopy (SEM), energy spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Inductively coupled plasma mass spectrometry (ICP-MS). Additionally, the hydrogels exhibited multiple reuse cycles, albeit with a gradual decline in degradation performance. Mechanistic investigations revealed that the hydroxyl radical derived from the Fenton reaction was the primary active species responsible for the degradation process. This research provides valuable insights into improving the mechanical properties of sodium alginate hydrogels, opening up avenues for their practical applications.

Upgrading MnO2@CuO with GO as a superior heterogeneous nanocatalyst for transesterification of dairy waste oils to biodiesel through electrolysis procedure

In this research, the electrolysis procedure was employed to synthesize biodiesel from dairy waste oil (DWO) utilizing MnO2@CuO and MnO2@CuO@GO as novel heterogeneous nanocatalysts. The structural attributes of MnO2@CuO and MnO2@CuO@GO nanocatalysts were scrutinized utilizing Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscopy (FESEM), Mapping, Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), Temperature-Programmed Desorption (CO2/TPD), Raman, X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analyses. Further, Proton Nuclear Magnetic Resonance (H NMR), Gas Chromatography–Mass Spectrometry (GC-MS), and FTIR spectra were utilized to characterize the chemical structure of biodiesel and DWO. According to the Box-Behnken Design statistical method, the highest biodiesel yield utilizing MnO2@CuO and MnO2@CuO@GO nanocatalysts was 94.15 and 98.07 %, respectively, which were obtained after 52.64 and 49.3 min, respectively. According to the results, MnO2@CuO@GO has a higher ability to generate biodiesel compared to MnO2@CuO. After 7 consecutive reuse cycles, the yield of biodiesel using MnO2@CuO and MnO2@CuO@GO nanocatalysts was 80.14 and 90.77 %, respectively, demonstrating that MnO2@CuO@GO is much more stable than MnO2@CuO. The kinetics of biodiesel generation showed that the reaction between DWO and methanol in the presence of MnO2@CuO@rGO is non-spontaneous and endothermic (ΔHo = 47.54 kJ/mol). In general, MnO2@CuO@GO, because of its easy synthesis, high biodiesel efficiency, and remarkable stability, is considered as a promising catalyst for industrial applications.

Facile synthesis of ball-milling and oxalic acid co-modified sludge biochar to efficiently activate peroxymonosulfate for sulfamethoxazole degradation: 1O2 and surface-bound radicals

A novel approach of ball milling and oxalic acid was employed to modify sludge-based biochar (BOSBC) to boost its activation performance for peroxymonosulfate (PMS) towards efficient degradation of sulfamethoxazole (SMX). 98.6% of SMX was eliminated by PMS/BOSBC system within 60 min. Furthermore, PMS/BOSBC system was capable of maintaining high removal rates for SMX (>88.8%) in a wide pH range from 3 to 9, and displayed a high tolerance to background electrolytes including inorganic ions and humic acid (HA). Quenching experiments, electron paramagnetic resonance (EPR) analysis, in-situ Raman characterization and PMS decomposition experiments confirmed that the non-radicals of 1O2 and surface-bound radicals were the main contributors to SMX degradation by PMS/BOSBC system. The results of ecotoxicity assessment illustrated that all transformed products (TPs) generated in PMS/BOSBC system were less toxic than that of SMX. After five reuse cycles, PMS/BOSBC system still maintained a high removal rate for SMX (77.8%). Additionally, PMS/BOSBC system exhibited excellent degradation performance for SMX in various real waters (Yangtze River water (76.5%), lake water (74.1%), tap water (86.5%), and drinking water (98.1%)). Overall, this study provided novel insights on non-metal modification for sludge-based biochar and non-radical mechanism, and offered a feasible approach for municipal sludge disposal.

Graphene Oxide from Graphite of Spent Batteries as Support of Nanocatalysts for Fuel Hydrogen Production

The increasing production of electronic waste and the rising demand for renewable energy are currently subjects of debate. Sustainable processes based on a circular economy are required. Then, electronic devices could be the main source for the synthesis of new materials. Thus, this work aimed to synthesize graphene oxide (GO) from graphite rod of spent Zn-C batteries. This was used as support for Ni/Co bimetallic nanocatalysts in the evolution of hydrogen from NaBH4 for the first time. The graphene oxide (GO) exhibited a diffraction peak at 2θ = 9.1°, as observed using X-ray diffraction (XRD), along with the presence of oxygenated groups as identified using FTIR. Characteristic bands at 1345 and 1574 cm−1 were observed using Raman spectroscopy. A leaf-shaped morphology was observed using SEM. GO sheets was observed using TEM, with an interplanar distance of 0.680 nm. Ni/Co nanoparticles, with an approximate size of 2 nm, were observed after deposition on GO. The material was used in the evolution of hydrogen from NaBH4, obtaining an efficiency close to 90%, with a kinetic constant of 0.0230 s−1 at 296.15 K and activation energy of 46.7 kJ mol−1. The material showed an efficiency in seven reuse cycles. Therefore, a route of a new material with added value from electronic waste was obtained from an eco-friendly process, which can be used in NaBH4 hydrolysis.

Removal of chromium from aqueous solution by CLCh/Fe/MWCNT/TiO2-Ag magnetic composite film: Simultaneous Cr(VI) reduction and Cr(III) adsorption

A catalyst CLCh/Fe/MWCNT/TiO2-Ag film was prepared using multi-walled carbon nanotubes (MWCNT) impregnated with magnetic iron oxide and silver-doped titanium dioxide (TiO2-Ag), being deposited on crosslinked chitosan (CLCh). The physicochemical characterization of the catalyst was performed by various analytical techniques such as ICP-MS, XRD, FTIR, SEM, EDS, Raman spectroscopy, N2 adsorption/desorption and UV–Vis diffuse reflectance spectra (DRS). A solution of Cr(VI) (30 mg/L) was used in the evaluation of the photoreduction of (Cr(VI) to Cr(III)) using UV–visible light (filter cut-off for λ > 300 nm). The composite film allowed, when applied in a solution of 30 mg/L of Cr(VI) at pH 2, the removal and simultaneous photoreduction of 97 % of Cr(VI) to Cr(III) in 120 min. The cationic Cr(III) generated remains retained in the composite film by adsorption on the hydroxyl and carboxyl groups of MWCNTs. The CLCh/Fe/MWCNT/TiO2-Ag film can be mechanically removed from the aqueous solution or by magnetic attraction. In ten consecutive cycles of reuse, the CLCh/Fe/MWCNT/TiO2-Ag film showed an efficiency of 84 % in the photoreduction of Cr(VI).

Membrane–protected magnetic covalent organic framework for efficient extraction of estrogens in dairy products

The presence of estrogens residues in dairy products is a growing concern due to their potential health risk. Herein, in this study, we have developed a membrane–protected magnetic solid–phase extraction (MP–MSPE) method that utilized a magnetic adsorbent (Fe3O4@COF–LZU1) with in–situ growth for the efficient extraction of estrone (E1), 17β–estradiol (E2), and estriol (E3). When combined with HPLC–FLD, this method allows for the efficient detection of estrogens in dairy products. The stability of the MP–MSPE was improved by the presence of a dialysis membrane, which remained a high extraction efficiency (90 %) even after ten reuse cycles. The hydrogen bonding, π–π interactions and pore size effect contribute to the excellent adsorption of three estrogens onto Fe3O4@COF–LZU1. Under optimal conditions, the method exhibits a low detection limit (0.01–0.15 μg L−1), wide linear range (0.1–800 μg L−1), and favorable recoveries (77.3 %–109.4 %) at three concentration levels (10, 50 and 100 μg L−1). This proposed method is characterized by its simplicity, high efficiency and eco–friendliness, making it a promising approach for extracting estrogens from dairy products.

A green synthesis of cellulose nanocrystals biosorbent for remediation of wastewater containing industrial dye

A novel cellulose nanocrystals biosorbent (CNCs) that has been synthesized, characterized, and used to remove indigo carmine blue (ICB) dye from wastewater. The characteristics of the cellulose nanocrystals biosorbent were assessed using various methods, including N2 adsorption-desorption isotherm, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), SEM, and Fourier-transform infrared spectroscopy (FTIR). To examine the influence of various reaction parameters, for instance temperature, initial dye concentration, pH, and contact time, on the adsorption of the ICB, a comprehensive study was carried out. Under the ideal conditions, the highest adsorption capacity reached 746.24 mg/g, achieved after 100 min at pH 4. The Langmuir model was employed to describe the adsorption isotherm, and the pseudo-second-order model was applied to describe the kinetics of the adsorption process. The adsorption of ICB is more accurately represented by the Langmuir model rather than the Freundlich model, indicating the formation of a selective monolayer on the CNCs surface. Both film and intraparticle diffusion contribute to the adsorption of the dye. The adsorption process is characterized as chemisorption, with an adsorption energy of 17 kJ/mol. The values of enthalpy change (∆H°) and entropy change (∆S°), which are 86.55 kJ/mol and 303.69 J/mol/K, respectively, suggest that the removal process of ICB is endothermic. The interaction mechanism between ICB dye and CNCs biosorbent likely involves various forces, such as π-π interactions, hydrogen bonding, electrostatic interactions, and pore filling. Furthermore, even after undergoing five consecutive cycles of reuse, the results consistently showed that the CNCs biosorbent maintained its effectiveness. These findings indicate that porous CNCs hold significant promise as an innovative biosorbent for the treatment of wastewater containing ICB.

Carbonic anhydrase-magnetite nanocomposites with an RF field controlled enzymatic activity

A magnetic enzymatic composite was synthesized from non-toxic magnetite nanoparticles modified by biomimetic polymerization of modified dopamine and carbonic anhydrase enzyme, which has a significant role in neurodegenerative processes. The mass fraction of the enzyme in the composite was 10% wt, which corresponded to about 120 enzyme molecules per nanoparticle. The composite showed Km about 10 folds higher compared to free enzyme (0.22 and 0.019 mmol/L respectively) and Vmax four times lower (0.17 and 0.69 mmol/min). The enzymatic composite had 17% higher thermal stability compared to free enzyme and retained 95% of its initial activity after seven consecutive reuse cycles. In a colloidal state, the composite showed no response to the RF field due to the ballistic mechanism of heat dissipation but in concentrated form, the material showed up to 155% enhanced catalytic activity under the influence of heating radio frequency magnetic fields. The observed results are discussed and explained.

Synthesis of an efficient MOF catalyst for the degradation of OPDs using TPA derived from PET waste bottles

In this study, a method for degrading PET-waste plastic bottles using ZnCl2:Urea as a catalyst was developed, resulting in high conversion (87%). The terephthalic acid obtained from the degradation of Waste PET Bottles (WPTs) was combined with copper and zinc salts to synthesize bimetallic metal–organic frameworks (MOF). The effectiveness of a bimetallic Cu-Zn(BDC)-MOF in catalyzing the reduction reaction of organic pollutant dyes (OPDs) was investigated, and the degradation efficiency of individual dyes was optimized, achieving over 95% degradation within 6–12 min under optimal conditions. Various techniques, including FT-IR, XRD, FE-SEM, EDS, and TEM were used to characterize the synthesized MOF. Results showed that the catalytic activity of Cu-Zn-MOF in reduction reaction of OPDs was enhanced by increasing the copper content. The reaction kinetics were investigated following pseudo-first-order kinetics with rate constants of 0.581, 0.43, 0.37, and 0.30 min−1 for Methylene Blue (MB), Methyl Orange (MO), 4-Nitrophenol (4-NP), and 4-Nitroaniline (4-NA), respectively. The investigations revealed that the produced catalyst exhibited excellent stability and recoverability, while its activity remained well-preserved even after undergoing three reuse cycles.