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The pyrolysis temperature strongly affects the properties of the peanut shell biochar, and influences its adsorption behavior and mechanisms for contaminant removal in aqueous solutions. In this study, peanut shells were pyrolyzed at 400 °C and 700 °C to prepare two biochars (PSBC400 and PSBC700), which were then characterized using scanning electron microscopy/X-ray energy spectrum analysis, Brunauer–Emmett–Teller, elemental analysis, X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorption behavior of typical tetracycline (TC) onto the biochars was investigated, and the potential adsorption mechanisms explored. The results show that compared with PSBC400, PSBC700 has a larger specific surface area and pore volume and contains higher levels of carbon and ash, but shows lower O, N, and H content. The hydrophilicity and polarity of PSBC700 is lower, but its aromaticity is higher. Furthermore, the mineral content of PSBC400 is higher than for PSBC700. The functional groups differ between PSBC400 and PSBC700, especially those containing C and O. The Elovich and two-compartment adsorption kinetic models are a good fit to the TC adsorption processes on both biochars, but the Langmuir adsorption isotherm model provides better results. The theoretical maximum adsorption capacities of TC onto PSBC700 and PSBC400 are 33.4346 mg·g−1 and 26.4185 mg·g−1, respectively. The main adsorption mechanisms of TC onto PSBC400 are hydrogen bonding and complexation, and are closely related to the functional groups and minerals found in PSBC400. In contrast, the main adsorption mechanisms of TC onto PSBC700 are pore filling and the π–π interaction, and are mainly determined by the surface area and graphited carbon structure of PSBC700. In summary, effective biochar can be manufactured from peanut shell biomass and can be used to remove TC from aqueous solutions.

Activation is an important pathway that can enhance the adsorption capacity of biochar. In this study, a modified tea waste biochar (MTWBC) was prepared via a two-step pyrolysis approach with KHCO3 activation. Pristine tea waste biochar (TWBC) was also produced as control via one-step pyrolysis without activation. Various characterizations were undertaken to investigate the influence of modification on the morphology, composition, carbon structure, surface area, and functional group of biochar, including scanning electron microscope (SEM), surface area and pore analyzer, element analysis, point of zero charge (pHPZC), X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). After KHCO3 activation treatment, the surface area, total pore volume, and micropore volume of MTWBC reached 1981 m2·g-1, 0.8547 cm3·g-1, and 0.6439 cm3·g-1 which were 7.34-fold, 7.27-fold, and 7.30-fold increases, respectively, compared with TWBC. The aromaticity, hydrophilicity, and polarity of the MTWBC increased after modification. More graphitization with less defective structures occurred in MTWBC after modification. The C-, O-, and N-containing groups in MTWBC also changed after the reaction of KHCO3. The pseudo-second-order and Freundlich models best described the adsorption process on biochar. The maximum adsorption capacity of tetracycline (TC) on MTWBC reached 293.46 mg·g-1, which was 15-fold more than that of TWBC (19.68 mg·g-1). An alkaline environment decreased the TC adsorption on biochars. The presence of Na+, K+, Ca2+, and Mg2+ inhibited TC adsorption onto biochars. The influence of Cu2+ on TC adsorption by biochars depends on its initial concentration. The enhanced adsorption capacity of TC on MTWBC was mainly attributable to the large surface area, the improved pore volume, and more aromatic structure. The adsorption mechanism was based on pore filling and π-π EDA interaction. Therefore, KHCO3 activated biochar has the potential to remove TC from aquatic environments.

In this work, novel dumbbell-like Mn2O3 was prepared using a low-cost and environmentally friendly template (gelatin) and applied to activate peroxymonosulfate (PMS) for pollutant degradation. The characterization results showed that dumbbell-like microstructures were formed by the self-assembly of tiny nanoparticles. Mn2O3-G (gelatin as the template) as a heterogeneous catalyst for PMS activation could effectively degrade various pollutants and exhibited an excellent degradation rate of rhodamine B (0.2333 min−1, in 30 min) for PMS activation compared to Mn2O3-C (carboxymethyl cellulose as the template), Mn2O3-N (without a template), and MnO2. The superior catalytic performance of Mn2O3-G was ascribed to its high oxygen vacancy content. The radical scavenging and EPR experiments revealed that SO4˙−, OH˙, O2˙−, and 1O2 were identified as reactive species generated from PMS activation. The oxygen vacancies participated in the generation of the reactive species. Thus, a facile and environmentally friendly method is provided for the synthesis of dumbbell-like Mn2O3 as a high-efficiency catalyst for PMS activation. Furthermore, this study shows a new mechanistic insight into PMS activation on Mn2O3.

Polycyclic aromatic hydrocarbons in biochars threaten their environmental application. The aging process may affect the concentration of PAHs, potential toxicity, and the properties of biochar. In this study, the aged biochars were obtained by simulated physical aging method (freeze-thaw treatment) and chemical aging method (H

Modification of pristine biochars has received increasing attentions due to the significant potential in enhancing adsorption performance. In this work, the co-modification of KOH and KMnO

Biochar was prepared from tea waste that had been heated to 300 °C, 500 °C, or 700 °C (TWBC300, TWBC500, and TWBC700, respectively), and was characterized by elemental analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Then, the Cd removal characteristics and mechanism for the biochar were investigated. The results showed that as the pyrolysis temperature increased, the hydrophilicity and polarity of the biochar became poor, and some functional groups (oxygen-containing groups) decreased. Furthermore, pH and the aromatic structure of the biochar were enhanced, but the carbon structural defects of the biochar also increased. The Langmuir isotherm model and the pseudo-second-order kinetic model accurately described the adsorption process. The maximum adsorption capacity for Cd by TWBC300, TWBC500, and TWBC700 was 8.90 mg g−1, 4.73 mg g−1, and 7.26 mg g−1, respectively. The adsorption capacities of the biochars greatly decreased after acid washing, which indicated that the soluble minerals in biochars played a key role during the Cd removal process. The characterization approach (FTIR, XPS, and Raman spectroscopy analysis) combined with measurements of the pH value, and the Ca and Mg in the supernatant after Cd adsorption inferred that the mechanisms between tea waste–based biochar (TWBC) and Cd were surface complexation, cation exchange, the cation-π interaction, and precipitation. The functional groups in TWBC300 could participate in Cd removal, and the aromatic structures in TWBC700 may also play an important role during Cd adsorption. The results suggest that all of the examined TWBC can act as an adsorbent to remove Cd. But, the best TWBC was TWBC300.

Developing a cost-effective and highly efficient sorbent for the recovery of rare-earth elements from aqueous solution is still an urgent need. In this study, a novel biosorbent, carboxyl-rich pine bark (CPB), was modified by UV-induced graft polymerization method to increase the carboxyl-containing functional groups and facilitate the adsorption of Ce3+. The grafting process was examined by Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM), indicating that high-density carboxyl functional groups are present on the surface of pine bark and the grafting yield of surface polymer brushes reaches up to 128%. Interestingly, the maximum adsorption capacity of Ce3+ on CPB could reach up to 256.5 mg/g. The adsorption mechanism of Ce3+ by CPB has been determined by the adsorption models and x-ray photoelectron spectroscopy (XPS), which can be inferred from these results that the high performance of CPB is attributed to the surface coordination between Ce3+ and hydroxyl or carbonyl groups. This work suggests that engineered surface functional groups of biomass could have an opportunity for the development of high performance rare-earth element adsorbents.

In this work, a novel catalyst, metal-doped zinc ferrite nanosphere, was prepared from metal-rich industrial wastewater using two-step method for the removal of organic contaminants in the Vis-light/catalyst/H2O2 system. The physicochemical properties of the catalyst were well characterized by XRD, FESEM, TEM, XPS, and UV−vis. The results indicated that the catalyst exhibited better catalytic performance than pure ZnFe2O4 synthesized from chemical reagents, and Congo red (CR) decolorization efficiency reached 94.6% within 3 h. During the photo-Fenton process, •OH played an key role, which was generated through the photo-generated holes and the oxidation of H2O2 by metal ions (Fe3+ and Mn3+) on the surface of catalysts. Moreover, 75.5% of CR decolorization efficiency could be still retained at the third run. Thus, metal-doped ZnFe2O4 nanosphere prepared from metal-rich industrial wastewater is a promising photocatalyst for the removal of organic chemicals in practical application of wastewater treatment.

Activation is an important pathway that can enhance the adsorption capacity of biochar. In this study, a modified tea waste biochar (MTWBC) was prepared via a two-step pyrolysis approach with KHCO

Tetracycline (TC) adsorption capacity on pristine biochar was limited. Biochar modification can greatly improve its adsorption amount. In this study, rice straw was mixed with FeCl3·6H2O and urea to prepare a Fe–N modified biochar via a one-pot pyrolysis method at 700 °C. Meanwhile, pristine biochar (RSBC), urea modified biochar (N–RSBC), FeCl3·6H2O-modified biochar (Fe–RSBC) were produced as control. More functional groups, more graphited carbon structure, and magnetic components were observed in Fe–N–RSBC. Compared with RSBC, the surface area, total pore and micropore volume of Fe–N–RSBC increased 3.4-fold, 3.0-fold and 2.3-fold, respectively. The maximum capacity of TC adsorption on Fe-N-RSBC reached 156 mg·g−1, which was 5.4 − fold, 8.2 − fold and 1.9 − fold increase to that of RSBC, N-RSBC, Fe-RSBC, respectively. The mechanism of TC adsorption on Fe-N-RSBC involved pore filling, hydrogen-bond interaction, surface complexation, and π–π interaction. Therefore, Fe-N-RSBC can be used as an effective adsorbent for TC removal from aqueous solution.

Pyrolysis process significantly influences the physicochemical properties and potential application of magnetic porous biochars (MPBCs). However, the effects of pyrolysis temperature on the properties of MPBCs as well as substantial adsorption are still unclear. This study reported a facile method to obtain the MPBC from tea waste via pyrolysis of a mixture of hydrochar, KHCO3, and FeCl3·6H2O under different temperatures (500–800 °C), and explored further the adsorption toward tetracycline (TC). Results showed pyrolysis temperature obviously influenced the physicochemical properties of MPBCs, and MPBC pyrolyzed at 700 °C (MPBC-700) has a highest specific surface area (1066 m2 g−1) and pore volume (2.693 cm3 g−1). However, the adsorption potential increased consistently from 59.35 mg g−1 for MPBC-500 to 333.22 mg g−1 for MPBC-800, suggesting that the surface area and pore volume were not the only factors determining TC adsorption. Further analysis showed that the pore-filling, π-π interaction, complexation, and hydrogen bonding contributed together to TC adsorption. Moreover, all MPBCs possessed a high saturation magnetization, indicating the easy separation by an external magnet. Therefore, MPBCs (especially at 700 °C) can act as the excellent adsorbents for contaminant removal due to their high separation, adsorption, and reuse performance.

The properties of biochars and their adsorption performance are highly dependent on the carbonation methods. In this study, five carbonation methods, namely, hydrothermal treatment (HT), direct carbonization (BC), carbonization of hydrochar (HBC), KHCO3 activation carbonation (KBC), and KHCO3 activation carbonation of hydrochar (KHBC), were adopted to prepare tea waste biochars. Adsorption behaviors and mechanisms toward tetracycline (TC) by biochar in the aquatic environment were investigated. The results showed that carbonation methods significantly influence the morphology, carbon structure, chemical composition, and functional groups of the biochars based on the characterization of surface area and pore volume analysis, Fourier Transform Infrared Spectroscopy, Raman spectrum, Scanning Electron Microscope, Transmission Electron Microscope, X-ray photoelectron spectroscopy, X-Ray Diffraction, and elemental analysis. Combination of hydrothermal treatment with KHCO3 activation can significantly increase the surface area and enlarge the pore structure of biochar (KHBC and KBC). The BET of KHCO3-activated BCs nearly increased 280 times (KHBC: 1350.80 m2 g−1; KBC: 1405.06 m2 g−1). BET, total pore volume and micropores volume of biochar has a positive influence on TC adsorption capacity. In addition, all adsorption processes can be well fitted by Langmuir and pseudo-second-order kinetic models. The maximum adsorption capacity of KHCO3-activated BCs nearly increased approximately 40 times (KHBC: 451.45 mg g−1; KBC: 425.17 mg g−1). The dominant mechanisms of biochar-adsorbed TC were pore-filling effect and π–π interactions, followed by hydrogen bonds and electrostatic interactions. Therefore, KHBC has the potential to act as sorbents for TC removal from aquatic environment.

Biochar is a promising material for removing metal ions from water and soil through adsorption. In this study, rice straw was pyrolyzed to prepare biochars at 300 °C (RSBC300), 500 °C (RSBC500), and 700 °C (RSBC700) in an oxygen-limited atmosphere. The biochars were used in batch experiments for adsorption of copper (Cu) ions in aqueous solution. The influence of various environmental conditions, including solution pH, solid-to-liquid ratio, contact time, and environmental temperature, on Cu removal were systematically investigated. To explore the adsorption mechanisms and ascertain the contribution of acid-soluble minerals, adsorption kinetics and isotherm analyses, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were performed. The results showed that the removal rate reached 99.6% when the experimental condition was a solid-to-liquid ratio of 1 g L−1, pH of 6.0, and the initial Cu concentration of 30 mg L−1. The pseudo-second-order model and the two-compartment kinetic model well fitted with the Cu adsorption kinetics process onto RSBC700, whereas the Freundlich, Temkin, and Dubinin–Radushkevich (D–R) models best described the Cu adsorption isotherm process on RSBC700. Higher temperatures improved Cu removal from solution with the maximum adsorption capacity being 52.5 mg g−1 at 45 °C. The influence of co-existing Ca2+ and Mg2+ on Cu removal by RSBC700 was limited, whereas tetracycline exhibited some inhibition effect. The role of acid-soluble minerals in biochar for Cu removal cannot be ignored, especially in treatment using RSBC500 (contribution rate at 47.2–57.1%). The mechanism underlying Cu removal by rice straw biochar involved electrostatic interaction, complexation, cation–π interaction, and precipitation. Therefore, high temperature-derived rice straw biochar can be expected to an adsorbent to alleviate Cu pollution in wastewater.

The nonsteroidal anti-inflammatory drug diclofenac (DCF) is considered a contaminant of emerging concern. DCF can co-exist with heavy metals in aquatic environments, causing unexpected risks to aquatic organisms. This study aimed to assess the combined effects of DCF and cadmium (Cd) at environmentally relevant concentrations on the bioconcentration and status of oxidative stress and detoxification in Chironomus riparius larvae. The larvae were exposed to DCF (2 and 20 μg L−1) and Cd (5 and 50 μg L−1) alone or in mixtures for 48 h. The combined exposure to DCF and Cd was found to reciprocally facilitate the accumulation of each compound in larvae compared with single exposures. As indicated by the antioxidant enzyme activities, reduced glutathione levels, and malondialdehyde contents, the low concentration of the mixture (2 μg L−1 DCF + 5 μg L−1 Cd) did not alter the oxidative stress status in larvae, while the high concentration of the mixture (20 μg L−1 DCF + 50 μg L−1 Cd) induced stronger oxidative damage to larvae compared with single exposures. The expression levels of eight genes (CuZnSOD, MnSOD, CAT, GSTd3, GSTe1, GSTs4, CYP4G, and CYP9AT2) significantly decreased due to the high concentration of the mixture compared with single exposures in most cases. Overall, the results suggest that the mixture of DCF and Cd might exert greater ecological risks to aquatic insects compared with their individual compounds.

Aminothiol levels are indicative of cellular and physiological statuses. A colorimetric and ratiometric dual-site fluorescent probe, NL-S, has been designed and synthesized. NL-S contains both a 2,4-dinitrobenzenesulfonyl group and an aldehyde group as recognition units for aminothiols. NL-S exhibited highly selective and sensitive detection of aminothiols, with a 27–44-fold enhancement of the fluorescent signal observed within 30 min of the addition of up to 20 equiv. of cysteine (Cys), homocysteine (Hcy) or glutathione (GSH) in aqueous media. The probe undergoes a turn-on excited-state intramolecular proton transfer process derived from cleavage and condensation reactions. The limits of detection for Cys, Hcy and GSH were 0.114, 0.146 and 0.202 μM, respectively. NL-S with negligible cytotoxicity was successfully employed to fluorescent imaging of aminothiols in living cells and zebrafish, suggesting good potential of NL-S in biological applications.

Improperly treated or directly discharged into the environment, wastewater containing dyes can destroy the quality of water bodies and pollute the ecological environment. The removal of dye wastewater is urgent and essential. In this study, corn stalk was pyrolyzed to pristine biochar (CSBC) in a limited oxygen atmosphere and modified using KOH and H3PO4 (KOH-CSBC, H3PO4-CSBC, respectively). The biochars were characterized by surface area and pore size, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), as well as their behavior in adsorbing methylene blue (MB). Results indicated that the pore structure of CSBC became more developed after modification by KOH. Meanwhile, H3PO4-CSBC contained more functional groups after activation treatment. The pseudo-second-order kinetic and the Langmuir adsorption isotherm represented the adsorption process well. The maximum MB adsorption capacity of CSBC, KOH-CSBC, and H3PO4-CSBC was 43.14 mg g&minus, 1, 406.43 mg g&minus, 1 and 230.39 mg g&minus, 1, respectively. Chemical modification significantly enhanced the adsorption of MB onto biochar, especially for KOH-CSBC. The adsorption mechanism between MB and biochar involved physical interaction, electrostatic interaction, hydrogen bonding and &pi, &ndash, &pi, interaction. Hence, modified CSBC (especially KOH-CSBC) has the potential for use as an adsorbent to remove dye from textile wastewater.

The propagation of antibiotic resistance is a challenge for human health worldwide, which has drawn much attention on the reduction of the resistance genes. To understand their occurrence during different treatment processes, in this study, four classes of antibiotics (tetracyclines, sulfonamides, quinolones, and macrolides), eight antibiotic resistance genes (ARGs) (tetB, tetW, sul1, sul2, gyrA, qepA, ermB, and ermF), and two mobile elements (int1 and int2) were investigated in a typical pharmaceutical plant. The total concentrations of antibiotics were detected in the range of 2.6 × 102 to 2.5 × 103 ng/L in the treatment processes, and the high abundance of ARGs was detected in the biological treatment unit. The dynamic trend analysis showed that antibiotics were partially removed in the anaerobic/aerobic processes, where ARGs were proliferated. The abundance of tetB and gyrA genes was positively correlated with pH and EC (p

Aliphatic polyacetylenes are nutraceuticals. Interactions of the polyacetylenes falcarinol, panaxydol and falcarindiol with human serum albumin (HSA) were studied via steady-state and time-resolved fluorescence, UV–Vis, circular dichroism and Fourier transform infrared (FT-IR) spectroscopies and molecular docking. The value of Stern-Volmer quenching constant (KSV) decreased with temperature increase in fluorescence quenching experiments, and the average fluorescence lifetime (τ) was calculated between 5.25 and 5.40 ns according to time-resolved fluorescence. The results indicated that the quenching mechanism of HSA by the three falcarinol-type polyacetylenes (FTPs) is a static process. FTPs most probably bind HSA at site II alone, located in domain IIIA, as evidenced by competitive ligand displacement and molecular docking studies. The FTPs could induce slight conformational and microenvironmental changes of HSA as determined by three-dimensional fluorescence, circular dichroism and FT-IR measurements, and energy transfer observed. The findings can offer important insights for the further design of potential biologically active FTPs.

A high-efficient iron-based heterogeneous catalyst is desired to active peroxymonosulfate (PMS). Due to a large catalytic contribution of atomically dispersed Fe-Nx sites, single-atom iron–nitrogen-carbon catalysts exhibit superior performance in the catalytic activation of PMS. Herein, a sequence of Fe-N-C SACs with atomically dispersed Fe-Nx sites, FeSA-N-C and FeSA-N/C, were prepared from Fe-doped ZIF-8 and FePc@ZIF-8, respectively. Single-atom Fe-Nx sites were confirmed to be the main active sites for PMS activation. FeSA-N/C-20 with a higher density of Fe-Nx sites exhibited superior catalytic performance to N/C, FeSA-N-C, FeSA-N/C-15, and FeSA-N/C-25 for BPA degradation. Integrated with chemical quenching experiments, electron spin resonance (ESR), in-situ Raman spectra, and electrochemical analysis, a nonradical pathway was demonstrated to dominate the degradation of BPA in the PMS + FeSA-N/C-20 system. More importantly, the nature of this nonradical pathway was found to be an electron-transfer regime instead of a high-valent iron or singlet oxygenation process. The BPA was adsorbed onto the Fe-Nx site by a “donor–acceptor complex” mechanism to form a nonradical PMS* intermediate during the process. Benefiting from this mechanism, the PMS + FeSA-N/C-20 system showed wide pH adaptation and high resistance to inorganic anions.

Facile modification of biochar to greatly improve its properties and then promoting its potential application is still a challenge. In this study, magnetic porous tea waste biochar (MKHBC) was produced first by hydrothermal pretreatment, impregnation with FeCl3·6H2O and KHCO3, and then pyrolysis at 700 °C to realize simultaneous carbonization, activation, and magnetization. Pristine biochar (HBC) was also prepared as a control. Biochars were characterized by SEM, TEM, XRD, Raman, BET, FTIR, XPS, and elemental analysis. The results showed that MKHBC had a surface area of 1035.11 m2 g−1, a total pore volume of 0.583 cm3 g−1, and a micropore volume of 0.344 cm3 g−1. More mesoporous structure was present in MKHBC. γ-Fe2O3 and Fe0, which determined the magnetic property of MKHBC, were observed in it. The saturated magnetization of MKHBC was 7.28 emu g−1, suggesting that rapid separation of adsorbent can be achieved by an external magnet. Carbon-, nitrogen-, and oxygen-containing groups in biochar significantly changed after modification. Langmuir isotherm and Elovich kinetic model fitted well with the adsorption process of tetracycline (TC) on biochar. The maximum adsorption capacity of TC on MKHBC reached 236.93 mg g−1, which was 14-fold than that of HBC (16.71 mg g−1). MKHBC could effectively remove TC in a wide pH range and in the presence of co-existing ions. The dominant mechanisms of TC removal on MKHBC were pore filling and π-π interaction, followed by surface complexation, and H bonding. Therefore, MKHBC has the potential to act as an adsorbent for TC removal from the aquatic environment.

Resource utilization is a critical pathway for sustainable solid waste treatment. Biochar was prepared from the co-pyrolysis of sewage sludge and tea waste. Brunauer–Emmett–Teller measurement, scanning electron microscopy and Fourier transform infrared analysis were employed to characterize the biochar. Then, the interface behavior between biochar and Cd from aqueous solution was investigated. The effect of adsorbent dose and pH on Cd adsorption was evaluated. Adsorption kinetics and the adsorption isotherm were studied, and the adsorption mechanism was explored. The results showed that the suitable adsorbent dose was 4 g L−1 and the optimal pH of the Cd solution remained at 6.0. Cadmium sorption on the biochar could be well described by the pseudo-second order kinetic model (R 2 > 0.98). The adsorption process was described using the Langmuir (R 2 > 0.86), Freundlich (R 2 > 0.86), Temkin (R 2 > 0.84) and Dubinin–Radushkevich (R 2 > 0.86) isotherm models. The proportion of organic constituents in biochar was 69.2–72.4%. Minerals that originated in biochar played an important role during the Cd adsorption process, and the contribution of minerals accounted for 27.6–30.8% of the total adsorption. The main mechanism of the Cd adsorption process by biochar involved ion exchange, surface complexation, electrostatic interaction, surface co-precipitation, and other mechanisms. Therefore, biochar created by the co-pyrolysis of sewage sludge and tea waste could be used as an adsorbent for the removal of metal ions from contaminated water.

This study was conducted to explore nitrogen transformation and associated microbial characteristics in a modified single-stage tidal flow constructed wetland (TFCW) at five different shunt ratios. Shunt ratio significantly affected nitrogen removal during operation of the TFCW with adoption of a modified step-feeding mode. When the shunt ratio was 1:2, TFCW had the best pollutant removal performance and was particularly effective for total nitrogen (TN). The abundance of nitrogen transformation microorganisms was also affected by the shunt ratio of the system. Molecular biological analyses demonstrated that both denitrification and anammox were enhanced when the shunt ratio was greater than 0:1, resulting in the development of multiple and complete nitrogen removal pathways in the TFCW. These results show that the optimal shunt ratio of the modified single-stage TFCW for effective nitrogen removal was 1:2.

In this study, biochar was produced from municipal sludge and was characterized by Surface area and porosity analysis, Scanning Electron Microscope–Energy Dispersive Spectrometer (SEM-EDS) and Fourier Transform Infrared Spectroscopy (FTIR). The effect factors including adsorbent dosage, contact time, pH, temperature on the adsorption properties of methylene blue (MB) from aqueous solution onto sludge-derived biochar were investigated in batch experiments. The adsorption kinetics, isotherm, thermodynamic and mechanism were also studied. The results showed that the adsorption kinetics of MB on biochar was accurately described by a pseudo-second-order model, indicating that liquid film diffusion, intra-particle diffusion and surface adsorption coexisted during MB adsorption on the biochar. The equilibrium adsorption data were well represented by the Langmuir isotherm equation (R2 > 0.99). As the initial MB concentration and temperature increased, the adsorption amount also increased and the adsorption was favorable. The thermodynamic analysis showed that MB adsorption onto sludge-derived biochar was spontaneous and endothermic. The desorption and reusability experiment indicated that sludge-derived biochar had the potential to be a reusable adsorbent for MB removal.The adsorption mechanism appeared to be related to electrostatic interaction, ion exchange, hydrogen bond interaction, n-π interaction, etc. Thus, sludge-derived biochar can be used as an effective absorbent to remove dyes from wastewater. As a beneficial by-product of sludge, sludge-derived biochar also can mitigate the environmental burden of sewage sludge.

The modification of biomass waste, as a multifunctional composite, has received tremendous attention for resource utilization and recycling. In this study, tea waste, which is a high level generator of biomass waste, was loaded with nano-Fe3O4 particles to prepare a magnetic tea waste/Fe3O4 (TW/Fe3O4) composite through a facile chemical co-precipitation approach. BET, SEM, TEM, XRD, magnetic properties, FTIR, XPS were used to characterize the TW/Fe3O4 composite. A superparamagnetic TW/Fe3O4 composite (Fe3O4: about 20 nm) was successfully synthesized and possessed the advantages of tea waste and nano-Fe3O4 particles. A chromium(VI) adsorption experiment showed that this material has a strong adsorption capacity for aqueous chromium ions, which reached 75.76 mg g−1 based on the Langmuir model. The adsorption process could be well fitted by a pseudo-second-order kinetic model and Langmuir, Temkin and Dubinin–Radushkevich (D–R) isotherm models, and was spontaneous and endothermic according to the thermodynamic analysis. The TW/Fe3O4 composite revealed good reusability and the removal rate was more than 70% after five recycling cycles. The mechanism of Cr(VI) removal involved electrostatic attraction, reduction process, ion exchange, surface complexation, etc. 70% of Cr(VI) was reduced to Cr(III) in this investigation. This study indicated that a TW/Fe3O4 composite could be an attractive option for heavy metal treatment.

2,7-Dibromocarbazole (2,7-DBCB) and 3,6-dibromocarbazole (3,6-DBCB) are emerging environmental pollutants, being potentially high risks to human health. In this study, interactions of the two compounds with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated by molecular modeling, density functional theory calculations (DFT) and multispectral techniques. The static quenching interaction deduced in the fluorescence quenching experiment is confirmed by the time-resolved analyses. The interactions of the two compounds with HSA/BSA induce molecular microenvironment and conformation changes, as assessed by synchronous and 3D fluorescence spectra, together with a destruction of polypeptide carbonyl hydrogen bond network by circular dichroism and Fourier transform infrared analyses. The thermodynamic analysis indicated that the spontaneous interaction was hydrogen bonding and hydrophobic forces. The binding constant Ka at 298 K was 3.54 × 105 M−1 in HSA-2,7-DBCB, 6.63 × 105 M−1 in HSA-3,6-DBCB, 1.32 × 105 M−1 in BSA-2,7-DBCB and 2.17 × 105 M−1 in BSA-3,6-DBCB. These results indicates that 3,6-DBCB binds HSA/BSA more strongly than 2,7-DBCB, which was estimated with DFT calculations. Site marker competition experiments coupled with molecular modeling studies confirmed that both compounds bind HSA/BSA at site I (subdomain IIA). The results suggest that interactions between 2,7-DBCB and 3,6-DBCB with HSA and BSA may affect the normal physiological activities in human and animals.

Biochar was generated from municipal sludge and tea waste through co-pyrolysis in this study and was characterized by Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The effect factors including dosage, contact time, pH, temperature on the adsorption properties of methylene blue (MB) onto biochar were investigated. The adsorption kinetics, isotherm, thermodynamic and mechanism also were also studied. The results showed that pseudo-second order kinetics was the most suitable model for describing the adsorption of MB onto biochar. Equilibrium data were well fitted to the Langmuir isotherm model. A rise in operating temperature enhances MB adsorption on biochar. Adsorption thermodynamic of MB on biochar showed that the adsorption was a spontaneous and endothermic process and revealed favorable spontaneous under higher temperature conditions. Meanwhile, the positive values of ∆ S suggest the increased randomness at the solid/solution interface during the sorption of MB onto biochar. The mechanism between MB and biochar involved electrostatic interaction, ion exchange, surface complexation, physical function and others. This work shows that the biochar hold promises acting as effective adsorbent to remove dyes in the wastewater.

Iron-mediated activation of peroxymonosulfate (PMS) has been widely investigated for recalcitrant pollutants. However, maximizing the dispersion degree of the active iron sites in the catalysts is still a great challenge and attracting tremendous attention. Herein, we demonstrated that well-dispersed single atomic Fe sites embedded into N-doped porous carbon (FeSA-N-C), which derived from chemically Fe-doped zeolitic imidazolate frameworks, could work as Fe-based catalyst for efficient catalytic oxidation of recalcitrant organics via PMS activation. As expected, FeSA-N-C exhibited remarkably higher degradation activity (8.1 times faster) to BPA (a model pollutant) than that of Fe based nanoparticles-loaded N-doped carbon (FeNP-N-C). The sufficient Fe-Nx sites with single Fe atom as the building units were proposed to be the main active sites for PMS activation. Based on that, unlike the traditional sulfate radical-based advanced oxidation processes, BPA degradation was achieved via high-valent iron-oxo species. More particularly, it could be used over a wide range of pH 3.0–7.5 with almost no loss of degradation efficiency. This study will provide insights into the design of heterogeneous Fenton-like catalysts.

Diclofenac (DCF), a non-steroidal anti-inflammatory drug, is widespread in aquatic environments and coexists with heavy metals to form combined pollution. However, the interactive effects of DCF and heavy metals on aquatic organisms remain unknown. This study aimed to investigate the interactive effects of DCF and copper (Cu) on the bioconcentration, oxidative stress status and detoxification-related gene expression in crucian carp (Carassius auratus). Fish were exposed to Cu (100 μg L−1) and DCF (1, 10, 100 and 1000 μg L−1) alone or in combination for 7 days. Results obtained showed that the treatment of Cu combined with high levels of DCF (100 and 1000 μg L−1) significantly decreased tissue concentrations of DCF and Cu compared to the correspondingly individual exposure. Concerning oxidative stress status, as reflected by the activities of antioxidant enzymes and malondialdehyde content, low exposure concentrations of DCF (1 and 10 μg L−1) seemed to mitigate the oxidative stress induced by Cu, whereas the co-exposure of Cu with the highest level of DCF (1000 μg L−1) led to stronger oxidative damage in fish liver than Cu exposure alone. With regarding to detoxification-related genes, in most cases, the expressions of cyp 1a, cyp 3a, gstα, gstπ, pxr and P-gp in crucian carp were significantly altered upon exposure to the compounds in combination compared to exposure to the compounds individually. Collectively, these findings indicate the capacity of each of these pollutants to alter bioconcentration potential, pro-oxidative effects and detoxification-related gene responses of the other when both co-occur at specific concentrations.

Although sulfadiazine (SDZ) is widespread in aquatic environments, information regarding the effects of SDZ on aquatic insects is still limited. In the present study, the bioconcentration and the effects of SDZ on the antioxidant system and the expression of endocrine and stress-related genes in Chironomus riparius larvae were investigated. The larvae were exposed to SDZ at the nominal concentrations of 2, 20 and 200 μg/L for 48 h. The results showed that SDZ was taken up by C. riparius despite presenting low bioconcentration factor values (0.99-3.92). In addition, superoxide dismutase activity was markedly reduced compared with the control group, whereas the levels of malondialdehyde were not significantly affected by SDZ. Moreover, the mRNA expression of genes related to heat shock proteins (Hsp70 and Hsp27) and ecdysone pathway (EcR and E74) were significantly up-regulated following all SDZ treatments. In aggregate, our work provides novel and interesting results regarding the potential biochemical and genetic effects of SDZ on freshwater insects.

Tea waste (biosorbent) was characterized by BET, SEM, FTIR, XPS, solid state 13C-NMR and applied to remove methylene blue (MB) from aqueous solution. The effect of different factors on MB removal, kinetics, isotherms and potential mechanism was investigated. The results showed that tea waste contains multiple organic functional groups. The optimum solid-to-liquid ratio for MB adsorption was 4.0 g&middot, L&minus, 1 and the initial pH of the MB solution did not need to be adjusted to a certain value. The pseudo-second-order model could well fit the adsorption kinetic process. The adsorption process could be divided into two stages: a fast adsorption stage and a slow adsorption stage. The adsorption isotherm could be well described by Langmuir and Temkin isotherm models. The maximum adsorption amount could reach 113.1461 mg&middot, g&minus, 1 based on Langmuir isotherm fitting. Desorption and reusability experiments showed that MB adsorption onto tea waste could be stable and could not cause secondary pollution. The interaction mechanism between tea waste and MB involved electrostatic attraction, hydrogen bond, ion exchange, &pi, &pi, binding. The organic functional groups of tea waste played an important role during the MB removal process. Therefore, tea waste has the potential to act as an adsorbent to remove MB from aqueous solution.

Antibiotic pollution has drawn considerable attention and the removal of antibiotic from water is crucial. In the present study, biochars were produced from rice straw under different pyrolytic temperatures of 300 °C, 500 °C, and 700 °C (RSBC300, RSBC500, and RSBC700, respectively). The biochars were used to remove tetracycline (TC) from aqueous solution and the influence of different experimental conditions on TC removal was investigated. The results showed that the order of adsorption was as follows: RSBC700 > RSBC500 > RSBC300. A pseudo-second-order model and Langmuir isotherm model described the adsorption process of TC on biochars. Maximum adsorption capacity could reach 50.72 mg g−1 at 35 °C based on Langmuir fitting. Initial pH of the solution had little influence on TC removal. The inhibitory effect of Ca2+ on TC removal was greater than that of Na+. High system temperature was beneficial for TC removal. Minerals in RSBC500 affected TC removal and minerals in RSBC300 and RSBC700 had little influence on TC removal. TC removal rate decreased from 58.86 to 27.84% when the minerals were removed from RSBC500. The main mechanism involved in high-temperature biochar and TC adsorption included EDA π-π interactions and electrostatic interactions. Therefore, high-temperature biochar derived from rice straw has the potential to act as an adsorbent to remove tetracycline from aqueous solution.

The herbicide atrazine is widely used across the globe, which is a great concern. To investigate its potential toxicity in the human body, human serum albumin (HSA) was selected as a model protein. The interaction between atrazine and HSA was investigated using steady-state fluorescence spectroscopy, synchronous fluorescence spectroscopy, UV-Vis spectroscopy, three-dimensional (3D) fluorescence spectroscopy and circular dichroism (CD) spectroscopy. The intrinsic fluorescence of HSA was quenched by the atrazine through a static quenching mechanism. Fluorescence spectra at two excitation wavelengths (280 and 295 nm) showed that the fluorescence quenched in HSA was mainly contributed to by tryptophan residues. In addition, the atrazine bound to HSA, which induced changes in the conformation and secondary structure of HSA and caused an energy transfer. Thermodynamic parameters revealed that this binding is spontaneous. Moreover, electrostatic interactions play a major role in the combination of atrazine and HSA. One atrazine molecule can only bind to one HSA molecule to form a complex, and the atrazine molecule is bound at site II (subdomain IIIA) of HSA. This study furthers the understanding of the potential effects posed by atrazine on humans at the molecular level.

This study was conducted to investigate the long-term impact of influent phosphorus concentration on denitrifying phosphorus removal and N2O production during denitrifying phosphorous removal process. The results showed that, denitrifying phosphate accumulating organisms (DPAOs) could become dominant populations quickly in anaerobic/anoxic SBR by providing optimum cultivating conditions, and the reactor performed well for denitrifying phosphorus removal. The influent phosphorus concentration significantly affected anaerobic poly-β-hydroxyalkanoates (PHA) synthesis, denitrifying phosphorus removal, and N2O production during the denitrifying phosphorus removal process. As the influent phosphorus concentration was more than 20 mg L(-1), the activity of DPAOs began to be inhibited due to the transformation of the available carbon source type. Meanwhile, N2O production was inhibited with the mitigation of anoxic NO2(-)-N accumulation. Adoption of a modified feeding could enhance denitrifying phosphorus removal and inhibit N2O production during denitrifying phosphorous removal processes.

Perfluorooctane sulfonate (PFOS) is one of the most widespread toxic substances in water distribution systems, posing a significant risk to public health and the environment due to its toxic and non-biodegradable nature. In this study, the effect of oxalate on PFOS adsorption/desorption to/from soil and sediment samples was studied with batch experiments. Dissolved organic carbon content in soil strongly enhanced the retention of organic halogens. Oxalate increased PFOS desorption by 1.43- to 17.14-fold and significantly increased the release of dissolved organic carbon and inorganic ions in soils. The effects of root exudates were similar to those of oxalate. Addition of low molecular weight dissolved organic carbon caused partial dissolution of the soil structure (e.g., through formation of organo-mineral complexes), resulting in the release of organic carbon and metal ions and subsequently enhancing PFOS desorption. The effects of oxalate on organic halogen desorption were influenced by dissolved organic carbon content and formation of calcium oxalate.

The biochars were produced from wheat straw (WSBC) at different pyrolytic temperatures. Biochars were characterized by multiple instrumental techniques and were applied to remove Cd from aqueous solution. The removal mechanism was explored, and the quantitative information regarding the relative contribution of related mechanisms to Cd sorption on biochars was provided. The results showed that pseudo-second-order kinetic model, TC (two-compartment) model, and Freundlich isotherm could well fit the process of Cd sorption on biochars. The sorption could be divided into fast and slow adsorption stages. The order of the Cd removal capacity by biochar was WSBC700WSBC500WSBC300. Adsorption amount of Cd by biochar reduced when the biochar was rinsed with 1.0 M HCl, which indicated that acid-soluble minerals in biochar played an important role during the Cd removal process, especially for the biochar obtained at high pyrolytic temperature. Various equipments were used to investigate the interaction mechanism between biochar and Cd. Mineral precipitation, surface complexation, and cation-π interaction were the main mechanisms of Cd sorption on the biochars. The contribution of cation-π mechanism was in the range of 25.42-48.58%, 2.18-19.30% for surface complexation and 32.12-72.41% for mineral precipitation, respectively. The pyrolytic temperature significantly influenced the removal capacity and mechanism of Cd on biochars. The cation-π mechanism was predominant for biochar obtained at lower pyrolytic temperature. However, mineral precipitation mechanism played a crucial role for biochar obtained at high pyrolytic temperature. These results are helpful for the design or screening of "engineered biochar" to act as sorbents to remove or immobilized Cd in polluted soil or water. Graphical abstract ᅟ.

Some tetrahydroisoindoline-1,3-dione derivatives (TDDs) possess potent herbicidal activity. To assess possible impacts of TDDs on humans, the interactions between TDDs and human serum albumin (HSA) were evaluated with steady-state and time-resolved fluorescence spectroscopy, synchronous fluorescence spectroscopy, Fourier transform-infrared spectroscopy, and circular dichroism spectroscopy. The thermodynamic data obtained at temperatures of 298, 307, and 316 K indicate that TDDs spontaneously bind to HSA and thus form a TDD-HSA complex. The conformation and secondary structure of HSA are changed, and the intrinsic fluorescence of HSA is statically quenched by TDDs. Moreover, the TDD-HSA complex is formed primarily through electrostatic interactions and has only one binding site on HSA. A competitive ligand-binding assay revealed that site II (subdomain IIIA) displays the greatest affinity for TDDs. In addition, an acute toxicity bioassay showed no zebrafish mortality upon exposure to 4000 μg L−1 of TDDs. This work is helpful for understanding interactions between TDDs and HSA.

The interactions of dihydroquinazolines with human serum albumin (HSA) were studied in pH 7.4 aqueous solution via fluorescence, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic techniques. In this work, 6-chloro-1-(3,3-dimethyl-butanoyl)-2(un)substitutedphenyl-2,3-dihydroquinazolin-4(1H)-one (PDQL) derivatives were designed and synthesized to study the impact of five similar substituents (methyl, methoxy, cyano, trifluoromethyl and isopropyl) on the interactions between PDQL and HSA using a comparative methodology. The results revealed that PDQL quenched the intrinsic fluorescence of HSA through a static quenching process. Displacement experiments with site-specific markers revealed that PDQL binds to HSA at site II (subdomain IIIA) and that there may be only one binding site for PDQL on HSA. The thermodynamic parameters indicated that hydrophobic interactions mainly drove the interactions between PDQL and HSA. The substitution using five similar groups in the benzene ring could increase the interactions between PDQL and HSA to some extent through the van der Waals force or hydrogen bond effects in the proper temperature range. Isopropyl substitution could particularly enhance the binding affinity, as observed via comparative studies