Rapid and Efficient Removal of Carbamazepine from Water by UiO-67

Zirconium Metal-Organic Frameworks as Micromotors with Enzyme-like Activity for Glutathione Detection

Herein, we report a novel UiO-67-Co(bpy)0.35 micromotor synthesized by a facile postsynthesis metalation via introducing cobalt salts ligated with 2,2'-bipyridine-5,5'dicarboxylic acid into UiO-67-bpy0.35 framework. The Co2+ active sites can decompose H2O2 to generate bubbles to power UiO-67-Co(bpy)0.35. Meanwhile, the UiO-67-Co(bpy)0.35 micromotor exhibits robust peroxidase-like activity through catalyzing H2O2 to generate •OH under neutral conditions. Based on this, a sensing platform was constructed for the colorimetric detection of GSH. Due to the synergy of self-driven motion and excellent peroxide-like activity, UiO-67-Co(bpy)0.35 micromotor can sensitively detect GSH with a low analytic limitation as 0.13 μM for GSH detection. This study provides a new sight of using the postsynthesis metalation method to prepare Zr(Co)-MOF micromotor for highly selective, sensitive, and facile detection of GSH.

Defect-enabling zirconium-based metal-organic frameworks for energy and environmental remediation applications

This comprehensive review explores the diverse applications of defective zirconium-based metal-organic frameworks (Zr-MOFs) in energy and environmental remediation. Zr-MOFs have gained significant attention due to their unique properties, and deliberate introduction of defects further enhances their functionality. The review encompasses several areas where defective Zr-MOFs exhibit promise, including environmental remediation, detoxification of chemical warfare agents, photocatalytic energy conversions, and electrochemical applications. Defects play a pivotal role by creating open sites within the framework, facilitating effective adsorption and remediation of pollutants. They also contribute to the catalytic activity of Zr-MOFs, enabling efficient energy conversion processes such as hydrogen production and CO2 reduction. The review underscores the importance of defect manipulation, including control over their distribution and type, to optimize the performance of Zr-MOFs. Through tailored defect engineering and precise selection of functional groups, researchers can enhance the selectivity and efficiency of Zr-MOFs for specific applications. Additionally, pore size manipulation influences the adsorption capacity and transport properties of Zr-MOFs, further expanding their potential in environmental remediation and energy conversion. Defective Zr-MOFs exhibit remarkable stability and synthetic versatility, making them suitable for diverse environmental conditions and allowing for the introduction of missing linkers, cluster defects, or post-synthetic modifications to precisely tailor their properties. Overall, this review highlights the promising prospects of defective Zr-MOFs in addressing energy and environmental challenges, positioning them as versatile tools for sustainable solutions and paving the way for advancements in various sectors toward a cleaner and more sustainable future.

Recent advancements in modifications of metal-organic frameworks-based materials for enhanced water purification and contaminant detection

Metal-organic frameworks (MOFs) have emerged as a key focus in water treatment and monitoring due to their unique structural features, including extensive surface area, customizable porosity, reversible adsorption, and high catalytic efficiency. While numerous reviews have discussed MOFs in environmental remediation, this review specifically addresses recent advancements in modifying MOFs to enhance their effectiveness in water purification and monitoring. It underscores their roles as adsorbents, photocatalysts, and in luminescent and electrochemical sensing. Advancements such as pore modification, defect engineering, and functionalization, combined synergistically with advanced materials, have led to the development of recyclable MOF-based nano-adsorbents, Z-scheme photocatalytic systems, nanocomposites, and hybrid materials. These innovations have broadened the spectrum of removable contaminants and improved material recyclability. Additionally, this review delves into the creation of multifunctional MOF materials, the development of robust MOF variants, and the simplification of synthesis methods, marking significant progress in MOF sensor technology. Furthermore, the review addresses current challenges in this field and proposes potential future research directions and practical applications. The growing research interest in MOFs underscores the need for an updated synthesis of knowledge in this area, focusing on both current challenges and future opportunities in water remediation.

Porphyrin-Based Metal-Organic Framework Materials: Design, Construction, and Application in the Field of Photocatalysis

Metal-organic frameworks (MOFs) are a novel category of porous crystalline materials with an exceptionally high surface area and adjustable pore structure. They possess a designable composition and can be easily functionalized with different units. Porphyrins with conjugated tetrapyrrole macrocyclic structures can absorb light from ultraviolet to visible light regions, and their structures and properties can be facilely regulated by altering their peripheral groups or central metal ions. Porphyrin-based MOFs constructed from porphyrin ligands and metal nodes combine the unique features of porphyrins and MOFs as well as overcoming their respective limitations. This paper reviewed the design and construction, light absorption and charge transfer pathways, and strategy for improving the photocatalytic performance of porphyrin-based MOFs, and highlighted the recent progress in the field of CO2 reduction, hydrogen evolution, organic synthesis, organic pollutant removal, and nitrogen fixation. The intrinsic relationships between the structure and the property of porphyrin-based MOFs received special attention, especially the relationships between the arrangements of porphyrin ligands and metal nods and the charge transfer mechanism. We attempted to provide more valuable information for the design and construction of advanced photocatalysts in the future. Finally, the challenges and future perspectives of the porphyrin-based MOFs are also discussed.

π-π stack driven competitive /complementary adsorption of aromatic compounds on MIL-53(Al)

In this study, the selective adsorption of aromatic compounds on mesoporous MIL-53(Al) was investigated, and followed the order: Biphenyl (Biph) > Triclosan (TCS) > Bisphenol A (BPA) > Pyrogallol (Pyro) > Catechol (Cate) > Phenol (Phen), and exhibited high selectivity toward TCS in binary compounds. In addition to hydrophobicity and hydrogen bonding, π-π interaction/stacking predominated, and more evidently with double benzene rings. TCS-containing halogens could increase π interaction on the benzene rings via forming Cl-π stacking with MIL-53(Al). Moreover, site energy distribution confirmed that complementary adsorption mainly occurred in the Phen/TCS system, as evidenced by ΔQ^pri (the decreased solid-phase TCS concentration of the primary adsorbate) < Q^sec (the solid-phase concentrations of the competitor (Phen)). In contrast, competitive sorption occurred in the BPA/TCS and Biph/TCS systems within 30 min due to ΔQ^pri = Q^sec, followed by substitution adsorption in the BPA/TCS system, but not for the Biph/TCS system, likely attributed to the magnitude of energy gaps (E_g) and bond energy of TCS (1.80 eV, 362 kJ/mol) fallen between BPA (1.74 eV, 332 kJ/mol) and Biph (1.99 eV, 518 kJ/mol) according to the density-functional theory of Gaussian models. Biph with a more stable electronic homeostasis than TCS lead to the occurrence of substitution adsorption in the TCS/BPA system, but not in the TCS/Biph system. This study provides insight into the mechanisms of different aromatic compounds on MIL-53(Al).

Activated carbon-based pomegranate peels as an efficient removal method for carbamazepine

Pharmaceutical products found in wastewater and various water systems have become an environmental concern. Various processes were developed to remove various pharmaceuticals, including adsorption processes utilizing activated carbon adsorbents derived from agricultural wastes. The present study investigates the removal of carbamazepine (CBZ) from aqueous solutions by activated carbon (AC) derived from pomegranate peels (PGPs). The prepared AC was characterized by FTIR. The adsorption kinetics of CBZ on AC-PGPs was well represented by the pseudo-second-order kinetic model. Moreover, the data were well explained by Freundlich and Langmuir isotherm models. The effect of various parameters (including pH, temperature, CBZ concentration, the adsorbent dosage, and contact time) on the efficiency of CBZ removal by AC-PGPs was studied. The CBZ removal efficiency was not affected by changes in pH values but was slightly enhanced at the outset of the adsorption experiment with increasing temperature. The highest percentage removal efficiency was 98.0% at 23 °C when the optimum adsorbent dose was determined as 400.0 mg and the CBZ initial concentration was 20.0 mg L^-1. The general and potential applicability of this method is presented by using available agricultural wastes as a low-cost source of AC and as an efficient removal method of pharmaceuticals from aqueous solutions.

The use of agro-waste-based adsorbents as sustainable, renewable, and low-cost alternatives for the removal of ibuprofen and carbamazepine from water

The occurrence of residual pharmaceuticals in the aquatic environment poses major toxicological impacts and adds to the increasing pressure on water resources. Many countries are already suffering from water scarcity, and with the burdening costs of water and wastewater treatment, the race towards innovative sustainable strategies for pharmaceutical remediation is ongoing. Out of the available treatment methods, adsorption proved to be a promising, environmentally friendly technique, particularly when efficient waste-based adsorbents are produced from agricultural residues, thus maximizing the value of wastes, minimizing production costs, and saving natural resources from depletion. Among the residual pharmaceuticals, ibuprofen and carbamazepine are heavily consumed and highly occurring in the environment. This paper aims to review the most recent literature on the application of agro-waste-based adsorbents as sustainable alternatives for the removal of ibuprofen and carbamazepine from contaminated waters. Highlights on the major mechanisms implicated in the adsorption of ibuprofen and carbamazepine are presented, and light is shed on multiple operational parameters that hold a key role in the adsorption process. This review also highlights the effects of different production parameters on adsorption efficiency and discusses many limitations currently encountered. Finally, an analysis is included to compare the efficiency of agro-waste-based adsorbents relative to other green and synthetic adsorbents.

Recent advances in application of metal-organic frameworks (MOFs) as adsorbent and catalyst in removal of persistent organic pollutants (POPs)

The presence of persistent organic pollutants (POPs) in the aquatic environment is causing widespread concern due to their bioaccumulation, toxicity, and possible environmental risk. These contaminants are produced daily in large quantities and released into water bodies. Traditional wastewater treatment plants are ineffective at degrading these pollutants. As a result, the development of long-term and effective POP removal techniques is critical. In water, adsorption removal and photocatalytic degradation of POPs have been identified as energy and cost-efficient solutions. Both technologies have received a lot of attention for their efforts to treat the world's wastewater. Photocatalytic removal of POPs is a promising, effective, and long-lasting method, while adsorption removal of persistent POPs represents a simple, practical method, particularly in decentralized systems and isolated areas. It is critical to develop new adsorbents/photocatalysts with the desired structure, tunable chemistry, and maximum adsorption sites for highly efficient removal of POPs. As a class of recently created multifunctional porous materials, Metal-organic frameworks (MOFs) offer tremendous prospects in adsorptive removal and photocatalytic degradation of POPs for water remediation. This review defines POPs and discusses current research on adsorptive and photocatalytic POP removal using emerging MOFs for each type of POPs.

Removal of organic micropollutans by adsorptive membrane

Various emerging organic micropollutants, such as pharmaceuticals, have attracted the interest of the water industry during the last two decades due to their insufficient removal during conventional water and wastewater treatment methods and increasing demand for pharmaceuticals projected to climate change-related impacts and COVID-19, nanosorbents such as carbon nanotubes (CNTs), graphene oxides (GOs), and metallic organic frameworks (MOFs) have recently been extensively explored regarding their potential environmental applications. Due to their unique physicochemical features, the use of these nanoadsorbents for organic micropollutans in water and wastewater treatment processes has been a rapidly growing topic of research in recent literature. Adsorptive membranes, which include these nanosorbents, combine the benefits of adsorption with membrane separation, allowing for high flow rates and faster adsorption/desorption rates, and have received a lot of publicity in recent years. The most recent advances in the fabrication of adsorptive membranes (including homogeneous membranes, mixed matrix membranes, and composite membranes), as well as their basic principles and applications in water and wastewater treatment, are discussed in this review. This paper covers ten years, from 2011 to 2021, and examines over 100 published studies, highlighting that micropollutans can pose a serious threat to surface water environments and that adsorptive membranes are promising, particularly in the adsorption of trace substances with fast kinetics. Membrane fouling, on the other hand, should be given more attention in future studies due to the high costs and restricted reusability.

Phenylamine/Amide Grafted in Silica as Sensing Nanocomposites for the Removal of Carbamazepine: A DFT Approach

This study aimed to remove carbamazepine from aqueous solutions, using functional silica phenylamine (SiBN), which is characterized and showed excellent chemical and thermal stability. Adsorbents based on silica were developed due to their unusually large surface area, homogenous pore structure, and well-modified surface properties, as silica sparked tremendous interest. It was determined to develop a novel silica adsorbent including phenylamine and amide (SiBCON). The adsorbents obtained were analyzed by various spectroscopy devices, including SEM, FT-IR and TGA analysis. The maximum removal rates for carbamazepine were 98.37% and 98.22% for SiBN and SiBCON, respectively, when optimized at room temperature, pH 9.0, initial concentration of 10 mg·L−1 and contact time of 15 min. Theoretical tools are widely used in the prediction of the power of interactions between chemical systems. The computed data showed that new amine modified silica is quite effective in terms of the removal of carbamazepine from aqueous solution. Calculation binding energies and DFT data showed that there is a powerful interaction between amine-modified silica and carbamazepine.

Folic Acid-Functionalized Metal-Organic Framework Nanoparticles as Drug Carriers Improved Bufalin Antitumor Activity Against Breast Cancer

Bufalin (Buf), an active ingredient of the traditional Chinese medicine Chansu, is known to have anticancer effects for breast cancer. However, its poor solubility, high toxicity, and extensive side effects limit its use. Metal-organic frameworks (MOFs) are a class of promising drug delivery systems known for their high porosity. Here, we designed and constructed pH-sensitive and redox-responsive folic acid–modified MOFs as drug carriers of Buf (FA-MOF/Buf). Moreover, the anticancer activity of nanomedicines was also explored in vitro and in vivo. Compared to free Buf, the FA-MOF/Buf nanoparticles demonstrated improved water solubility and stability, higher intracellular uptake, and enhanced cytotoxicity in breast cancer cells in vitro. Furthermore, it displayed improved accumulation in the tumor site, enhanced anticancer activity, and reduced side effects in vivo. Our results demonstrated that FA-MOF could be developed as a potential delivery system for Buf to improve its antitumor activity for breast cancer treatment.

Adsorptive removal of dyes from wastewater using a metal-organic framework: A review

Water pollution from synthetic dyes is a growing environmental concern because many dyes have carcinogenic effects on humans and aquatic life. Adsorption is a widely used technology for the separation and removal of dyes from wastewater. However, the dye removal process using conventional adsorbents is not sufficiently efficient for industrial wastewater. Metal-organic frameworks (MOFs) addresses these drawbacks. MOF showed excellent dye removal and degradation capacity owing to its multifunctionality, water-stability, large surface area, tunable pore size and recyclability. Magnetic MOFs retained excellent performance up to several consecutive cycles. Modified MOFs performed as Fenton-like catalysis process which generated abundant reactive radicals that degraded complex organic dyes into simple and less toxic forms which were further adsorbed onto the MOF. This review systematically compiles in-depth studies on the adsorptive removal of dyes from wastewater, MOF adsorption mechanisms, major influencing factors, to adsorption efficiency of MOFs. While all MOFs adsorb dyes through electrostatic attraction, the type of MOF, presence of functional groups, ligands, and pH significantly control the adsorption mechanism. Before developing an MOF, optimization and upgradation of factors and interaction between available adsorption site and adsorbate is needed. Finally, the prospects and new frontiers of MOFs in sustainable water treatment is discussed.

Effects of electrolytes and fractionated dissolved organic matter on selective adsorption of pharmaceuticals on terephthalic acid-based metal-organic frameworks

In this study, we investigated the synergetic effects of coexisting electrolytes and dissolved organic matter (DOM) on Carbamazepine (CBZ) and Ciprofloxacin (CIP) adsorption on the 1D flexible structure of MIL-53(Al) and 3D rigid structure of UiO-66(Zr). The effects of electrolytes on the adsorption of CBZ and CIP on 1D flexible framework of MIL-53(Al) were more significant than those observed from the 3D framework of UiO-66(Zr). The presence of sulfate, nitrate, and phosphate anions indicates high potential to promote the adsorption of CBZ and CIP onto MIL-53(Al) and UiO-66(Zr) because of the decrease of solubility and strengthening of electrostatic interactions by substitution of oxo-anions at the metal complex node via covalent bonding. The lower hydration energy of the potassium ion enhanced CBZ adsorption on MIL-53(Al), while the higher hydration energy of calcium and magnesium ions reduced the adsorption capacity of CBZ and CIP on MIL-53(Al) and UiO-66(Zr). CBZ interacted with fractionated humic acid better than CIP. High-density carboxylic and aromatic functional groups on humic acid ensured that only humic acid larger than 1KDa was adsorbed by MIL-53(Al). Tryptophan-like and humic acid-like DOM were both detected in real hospital effluent, and their effects on CIP and CBZ adsorption onto MIL-53(Al) were investigated. The presence of tryptophan did not affect CBZ adsorption on MIL-53(Al) (except when coexisting with calcium ions). Conversely, tryptophan interfered with CIP adsorption. The presence of humic acid lower than 1KDa promoted the adsorption of CBZ and CIP by increasing the breathing effect of MIL-53(Al)'s 1D flexible framework. The presence of humic acid with molecular size greater than 1KDa enhanced both CBZ and CIP adsorption via a multilayer adsorption mechanism.

Advanced applications of Zr-based MOFs in the removal of water pollutants

The global water pollution is caused by the increase of industrial and agricultural activities, which have produced various toxic pollutants. Pollutants in water generally consist of metal ions, pharmaceuticals and personal care products (PPCPs), oil spills, organic dyes, and other organic pollutants. Amongst the adsorbents that have been developed to deal with pollutants in water, Zr-based metal-organic frameworks (MOFs) have drawn scientists' great attention due to their excellent stability and adjustable functionalization. Herein, the present review article introduces the synthetic methods of functionalized Zr-based MOFs and summarizes their applications in water pollution treatment. It also clarifies the interactions and removal mechanisms between pollutants and Zr-based MOFs. The use of these MOFs with eminent adsorption ability and recycling performance have been discussed in detail. Zr-based MOFs also face some challenges such as high cost, lack of real water environment applications, selective removal of pollutants, and low ability to remove composite pollutants. Future research should focus on addressing these issues. Although there is still a blank of the practical utility of Zr-based MOFs on a commercial scale, the research reported to date clearly shows that they are very promising materials for the water treatment.

Silica-clay nanocomposites for the removal of antibiotics in the water usage cycle

The increasingly frequent detection of resistant organic micropollutants in waters calls for better treatment of these molecules that are recognized to be dangerous for human health and the environment. As an alternative to conventional adsorbent material such as activated carbon, silica-clay nanocomposites were synthesized for the removal of pharmaceuticals in contaminated water. Their efficiency with respect to carbamazepine, ciprofloxacin, danofloxacin, doxycycline, and sulfamethoxazole was assessed in model water and real groundwater spiked with the five contaminants. Results showed that the efficacy of contaminant removal depends on the chemical properties of the micropollutants. Among the adsorbents tested, the nanocomposite made of 95% clay and 5% SiO₂ NPs was the most efficient and was easily recovered from solution after treatment compared with pure clay, for example. The composite is thus a good candidate in terms of operating costs and environmental sustainability for the removal of organic contaminants.

Adsorptive removal of pharmaceuticals from water using metal-organic frameworks: A review

Pharmaceutical pollution has emerged as a highly concerned issue due to its adverse effects. Elevated concentrations of pharmaceuticals in water should be regulated to satisfy the requirement for the provision of clean water. Metal-organic frameworks (MOFs) with high specific surface area, controllable porous structure, and facile modification can serve as promising adsorbents for the removal of pharmaceutical contaminants from water. In this review, a selected collection illustrating the reliable strategies and concepts to prepare the MOFs-based materials with superior water stability is described. In addition, recent progress on the adsorptive removal of pharmaceutical pollutant using burgeoning and functional MOFs is also summarized in terms of maximum capacity, equilibrium time, and regenerate ability. Meanwhile, to understand the adsorption mechanism, related interactions including coordination with unsaturated site, pore-filling effect, hydrogen bonding, electrostatic, and π-π stacking are further discussed. Finally, critical perspectives/assessment of future research emphasising on fabricating desirable MOFs and establishing structure-property relationships to facilitate capture performance are identified.

Adsorption and removal of a selected emerging contaminant, carbamazepine, using Humic acid, Humasorb and Montmorillonite. Equilibrium isotherms, kinetics and effect of the water matrix

Carbamazepine is an antiepileptic drug that is not easily degraded in the environment. In this study, the removal of carbamazepine, an emerging contaminant, dissolved in deionized water and wastewater matrices by means of their adsorption onto Humic Acid, Humasorb and Montmorillonite was investigated. The effect of various parameters including adsorption time, adsorbent dosage, and initial adsorbate concentration was determined. The optimum exposure time for the removal of carbamazepine by Humic Acid was 30 min and by Humasorb and Montmorillonite were 2 h, in both distilled and wastewater. The maximum percent removal of carbamazepine by Humic Acid, Humasorb and Montmorillonite in deionized water was 90.5 ± 3.1%, 85.2 ± 2.3% and 83.8 ± 4.5% and in wastewater was 87.0 ± 1.5%, 87.3 ± 5.1% and 78.2 ± 1.2%, respectively, when the initial concentration of carbamazepine was 20 µg/mL and the mass of absorbent 100 mg in 10 mL samples. Three isotherms models including Langmuir, Freundlich, and Elovich were applied to the experimental data. It was found that the adsorption isotherms for the two adsorbents best matched Langmuir model indicating surface adsorption from deionized water (R²= 0.986 for Humic Acid, R² = 0.955 for Humasorb and R² = 0.865 for Montmorillonite) as well as from wastewater (R² = 0.893 for Humic Acid, R² = 0.949 for Humasorb and R² = 0.984 for Montmorillonite). According to the kinetic studies, the pseudo-second-order kinetic model better fits to the removal of carbamazepine by the three adsorbents from both water matrices. However, pseudo-second-order model cannot exclusively explain the experimental data trend, but it could be explained by diffusion.

Removal performance and optimisation of pharmaceutical micropollutants from synthetic domestic wastewater by hybrid treatment

Occurrence of pharmaceutical micropollutants in aquatic environments has been one amongst serious environmental problems. During this study, two reactors, including a sequencing batch reactor (SBR) + powdered composite adsorbent (CA) (first reactor, SBR + CA) and a sequencing batch reactor (second reactor, SBR), were designed to treat synthetic wastewater. Powdered CA was added with a dosage of 4.8 g L^-1 to the first reactor. Tap water was contaminated with chemical oxygen demand (COD), ammonia and three pharmaceuticals, namely, atenolol (ATN), ciprofloxacin (CIP) and diazepam (DIA) to produce synthetic wastewater. The SBR + CA illustrated a better performance during synthetic municipal wastewater treatment. Up to 138.6 mg L^-1 (92.4%) of COD and up to 114.2 mg L^-1 (95.2%) of ammonia were removed by the first reactor. Moreover, optimisation of pharmaceuticals removal was conducted through response surface methodology (RSM) and artificial neural network (ANN). Based on the RSM, the best elimination of ATN (90.2%, 2.26 mg L^-1), CIP (94.0%, 2.35 mg L^-1) and DIA (95.5%, 2.39 mg L^-1) was detected at the optimum initial concentration of MPs (2.51 mg L^-1) and the contact time (15.8 h). In addition, ANN represented a high R² value (>0.99) and a rational mean squared error (<1.0) during the optimisation of micropollutants removal by both reactors. Moreover, adsorption isotherm study showed that the Freundlich isotherm could justify the abatement of micropollutants by using CA better than the Langmuir isotherm.

Insights to perfluorooctanoic acid adsorption micro-mechanism over Fe-based metal organic frameworks: Combining computational calculation with response surface methodology

Adsorption performance, interfacial interaction mechanism and contribution of pores concerning PFOA adsorption to Fe-based metal-organic frameworks (MOFs) including Fe-BTC, MIL-100-Fe and MIL-101-Fe are investigated using experiments and computational calculation at molecular level even electronic level. Fe-BTC (418 mg/g) with more Lewis acid sites demonstrates higher adsorption capacity of PFOA in comparison with MIL-100-Fe (349 mg/g) and MIL-101-Fe (370 mg/g). Adsorption isotherms and kinetics indicate presence of monolayer adsorption and chemisorption in adsorption process. The pH dependence of PFOA adsorption to Fe-based MOFs is statistically revealed by experiments and analysis of variance of response surface methodology (RSM). XPS spectra of MOF-PFOA corroborate that decreasing binding energy of Fe2p and increasing binding energy of F1s, suggesting the presence of Lewis acid/base complexing (LAB) and hydrophobic interaction in adsorption process. Differential charge demonstrates that Fe center and benzene of organic ligands are respectively electron acceptor and donor in adsorption process. Electronic level mechanism finds that LAB complexing dominates adsorption process due to highest overlap of electron cloud. Smaller pores such as triangle and pentagonal pores of Fe-based MOFs contribute to the load of PFOA, while larger hexagonal one enable PFOA to enter into cages, as revealed by computational calculation.

Cross-linked chitosan/zeolite as a fixed-bed column for organic micropollutants removal from aqueous solution, optimization with RSM and artificial neural network

Organic micropollutants (MPs) in low concentrations can affect aquatic ecosystems and human health. Adsorption technique is one of the promising methods to remove MPs. Chitosan and zeolites are environmentally friendly and low-cost adsorbents. Thus, removal of organic MPs (such as bisphenol A (BPA), carbamazepine (CBZ), ketoprofen (KTF) and tonalide (TND) from aqueous solution via cross-linked chitosan/zeolite, as a fixed-bed column, was investigated in the current study. Hydraulic retention time was set at 0.8 h pH and concentration of organic MPs ranged from 4 to 8 and 0.50 mg/L to 2.0 mg/L, and they were considered as factors in optimizing the removal of pollutants via response surface methodology (RSM). Approximately 1.4560 mg/L (89.0%) of BPA, 1.4724 mg/L (90.0%) of CBZ, 1.4920 mg/L (91.2%) of KTF and 1.4118 mg/L (86.3%) of TND were removed at 5.1 pH and 1.636 mg/L initial concentration as the optimum removal efficiency on the basis of RSM. Artificial neural network (ANN) was used to optimise removal effectiveness for each MP. The high R² values and reasonable mean squared errors indicated that ANN optimized MP removal in a logical aspect. Adsorption isotherm studies revealed that organic MP removal through chitosan/zeolite could be explained with Freundlich and Langmuir isotherms.

Mechanistic insight into the adsorption of diclofenac by MIL-100: Experiments and theoretical calculations

The development of high-efficiency adsorbents and the exploration of their adsorption mechanisms are major challenges in environmental remediation. Herein, MIL-100 was prepared, characterized, and utilized for the adsorptive removal of diclofenac sodium (DCF) from aqueous solutions. A high monolayer adsorption capacity of 773 mg g^-1 was recorded. The adsorption mechanism was proposed based on different contributions of two types of pore structure of MIL-100 to the adsorption of DCF from aqueous solutions according to the experimental results and theoretical calculation. During adsorption process, DCF (5.2 × 7.4 × 10.3 Å) diffused through the free area of hexagonal pores (8.6 × 8.6 Å) into the cages of MIL-100, whilst it was adsorbed by the pentagonal pores (4.8 × 5.8 Å) preferentially. Internal mass transfer resistance, which was identified as one of the dominant rate-limiting steps by the mass transfer resistance kinetic models based on the Sips model, will be derived from the diffusion process, which was affected by the size-sieving effect of the pore structure of MIL-100. The successful diffusion of DCF into the interior of MIL-100 and the stable configuration between MIL-100 and DCF accounted for the high adsorption capacity. The capture of DCF into MIL-100 also resulted in the pore size distribution variation of adsorbent, which provided vital experimental evidence for the proposed mechanism. This study may offer deeper insights into other pollutants removal by metal-organic frameworks type adsorbents.

An Easy Synthesis for Preparing Bio-Based Hybrid Adsorbent Useful for Fast Adsorption of Polar Pollutants

For the first time, γ-Al₂O₃ and Bio-Based Substances (BBS) hybrids (A-BBS) were prepared through a simple electrostatic interaction occurring between alumina, used as a support, and BBS (Bio-Based Substance from composted biowastes) carrying positive and negative charges, respectively. We evaluated the optimal amount of BBS to be immobilized on the support and the stability of the resulting A-BBS in order to use this novel hybrid material as an adsorbent for the removal of polar pollutants. Characterization was carried out by X-Ray Diffraction (XRD) for evaluating the crystal structure of the support, Fourier transform infrared spectroscopy (FT-IR) to evidence the presence of BBS on the hybrid material, thermogravimetric analysis (TGA) to measure the thermal stability of the hybrid materials and quantify the BBS amount immobilized on the support, N₂ adsorption at 77 K for the evaluation of the surface area and porosity of the systems, Zeta potential measurements to evaluate the effect of BBS immobilization on the surface charge of the particles and choose the substrates possibly interacting with them. Firstly, we tested the adsorption capability of three samples differently coated with BBS toward cationic species considering various adsorbate/adsorbent ratio. Crystal Violet (CV) was chosen as model pollutant to compare the performance of the hybrid materials with those of other materials described in the literature. The adsorption data were modeled by Langmuir and Freundlich adsorption isotherms. Then, we studied the adsorption capability of the developed material towards molecules with different structures; for this purpose, two contaminants of emerging concerns (carbamazepine and atenolol) were tested. The results indicate that A-BBS could be applied in wastewater treatment for the removal of a significant amount of polar species. In addition, a comparison with literature data concerning CV adsorption was carried out in order to evaluate the environmental impact of synthetic routes used to prepare different adsorbents.

Determination of carbamazepine in urine and water samples using amino-functionalized metal-organic framework as sorbent

A stable and porous amino-functionalized zirconium-based metal organic framework (Zr-MOF-NH₂) containing missing linker defects was prepared and fully characterized by FTIR, scanning electron microscopy, powder X-ray diffraction, and BET surface area measurement. The Zr-MOF-NH₂ was then applied as an adsorbent in pipette-tip solid phase extraction (PT-SPE) of carbamazepine. Important parameters affecting extraction efficiency such as pH, sample volume, type and volume of eluent, amount of adsorbent, and number of aspirating/dispensing cycles for sample solution and eluent solvent were investigated and optimized. The best extraction efficiency was obtained when pH of 100 µL of sample solution was adjusted to 7.5 and 5 mg of the sorbent was used. Eluent solvent was 10 µL methanol. Linear dynamic range was found to be between 0.1 and 50 µg L⁻¹ and limit of detection for 10 measurement of blank solution was 0.05 µg L⁻¹. This extraction method was coupled to HPLC and was successfully employed for the determination of carbamazepine in urine and water samples. The strategy combined the advantages of fast and easy operation of PT-SPE with robustness and large adsorption capacity of Zr-MOF-NH₂.