Regeneration Cycles Research Articles

Experimental and DFT calculation study on the efficient removal of high fluoride wastewater from metallurgical wastewater by kaolinite

Fluoride pollution and water scarcity are urgent issues. Reducing fluoride concentration in water is crucial. Kaolinite has been used to study adsorption and fluoride removal in water and to characterize material properties. The experimental results showed that the adsorption capacity of kaolinite decreased with increasing pH. The highest adsorption of fluoride occurred at pH 2, with a capacity of 11.1 mg/g. The fluoride removal efficiency remained high after four regeneration cycles. The fitting results with the Freundlich isotherm model and the external diffusion model showed that the non-homogeneous adsorption of kaolinite fit the adsorption behavior better. Finally, the adsorption mechanism was analyzed by FT-IR and XPS. The binding energies of various adsorption sites and the chemical adsorption properties of atomic states were discussed in relation to DFT calculations. The results showed that Al and H sites were the main binding sites, and the bonding stability for different forms of fluoride varies, with the size of Al–F (−7.498 eV) > H–F (−6.04 eV) > H–HF (−3.439 eV) > Al–HF (−3.283 eV). Furthermore, the density of states and Mulliken charge distribution revealed that the 2p orbital of F was found to be active in the adsorption process and was the main orbital for charge transfer.

Regeneration diagnosis for the service lifespans of residential buildings on a circular economy perspective

As urbanized areas progress into the era of stock, an immense number of existing residential buildings (RBs) are destined to undergo replacement and renovation. The irrational decision of urban renewal led to serious economic waste and environmental unsustainability. In this regard, this study proposes and validates a method for regeneration diagnosis and optimal regeneration of RBs based on circular economy (CE) theory. A hybrid diagnostic tool of life cycle cost (LCC)-life cycle assessment (LCA) model to systematically evaluate the economic and environmental impact of RBs throughout the circular lifecycle was proposed. On this basis, with the minimum average annual economic and environmental impact as the objective function, the optimal dynamic regeneration cycle of RBs is obtained using a multi-objective optimization method. The results of the case study show that: (1) The discount rate and deterioration rate changes the development tendency of economic and environmental data, which brings a new regenerating time point, (2) the economic impact of RBs’ regeneration tends to be more pronounced during the intermediate stages, while the environmental impact becomes more significant in the later stages, (3) the environmental benefits of regeneration outweigh the economic benefits, (4) the regeneration of all building elements at the local optimal level leads to enhanced comprehensive benefits compared to multiple regenerations of a single building element. The feasibility of the method employed in this study has been corroborated by practical case studies. This approach transcends the limitations of quantitative analysis in assessing the regeneration of RBs in a circular lifecycle and offers profound implications for the development of urban renewal and sustainable strategies.

Introducing Diels‐Alder reaction with carbon nanotubes for the enhanced repair performance of epoxy resin modified asphalt

AbstractEpoxy asphalt, a thermosetting polymer, is characterized by stable, irreversible internal chemical bonds that prevent recovery and spontaneous micro‐crack healing, unlike conventional asphalt. This study introduces a renewable nano‐modifier synthesized via esterification of carboxyl‐functionalized carbon nanotubes (CNTs‐COOH) and furfuryl alcohol (FA), termed CNTs‐FA. The successful synthesis of CNTs‐FA was confirmed through various microscopic techniques. Integrating CNTs‐FA into epoxy asphalt materials, the optimal dosage was identified as 0.05% of the total epoxy asphalt mass using tensile tests and fluorescence microscopy. Thermal reversible effects and mechanisms were further analyzed through multiple regeneration cycles using tensile properties, fluorescence microscopy, and infrared spectroscopy. The study elucidates that the thermal reversibility in epoxy asphalt is facilitated by the Diels‐Alder (DA) reaction between the conjugated diene structure in FA and the curing agent oleylamine. This research provides an effective solution to the non‐recoverability and unrepairable micro‐cracks of traditional epoxy asphalt mixtures.Highlights CNTs‐FA was successfully prepared by esterification reaction. Using nano modification methods, introduce DA reaction into curing system. Renewable function of epoxy asphalt by DA reversible reaction.

Construction of coal fly ash-based spherical grain adsorbents and their adsorption characteristics on phenolic compounds

Addressing the significant emissions and severe pollution hazards posed by coal fly ash waste in the coal chemical industry, as well as the challenges in recovering phenolic substances from coal chemical wastewater, this study utilized coal fly ash as a raw material to construct two types of spherical grain adsorbents: coal fly ash and coal gangue spherical grain (CFAGsg) and coal fly ash and pyrite spherical grain (CFAPsg). The adsorption performance of CFAGsg and CFAPsg towards phenolic substances in coal chemical wastewater was investigated. The research results demonstrated that CFAGsg and CFAPsg exhibited adsorption capacities of 20.31 mg/L and 30.42 mg/L for phenol, respectively, and maintained stable adsorption performance even after multiple regeneration cycles. Further analysis using kinetic, isotherm, and thermodynamic models, along with various characterization techniques, revealed that the adsorption of phenol onto CFAGsg and CFAPsg was primarily governed by physical and chemical adsorption, involving an endothermic reaction. Moreover, the study on the adsorption mechanism of phenol revealed that the adsorption behavior of CFAGsg and CFAPsg was mainly driven by pore filling, π-π stacking, and hydrogen bonding. Additionally, hydrophobic interactions were involved in the adsorption of phenol onto CFAGsg, while surface complexation forces played a role in the adsorption of phenol onto CFAPsg. Overall, the research findings provide vital theoretical support and practical application prospects for the high-value utilization of coal fly ash and the clean production of the coal chemical industry.

Adsorption characteristics and applications of andesite in removing some pollutants from wastewater

Andesite was employed to effectively extract mercury(II) in an aqueous solution. After evaluating its characteristics, andesite was characterized by applying modern techniques such as BET and TGA methods. The study employed SEM and TEM measurements to analyze the variation in the surface shape and crystallinity of the metal due to adsorption. Using the EDX process, the chemical composition, weight, and atomic percentage of each element of andesite were determined. FTIR techniques were also used to confirm the TEM–EDX findings. Zeta potential was estimated. Cycles of regeneration and desorption have been examined. 99.03% was the highest uptake percentage. Adsorbent quantity (0.0025–0.05) g/L, contact time (5–60) min, pH (2–10), temperature (25–60) °C, and dose (0.0027, 0.0044, 0.0125, 0.0155, and 0.0399) mg/L all affect the amount of removal that increases with the increase in contact time, pH, dose, and temperature but drops as the metal ion concentration rises. The ideal values for contact time, pH, metal ion concentration, dose, and temperature were found to be, respectively, 30 min, 0.0155 mg/l, 0.02 g/l, and 40 °C. The calculation of thermodynamic parameters, including ΔH, ΔG, and ΔS, was imperative in establishing that the mechanism of heavy metal adsorption on andesite was endothermic, exhibiting a physical nature that escalated with temperature rise. The Freundlich adsorption equation's linear form is matched by the adsorption of mercury(II) on andesite; constant n was 1.85, 1.06, 1.1, and 1.1, whereas the Langmuir constant qm was found to be 1.85, 2.41, 3.54, and 2.28 mg/g at 25–60 °C. Furthermore, adsorption follows a pseudo-second-order rate constant of (3.08, 3.24, 3.24, and 13) g/mg/min under identical temperature conditions, as opposed to a first-order rate constant of 4, 3, 2.6, and 2. Hg2+, NH4+, Cl−, Br−, NO3−, SO42−, Na+, K+, H2S, and CH3SH were all extracted from wastewater by this application.

High surface area biochar for the removal of naphthenic acids from environmental water and industrial wastewater.

This study reports the production of biochar adsorbents from two major crop residues (i.e., rice and wheat straw) to remove naphthenic acids from water. The alkali treatment approach was used for biochar activation that resulted in a tremendous increase in their surface area, i.e., up to 2252 and 2314 m2/g, respectively, for rice and wheat straw biochars. Benzoic acid was used as a model compound to optimize critical adsorption parameters. Its maximum monolayer adsorption capacity of 459.55 and 357.64mg/g was achieved for activated rice and wheat straw biochars. The adsorption of benzoic acid was exothermic (∆H° = - 7.06 and - 3.89kJ/mol) and identified possibly as physisorption (Gibbs free energy ranges 3.5-4.0kJ/mol). The kinetic study suggested that adsorption follows pseudo-second-order kinetics with qe2 for rice straw and wheat straw-derived adsorbents at 200 and 194mg/g, respectively. As adsorbent, the recyclability of activated biochars was noticed with no significant loss in their efficiency for up to ten successive regeneration cycles. The adsorption results were validated using a commercial naphthenic acid mixture-spiked river water and paper/pulp industrial effluent. The activated rice and wheat straw biochars exhibited excellent adsorption efficiency of 130.3 and 74.6mg/g, respectively. The naphthenic acid adsorption on biochar surface was due to various interactions, i.e., weak van der Waal's, pore filling, π-π stacking, and ionic interactions. This study offers a cost-effective and eco-friendly approach to valorizing agricultural residues for pollutant removal from industrial wastewater, including petroleum refineries.

Synthesis of 4A Zeolite Molecular Sieves by Modifying Fly Ash with Water Treatment Residue to Remove Ammonia Nitrogen from Water

The widespread presence of ammonia nitrogen (NH4+–N) pollutants poses a serious threat to water environment health. In this study, a novel zeolite (WTR–CFA zeolite) with excellent adsorption performance is synthesized using CFA as the raw material and water treatment residue (WTR) as the aluminum source through an ultrasonic–assisted alkali melt hydrothermal method. Compared with traditional CFA–zeolite, WTR–CFA zeolite only generates 4A zeolite with a single crystal phase, and the peak shape is sharp, which results in better crystallization. WTR–CFA zeolite perfectly solves the technical problems of the low utilization rate and poor controllability of the crystal form in traditional artificially synthesized zeolites. The maximum NH4+–N adsorption capacity of WTR–CFA zeolite is 29.80 mg/g, which is higher than that of most adsorbents reported in previous studies. After five cycles of adsorption regeneration, the regeneration efficiency of WTR–CFA zeolite only decreased from 98.84% to 97.12%, which demonstrates excellent environmental value. The adsorption isotherms and kinetics of NH4+–N conform to the Langmuir model and quasi–second order kinetic model, respectively, which indicates that ion–exchange–dominant chemical adsorption plays a major role in the adsorption mechanism. In summary, this study combines the use of CFA and WTR resources with the treatment of aquatic pollution to reduce material synthesis costs, control the crystal structure of WTR–CFA zeolite, and increase adsorption capacity. This approach achieves the goals of “waste treatment and turning waste into treasure”.

O-055 Understanding endometrial functionality and embryo-maternal communication via in vitro “OMICs’’ platforms

Abstract The uterus (womb) is perhaps the most fascinating organ in the human body. It undergoes cyclical regeneration of its inner layer, the endometrium, and is notoriously unreceptive to implantation, except for a short period of time known as the window of implantation (WoI), the only time when it becomes receptive to the implantation of an embryo resulting in pregnancy. A common reason for pregnancy failure is implantation failure. Similarly, many in vitro fertilisation (IVF) treatments that do not result in a live birth fail because the embryo does not successfully implant. This is a significant challenge as there is limited understanding of the exact timing and cellular/molecular characteristics of the human endometrium during WoI. Here I will present results on the characterisation of the WoI in humans, contextualised with results from “omics’ platforms. Moreover, we will provide 3D data on the structural development of the human uterus, paving the way to develop innovative culture platforms to investigate embryo-maternal communication.

Optimization of catalyst service cycle and start-up considering the reactor-distillation-HEN integration and climate

Considering the catalyst deactivation and seasonal temperature variation, a systematic method is proposed for clarifying the dynamic variation of system operating parameters and targeting the optimal catalyst regeneration cycle and start-up date. Relationships between catalyst activity, reactor inlet and outlet temperatures, reactor heat load, and running time are deduced, as well as that between column temperatures, pressures, energy demands, processing capacity, and production month. Diagrams are constructed to illustrate the parameter variations. With the energy consumption and processing capacity combined, an evaluation index is introduced for integrating the reactor-separator-heat exchanger network (HEN) and optimizing the production start-up date. The proposed method is intuitive and efficient and can be used for system design, guiding production, or fault diagnosis. A benzene alkylation process is studied; the optimal regeneration cycle of the ZSM-5 catalyst is 11 months, and the best start-up date is August, saving 2.32 × 105 kgce (kg standard coal) per production cycle.

The impact of PAC-loaded polymer membrane thickness on chloroform removal and comparison of solvent and thermal membrane regeneration methods.

Powdered activated carbon (PAC) has better adsorption performance than granular activated carbon (GAC) and is widely used in water purification. In most cases, PAC is dosed into water directly, then precipitated as sludge, and landfilled. In this study, PAC was mixed with a polymer and dissolved in dimethylformamide (DMF) solvent to form a PAC-loaded membrane, which was then tested for chloroform removal. The chloroform adsorption capacity of the PAC membrane increased with increasing membrane thickness because of higher carbon loading. However, regardless of membrane thickness, the flux of the PAC membranes was similar since flux resistance predominantly occurred at the top dense polymer surface. This dense surface can be removed by sandpaper polishing, where the adsorption capacity of the polished PAC membranes was 20% higher than the unpolished membranes because of more even distribution of feed water on the polished surface. Removal of the dense surface via polishing increased the flux by 97% to 130%, exceeding the flux of typical household carbon block filters. Using DMF to regenerate the membrane recovered 48% to 66% of the initial adsorption capacity. Thermal regeneration of the exhausted PAC membrane at 250°C was more effective than DMF regeneration (both in terms of cost and performance), with 83% to 94% PAC membrane regeneration efficiency over four regeneration recycles. After four thermal regeneration cycles, flux increased by 300% and the membrane became brittle because of thermal aging of the polymer, indicating that a total of 6h of regeneration time (equivalent to three cycles in this study) was the limit for effective PAC membrane performance. PRACTITIONER POINTS: Powdered activated carbon was immobilized on a membrane to remove chloroform from water. Thicker membranes increased adsorption capacity but did not impact flux. Flux and capacity increased using polishing to remove the dense polymer surface and more evenly distribute flow across the membrane. Thermal regeneration of the membrane at 250°C was effective for up to three cycles and outperformed solvent-based regeneration. PAC-loaded filters are relevant for applications such as household carbon block filtration.

Vanadium-doped TiO<sub>2</sub> Adsorbent-Photocatalyst for Organic Dye Treatment

This study focuses on the synthesis of V-doped TiO2 materials using a modified polyol method to enhance their efficiency. The obtained materials were characterized by various methods such as XRD, EDX, FTIR, SEM, TEM-SAED, Raman, and UV-Vis DRS. The results indicated the crystalline anatase phase of TiO2, with spherical morphology and an average size of 30nm. The UV-DRS measurement demonstrated that doped materials have a lower bandgap than the pristine TiO2. The material possesses dual functionality, with adsorption capability and photocatalytic activity applied to treat organic dye contaminants. Evaluation of MB degradation under UV irradiation revealed an exceptional efficiency of up to 99% within a remarkably short duration of 30 minutes. Furthermore, the catalyst exhibited robust recovery efficiency exceeding 99% after 2 regeneration cycles and retention of approximately 80% after four cycles.

Adsorptive removal of cationic dye from aqueous solutions using activated carbon prepared from Crataegus monogyna/sodium alginate/polyaniline composite beads: Experimental study and molecular dynamic simulation

This study presents a novel composite beads, AC@Alg-PANI, consisting of activated carbon (AC) derived from Crataegus monogyna, sodium alginate (Alg), and polyaniline (PANI), tested for the removal of methylene blue (MB). The physicochemical characteristics of the composite beads were analyzed using methods such as pHPZC, FTIR, TGA/DTA, SEM, and BET. Moreover, factors affecting the adsorption of MB, such as initial pH, dye concentration, adsorbent weight, ionic strength, and temperature, were also explored. A full factorial design was implemented to identify the optimum conditions for removal, which were found to be a pH of 6, an adsorbent amount of 100 mg, and a dye concentration of 100 mg/L. The isotherm data indicated that the adsorption of MB by AC@Alg-PANI follows the Langmuir model, with a maximum adsorption capacity of 774.6 mg/g. The adsorption kinetics followed the pseudo-first-order model, indicating that the adsorption process is physical in nature. The thermodynamic results suggest that MB adsorption on AC@Alg-PANI was favorable, spontaneous, and endothermic. Additionally, after five regeneration cycles, the composite beads demonstrated excellent recyclability for MB dye removal with high efficiency. Furthermore, molecular dynamics simulations (MDS) of the adsorption energy highlighted the physically spontaneous nature of the process, involving various weak interactions, including van der Waals forces, intermolecular interactions, hydrogen bonding, and π-electron interactions.

Comprehensive batch studies on removal of fluoride from aqueous solution by acid and alkali-activated adsorbents prepared from Dal lake weeds: Mechanism, Kinetics and Thermodynamics

An efficient and economical way of eliminating fluoride from water is being investigated by employing the buoyant aquatic plant (Dal weed). Two post-pyrolysis chemical activation alteration techniques were implemented: acidic activation by employing sulfuric acid (H-activation) and alkaline activation using sodium hydroxide (OH-activation). The batch kinetic studies have been carried out considering varying starting fluoride levels such as 2–10 mg/L. The impact of diverse procedural factors, including dosage of Dal weed, starting fluoride level, pH and contact duration was observed to determine their influence on fluoride adsorption kinetics. Based on analyzed exploratory results, removal efficacy of 63% for the OH-activated carbon and 83% for H-activated carbon was achieved at commencing fluoride level of 10 mg/L, adsorbent dosage of 0.8 g, at 25 °C after 120 min. The maximal fluoride uptake capacity for H-activated carbon was observed to be 78.158 mg/g. Kinetic investigations showed that the Freundlich isotherm model provided a satisfactory match with an R2 value of 0.99. The reaction order nature adhered to kinetics resembling pseudo second order. Thermodynamic investigation revealed endothermic sorption, with negative ΔG indicating spontaneous fluoride uptake. In comparison, the positive number for ΔS suggested random behavior at the contact involving the adsorbent and adsorbate. The investigations into the regeneration capabilities of the adsorbent material revealed that even after undergoing for five consecutive cycles of adsorption and regeneration, the adsorbent exhibited an uptake potential of 45%. The presence of competing ions in the solution negatively impacted defluoridation efficacy, with the influence following the order of HCO3−< NO3−< Cl−< SO42−< PO43−.

Reusable MIL-100(Fe)-polyacrylonitrile-TiO2 nanofiber webs for adsorption and decomposition of toluene

Due to rapid industrialization and urbanization, addressing the pressing issue of environmental pollution, particularly indoor air quality, demands innovative solutions. Volatile organic compounds (VOCs), notably toluene, are prevalent indoor pollutants that necessitate effective adsorption and removal strategies due to their adverse health impacts. Here, we propose a novel method for crafting a multifunctional air-filter membrane capable of simultaneous toluene adsorption and photocatalytic degradation across diverse light conditions, thus facilitating the development of a reusable air filtration system. This study outlines the successful synthesis of an air filter membrane by illustrating the in-situ growth of MIL-100(Fe) particles on polyacrylonitrile (PAN) nanofibers loaded with TiO2 nanoparticles, resulting in the formation of a PTF membrane. The PTF membrane exhibits an exceptional toluene adsorption efficiency of 98 % and a high toluene capacity of 383.94 mg g−1 (4.166 mmol/g), with a corresponding partition coefficient (PC) of 38.39 L/g ± 1.41. Notably, its design enables functionality, demonstrating impressive photocatalytic degradation efficiencies of 62.3 %, 71.3 %, and 80.2 % under UV, visible, and combined UV–visible light, respectively. This high efficiency is attributed to the PTF membrane’s reduced bandgap and enhanced light-absorption capabilities. Under the combined light conditions, the PTF membrane achieved the highest space–time yield (STY) of 0.197 mol/g/h and the highest reaction kinetic rate for toluene degradation, determined to be 6.34 × 10-8, surpassing the performance observed under individual UV and visible light sources. Moreover, the regeneration cycle of the PTF membrane demonstrates minimal efficiency loss, ensuring prolonged performance. The developed PTF membranes demonstrate notable stability and resilience even under the most extreme humid conditions, suggesting their strong potential for future applications in air filtration. This innovative approach offers a straightforward and environmentally friendly method for fabricating metal–organic framework (MOF)-based photocatalytic filters tailored to indoor VOC purification systems. This study is expected to significantly advance efforts aimed at improving and managing air quality, thereby fostering a healthier and more sustainable environment.

Facile construction of pH-responsive graphene oxide-based aerogel and its efficient and selective adsorption performance toward methylene blue

In regard to serious environmental pollution by methylene blue (MB) dye, it was crucial to design an efficacious adsorbent for the elimination of MB. Utilizing tannic acid (TA) to functionalize graphene oxide (GO) and employing acrylic acid (AA) and sodium p-styrenesulfonate (SSS) as the monomers, a pH-responsive TGO/P(SSS-co-AA) aerogel (where TGO represented TA-modified GO, and P(SSS-co-AA) denoted the copolymer of SSS and AA) was synthesized by a facile and green one-pot method. The resulting aerogel was subjected to a variety of characterizations, and its adsorption behaviors were systematically explored with MB as the model dye. The results indicated the pH-responsive TGO/P(SSS-co-AA) aerogel possessed the maximum theoretical adsorption capacity of 1782.5 mg/g, and the adsorption process could be accurately described by quasi-second order kinetics model and Langmuir model. The adsorption thermodynamics revealed that the adsorption was a spontaneous, endothermic, and entropy-increasing process. TGO/P(SSS-co-AA) aerogel exhibited highly selective adsorption property and excellent regeneration performance. Even following five regeneration cycles, adsorption capacity of the aerogel could still maintain 936.09 mg/g. In conclusion, TGO/P(SSS-co-AA) aerogel exhibited exceptional performance as an adsorbent for removing MB, providing an inspiration for the construction of GO-based composite aerogel and its actual application in efficient and selective wastewater treatment.

Efficient CO2 capture by non-aqueous imide/ethylene glycol solvent

Man-made CO2 emissions give rise to an important influence on climate and human survival, which has attracted widespread attention. Traditional absorbents such as aqueous amines used for CO2 capture often suffer from high regeneration energy and corrosiveness. In this regard, non-aqueous amine solutions have high energy-saving potential because organics have lower vaporization enthalpy and heat capacity than water. Herein, we explored the potential absorbent composed of ethylene glycol and imide-based bases to capture CO2. The CO2 uptake in imide-based ethylene glycol absorbent was studied, experimental results showed that succinimide/glycol-20 wt% have the highest CO2 solubility, and still maintains a high absorption capacity after 8 regeneration cycles. And the absorption mechanism has been confirmed the possible intermolecular hydrogen bonding and van der Waals forces between carbon dioxide and succinimide molecules through molecular simulation. The regeneration energy consumption is only 2.243 GJ/t CO2 through process simulation calculation, which is lower than the conventional absorbent, further indicating that the fabricated absorbent have exhibits the large potential to absorb CO2 from flue gas.

Synergistic degradation of metronidazole and penicillin G in aqueous solutions using AgZnFe2O4@chitosan nano-photocatalyst under UV/persulfate activation

In recent years, the persistence of pharmaceutical contaminants like metronidazole (MNZ) and penicillin G (PG) in water bodies has become a major environmental concern. The present research studied the simultaneous degradation of MNZ and PG utilizing an AgZnFe2O4@Ch catalyst generated through the co-precipitation technique as an effective stimulator for persulfate (PS) in the existence of UV light. The structure of the AgZnFe2O4@Ch catalyst was characterized using X-ray powder diffraction, Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, vibrating-sample magnetometer, and energy dispersive spectroscopy mapping. After 50 minutes of reaction time under the ideal operating conditions, which included 0.4 g/L of catalyst, 4 mM of PS, 5 mg/L of MNZ and PG, and a pH of 5, the highest MNZ and PG degradation of 81.5 % and 82.3 % were obtained. Statistical parameters, including the R2 values of 0.985 for MNZ and 0.981 for PG, indicate a very good agreement between the predicted and observed values. The Garson's method analysis revealed that PS dosage had the greatest impact on MNZ degradation, while the initial concentration of PG exerted the most significant influence on PG degradation. The Langmuir-Hinshelwood model has surface reaction rate constants (Kc) of 0.954 (mg/L.min) and adsorption equilibrium constants (KL-H) of 0.032 (L/mg) for both antibiotics, respectively. The claimed mechanism was illustrated by the free radical scavenging studies, which demonstrated that the SO•4- radicals were the main radicals involved in the degradation of MNZ and PG. A last investigation of the catalyst's regeneration revealed that it had satisfactory chemical stability after five cycles of usage and regeneration using chemical approaches.

Fast and effective hydroquinone adsorption by poly (2-dimethylaminoethyl methacrylate)/zinc oxide nanocomposite hydrogel in textile wastewater treatment

ABSTRACT Hydroquinone, a widely used phenolic compound, poses significant health and environmental risk and must be removed from wastewater. In this study, a novel adsorbent was developed for the removal of hydroquinone from aqueous solutions through the in-situ polymerisation of 2-(dimethylamino)ethyl methacrylate (DMAEMA) in the presence of zinc oxide nanoparticles (ZnO NPs). The kinetics of equilibrium swelling in deionised water (DI) and the effect of pH on the swelling behaviour were investigated. The structure of the nanocomposite hydrogel was analysed using FTIR, XRD, FESEM, EDX, TEM, and BET analysis. Various factors affecting the adsorption process, such as solution pH (2–12), initial concentration (25–200 mg/L), adsorbent dosage (4.0–80 mg/100 mL), NaCl concentration (0.1–1.0 mol/L), and temperature, were also investigated. The adsorption capacity of hydroquinone and the removal efficiency of PDMAEMA@ZnO reached 455 mg/g and 91%, respectively, at pH 11 within 15 minutes. Furthermore, PDMAEMA@ZnO showed a high removal efficiency of 99.47% in tests with real wastewater. Reusability studies showed that the adsorbent retained its ability to remove hydroquinone after four regeneration cycles. The adsorption data were well described by the pseudo-second order and Langmuir models. The thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. Therefore, the adsorbent, has considerable industrial potential as it quickly and efficiently adsorbs phenolic impurities such as hydroquinone from real textile wastewater.

Adsorption of tetracycline by hydrochar derived from co-hydrothermal carbonization of polyvinyl chloride and garden waste: Adsorption characteristics and enhancement mechanism

The environmental risk posed by tetracycline (TC) in aquatic environments cannot be overlooked, and hydrochar has shown promising potential for adsorbing and removing TC. This study utilized polyvinyl chloride (PVC) and garden waste (GW) as feedstock, preparing hydrochar through co-hydrothermal carbonization (co-HTC), aiming to investigate its adsorption performance for TC. The results demonstrated that the equilibrium adsorption amount of hydrochar produced via co-HTC (HPG) for TC was increased by 28.11% and 406.03% compared to hydrochar derived from PVC and GW, respectively. The HTC temperature and reaction time were positively correlated with the TC adsorption amount of HPG, but the increase was limited beyond 220 °C and 4 h, while the PVC blending ratio had a minor effect on TC adsorption. Subsequently, the adsorption characteristics of HPG for TC were systematically investigated to clarify the effects of adsorption conditions, environmental factors, and regeneration cycles on the adsorption performance of HPG; and further through the properties characterization of HPG and hydrochar prepared from the individual feedstock, the potential mechanism enhancing TC adsorption in co-HTC was explored. HPG adsorbed TC through the interaction between surface carbonyl groups and TC's π-electrons, while PVC produced carbonyl compounds through dechlorination and intramolecular dehydration during co-HTC. GW facilitated the dechlorination process of PVC and provided a substrate for the linkage of carbonyl compounds. This study revealed the adsorption performance and mechanism of hydrochar derived from co-HTC of PVC/GW for TC, offering insights for utilizing hydrochar from organic waste for antibiotic pollution control.

Imidacloprid removal by modified graphitic biochar with Fe/Zn bimetallic oxides

Coping with the critical challenge of imidacloprid (IMI) contamination in sewage treatment and farmland drainage purification, this study presents a pioneering development of an advanced modified graphitic white melon seed shells biochar (Fe/Zn@WBC). The Fe/Zn@WBC demonstrates a substantial enhancement in adsorption efficiency for IMI, achieving a remarkable removal rate of 87.69% within 30 min and a significantly higher initial adsorption rate parameter h = 4.176 mg g−1·min−1. This significant improvement outperforms WBC (12.22%, h = 0.115 mg g−1·min−1) and highlights the influence of optimized adsorption conditions at 900 °C and the graphitization degree resulting from Fe/Zn bimetallic oxide modification. Characterization analysis and batch sorption experiments including kinetics, isotherms, thermodynamics and pH factors illustrate that chemical adsorption is the main type of adsorption mechanism responsible for this superior ability to remove IMI through pore filling, hydrogen bonding, hydrophobic interaction, electrostatics interaction, π-π interactions as well as complexation processes. Furthermore, we demonstrate exceptional stability of Fe/Zn@WBC across a broad pH range (pH = 3–11), co-existing ions presence along with humic acid under various real water conditions while maintaining high removal efficiency. This study presents an advanced biochar adsorbent, Fe/Zn@WBC, with efficient adsorption capacity and easy preparation. Through three regeneration cycles via pyrolysis method, it demonstrates excellent pyrolysis regeneration capabilities with an average removal efficiency of 92.02%. The magnetic properties enable rapid separation facilitated by magnetic analysis. By elucidating the efficacy and mechanistic foundations of Fe/Zn@WBC, this research significantly contributes to the field of environmental remediation by providing a scalable solution for IMI removal and enhancing scientific understanding of bimetallic oxides-hydrophilic organic pollutant interactions.