Effect of molecular structure on the adsorption affinity of sulfonamides onto CNTs: Batch experiments and DFT calculations

Interaction patterns and keystone taxa of bacterial and eukaryotic communities during sulfamethoxazole mineralization in lake sediment

Sulfamethoxazole (SMX) is a common antibiotic pollutant in aquatic environments, which is highly persistent under various conditions and significantly contributes to the spread of antibiotic resistance. Biodegradation is the major pathway to eliminate antibiotics in the natural environment. The roles of bacteria and eukaryotes in the biodegradation of antibiotics have received considerable attention; however, their successions and co-occurrence patterns during the biodegradation of antibiotics remain unexplored. In this study, 13C-labled SMX was amended to sediment samples from Zhushan Bay (ZS), West Shore (WS), and Gonghu Bay (GH) in Taihu Lake to explore the interplay of bacterial and eukaryotic communities during a 30-day incubation period. The cumulative SMX mineralization on day 30 ranged from 5.2 % to 19.3 %, which was the highest in WS and the lowest in GH. The bacterial community showed larger within-group interactions than between-group interactions, and the positive interactions decreased during incubation. However, the eukaryotic community displayed larger between-group interactions than within-group interactions, and the positive interactions increased during incubation. The proportion of negative interactions between bacteria and eukaryotes increased during incubation. Fifty genera (including 46 bacterial and 4 eukaryotic genera) were identified as the keystone taxa due to their dominance in the co-occurrence network and tolerance to SMX. The cumulative relative abundance of these keystone taxa significantly increased during incubation and was consistent with the SMX mineralization rate. These taxa closely cooperated and played vital roles in co-occurrence networks and microbial community interactions, signifying their crucial role in SMX mineralization. These findings broadened our understanding of the complex interactions of microorganisms under SMX exposure and their potential functions during SMX mineralization, providing valuable insights for in situ bioremediation.

Promoting the suitability of graphitic carbon nitride and metal oxide nanoparticles: A review of sulfonamides photocatalytic degradation

The widespread consumption of pharmaceutical drugs and their incomplete breakdown in organisms has led to their extensive presence in aquatic environments. The indiscriminate use of antibiotics, such as sulfonamides, has contributed to the development of drug-resistant bacteria and the persistent pollution of water bodies, posing a threat to human health and the safety of the environment. Thus, it is paramount to explore remediation technologies aimed at decomposing and complete elimination of the toxic contaminants from pharmaceutical wastewater. The review aims to explore the utilization of metal-oxide nanoparticles (MONPs) and graphitic carbon nitrides (g-C3N4) in photocatalytic degradation of sulfonamides from wastewater. Recent advances in oxidation techniques such as photocatalytic degradation are being exploited in the elimination of the sulfonamides from wastewater. MONP and g-C3N4 are commonly evolved nano substances with intrinsic properties. They possessed nano-scale structure, considerable porosity semi-conducting properties, responsible for decomposing wide range of water pollutants. They are widely applied for photocatalytic degradation of organic and inorganic substances which continue to evolve due to the low-cost, efficiency, less toxicity, and more environmentally friendliness of the materials. The review focuses on the current advances in the application of these materials, their efficiencies, degradation mechanisms, and recyclability in the context of sulfonamides photocatalytic degradation.

Study on the lignin-derived sp2-sp3 hybrid hard carbon materials and the feasibility for industrial production

Hard carbon has been widely used in anode of lithium/sodium ion battery, electrode of supercapacitor, and carbon molecular sieve for CO2 capture and hydrogen storage. In this study the lignin derived hard carbon products are investigated, and the conclusions are abstracted as follows. (1) The lignin derived hard carbon products consist of microcrystal units of sp2 graphene fragments, jointed by sp3 carbon atoms and forming sp2-sp3 hybrid hard carbon family. (2) From the lignin precursors to the sp2-sp3 hybrid hard carbon products, most carbon atoms retain their original electron configurations (sp2 or sp3) and keep their composition in lignin. (3) The architectures of lignin-derived hard carbon materials are closely dependent on the forms of their lignin precursors, and could be preformed by different pretreatment techniques. (4) The carbonization of lignin precursors follows the mechanism "carbonization in situ and recombination nearby". (5) Due to the high carbon ratio and abundant active functional groups in lignin, new activation techniques could be developed for control of pore size and pore volume. In general lignin is an excellent raw material for sp2-sp3 hybrid hard carbon products, a green and sustainable alternative resource for phenolic resin, and industrial production for lignin derived hard carbon products would be feasible.

Effects of charge-assisted hydrogen bond on sorption and co-sorption of pharmaceutical contaminants on carbonaceous materials: Spectroscopic and theoretical studies

Charge-assisted hydrogen bond (CAHB) is a key mechanism that affects the environmental behavior of pharmaceutical pollutants (PCs). However, the strength and stability of various CAHBs, and their effects on the co-sorption behavior of PCs are still unclear. Herein, DFT calculation with different solvent models including two implicit solvent model (PCM and SMD), and one explicit solvent model (ESM) were applied in this study, to investigate the effects of different CAHBs on the sorption and co-sorption behavior of four PCs (e.g., clofibric acid, p-aminobenzoic acid, acetaminophen, and sulfamerazine) on three model carbonaceous materials. First, the appearance of new peaks in the very low field of 1H NMR, and the blue shift of OH and NH2 peaks in FTIR indicated that CAHBs were indeed formed between PCs and carbonaceous materials. Next, according to the principal component analysis and correlation analysis of parameters (e.g., ΔEads, bond length, bond angle, Egap, and ΔG) of these CAHBs calculated by the DFT with different solvent models, the results showed that SMD is the optimal model for calculating the strength and stability of CAHBs by DFT, and the strength and stability of CAHBs formed between PCs and carbonaceous materials in this study were in the order of homonuclear [O⋯H⋯O]- CAHB > heteronuclear [O⋯HN]-/[N⋯HO]+ type of CAHB > homonuclear [N⋯H⋯N]+. Also, the co-sorption behavior of different PCs co-existing in binary systems further confirmed that, all above types of CAHBs formed between PCs and carbonaceous materials can produce obvious competition effect on the co-existing PCs that only OHB formed between them. This study not only reveals the environmental behavior of co-existing PCs, but also provides a theoretical basis for the design of obligate sorption materials for PCs in the natural environment.

Adsorption characteristics of sulfonamide antibiotic molecules on carbon nanotube and the effects of environment

CONTEXT

In this paper, the adsorption characteristics of five sulfonamide antibiotic molecules on carbon nanotubes were investigated using density functional theory (DFT) calculations. The adsorption configurations of different adsorption sites were optimized, and the most stable adsorption configuration of each sulfonamide molecule was determined by adsorption energy comparison, and the relative adsorption stability of five sulfonamide molecules on carbon nanotubes was determined by comparing their adsorption energies, i.e., sulfamethazine > sulfadiazine > sulfamerazine > sulfamethoxazole > sulfanilamide. The electron densities of the adsorption configurations were then calculated to confirm that the adsorption of five sulfonamide drug molecules on carbon nanotubes should be physical adsorption. Moreover, the adsorption energy of five sulfonamide molecules on carbon nanotubes in the aqueous environment was larger than that in the vacuum even though the adsorption process remain to be physical adsorption. The adsorption characteristics of the five sulfonamide molecules in various acid-base environments were finally investigated. In contrast, the adsorption energies of the five drug molecules in acid-base environments were significantly reduced, indicating that carbon nanotubes may need to have a suitable pH range to achieve the optimal adsorption effect when they are used for the treatment of sulfonamide antibiotics.

METHODS

In this paper, we use density functional theory (DFT) with PBE functional to study the adsorption properties of five sulfonamides on carbon nanotubes. The structural optimization and the calculation of electronic structural properties are carried out by CP2K package (version 7.1), adopting the DZVP-MOLOPT-SR-GTH basis set and Goedeck-Teter-Hutter (GTH) pseudo potential. Grimme's D3 correction is used to during all the calculations to correctly capture the influence of the van der Waals interactions.

Enhanced Adsorption of Sulfonamides by Attapulgite-Doped Biochar Prepared with Calcination

The extensive use of sulfonamides seriously threatens the safety and stability of the ecological environment. Developing green inexpensive and effective adsorbents is critically needed for the elimination of sulfonamides from wastewater. The non-modified biochar exhibited limited adsorption capacity for sulfonamides. In this study, the attapulgite-doped biochar adsorbent (ATP/BC) was produced from attapulgite and rice straw by calcination. Compared with non-modified biochar, the specific surface area of ATP/BC increased by 73.53−131.26%, and the average pore width of ATP/BC decreased 1.77−3.60 nm. The removal rates of sulfadiazine and sulfamethazine by ATP/BC were 98.63% and 98.24%, respectively, at the mass ratio of ATP to rice straw = 1:10, time = 4 h, dosage = 2 g∙L−1, pH = 5, initial concentration = 1 mg∙L−1, and temperature = 20 °C. A pseudo-second-order kinetic model (R2 = 0.99) and the Freundlich isothermal model (R2 = 0.99) well described the process of sulfonamide adsorption on ATP/BC. Thermodynamic calculations showed that the adsorption behavior of sulfonamides on the ATP/BC was an endothermic (ΔH > 0), random (ΔS > 0), spontaneous reaction (ΔG < 0) that was dominated by chemisorption (−20 kJ∙mol−1 > ΔG). The potential adsorption mechanisms include electrostatic interaction, hydrogen bonding, π−π interaction, and Lewis acid−base interactions. This study provides an optional material to treat sulfonamides in wastewater and groundwater.

Selective reduction of nitrite to nitrogen by polyaniline-carbon nanotubes composite at neutral pH

The selective reduction of nitrite (NO₂^-) to nitrogen by chemical reductant is a desirable strategy to remove NO₂^- from polluted water and wastewater. However, the residue and reuse of chemical reductant are two main issues to be addressed. Herein, a novel polyaniline-carbon nanotubes composite (PANI-CNTs) was developed by in-situ polymerization to selectively reduce NO₂^- to nitrogen gas (N₂). The used PANI-CNTs could be reused after regeneration with NaBH₄. The PANI-CNTs could reduce NO₂^- with 93.9% N₂ selectivity at initial pH of 6.8. The NO₂^- removal efficiency only decreased by 12.08% after five cycles of reduction/regeneration. The interconversion between imine nitrogen (-N) and amine nitrogen (-NH-) groups induced the chemical reduction of NO₂^- and regeneration of PANI-CNTs. PANI-CNTs exhibited an excellent performance for the removal of NO₂^- in the presence of competitive ions and in actual water and wastewater samples. This new PANI-CNTs composite may have great potential for water purification and wastewater denitrification.

Pore creation nanoarchitectonics from non-porous metal-organic framework to porous carbon for adsorptive elimination of sulfanilamide and chloroxylenol from aqueous solution

Three isomeric metal-organic frameworks (MOFs) such as MAF-5, - 6, and - 32 (with the same composition of [Zn(2-ethylimidazole)₂]) were carbonized and, for the first time, activated further with KOH to prepare highly porous MOF-derived carbons (MDCs). Importantly, MDC-32 derived from non-porous MAF-32 had the highest porosity among the three MDCs although it has the lowest porosity when no KOH activation was done. Adsorption of sulfanilamide and chloroxylenol from water was investigated with the MDCs. Among the MDCs, MDC-32 showed the best adsorptive performance for sulfanilamide and chloroxylenol. Moreover, MDC-32, had the highest adsorption capacity (256 mg/g) for removing sulfanilamide from water, compared with any adsorbent reported so far. Based on the observed adsorption and properties of the adsorbate and adsorbent, π-π and hydrogen bonding interactions, with a slight contribution of repulsive electrostatic interaction, could be suggested as the mechanism for the sulfanilamide adsorption over the MDC-32. Moreover, the MDC-32 could be recycled easily for up to four cycles. It could be suggested that non-porous MOFs can be a good precursor for highly porous MDCs, if activated well using KOH, for example. Finally, MAF-32-derived carbon, MDC-32, might be suggested as a plausible adsorbent to eliminate organics such as sulfanilamide from water.

Preparation of β-cyclodextrin/dopamine hydrochloride-graphene oxide and its adsorption properties for sulfonamide antibiotics

To develop high-efficiency antibiotic adsorbents, β-cyclodextrin and dopamine hydrochloride were used to modify graphene oxide to prepare a new type of ternary composite material (β-cyclodextrin/dopamine hydrochloride-graphene oxide, CD-DGO). The material was characterized using scanning electron microscopy, Fourier infrared spectrometry, transmission electron microscopy, and specific surface area optical analysis. Two typical sulfonamides antibiotics (sulfamethoxazole, sulfadiazine) adsorption capacity were evaluated in terms of the dosage of composite materials, the ratio of each component, and the pH of the solution. We analyzed the adsorption characteristics via adsorption kinetics and adsorption isotherms, and then investigated the stability of the adsorbent through desorption and regeneration of the adsorbent. The results show that the adsorption effect of sulfonamides antibiotics is best at pH = 2; the adsorption kinetics conform to the pseudo-second-order kinetic model, and the adsorption equilibrium follows the Langmuir adsorption isotherm; the maximum adsorption capacity of CD-DGO for sulfamethoxazole and sulfadiazine is 144 mg·g^-1 and 152 mg·g^-1, respectively. The material has good reusability, and the dominant force in the adsorption process is the π-π electron conjugation effect with hydrogen bonding. This offers a theoretical basis for the treatment of sulfonamides antibiotics water pollution.

Decipher the molecular descriptors and mechanisms controlling sulfonamide adsorption onto mesoporous carbon: Density functional theory calculation and partial least-squares path modeling

Mesoporous carbons (MCs) exhibit excellent removal efficiencies to various organic chemicals. However, how the properties of chemicals influence the adsorption mechanisms and further determine their adsorption onto MCs are poorly understood. We investigated the adsorption of 22 sulfonamides (SAs) onto four MCs, and further uncovered the major molecular descriptors and adsorption mechanisms influencing the adsorption by density functional theory (DFT) and partial least-squares path modeling (PLS-PM). The results revealed that the excess molar refraction (E), McGowan's molar volume (V), energy of the highest occupied molecular orbital (E_HOMO), hardness (H), and most positive net charge on carbon atom (Q_c⁺) were identified as the indirect factors affecting the distribution coefficient (logK_D), by influencing the BE(π-π), BE(H), and logK_ow. BE(π-π) and logK_ow displayed significant direct impacts on logK_D (p < 0.05), while BE(H) showed insignificant direct influences on logK_D (p > 0.05). The PLS-PM results indicate the main driving forces for SAs adsorption including π-π interactions, hydrophobic effects, and hydrogen bonding. This study provides a new perspective on revealing the adsorption mechanisms, and the identified factors can be used to develop the quantitative model to further predict the adsorption of SAs onto MCs.

Green synthesis of Ag2O nanoparticles using Punica granatum leaf extract for sulfamethoxazole antibiotic adsorption: characterization, experimental study, modeling, and DFT calculation

Silver oxide (Ag₂O) nanoparticles (NPs) were generated by synthesizing green leaf extract of Punica granatum, and afterwards they were used as adsorbent to remove the antibiotic additive sulfamethoxazole (SMX) from aqueous solutions. Prior of their use as adsorbent, the Ag₂O NPs were characterized by various methods such as X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), scanning electron microscopy/energy-dispersive X-ray (SEM-EDX), and transmission electron microscopy (TEM). The Ag₂O NPs were found to be spherically shaped and stabilized by the constituents of the extract. Further, at SMX antibiotic concentration of 100 mg L^-1, the Ag₂O NPs achieved almost complete removal of 98.93% within 90 min, and by using 0.8 g L^-1 of adsorbent dose at pH=4 and temperature T=308 K. In addition, the experimental data were well fitted with the theoretical Langmuir model indicating homogeneous adsorbed layer of the SMX antibiotic on the Ag₂O NPs surface. The maximum uptake capacity was 277.85 mg g^-1. A good agreement was also found between the kinetic adsorption data and the theoretical pseudo-second-order model. Regarding the thermodynamic adsorption aspects, the data revealed an endothermic nature and confirmed the feasibility and the spontaneity of the adsorption reaction. Furthermore, the regeneration study has shown that the Ag₂O NPs could be efficiently reused for up to five cycles. The geometric structures have been optimized and quantum chemical parameters were calculated for the SMX unprotonated (SMX^+/-) and protonated (SMX⁺) using density functional theory (DFT) calculation. The DFT results indicated that the unprotonated SMX^+/- reacts more favorably on the Ag₂O surface, as compared to the protonated SMX⁺. The SMX binding mechanism was predominantly controlled by the electrostatic attraction, hydrogen bond, hydrophobic, and π-π interactions. The overall data suggest that the Ag₂O NPs have promising potential for antibiotic removal from wastewater.

Preparation of carbonyl, hydroxyl, and amino-functionalized microporous carbonaceous nanospheres from syrup-based waste to remove sulfamethazine

Sulfadiazine (SDZ) was a persistent sulfonamide antibiotic with a potential risk to human health. The waste dipping syrup was considered useless and environmentally unfriendly solution. In this work, carbonyl-, hydroxyl-, and amino-functionalized microporous carbonaceous nanospheres were synthesized using waste dipping syrup with glucose, fructose, and nitrogen, which was used as precursor for hydrothermal and pyrolysis process. The products were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), the point of zero charge (PZC), Xray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). The carbonaceous nanospheres with large BET surface area (924.528 m²/g), micropores (2.127 nm), and high micro-porosity (89.54 %) allowed the rapid diffusion of SDZ (0.512nm×0.738 nm) into micropores of nanospheres. The majority SDZ (initial concentration = 20 mg/L) was removed (>96.8%) in the presence of 1.0 g/L nanoparticles after 40-min reaction at pH = 6.0. The adsorption capacity of SDZ onto nanospheres was 96.6 mg/g. The adsorption kinetic and equilibrium followed pseudo-first-order model and Langmuir isotherm, respectively. The intra-particle diffusion model indicated a three-step adsorption process. In addition, the regenerated nanospheres could be reused over four recycles. The optimal fabrication was realized at lower hydrothermal and pyrolysis temperature of 180 °C and 400 °C, respectively, which involved no additional chemical activating agent and had a high yield (70.8 %). Collectively, hydroxylation, carboxylation, amination, large specific surface area, and multi-microporosity may be responsible for improved adsorption performance of SDZ onto nanospheres. The findings provided a novel pathway for SDZ-loading wastewater treatment using waste syrup.

Adsorption behavior and mechanism of sulfonamides on controllably synthesized covalent organic frameworks

In this work, four kinds of covalent organic framework (COF) materials (TpPa-1, TpBD, TpDT, and TFBBD) with different pore sizes or functional groups were synthesized by an ultrasonic method for the adsorption of five sulfonamides. Optimization experiments regarding the adsorption time, vortex speed, and pH were carried out to improve adsorption efficiency. In addition, kinetic and thermodynamic experiments were conducted to explore the adsorption mechanism of the sulfonamides on the different COFs. The adsorption processes of the five sulfonamides on the four COFs fit the pseudo-second-order kinetic model and Langmuir adsorption isotherm model. Additionally, pore filling, hydrogen bond interactions, and electrostatic attraction were found to be the main adsorption mechanisms.

Adsorption of Sulfonamides in Aqueous Solution on Reusable Coconut-Shell Biochar Modified by Alkaline Activation and Magnetization

Biochar is a low-cost adsorbent for sorptive removal of antibiotics from wastewater, but the adsorption efficiency needs to be improved. In this study, coconut-shell biochar was activated with KOH to improve the adsorption efficiency and magnetically modified with FeCl₃ to enable recycling. The amount of KOH and the concentration of FeCl₃ were optimized to reduce the pollution and production cost. The KOH-activated and FeCl₃-magnetized biochar gave good sulfonamide antibiotic (SA) removal. The maximum adsorption capacities for sulfadiazine, sulfamethazine and sulfamethoxazole were 294.12, 400.00 and 454.55 mg g⁻¹, respectively, i.e., five to seven times higher than those achieved with raw biochar. More than 80% of the adsorption capacity was retained after three consecutive adsorption-desorption cycles. A combination of scanning electron microscopy, Brunauer-Emmett-Teller analysis, X-ray diffraction, Fourier-transform infrared and Raman spectroscopies, and magnetic hysteresis analysis showed that KOH activation increased the specific surface area, porosity, and number of oxygen-rich functional groups. Iron oxide particles, which were formed by FeCl₃ magnetization, covered the biochar surface. The SAs were adsorbed on the modified biochar via hydrogen bonds between SA molecules and -OH/-COOH groups in the biochar. Investigation of the adsorption kinetics and isotherms showed that the adsorption process follows a pseudo-second-order kinetic model and a monolayer adsorption mechanism. The adsorption capacity at low pH was relatively high because of a combination of π⁺-π electron-donor-acceptor, charge-assisted hydrogen-bonding, electrostatic, and Lewis acid-base interactions, pore filling, van der Waals forces and hydrophobic interactions. The results of this study show that magnetically modified biochar has potential applications as an effective, recyclable adsorbent for antibiotic removal during wastewater treatment.

Preparation of Fe/Ni Bimetallic Oxide Porous Graphene Composite Materials for Efficient Adsorption and Removal of Sulfonamides

An iron-nickel bimetallic oxide porous graphene composite material (Fe/Ni-PG) was prepared by a simple partial combustion method, which can be used to effectively remove sulfonamides (SAs) from an aqueous solution. The adsorption performance of Fe/Ni-PG, Fe-PG, and Ni-PG on six kinds of SAs was compared, and the influence of time, temperature, pH, and initial concentration of SAs on the adsorption behavior of SAs of Fe/Ni-PG in an aqueous solution was studied. The adsorption kinetics and thermodynamics exhibited that the Langmuir model and pseudo-second-order kinetics model can describe the adsorption isotherm and kinetics. The maximum adsorption capacities of sulfadiazine (SD), sulfamerazine (SM), sulfamethazine (SDM), sulfathiazole (STZ), sulfapyridine (SPD), and sulfisoxazole (SIZ) calculated by the Langmuir model were 26.3, 50.3, 42.2, 27.3, 34.5, and 41.7 mg/g, respectively, which exceeded those of most reported adsorbents. In the adsorption process, hydrogen bonding, π-π electron donor-acceptor, electrostatic interaction, and bimetallic synergies play a major role, and the entire adsorption process is spontaneously endothermic. In addition, the material has excellent stability, and the Fe/Ni-PG after desorption is consistent with the raw material. This work provides a favorable way for the removal of SAs in the environment.

A novel CNTs-Fe3O4 synthetized via a ball-milling strategy as efficient fenton-like catalyst for degradation of sulfonamides

A novel composite (CNTs-Fe₃O₄) was synthesized by a ball-milling strategy and characterized by BET, SEM, FTIR, XRD and VSM. The as-fabricated CNTs-Fe₃O₄ was used to remove six sulfonamides by a Fenton degradation process, including sulfanilamide (SAM), sulfamerazine (SMR), sulfadimethoxine (SMX), sulfadiazine (SDZ), sulfamethazine (SMT) and sulfametoxydiazine (SMD). The degradation behaviors of six sulfonamides in CNTs-Fe₃O₄/H₂O₂ system and the relationship between molecular structure of sulfonamides and their degradation behaviors were investigated systematically. Batch experimental results showed that the as-fabricated CNTs-Fe₃O₄ had excellent Fenton catalytic activity for the degradation of sulfonamides due to its unique porous structure and the good combination mode of CNTs with Fe₃O₄ particles. The first-order kinetic mode could better describe the degradation behaviors of six sulfonamides in CNTs-Fe₃O₄/H₂O₂ system, and the degradation rate constant could be ordered as: SAM < SMT < SDZ < SMR < SMD < SMX. The quantitative relationship between the Mulliken charge of sulfonamides (x) and their degradation rate constant (y) in CNTs-Fe₃O₄/H₂O₂ system could be described as: y = - 28.719x + 15.67 (R² = 0.957). Finally, the possible synthesis mechanisms of CNTs-Fe₃O₄ and the degradation mechanisms of sulfonamides in CNTs-Fe₃O₄/H₂O₂ system was proposed.

Toxicity and remediation of pharmaceuticals and pesticides using metal oxides and carbon nanomaterials

The worldwide development of agriculture and industry has resulted in contamination of water bodies by pharmaceuticals, pesticides and other xenobiotics. Even at trace levels of few micrograms per liter in waters, these contaminants induce public health and environmental issues, thus calling for efficient removal methods such as adsorption. Recent adsorption techniques for wastewater treatment involve metal oxide compounds, e.g. Fe2O3, ZnO, Al2O3 and ZnO-MgO, and carbon-based materials such as graphene oxide, activated carbon, carbon nanotubes, and carbon/graphene quantum dots. Here, the small size of metal oxides and the presence various functional groups has allowed higher adsorption efficiencies. Moreover, carbon-based adsorbents exhibit unique properties such as high surface area, high porosity, easy functionalization, low price, and high surface reactivity. Here we review the cytotoxic effects of pharmaceutical drugs and pesticides in terms of human risk and ecotoxicology. We also present remediation techniques involving adsorption on metal oxides and carbon-based materials.

Simulation and surface topology of activity of pyrazoloquinoline derivatives as corrosion inhibitor on the copper surfaces

In the present study, corrosion inhibition performances of some pyrazolo [3,4-b] quinoline-3,5-dione derivatives against the corrosion of copper metal were investigated using B3LYP/6-311++g(d,p) calculation level in aqueous media. Additionally, interaction energies were calculated for all the pyrazoloquinoline derivatives compounds. In the calculations it is observed that studied molecules adsorb on metal surface with the help of electron donor heteroatoms in their molecular structures. Chemical thermodynamic parameters regarding the interaction between inhibitor molecule and copper surface were estimated and discussed. Density of the electron profile analysis and chemical electrostatic potential of nuclear charges in the molecule were applied to consider the nature of a number of probable interactions between Cu metal surface and inhibitors in terms of bond critical point (BCP). Calculated quantum chemical parameters showed that the pyrazoloquinoline derivatives including the OH and NO₂ exhibit high inhibition performance.

Understanding mechanisms in the adsorption of lead and copper ions on chili seed waste in single and multicomponent systems: a combined experimental and computational study

In the current work, a deep study to understand the adsorption phenomena occurring in single and multicomponent systems was conducted by using spectroscopic characterization, and computational tools. The experimental results showed that the adsorption capacity of chili seed is higher for Pb2+ (48 mg/g) than Cu2+ (4.1 mg/g) ions in single systems. However, the adsorption study in multicomponent systems provides important conclusions of the concentration effect of the metal ions, showing a significant antagonistic and competitive effect of both ions under equivalent concentrations of them (qPb2+ is 56% reduced) or high concentration of Pb2+ (qCu2+ is 50% reduced). Computational results correlated well with the experimental ones and evidenced all interactions proposed from spectroscopy results, accounting for the occurrence of complexation and electrostatic mechanisms between metal ions and the surface oxygenated functional groups (hydroxyl, carboxyl, and carboxylate) onto chili seed. Chemistry quantum descriptors supported the reactivity behavior of the chemical species implicated. All results evidenced that Pb2+ and Cu2+ adsorption on chili seed surface is governed by the occurrence of combined ionic exchange, π-interaction, complexation, and electrostatic attraction.

Sulfadiazine dissipation as a function of soil bacterial diversity

Antibiotic residues in the environment are concerning since results in dispersion of resistance genes. Their degradation is often closely related to microbial metabolism. However, the impacts of soil bacterial community on sulfadiazine (SDZ) dissipation remains unclear, mainly in tropical soils. Our main goals were to evaluate effects of long-term swine manure application on soil bacterial structure as well as effects of soil microbial diversity depletion on SDZ dissipation, using "extinction dilution approach" and ¹⁴C-SDZ. Manure application affected several soil attributes, such as pH, organic carbon (OC), and macronutrient contents as well as bacterial community structure and diversity. Even minor bacterial diversity depletion impacted SDZ mineralization and non-extractible residue (NER) formation rates, but NER recovered along 42 d likely due to soil diversity recovery. However, this period may be enough to spread resistance genes into the environment. Surprisingly, the non-manured natural soil (NS-S1) showed faster SDZ dissipation rate (DT₉₀ = 2.0 versus 21 d) and had a great number of bacterial families involved in major SDZ dissipation pathways (mineralization and mainly NER), such as Isosphaeraceae, Ktedonobacteraceae, Acidobacteriaceae_(Subgroup_1), Micromonosporaceae, and Sphingobacteriaceae. This result is unique and contrasts our hypothesis that long-term manured soils would present adaptive advantages and, consequently, have higher SDZ dissipation rates. The literature suggests instantaneous chemical degradation of SDZ in acidic soils responsible to the fast formation of NER. Our results show that if chemical degradation happens, it is soon followed by microbial metabolism (biodegradation) performed by a pool of bacteria and the newly formed metabolites should favors NER formation since SDZ presented low sorption. It also showed that SDZ mineralization is a low redundancy function.

Multi-spectroscopic and molecular docking studies of human serum albumin interactions with sulfametoxydiazine and sulfamonomethoxine

Sulfonamides are a kind of antibiotics which have been widely used as feed additives for livestock and poultry. However, sulfa drugs have raised worldwide concerns because of their adverse impact on human health. In this study, two sulfonamides, sulfametoxydiazine (SMD) and sulfamonomethoxine (SMM), were selected to explore the binding modes with human serum albumin (HSA). The spectroscopic approaches revealed that SMD or SMM could spontaneously enter into the binding site I of HSA through hydrogen bond interactions and van der Waals forces, and that SMD exhibited much stronger binding affinity toward HSA than SMM at different temperatures (p < 0.01, n = 3). The binding constants for SMD-HSA and SMM-HSA were determined to be (8.297 ± 0.010) × 10⁴ L·mol^-1 and (1.178 ± 0.008) × 10⁴ L·mol^-1 at 298 K, respectively. The interaction of SMD or SMM to HSA induced microenvironmental and conformational changes in HSA, where SMD had a greater effect on the α-helix content of HSA. Results from molecular docking implied that the amino acid residues of HSA, such as Arg222, Ala291 and Leu238, played key roles in the sulfonamide-HSA binding process. Meanwhile, hydrogen bonds might be a key factor contributing to the binding affinity of sulfa drugs and HSA. Additionally, the combined use of SMD and SMM led to an obvious variation in K_a values of binary systems (p < 0.01, n = 3). These findings might be helpful to understand the biological effects of sulfonamides in humans.

Hierarchical porous biochar with ultra-high specific surface area for rapid removal of antibiotics from water

Onion skin derived hierarchical porous biochar prepared by a facile and cost-efficient strategy exhibited rapid and efficient adsorption properties for antibiotics in water.

Removal of sulfadiazine from aqueous solution by in-situ activated biochar derived from cotton shell

Phosphoric acid is used to in-situ activate biochar pyrolyzed by cotton shells to enhance the adsorption ability of sulfadiazine (SDZ). To confirm the optimum condition, different impregnation ratios and impregnation times were investigated. It was found that the biochar (BC) pyrolyzed under the condition of an impregnation ratio of 2.5 and an impregnation time of 6 h showed the highest performance for the removal of SDZ. The maximum adsorption ability was 86.89 mg/g at a temperature of 298 K. The pseudo-second-order model was used to disclose the adsorption process of SDZ by BCs. The experimental data were described by the Langmuir and Temkin isotherms at different temperatures. It was found that the sorption of SDZ was an exothermic process according to the thermomechanical analysis. The activated BC could be recycled for at least five times with a high removal rate of SDZ. Thus, activated BCs are regarded as promising adsorbents for SDZ removal.