Electron Donor-acceptor Interactions Research Articles

Knowledge graph and development hotspots of biochar as an emerging aquatic antibiotic remediator: A scientometric exploration based on VOSviewer and CiteSpace

As an emerging material in the field of environmental remediation, biochar produced by carbonisation of organic solid waste has been widely used in the remediation of antibiotic wastewater due to its environmental friendliness and excellent adsorption properties. This study analyses the current literature in the field in a comprehensive and scientific manner using CiteSpace and VOSviewer technologies. Between 2011 and 2023, a total of 1162 papers were published in this domain, spanning three distinct stages: applied methods, mechanism investigation, and enhanced improvement. The results of keyword clustering indicate that the remediation of antibiotics complexed with multiple pollutants by biochar is the main research topic, followed by the remediation of antibiotics by biochar in combination with other technologies. Furthermore, drawing from current research hotspots in antibiotic remediation using biochar, this study identified the pivotal mechanisms involved: (1) The primary mechanisms by which raw biochar remediates antibiotics include π-π electron donor-acceptor interactions, hydrophobic interactions, electrostatic interactions, hydrogen-bonding, and pore filling. (2) Steam activation, acid/base, metal salt/metal oxide, and clay mineral modification can improve the physical/chemical properties of biochar, enhancing its adsorptive removal of antibiotics. (3) Biochar activated persulfate and degraded antibiotics via free radical pathways (SO4−•, •OH and O2−•) as well as non-free radical pathways (1O2 and electron transfer). In addition, the challenge and prospect of biochar engineering applications for antibiotic remediation lies in improving the main mechanism of antibiotic remediation by biochar. The prospective utilization of biochar in enhancing the remediation of antibiotic-related pollutants holds tremendous value for the future.

Preparation of imprinted phenol gel with ultra-high adsorption capacity based on porous biochar: 5-stage tandem column, response surface method, and mechanism analysis

Wastewater from industries like petroleum refining and pharmaceuticals contains high levels of phenolic compounds. Discharging this untreated wastewater can severely pollute water bodies. To address this issue, a biochar-based composite imprinting phenol gel(MgNBC@MIP) was designed to effectively remove phenolic compounds and control phenol levels in water environments. The adjustment of the aromatic structure and pore architecture of the biochar effectively enhanced its affinity for phenolic compounds. Subsequently, the individual effects of factors such as pH, salt, and humic acid on adsorption were explored. Optimization of the adsorption process was carried out using a four-factor, three-level response surface method, yielding a theoretical formula for the adsorption amount, with a maximum adsorption capacity of 308.311 mg/g. Moreover, the adsorption of phenol and its derivatives by MgNBC@MIP followed the Langmuir isothermal model and the PSO kinetic model. A comprehensive mechanism analysis elaborated in detail on the diffusion and adsorption process of phenol from the aqueous phase to the adsorption site. Correlation FTIR and XPS analysis confirmed that π-π electron donor–acceptor interactions, hydrogen bonding, pore filling, and metal complexation were the primary driving forces for phenol adsorption. Significantly, MgNBC@MIP exhibited good reusability in the adsorption–desorption cycle. The design of a five-stage tandem column adsorption experiment opens up avenues for the industrial application of MgNBC@MIP.

Effective strategy for alleviation of oil contamination in marine via the superhydrophobic biochar: Performances, mechanisms and environmental recalcitrance

The performance of layered double hydroxides (LDH)-biochar composite on alleviating oil spill pollution is poorly understood. A superhydrophobic biochar (NCY) was synthesized from the pristine wood chips biochar (WCB) after the surface deposition of NiCo-LDH (NCB) and hydrophobic modification with stearate. The oil removal potential of the designed biochars was investigated via the diesel oil/crude oil adsorption experiments and the environmental recalcitrance evaluation. The compared characterization results revealed that NiCo-LDH was successfully deposited onto biochar matrix via the electrostatic attraction and pore filling effect, which facilitated a special flower-like hierarchical architecture rough surface for biochar and hinder the multi-layer stacking of LDH. Benefit from the constructed hierarchical architecture, the occupancy of oxygen-containing functional groups and hydrophobic modification of stearate, the water contact angle of NCY (156°) was remarkably larger than NCB (117°) and WCB (50.1°), which exhibit a superhydrophobic. The maximum diesel oil sorption capacities of biochars increased from 3.28 g/g in WCB to 5.64 g/g in NCB and 11.6 g/g in NCY, as well as the maximum crude oil sorption capacities of biochars showed a similar trend (WCB: 4.64 g/g, NCB: 8.74 g/g, NCY: 18.6 g/g). Accordingly, NCY showed higher oil adsorption capacity than NCB and WCB mainly due to the enhanced hydrophobic forces and the π-π electron donor-acceptor interaction resulted from lower amount of O-containing functional groups and superhydrophobic surface wettability. Furthermore, the application of LDH remarkably improved the environmental recalcitrance of biochar (resist to the chemical oxidation and thermal decomposition in marine) due to the coating of NiCo-LDH could enhance the bulk stability of biochar and increase the liable carbon content in biochar. This study proved that the application of NiCo-LDH and stearate could be an effective approach for improve the oil pollution remediation capacity and the environmental recalcitrance of biochar.

Selective adsorption of anionic dyes by a macropore magnetic lignin-chitosan adsorbent

Dyes pollution is well known for their hazardous impacts on human health and the environment. The removal of dyes from wastewater has become an important issue. In this study, magnetic micrometer-sized particles AL-CTS@MNPs were synthesized from alkaline lignin (AL) and chitosan (CTS) by “one-pot method”. The adsorbent presented higher selectivity adsorption effect on anionic dyes than amphoteric and cationic dyes, and even no adsorption effect on cationic methylene blue (MB), which showed that the anionic dyes could be better separated from the other two types of dyes. The adsorption isotherms of the dyes were highly consistent with the Langmuir model, and the maximum adsorption capacity was 329.50 mg/g for methyl orange (MO) and 20.00 mg/g for rhodamine B (RhB). AL-CTS@MNPs showed good adsorption of anionic dyes (MO) in the pH range of 3–9. Meanwhile, the adsorbent AL-CTS@MNPs were also characterized, showing rough surface with specific surface areas of 37.38 m2/g, pore diameter of 95.8 nm and porosity of 17.62 %. The particle sizes were ranged from 800 μm to 1300 μm. The electrostatic attraction and π-π* electron donor-acceptor interactions were the main forces between the adsorbent and anionic dyes. While the electrostatic repulsive force between the adsorbent and the cationic dyes resulted in the non-absorption of MB by AL-CTS@MNPs. Subsequently, the adsorbent maintained a removal rate of >95 % after five adsorption-desorption cycles, demonstrating its excellent stability and recoverability. Ultimately, the prepared AL-CTS@MNPs illuminated good prospect on complex components dyes wastewater treatment.

Exploring the adsorption of five emerging pollutants on activated carbon: A theoretical approach

The identification and management of contaminants of emerging concern (CECs) in water systems is crucial for protecting public and environmental health. This paper reports a theoretical approach to studying the adsorption of five CECs: Atrazine (ATZ), Caffeine (CAF), Carbamazepine (CBZ), Sulfamethoxazole (SMX), and Ibuprofen (IBU) - onto Activated Carbon (AC). A set of computational methods, including electrostatic molecular potential maps, conceptual density functional theory, Fukui functions, thermodynamic analysis, and tight-binding molecular dynamics simulations, were employed to analyze the electronic/energetic interactions and mechanisms involved in the adsorption of CECs on AC. The theoretical methodology offered valuable predictions on reactivity sites, stability, and binding mechanisms. Results showed that adsorption primarily occurred through non-covalent interactions like π-π electron donor-acceptor interactions, van der Waals forces, and hydrophobic interactions. Thermodynamic properties suggested the adsorption process was spontaneous and exothermic. However, for the AC/SMX system, the Gibbs free energy reveals that adsorption may be unfavorably compared to the other study systems. Molecular dynamics simulations validated the kinetic stability in the following order CAF (0.13 Å)>CBZ (0.23 Å)>ATZ (0.75 Å)> IBU (1.28 Å)>SMX (1.54 Å). This exploratory theoretical study provides a deep understanding of the interactions between AC and five CECs, aiding in the rational design and optimization of AC-based treatment systems for environmental and industrial applications.

Removal of pesticide acetamiprid using KOH activated biochar derived from crayfish shell: Behavior and mechanism

Over the past few decades, the excessive use of pesticides has resulted in serious environment pollution, and residual pesticides prompt significant concern regarding their potential harm to both the ecological security and human health. In this study, KOH activated crayfish shell biochar (KBC) was successfully prepared and used to effectively remove acetamiprid (ACE) and triadimefon (TDM) from aqueous solutions. Batch experiments results indicated that, the adsorption process of ACE was predominantly by chemical reaction and controlled by multiple mechanisms, and ACE adsorption was a thermodynamically spontaneous and exothermic reaction. The KBC exhibited exceptional adsorption performance in removing ACE with a maximum adsorption capacity of 40.41 mg g−1. A superior adsorption capacity toward both ACE and TDM over KBC could be achieved at lower concentration levels, and KBC exhibited good reuse for the removal of ACE and TDM. Different adsorption models and characterization results revealed the adsorption mechanism of ACE and TDM by KBC, including van der Waals forces, pore filling, hydrogen bonding, and π-π electron donor-acceptor interactions. These findings suggested that KBC was an excellent adsorbent for removing pesticide-contaminated water.

Disclosing the intrinsic nature of efficient removal of antibiotics in N/S dual-doped porous carbon-based materials: The manipulation of internal electric field

N/S co-doping has emerged as a prevailing strategy for carbon-based adsorbents to facilitate the antibiotic removal efficiency. Nevertheless, the underlying interplay among N, S, and their adjacent vacancy defects remains overlooked. Herein, we present a novel in situ strategy for fabricating pyridinic-N dominated and S dual-doped porous carbon adsorbent with rich vacancy defects (VNSC). The experimental results revealed that N (acting as the electron donor) and S (acting as the electron acceptor) form an internal electric field (IEF), with a stronger IEF generated between pyridinic-N and S, while their adjacent vacancy defects activate carbon π electrons, thus enhancing the charge transfer of the IEF. Density functional theory (DFT) calculations further demonstrated that the rich charge transfer in the IEF facilitated the π-π electron donor-acceptor (EDA) interaction between VNSC and tetracycline (TC) as well as norfloxacin (NOR), and thus is the key to adsorption performance of VNSC. Consequently, VNSC exhibited high adsorption capacities toward TC (573.1 mg g−1) and NOR (517.0 mg g−1), and its potential for environmental applications was demonstrated by interference, environmentally relevant concentrations, fixed-bed column, and regeneration tests. This work discloses the natures of adsorption capacity for N/S dual-doped carbon-based materials for antibiotics.

One-pot synthesis of ultrahigh surface area porous carbon from coal tar residue: Characterization and application in phenol removal

Coal tar residue (CTR) is a hazardous industrial waste and its appropriate disposal evokes great concerns. In this work, superb surface area porous carbon was synthesized from extracted residue in CTR through one-pot KOH chemical activation and applied for phenol adsorption. Results revealed that micro-mesoporous porous carbon (MPC-3–850) with ultrahigh specific surface area of 5465 m2/g, and multiple oxygen-containing functional groups was synthesized at optimized conditions (mass proportion of KOH/MCTR was 1:3, pyrolysis temperature was 850℃). Adsorption results showed that the optimized absorbent dosage was 2 g/L, and adsorptive equilibrium time was 120 min. Maximum adsorption capacity of MPC-3–850 in experiment was reached higher than 360 mg/g and decreased at elevated temperatures. Near neutral conditions (pH=6–8) and lower co-existing ions (Mg2+, K+, Na+) strength had a slightly effect on adsorption performance. Adsorption process adhered to pseudo-second-order kinetic and Freundlich isotherm models, and was exothermic and spontaneous. The adsorption mechanism included pore filling, van der Waals forces, electron donor-acceptor interaction, hydrogen-bonding interaction, and π-π interaction. MPC-3–850 had a good ability to adsorb phenol in real coke wastewater and excellent adsorption capacity after 4 desorption-adsorption cycles.

Investigation the existence and mechanism of Cu(II)-sulfamethoxazole co-pollution by road-deposited sediments in stormwater runoff

In recent years, the escalating attention on Pharmaceutical and Personal Care Products (PPCPs) and Heavy Metals in urban stormwater runoff highlights the critical role of Road-deposited sediments (RDS) as a significant carrier for pollutant occurrence and transport in runoff. However, existing research has overlooked the composite characteristics of PPCPs and Heavy Metals, hampering a holistic understanding of their transformation in diverse forms within runoff. This limitation impedes the exploration of their subsequent migration and conversion properties, thereby obstructing coordinated strategies for the control of co-pollution in runoff. This study focuses on the typical PPCP sulfamethoxazole (SMX) and heavy metal Cu(II) to analyze their occurrence characteristics in the Runoff-RDS system. Kinetics and isotherm studies reveal that RDS effectively accumulates SMX and Cu(II), with both exhibiting rapid association with RDS in the early stages of runoff. The accumulation of SMX and Cu(II) accounts for over 80 % and 70 % of the total accumulation within the first 240 min and 60 min, respectively. Moreover, as runoff pH values decrease, the initially synergistic effect between the co-pollutant transforms into an antagonistic effect. In the composite system, varying pH values from 2.0 to 6.0 lead to an increase in SMX accumulation from 4.01 mg/kg to 6.19 mg/kg and Cu(II) accumulation from 0.43 mg/g to 3.39 mg/g. Compared to the single system, the composite system capacity for SMX and Cu(II) increases by 0.04 mg/kg and 0.33 mg/g at pH 4.0. However, at pH 3.0, the composite system capacity for SMX and Cu(II) decreases by 0.21 mg/kg and 0.36 mg/g, respectively. Protonation/deprotonation of SMX under different pH conditions influences electrostatic repulsion/attraction between SMX and RDS. The mechanism of RDS accumulation of SMX involves Electron Donor-Acceptor (EDA) interaction, hydrogen bond interaction, and Lewis acid-base interaction. Cu(II) enrichment on RDS includes surface complexation reaction, electrostatic interaction, and surface precipitation. Complex formation enhances the accumulation of both SMX and Cu(II) on RDS in runoff. This study elucidates the co-occurrence characteristics and mechanisms of SMX and Cu(II) co-pollution in runoff systems. The findings contribute valuable insights to understanding the existence patterns and mechanisms of co-pollution, providing a reference for investigating the migration and fate of co-pollutant in runoff. Moreover, these insights could offer guidance for the development of effective strategies to mitigate co-pollution in rainwater.

Preparation of Chladophora‐Based Biochar and Its Adsorption Properties for Antibiotics

AbstractThe biochar prepared by Chladophora (CB) was used to adsorb the ibuprofen and ofloxacin in sewage. SEM showed that CB preserved the natural tubular structure and increased its specific surface area. According to the BET results, the specific surface area of CB was 296.831 m2 g‐1. The adsorption of ibuprofen and ofloxacin on biochar conformed to the pseudo second‐order kinetic model, indicating that their adsorption rate was controlled by the chemical adsorption mechanism. According to the adsorption isotherms study, the adsorption of ibuprofen on CB met the Dubin‐Radushkevich model, while it fitted well with the Freundlich model for ofloxacin adsorption, making their adsorption onto biochar relating to non‐uniform surface and adsorption layer, respectively. The pore filling and electrostatic interaction were considered the main mechanism for the adsorption of pharmaceuticals and personal care products on CB, whereas the π‐π electron donor acceptor (EDA) interaction and hydrogen bond would also partially contribute to the adsorption process.

Adsorption Properties of Magnetic Phosphorous Camellia Oleifera Shells Biochar to Sulfamethoxazole in Water

Magnetic phosphorous biochar （MPBC） was prepared from Camellia oleifera shells using phosphoric acid activation and iron co-deposition. The materials were characterized and analyzed through scanning electron microscopy （SEM）， X-ray diffractometry （XRD）， specific surface area and pore size analysis （BET）， Fourier infrared spectroscopy （FT-IR）， and X-ray photoelectron spectroscopy （XPS）. MPBC had a high surface area （1 139.28 m2·g-1） and abundant surface functional groups， and it could achieve fast solid-liquid separation under the action of an external magnetic field. The adsorption behavior and influencing factors of sulfamethoxazole （SMX） in water were investigated. The adsorbent showed excellent adsorption properties for SMX under acidic and neutral conditions， and alkaline conditions and the presence of CO32- had obvious inhibition on adsorption. The adsorption process conformed to the quasi-second-order kinetics and Langmuir model. The adsorption rate was fast， and the maximum adsorption capacity reached 356.49 mg·g-1. The adsorption process was a spontaneous exothermic reaction， and low temperature was beneficial to the adsorption. The adsorption mechanism was mainly the chemisorption of pyrophosphate surface functional groups （C-O-P bond） between the SMX molecule and MPBC and also included hydrogen bonding， π-π electron donor-acceptor （π-πEDA） interaction， and a pore filling effect. The development of MPBC adsorbent provides an effective way for resource utilization of waste Camellia oleifera shells and treatment of sulfamethoxazole wastewater.

Efficient and selective separation of Re(VII), an analogue of Tc(VII), by a defective biochar with honeycomb‐like porous structure

AbstractBACKGROUNDIn this study, a defective biochar with honeycomb‐like porous structure (BC‐PH) was successfully prepared by the activation of pristine biochar derived from bamboo shoot shell with the chemical reagent KOH, and was applied to selectively separate ReO4− (a chemical analogue for radioactive TcO4−) from acidic solutions.RESULTSThe diffusion, mass transfer and recovery for ReO4− could be significantly improved by the large specific surface area (SBET, 2412 m2 g−1) and high total volume (Vtot, 1.26 cm3 g−1) of BC‐PH. The influence of adsorbent dosage, system pH and coexisting ions with different valence states on the adsorption capability and selectivity of BC‐PH toward ReO4− was systematically investigated. BC‐PH exhibited high adsorption capacity and selectivity for ReO4− with a maximal sorption capacity (qm) of 73.11 mg g−1 at initial pH 2. By applying an analysis of kinetics and isotherm adsorption studies, the liquid film diffusion was verified to be the primary rate‐controlling step for the sorption of ReO4− and the multilayer adsorption process occurred on the heterogeneous surface of BC‐PH. Besides, the recovery of ReO4− using BC‐PH occurred in an exothermic and spontaneous manner according to thermodynamic analysis. Furthermore, an investigation of the adsorption mechanism suggested that pore filling and electron donor–acceptor interaction were mainly related to the removal of ReO4−.CONCLUSIONThese results suggest that BC‐PH has great potential for the application of TcO4− separation in consideration of its high adsorption capacity and selectivity. © 2024 Society of Chemical Industry (SCI).

Effect of pyrolytic temperatures on the 2,4-dichlorophenol adsorption performance of biochar derived from Populus nigra.

To investigate the correlation between the physicochemical properties of biochar and its adsorption performance for 2,4-dichlorophenol (2,4-DCP), Populus nigra was subjected to oxygen-limited pyrolysis at temperatures ranging from 300 to 600 ℃. The experimental results showed that as the pyrolysis temperature increased, the specific surface area and degree of graphitization of the resultant biochar increased, but the amount of oxygen-containing functional groups decreased. Populus nigra biochar produced at 450 ℃ exhibits the best adsorption performance for 2,4-DCP due to its excellent physicochemical properties and greater electron exchange capability. The removal of 2,4-DCP is a multi-step adsorption process dominated by chemisorption, which involved oxygen-containing functional groups-mediated hydrogen bonding, as well as π-π electron donor-acceptor (EDA) interaction between the aromatic rings and Cl atoms. The study highlights the potential of Populus nigra residues for producing biochar as an affordable and effective adsorbent for 2,4-DCP removal.

Comparative Analysis of Nickel-Phosphine Complexes with Cumulated Double Bond Ligands: Structural Insights and Electronic Interactions via ETS-NOCV and QTAIM Approaches.

This study presents a comprehensive analysis of nickel-phosphine complexes, specifically Ni(PH3)2(OCCH2), Ni(PH3)2(H2CCO), Ni(PH3)2(H2CCCH2), Ni(PH3)2(NNCH2), and Ni(PH3)2(η1-H2CNN). Utilizing ETS-NOCV analysis, we explored orbital energy decomposition and the Hirshfeld charges of the ligands, providing insights into the electronic structures and donor-acceptor interactions within these complexes. The interactions in the ketene and allene complexes exhibit similar deformation densities and NOCV orbital shapes to those calculated for Ni(PH3)2(NNCH2), indicating consistent interaction characteristics across these complexes. The total interaction energy for all η2 complexes is observed to be over 60 kcal/mol, slightly exceeding that of the analogous carbon dioxide complex reported earlier. Furthermore, the study highlights the stronger back-donation as compared to donor interactions across all η2 complexes. This is further corroborated by Hirshfeld analysis, revealing the charge distribution dynamics within the ligand fragments. The research offers new perspectives on the electron distribution and interaction energies in nickel-phosphine complexes, contributing to a deeper understanding of their catalytic and reactive behaviors.

Adsorption mechanisms and optimal production of magnetic biochar composites from red mud and soft wood biomass

We investigated the adsorption capacity of four composites generated by co-pyrolyzing red mud, an iron rich waste product from the production of alumina, together with Canadian soft wood biomasses, including Douglas fir, pine wood, red cedar and hemlock. Pyrolysis conditions included manually mixing of both biomass and red mud together before pyrolyzing at 800 °C for 3 h, with a ramp rate of 10 °C/min and a flow rate of 2 mL/min of CO2. Differences in the surface functional groups and aromaticity were observed in the biochars produced from these biomasses. It was found that oxygen containing functional groups had a greater impact on π-π electron-donor acceptor interactions, whereas greater amounts of carbonyl groups increased the adsorption of compounds with electron donating groups over compounds with electron withdrawing groups. Furthermore, optimal ratios of biomass to red mud were investigated for co-pyrolysis to achieve both strong adsorptive and magnetic properties. A greater biomass content during co-pyrolysis showed greater adsorptive properties, while only a small amount of red mud, as low as 10 wt%, was sufficient to provide the desired magnetic properties. This work was able to successfully produce an adsorbent capable of adsorbing up to 32.8 mg/g of acetaminophen by co-pyrolyzing red mud and pine wood biomass at a 9:1 ratio. The resulting composite also maintained magnetic properties, allowing the adsorbent to be easily removed from water after adsorption.

Inhibition mechanisms of biochar-derived dissolved organic matter to triclosan photodegradation: A remarkable role of aliphatics

Endocrine disrupting chemicals like triclosan (TCS) have been thought to be an emergent environmental pollutant. The ubiquitous dissolved organic matter (DOM) is able to interrelate with TCS and hamper its phototransformation. However, how the components in DOM can inhibit the photodegradation of DOM/TCS complex is largely unknown. Herein, we discovered that TCS photodegradation with biochar-derived DOM (BDOM) was interfered by both binding affinity and reactive oxygen species (ROS) productivity. BDOM can not only stimulate TCS photodegradation by producing ROS, but also inhibit the removal of TCS through the interactions between BDOMs and TCS. The quantification of BDOM's impact on TCS photodegradation revealed that BDOM hampered TCS removal with the proportion of −7.95 to −11.24% at pH 8.5, but strengthened it to 13.20% at pH 7.0. Binding process was more easily to inhibit TCS photodegradation in molecular form, while anionic TCS photodegradation was dominated by ROS productivity. Different inhibition mechanisms were involved in TCS photodegradation depending on the components of BDOMs. The hydroxyls and aromatic carbonyls might have hindered the attack of ROS on the phenolic hydroxyl of TCS via hydrogen bond interaction or π-π electron donor-acceptor interaction. Through hydrophobic interaction, the mobile aliphatics could greatly shield TCS to prevent ROS attack by wrapping or twining TCS, playing a significant role in inhibiting TCS removal. Results from this present study can afford a new viewpoint in elucidating the function of BDOMs in the phototransformation of organics and decrease the spread of antibiotic resistance genes.

Efficient adsorption of chloroquine phosphate by a novel sodium alginate/tannic acid double-network hydrogel in a wide pH range

In this work, a novel double-network composite hydrogel (SA/TA), composed of sodium alginate (SA) and tannic acid (TA), was designed and fabricated by a successive cross-linking method using Ti(IV) and Ca(II) as crosslinkers. SA/TA exhibited reinforced mechanical strength and anti-swelling properties because of the double-network structure. SA/TA was used as an adsorbent for removal of a popular antiviral drug, chloroquine phosphate (CQ), in water. The adsorption performance of SA/TA was systematically investigated, to study various effects including those of TA mass content, solution pH, adsorption time, and initial CQ concentration. Adsorption was also examined in presence of inorganic and organic coexisting substances commonly found in wastewater, and under different actual water samples. Batch experimental results indicated that SA/TA could maintain higher and more stable CQ uptakes within a wide solution pH range from 3.0 to 10.0, compared to its precursor, SA hydrogel, owing to the addition of TA-Ti(IV) coordination network. The maximum experimental CQ uptake exhibited by the 1:1 (by wt) SA/TA (SA/TA2) was as high as 0.699 mmol/g at the initial pH of 9.0. A high concentration of coexisting NaCl evidently reduced the CQ uptakes of SA/TA2 due to the electrostatic shielding effect, moreover, divalent cations including Ca(II) and Mg(II) also inhibited the adsorption of CQ due to competitive adsorption. However, humic acid had little effect on this adsorption. Considering the apparent adsorption performance, the aforementioned effects of various factors and the spectroscopic characterizations, multi-interactions are suggested for adsorption including chelation, electrostatic interactions, π-π electron donor-acceptor interaction and hydrogen bonding. SA/TA showed a slight loss in adsorption capacity toward CQ and sustained physicochemical structural stability, even after six adsorption–desorption cycles. In addition to CQ, SA/TA could be efficiently used for adsorption of two other antivirus drugs, namely, hydroxychloroquine sulfate and oseltamivir phosphate. This work provides an effective strategy for the design and fabrication of novel adsorbents that can effectively adsorb antiviral drugs over a wide pH range.

Phosphoric acid activation of cow dung biochar for adsorbing enrofloxacin in water: Icing on the cake

In this study, we used different concentrations of H3PO4 to activate pristine biochar (BC) derived from cow dung (BC and BC modified with phosphoric acid at concentrations of 10% (10P-BC), 30% (30P-BC), and 50% (50P-BC)) in order to obtain cheap, high-performance adsorbents. Brunauer–Emmett–Teller analysis, scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, organic element composition determination, and other analyses showed that activation with H3PO4 increased the porosity and hydrophilicity compared with the original BC, thereby enhancing the adsorption properties. The Langmuir isotherm model obtained the best fit and the maximum capacities for adsorbing enrofloxacin by BCs were 12.66 mg/g for BC, 51.90 mg/g for 10P-BC, 63.61 mg/g for 30P-BC, and 26.79 mg/g for 50P-BC. The main mechanisms responsible for antibiotic loading on BC were hydrogen bonding, π–π electron donor–acceptor interactions, pore filling, and electrostatic interactions. Calculations of fixed carbon retention before and after pyrolysis, and adsorption showed that activated BC had a good carbon fixation capacity and it was more capable of adsorbing enrofloxacin compared with the original BC, thereby providing a new method for removing organic pollutants from the environment and reducing carbon emissions. The cost efficiency was analyzed using the improved fuzzy comprehensive evaluation model based on the entropy method. Removal efficiency and utilization efficiency indicators were calculated for the different phosphoric acid activated BCs. The pollutant removal efficiencies were better for 10P-BC and 30P-BC, and the optimal removal efficiency was determined for 30P-BC. Given the current global climate change situation, using 10P-BC and 30P-BC could also help to meet China's carbon neutrality goals by reducing emissions of pollutants containing carbon.

Adsorption Behavior of a Ternary Covalent Organic Polymer Anchored with SO3H for Ciprofloxacin.

Owing to the poor treatment efficiency of wastewater containing fluoroquinolones (FQs), effective removal of such pollutants has become a significant issue in waste management. In this study, a ternary covalent organic polymer anchored with SO3H (COP-SO3H) was designed using the Schiff reaction and a multicomponent solvent thermal method. The synthesized COP-SO3H polymer possesses multiple functional binding sites, including amide groups, sulfonic groups, and aromatic frameworks, enabling it to effectively adsorb ciprofloxacin (which belongs to FQs) through mechanisms such as pore-filling effects, electrostatic interactions, hydrogen bonding, π-π electron donor-acceptor (EDA) interactions, and hydrophilic-lipophilic balance. COP-SO3H demonstrated outstanding adsorption performance for ciprofloxacin, exhibiting a high adsorption capacity, broad pH stability, strong resistance to ionic interference, and good regenerability. Moreover, it displayed preferential selectivity toward fluoroquinolone antibiotics. The present study not only investigates the intricate structural and functional design of COP-SO3H materials but also presents potential applications for the efficient adsorption of specific antibiotics.

Embedding Carbon Quantum Dots into Crystalline Polyimide Covalent Organic Frameworks to Enhance Water Oxidation for Achieving Dual-Channel Photocatalytic H2O2 Generation in a Wide pH Range.

Photocatalytic technique is regarded as the cleanest approach for producing H2O2. Herein, two kinds of novel polyimide COFs decorated with CQDs (namely, MPa-COFs/CQDs and MNd-COFs/CQDs) were constructed by using the one-pot hydrothermal method. Due to the electron donor role of CQDs, the recombination of photoinduced electrons and holes was suppressed after the combination of polyimide COFs with CQDs. Importantly, the introduction of CQDs not only boosted the absorbing ability of polyimide COFs toward visible light but also reduced the impedance and improved the charge transfer efficiency. After CQDs were embedded into polyimide COFs, the surface hydrophilicity of catalysts was significantly improved, which provided convenience for the water oxidation reaction. Benefiting from the electron donor-acceptor interaction between polyimide COFs and CQDs, a step-by-step two-electron oxygen reduction reaction over polyimide COFs was enhanced. More interestingly, the embedding of CQDs can create a direct two-electron water oxidation reaction pathway, which played an important role in photocatalytic H2O2 generation. Meanwhile, H+ generated from water oxidation can also be used for the reduction of oxygen to form H2O2. Under the synergistic effects of water oxidation and oxygen reduction, as-prepared MPa-COFs/CQDs-2 displayed excellent performance in photocatalytic H2O2 generation, and its yield was as high as 540 μmol/g within 60 min. In short, the current work shared an effective strategy to improve the performance of polyimide COFs in photocatalytic H2O2 production.