Adsorption Mechanism Research Articles

Heavy metals remediation through alkali assisted ball-milling activation of copper smelting slag for resource utilization

This study describes the preparation of Silico-Calcium-adhesive (CS-SS) by alkali-assisted ball milling to activate copper smelting slag (CS) for the remediation of heavy metals contamination and consequent resource utilization. The adsorption behavior and mechanisms of Cd(II), Cu(II) and Pb(II) in mono-metallic and polymetallic coexisting systems were investigated. The adsorption capacities of CS-SS were 21.906mg/g, 30.893mg/g and 93.593mg/g for Cd(II), Cu(II) and Pb(II) at a pH of 6, respectively. Based on the experimental results of monometallic system indicated that CS-SS exhibited the highest adsorption capacity for Pb(II), followed by Cu(II) and Cd(II). In the polymetallic system, the inhibitory impact of Pb(II) was more potent compared to Cd(II) and Cu(II). The adsorption mechanisms included electrostatic attraction, chemical adsorption, physical adsorption, ion exchange, functional group complexation and surface precipitation. Simple economic estimates show that it costs about $4.72 to treat 1 m3 of Cd(II)-20 mg/L, Cu(II)-30 mg/L and Pb(II)-90 mg/L containing wastewater. Therefore, the CS treatment method proposed in this study has certain feasibility and economic applicability.

Successful synthesis of eco-friendly Metal-Organic framework ([Ni(BDC)]n) allows efficient extraction of multiresidues pesticides and dyes from fish samples

Contaminants such as pesticides and dyes pose substantial challenges to environmental and human health, especially when found in aquatic ecosystems and ingested through the food chain. This requires the development of methods that are efficient, safe and environmentally friendly. In this scenario, this study presents the synthesis and characterization of a metal–organic framework (MOF), specifically [Ni(BDC)]n, designed as a solid adsorbent for the determination of pesticides, including atrazine, bifenthrin, chlorpyrifos, endrin, heptachlor, flutriafol and permethrin, as well as dyes such as crystal violet (CV) and Congo red (CR) in fish samples. Using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), and Brunauer-Emmett-Teller (BET), we verified the success of the MOF synthesis. BET analysis indicated MOF surface area and total pore volume of 2700 m2/g and 0.0136 cm3 g−1, respectively. The adsorption study revealed high affinity of the MOF for the target analytes, with qmax = 208.33 mg g−1 for pesticides and qmax = 4.18 mg g−1 for dyes. The kinetic study demonstrated that the adsorption mechanism follows a pseudo-second order model for all analytes. Furthermore, employing [Ni(BDC)]n, we have developed an efficient extraction method using Matrix-Solid Phase Dispersion (MSPD) combined with Gas Chromatography-Mass Spectrometry (GC–MS) and UV/Vis spectrophotometry for determination of pesticide and dyes, respectively, with pre-concentration factor ranging from 10 to 100 times for the studied analytes. The methods showed satisfactory linearity for both contaminants (pesticides and dyes), with recovery efficiency ranging from 81-103 % and precision < 13 % (n = 3) for the analytes. Linear ranges covering 10.0–500.0 μg L−1 (R2 > 0.995) for pesticides and 100.0–1000.0 μg L−1 (R2 > 0.988) for dyes. The limits of detection (LOD) and quantification (LOQ) ranged from 0.5-1.6 μg L−1 and 1.7–5.6 μg L−1 for pesticides, respectively, while for dyes, LOD and LOQ ranged from 2.0-12.0 μg L−1 and 7.6–39.6 μg L−1, respectively. These results highlight the potential of [Ni(BDC)]n as a promising material for efficient and selective extraction in the sustainable determination of pesticides and dyes in fish samples, with satisfactory reuse.

Insights into remediation of cadmium and lead contaminated-soil by Fe-Mn modified biochar

Heavy metal contamination, particularly by lead and cadmium, poses a significant environmental challenge. Indiscriminate disposal of crop residues exacerbates environmental concerns. In this study, broad bean straw was utilized to produce biochar (BC), and further modifications were made using FeCl3-6H2O and KMnO4 to obtain Iron-Manganese Modified Biochar (FMBC) for remediating cadmium and lead-contaminated soil. Results show that both BC and FMBC increased soil pH, available phosphorus, and potassium compared to the control groups. Adding 5% BC led to a notable reduction of 60.98% in available cadmium and 51.63% in available lead. Simultaneously, FMBC decreased active cadmium and lead by 57.51% to 73.73% and 52.25% to 69.87%, respectively. Furthermore, FMBC decreased the content of cadmium and lead in the unstable state while increasing content in the residual state, demonstrating its ability to reduce accumulation in plant tissues. FMBC adsorption mechanisms primarily involve surface complexation and co-precipitation, where oxygen-containing functional groups form stable complexes with free cadmium and lead ions. In conclusion, FMBC proved to be an effective, environmentally friendly soil remediation agent with strong adsorption capabilities and a prolonged shelf-life. This provides a promising solution to alleviate the pollution of heavy metals such as cadmium and lead in soil.

Soft-Hard segments regulated framework of Nitrogen-Doped reduced graphene oxide aerogel for efficient adsorption of pollutants

Graphene aerogel (GA) is recognized for its high porosity, rendering it a promising candidate for water treatment applications. However, its reuse potential is hampered due to inherent limitations. To address this, the present study introduces a nitrogen-doped graphene aerogel (NGA) developed by integrating polydopamine soft segments and polyaniline hard segments into the GA matrix. This approach promotes the formation of a cohesive and durable 3D network by bridging reduced graphene oxide (rGO) nanosheets, with the hard segments of polyaniline interposed among rGO layers to mitigate significant restacking, thereby enhancing surface area and adsorption sites. NGA demonstrates remarkable properties including strength (67 kPa), reversible compressibility under 64 % strain, low density (12.26 mg/cm3), and thermal stability (Tdecomposition = 679.6 °C in air), which collectively enhance its adsorption capacity and recyclability. This study further examines the influence of various factors such as pH, adsorbates (dyes and organic solvents), initial concentration, and cycle times on the aerogel’s adsorption efficacy. Additionally, simulation outcomes reveal that NGA’s adsorption kinetics and thermodynamics align more closely with the endothermic pseudo-first-order kinetic model, indicative of predominant physical adsorption mechanisms. Given its superior adsorption capabilities for pollutants, NGA holds significant promise for application in water treatment.

Sustainable Zn2+ removal using highly efficient, novel, and cost-effective chitosan-magnetic biochar composite.

This study focused on the development of a sustainable and low-cost adsorbent derived from the chitosan-biochar composite for the removal of Zn2+ from an aqueous solution. Biochar was prepared from cotton stalk residue by pyrolysis at 600°C for 2h, modified with FeCl3, and composed with chitosan in various ratios (1:3, 1:1, 3:1), leading to the formation of an efficient, thermally stable, and rich with functional groups chitosan-biochar composite denoted as CHB-Fe-CS. Functional groups (hydroxyl, carboxyl, and amine) were identified as key contributors to the adsorption mechanism. Langmuir isotherm (R2 = 0.99) and Pseudo-Second order (R2 = 0.99) were best fitted models with the experimental results indicating chemisorption-driven monolayer adsorption. The results revealed CHB-Fe-CS (3:1) composite obtained the highest adsorption capacity of 117.50mg/g for Zn2+ under optimal conditions viz., 180min batch time, 500mg/l metal concentration, 4g/l adsorbent dosage, 40°C solution temperature, and 5.0 pH. Regeneration of the used adsorbent was performed using 0.2mol/l HCl and obtained desorption efficiency of 67.48% and 51.48% after the 4th and 8th cycles. The adsorption mechanisms were dominated by ion exchange, surface complexation, and electrostatic attraction compared to intra-particle diffusion and physisorption. The CHB-Fe-CS demonstrated an economical, environment friendly, and good performing adsorbent for water decontamination.

Adsorption of Glycine on TiO2 in Water from On-the-fly Free-Energy Calculations and In Situ Electrochemical Impedance Spectroscopy.

We report here an experimental-computational study of hydrated TiO2 anatase nanoparticles interacting with glycine, where we obtain quantitative agreement of the measured adsorption free energies. Ab initio simulations are performed within the tight binding and density functional theory in combination with enhanced free-energy sampling techniques, which exploit the thermodynamic integration of the unbiased mean forces collected on-the-fly along the molecular dynamics trajectories. The experiments adopt a new and efficient setup for electrochemical impedance spectroscopy measurements based on portable screen-printed gold electrodes, which allows fast and in situ signal assessment. The measured adsorption free energy is -30 kJ/mol (both from experiment and calculation), with preferential interaction of the charged NH3+ group which strongly adsorbs on the TiO2 bridging oxygens. This highlights the importance of the terminal amino groups in the adsorption mechanism of amino acids on hydrated metal oxides. The excellent agreement between computation and experiment for this amino acid opens the doors to the exploration of the interaction free energies for other moderately complex bionano systems.

Temperature effects on adsorption and capillarity water retention mechanisms in constrained unsaturated soils

AbstractThis paper focuses on the impact of elevated temperatures on the adsorptive and capillarity water retention mechanisms of unsaturated soils under constrained (constant volume) conditions. This topic is critical for simulating the thermo-hydraulic behavior of soils in hydrogeological or geotechnical applications, including climate change effects on near surface soils, energy piles or soil borehole thermal energy storage systems in unsaturated soil layers, and buffers for geological nuclear waste repositories. A nonisothermal soil water retention curve (SWRC) that separately considers the temperature-dependency of the key parameters governing adsorptive and capillarity water retention mechanisms and soil physical parameters (e.g., surface tension, contact angle, adsorption capacity, cation exchange capacity, mean cavitation suction, air entry value and equilibrium film thickness) was developed to provide insights into the impact of temperature on water retention over the full suction range. The nonisothermal SWRC was validated using experimental data on high plasticity clays, with a good prediction of temperature effects on adsorption and capillarity water retention mechanisms in constrained unsaturated soils.

Understanding water adsorption in hierarchical carbon — The significance of pore connectivity and functional group configurations

Hierarchical carbon has drawn considerable attention due to its high capacity and fast kinetics in gas separation and purification in the fuel industry. The presence of water in most applications poses a challenge; hence, understanding how water interferes with the removal of undesired substances in the micro-mesoporous structure of the hierarchical carbon is required to assess and manage its impacts. Monte Carlo simulation was conducted in this paper to investigate water adsorption in a serially connected micro and mesopore model that mimics the hierarchical carbon. Our results reveal the critical role of pore connectivity, the topology of the junction between micropore and mesopore, and functional groups. Notably, the junction facilitates the formation of water clusters having a convex interface at the junction, followed by their coalescence with the localized clusters in the mesopore to form a liquid-like condensate with the concave interface. It is this transition from clusters with a convex interface to condensate with the concave interface that is the prerequisite for mesopore filling. Temperature has an opposing effect in the filling of micropores and mesopores; for the former, the onset of filling occurs at higher reduced pressure as the temperature is increased, while the opposite is true for mesopores. Our simulation results provide significant insights into the mechanism of water adsorption, which paves the path for utilizing hierarchical carbon in removing harmful substances from water-laden feed streams.

Mechanism of targeted adsorption and specific action of bone char on ionic organic pollutants: An analysis based on differences in physicochemical properties

Adsorption is a widely recognized and effective method for treating high-concentration organic industrial wastewater. Bone char (BC) is a promising adsorbent for removing ionic organic pollutants (IOPs) from printing and dyeing wastewater due to its advantageous adsorption properties. To analyze BC's targeted adsorption and specific action mechanism on IOPs, the author first elucidated the physicochemical properties of BC under different preparation conditions. Subsequently, the study compared the targeted adsorption efficacy of BC on various types and molecular structures of IOPs. Through correlation analysis, feature importance analysis, and consideration of the properties of the target substance, the study investigated the targeted adsorption laws of BC for IOPs. Lastly, for substances with specific adsorption characteristics, range analysis, structure–activity relationship analysis, and quantitative analysis of adsorption mechanisms were employed to elucidate the action mechanism of BC. The results indicate that the differences in physicochemical properties (especially CEC and pH) caused by the inorganic mineral components of BC and the number of conjugated double bonds in the molecular structure of IOPs are key factors determining the adsorption effect. Controlling BC's pore structure and electrical conductivity based on the aggregates' conjugated double bonds and particle size can improve adsorption outcomes. The hierarchy of preparation factors influencing the adsorption performance of BC is pyrolysis temperature > particle size > pyrolysis atmosphere. The adsorption of malachite green (MG) by BC primarily involves chemical reactions, including mineral complexation effect (52.38 %), electrostatic interaction (24.76 %), π-π interaction (8.15 %), metal ion exchange (8.12 %), and physical pore filling (6.59 %). It is speculated that the primary interaction mechanism between BC and MG is through cation-π bonds formed between metal cations dissociated from the inorganic mineral components of BC and MG, facilitated by strong electrostatic interaction. The findings offer a theoretical basis for the practical utilization of BC in adsorbing IOPs.

Development of a novel polydopamine-imprinted MOFs targeted for removal of refractory organic pollutants: Synergistic mechanisms of adsorption and degradation

In this study, a novel dopamine-imprinted MOFs (metal organic frameworks) was developed for the first time to achieve targeted degradation of refractory organic pollutants (ROPs) in advanced oxidation process. The targeted adsorption and degradation capacity of sulfamethoxazole (SMX) by molecularly imprinted catalyst (Fe-MOFs@MIP) was 3.17 times and 5.47 times that of Fe-MOFs, respectively. The results showed that the polydopamine (PDA) imprinted layer not only enhanced the targeted adsorption of SMX, but also improved the activity of the catalyst by promoting electron transfer. The physicochemical properties of Fe-MOFs@MIP were investigated. In situ Fourier transform infrared spectroscopy and molecular dynamics theory were used to investigate targeted adsorption mechanism. The active species were identified by quenching experiments and electron paramagnetic resonance (EPR). The reaction sites of SMX were predicted using density functional theory (DFT) and the possible degradation pathways of SMX were proposed. Finally, the targeted degradation mechanism of Fe-MOFs@MIP was elucidated. This study has a guiding significance for the deep removal of refractory organic pollutants in wastewater.

Evaluation of Kinetic and Isotherm Models for Adsorption of Boron Under Different Soil Orders in Oil Palm Plantations of India

ABSTRACT Adsorption isotherm and kinetic models are essential in predicting the adsorption mechanisms, which helps in boron (B) recommendation at appropriate doses. This study is formulated with the objective of assessing different kinetic and adsorption models for the adsorption of B in different soil orders (Entisol, Alfisol, Inceptisol and Vertisol) in Oil Palm plantations in India. The B adsorption in soils followed the order: Vertisol > Alfisol > Inceptisol > Entisol. The results revealed that, the Langmuir adsorption model fitted well for alfisol (part1 R2 = 0.9912 & part2 R2 = 0.9678), entisol (R2 = 0.9862) and inceptisol (R2 = 0.9924), while the Freundlich model fitted well for vertisol (R2 = 0.9943). The soils under entisol and inceptisol showed linear isotherms whereas, the vertisol and alfisol had curvilinear isotherms and the split Langmuir isotherm was worked out. High bonding energy at the lower part of split isotherm represented stronger retention of B at lower B concentrations. The B equilibrium was attained in 24 h in alfisol and inceptisol, and 12 h in entisol, whereas in vertisol, the equilibrium was not completed until 72 h. From the correlation coefficients obtained from all models, the pseudo-second-order kinetic model explained the B sorption in a better way followed by elovich and power function kinetic models in different soil types. Desorption of B is higher in entisol in most of the added B concentrations. The study suggests a higher rate of B fertilizer application than the recommended in soils having high B adsorption capacity for optimum crop growth and yield.

Secondary Enrichment of REE in Weathered Granite, South Bangka, Indonesia

Rare earth elements (REEs) are essential materials for the manufacture of advanced technology. Secondary REE indications were found in alluvial and lateritic tin deposits within Southeast Asia Tin Belt. This study aims at the REE enrichment of weathering profiles underlain by Toboali Pluton of the main range S-type granite of this belt. Granite and weathering samples were collected and analyzed using XRF, ICP-MS/OES, XRD, SEM-EDX, and EPMA. The Chondrite-normalized REE patterns of granite in Toboali showed enrichment in REE with the highest value of 1,126 ppm. The Toboali Pluton is enriched in LREE and depleted in HREE. The enrichment of REE from the upper to lower horizon of weathering profiles was pointed out by the increase in REE values from a range of 156-188 ppm (horizon B) to 196-268 ppm (horizon C) in Toboali, and from a range of 230-330 ppm (horizon B) to 342-450 ppm (horizon C) in Air Gegas. These coincided with the presence of kaolinite with elevated REE and CeO2 in horizon C of weathering profile. Leaching test result proved that kaolinite plays a role in REE enrichment in the weathering profile through ion adsorption mechanisms in the Air Gegas. The weathering process of REE fluoro-carbonate (bastnäsite-(Ce)) and parisite-(Ce) in granite is believed to contribute in enrichment due to its high dissolution rate, which enhances kaolinite adsorption. In contrast, REE phosphates such as monazite-(Ce) and xenotime-(Y), because of their strong resistance and low solubility, are thought to be only slightly soluble, and most of these minerals remain in Toboali weathering products.

Unraveling the Phosphorus Adsorption Mechanisms in Three-dimensional Reduced Graphene Oxide Materials.

To prevent eutrophication, controlling the phosphate concentration levels is one of the most important issues in surface water management. One of the most utilized methods is phosphate adsorption. However, its application faces a bottleneck due to the unclear understanding of adsorption and interaction mechanisms. The present work unlocks the phosphorus adsorption mechanisms in three-dimensional reduced graphene oxide with different reduction levels and pore sizes to remove phosphate from water using experiments and multiscale simulations. Experiments were performed to evaluate the influence of pH, ionic strength, and temperature on the adsorption. Molecular Dynamics and Ab Initio simulations evaluated the influence of the pore size and oxidation degrees of the materials. We show that the adsorption capacity of the materials increases with increasing pH and ionic strength and decreasing temperature. It is observed that the more oxidized the material and the less compact the structure, the better the adsorption. These results are theoretically explained in terms of the interaction of functional groups and the clustering of phosphate ions, which results in better adsorption in materials with larger pores. The underlying mechanisms for the 3D-reduced graphene oxide performance were confirmed by spectroscopy analysis. All the results show that 3D-reduced graphene oxide can sorb phosphate in different complex water remediation systems with characteristics that can be modulated by changing the material synthesis method.

Urban air PCDD/Fs: Atmospheric concentrations, temporal changes, gas/particle partitioning, possible sources and cancer risks

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) are pollutants of concern due to their toxic effects. No active sampling study on PCDD/Fs has been conducted in Bursa. This study aimed to fill this gap by measuring PCDD/F levels in the region. Accordingly, the samples were collected from an urban area in Bursa, covering four seasons between June 2022 and April 2023. The total (gas+particulate) ambient air concentrations were between 312.23 and 829.80 fg/m3 (mean: 555.05 ± 173.62 fg/m3). In terms of toxic equivalents (TEQ), the average concentration was 43.29 ± 9.18 fg WHOTEQ/m3. Based on the concentration values obtained, cancer and non-carcinogenic risk values of PCDD/Fs were calculated for three different age groups. The results indicated negligible health risks for all age groups. In addition, a seasonal assessment was also made and it was observed that PCDD/F concentration values varied with the ambient air temperatures. In general, higher values were measured in colder months compared to warmer months. This was probably due to the additional sources and adverse meteorological conditions. Moreover, the gas/particle partitioning of PCDD/Fs was investigated in detail. The average gas and particulate phase concentrations for PCDD/Fs were 101.81 ± 20.77 and 453.24 ± 172.50, respectively. It was found that an equilibrium state was not reached in the gas/particle partitioning. Two different gas/particle partition models based on adsorption and absorption mechanisms were compared, and the absorption model gave more consistent predictions. The Principal Component Analysis (PCA) was employed to identify the possible PCDD/F sources. The results indicated that the region was influenced by vehicle emissions, residential heating, organized industrial zones and metal recycling facilities. In addition, 72-hour backward air mass trajectory analyses were performed to understand the long-range transported air masses. However, it was found that the transported air masses did not significantly affect the concentration values measured in the sampling site.

Adsorption Capacity and Mechanism of MgO Nanomaterials Prepared by Ultrasonic Electrodeposition for Pb (II)

Adsorption Capacity and Mechanism of MgO Nanomaterials Prepared by Ultrasonic Electrodeposition for Pb (II)

Study on the adsorption mechanism of droplets on parallel flow interfaces in U-shaped microchannels

The adsorption process of deionized water droplets on the parallel flow interface between ionic liquid [BMIM][PF6] and mineral oil is investigated in U-shaped microchannels. Three flow patterns of the efficient adsorption, moderate adsorption, and inefficient adsorption based on the adsorption efficiency were observed. The dimensionless droplet length D/W > 0.72 is conducive to efficient adsorption of droplets. When droplet shape factor β > 1, the lubrication pressure generated within the curved liquid film has a more significant hindrance on the adsorption process, and the reverse lubrication pressure at the outlet of the liquid film is the main reason for the rupture of the liquid film. An increase in the velocity of phase interface A-B movement can lead to an increase in lubrication pressure. A correlation model is established between the dimensionless adsorption length L* and the dimensionless adsorption time t*, and the influence of Laplace pressure is analyzed.

Development and optimization of a polysilicon-aluminum alkali mineral-enhanced biochar composite for effective heavy metal removal in acidic environments

While traditional biochar demonstrates promising performance in diverse settings, its efficacy may be constrained under specific conditions of high acidity and heavy metal concentrations. In this study, researchers developed a new polysilicon-aluminum alkali mineral-enhanced biochar composite material, GBMSs (green biochar-metakaolin-sodium silicate), by pyrolyzing fibers from dragon fruit peels and blending them with metakaolin and sodium silicate. Using a response surface methodology, this environmentally friendly composite material was optimized for removing copper and zinc contaminants across a range of initial pH levels from 2 to 6. Experimental findings indicated that the adsorption capacity of GBMSs for copper and zinc was significantly enhanced, ranging from 1.5 to 4 times greater compared to pure biochar or biochar mixed solely with a silicon-aluminum mineral. Various analytical techniques including scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were utilized to examine the influence of poly-silica-aluminum alkali minerals (GBMSs) on biochar composites. The findings revealed an upsurge in surface binding locations and oxygen-related functional groups because of integrating GBMSs. This augmentation of electronegative features on the biochar surface was credited to the development of stabilizing silica-aluminum connections, ultimately boosting its adsorption effectiveness in acidic surroundings. By applying Langmuir and Freundlich models, it was deduced that the adsorption of GBMSs adheres to a multilayer uniform adsorption mechanism, with surface ion interchange and complexation restricting the adsorption capability. This research highlights the potential of clay mineral-altered biochar in efficiently dealing with intricate environmental contamination.

A review on sustainable management of biomass: physicochemical modification and its application for the removal of recalcitrant pollutants-challenges, opportunities, and future directions.

Adsorption is one of the most efficient methods for remediating industrial recalcitrant wastewater due to its simple design and low investment cost. However, the conventional adsorbents used in adsorption have several limitations, including high cost, low removal rates, secondary waste generation, and low regeneration ability. Hence, the focus of the research has shifted to developing alternative low-cost green adsorbents from renewable resources such as biomass. In this regard, the recent progress in the modification of biomass-derived adsorbents, which are rich in cellulosic content, through a variety of techniques, including chemical, physical, and thermal processes, has been critically reviewed in this paper. In addition, the practical applications of raw and modified biomass-based adsorbents for the treatment of industrial wastewater are discussed extensively. In a nutshell, the adsorption mechanism, particularly for real wastewater, and the effects of various modifications on biomass-based adsorbents have yet to be thoroughly studied, despite the extensive research efforts devoted to their innovation. Therefore, this review provides insight into future research needed in wastewater treatment utilizing biomass-based adsorbents, as well as the possibility of commercializing biomass-based adsorbents into viable products.

Phytic acid-functionalized polyamidoxime/alginate hydrogel for targeted uranium extraction from acidic wastewater

Efficient removal of uranium from radioactive wastewater is crucial for both environmental protection and sustainable development of nuclear energy. However, selectively extracting uranium from acidic wastewater remains a significant challenge. Here we present a phytic acid-functionalized polyamidoxime/alginate hydrogel (PAG) via a facile one-step hydrothermal reaction. The PAG, leveraging the robust binding affinity of phytic acid and the selective coordination of amidoxime for U(VI), exhibited high efficiency and selectivity in adsorbing U(VI) from acidic uranium-containing wastewater. At pH 2.50, U(VI) adsorption equilibrium was achieved within 60 min, showcasing a maximum theoretical adsorption capacity of 218.34 mg/g. Additionally, the PAG demonstrated excellent reusability, maintaining a uranium removal rate exceeding 90 % over five adsorption-desorption cycles. Remarkably, the as-synthesized PAG removed 94.1 % of U(VI) from actual acidic uranium-contaminated groundwater with excellent anti-interference performance, reducing U(VI) concentration from 272.0 μg/L to 16.1 μg/L and making it meet the WHO drinking water standards (30 μg/L). The adsorption mechanism was elucidated through XPS and DFT calculation, revealing that the uranyl ion primarily coordinated with phosphate and amidoxime groups on phytic acid and polyamidoxime, respectively. These findings underscore the promising potential of PAG hydrogel for addressing acidic uranium-containing wastewater from uranium mining and metallurgy.

Cu (II)-based metal-organic framework functionalized with graphene oxide as a sorbent for the dispersive micro-solid-phase extraction of losartan potassium from water

AbstractIn this study, a new metal–organic framework (MOF) based on copper (II) functionalized with graphene oxide (MOF-Cu@GO) was successfully synthesized and applied as an efficient sorbent for dispersive micro-solid phase extraction (D-μSPE) of losartan potassium (LP) from water. The MOF-Cu@GO sorbent was characterized using DRX, FTIR, XPS, TGA, RAMAN, BET, SEM, EDX, and potential Z. The influence of different parameters in the D-μSPE method was studied and optimized using the fractional factorial design 25–1 and central composite design. The results indicated that the adsorption process was spontaneous and endothermic followed the pseudo-second order model kinetics and the Freundlich isotherm. The maximum adsorption capacity of MOF-Cu@GO sorbent was 415 mg g−1. The adsorption mechanism proposed of LP onto MOF-Cu@GO proceeded via electrostatic interaction, hydrogen bonds, unsaturated sites of the ligand, and π-π interactions. The microextraction procedure was followed by determination of LP with high performance liquid chromatography (HPLC–UV-Vis). Under optimized conditions, the limits of detection and quantitation were found to be 25 and 80 ng ml−1 respectively, the method exhibited a linear response (r = 0.998) in the concentration range of 0.1–50 µg ml−1 of LP, with a relative standard deviation less than 2% (n = 5). The D-μSPE method showed preconcentration factor of 684.9 and high percentage of LP extraction of 99.78% ± 2.62, the accuracy of the method was demonstrated by studying the recovery of LP from water samples of 100.3 ± 1.06. The material obtained can be used up to 3 cycles with time for the sorption and determination of 30 min indicating good stability and reusability. The MOF-Cu@GO proposed is an efficient and fast sorbent in the D-μSPE for determination of LP from aqueous solutions.