At present, the simultaneous removal of organic dyes and heavy metals in complex wastewater has raised considerable concern, owing to their striking differences in physicochemical properties. Adsorption, as one of the few removal methods, has attracted extensive attention and gained popularity. Herein, a versatile EDTA and chitosan bi-functionalized magnetic bamboo biochar adsorbent (ECMBB) was synthesized for coinstantaneous adsorption of methyl orange (MO) and heavy metals (Cd(II) and Zn(II)). In this case, the as-synthesized ECMBB composites inherited favorable anionic MO removal performance from bamboo biochar (BB) obtained at 700 °C through electrostatic attraction, hydrogen bonding and π-π interaction, also enhanced the binding of cationic metals by introducing amino groups of chitosan and carboxyl groups of EDTA. In the unitary system, the removal of MO, Cd(II) and Zn(II) by three as-prepared adsorbents can be well illuminated by pseudo-second-order kinetic model and Langmuir isotherm theory. The saturated capture amounts of ECMBB at 25 °C are 305.4 mg g⁻¹ for MO, 63.2 mg g⁻¹ for Cd(II) and 50.8 mg g⁻¹ for Zn(II), which, under the same conditions, are 1.3, 2.6 and 2.5 times those of chitosan-modified magnetic bamboo biochar (CMBB) and 1.9, 6.1 and 5.4 times those of magnetic bamboo biochar (MBB), respectively. Remarkably, in MO-metal binary system, coexisting MO visibly enhanced the adsorption of Cd(II) and Zn(II), while coexisting heavy metals had no significant impact on MO adsorption. Furthermore, ECMBB exhibited no significant loss in adsorption efficiency even after eight adsorption-desorption experiments. This study lays the foundation for fabricating desired integrative biochar adsorbents in the simultaneous purification of organic and metallic pollutants from complex wastewater.

Dissolved organic matter (DOM) plays a significant role in the photochemical behavior of nano- and micro-plastic particles (NPs/MPs). We investigated the influence of DOM on the mechanism on the photoaging of NPs/MPs with different molecular structures under UV₃₆₅ irradiation in water. DOM components used in this study are mainly humic acid and fulvic acid. The results showed that DOM promoted the weathering of aliphatic NPs/MPs (polypropylene (PP)), but inhibited or had only a minor effect on the photoaging of aromatic NPs/MPs (polystyrene (PS) NPs/MPs, carboxyl-modified PS NPs, amino-modified PS NPs, and polycarbonate MPs). NPs with a large surface area may adsorb sufficient DOM on the particle surfaces through π-π interactions, which competes with NPs for photon absorption sites, thus, can delay the photoaging of PS NPs. Aromatic MPs may release phenolic compounds that quench •OH, thereby weakening the photoaging process. For aliphatic MPs, the detection of peracid, aldehyde, and ketone groups on the polymer surface indicated that DOM promoted weathering of PP MPs, which was primarily because the generation of •OH due to DOM photolysis may attack the polymer by C–C bond cleavage and hydrogen extraction reactions. This study provides insight into the UV irradiation weathering process of NPs/MPs of various compositions and structures, which are globally distributed in water.

Fe–N co-doped biochar is recently an emerging carbocatalyst for persulfate activation in situ chemical oxidation (ISCO). However, the involved catalytic mechanisms remain controversial and distinct effects of coexisting water components are still not very clear. Herein, we reported a novel N-doped biochar-coupled crystallized Fe phases composite (Fe@N-BC₈₀₀) as efficient and low-cost peroxydisulfate (PDS) activators to degrade bisphenol A (BPA), and the underlying influencing mechanism of coexisting inorganic anions (IA) and humic constituent. Due to the formation of graphitized nanosheets with high defects (AI index>0.5, ID/IG = 1.02), Fe@N-BC₈₀₀ exhibited 2.039, 5.536, 8.646, and 23.154-fold higher PDS catalytic activity than that of Fe@N-BC₆₀₀, Fe@N-BC₄₀₀, N-BC, BC. Unlike radical pathway driven by carbonyl group and pyrrolic N of low/mid-temperature Fe@N–BCs. The defective graphitized nanosheets and Fe-Nx acted separately as electron transfer and radical pathway active sites of Fe@N-BC₈₀₀, where π-π sorption assisted with pyrrolic N and pore-filling facilitated BPA degradation. The strong inhibitory effects of PO₄³⁻ and NO₂⁻ were ascribed to competitive adsorption of phosphate (61.11 mg g⁻¹) and nitrate (23.99 mg g⁻¹) on Fe@N-BC₈₀₀ via electrostatic attraction and hydrogen bonding. In contrast, HA competed for the pyrrolic-N site and hindered electron delivery. Moreover, BPA oxidation pathways initiated by secondary free radicals were proposed. The study facilitates a thorough understanding of the intrinsic properties of designed biochar and contributes new insights into the fate of degradation byproducts formed from ISCO treatment of micropollutants.

The catalytic hydrogenolysis of a typical model compound of mulching film waste, polyethylene, was investigated as a potential way to improve economic efficiency of mulching film recycling. Nickel-based heterogeneous catalysts are proposed for polyethylene hydrogenolysis to produce liquid hydrocarbons. Among catalysts supported on various carriers, Ni/SiO₂ catalyst shows the highest activity which may due to the interactions between nickel and silica with the formation of nickel phyllosilicate. As high as 81.18% total gasoline and diesel range hydrocarbon was obtained from the polyethylene hydrogenolysis at relatively mild condition of 280 °C, and 3 MPa cold hydrogen pressure. The result is comparable to what have been reported in previous studies using noble metal catalysts. The gasoline and diesel range hydrocarbon are n-alkanes with a distribution at a range of C₄–C₂₂. The gas products are primarily CH₄ along with a small amount of C₂H₆ and C₃H₈. High yield of CH₄ as much as 9.68% was observed for the cleavage of molecule occurs along the alkane chain.

Zero valent iron-loaded biochar (Fe⁰-BC) has shown promise for the removal of various organic pollutants, but is restricted by reduced specific surface area, low utilization efficiency and limited production of reactive oxygen species (ROS). In this study, iron carbide-loaded activated biochar (Fe₃C-AB) with a high surface area was synthesized through the pyrolysis of H₃PO₄ activated biochar with Fe(NO₃)₃, tested for removing bisphenol A (BPA) and elucidated the adsorption and degradation mechanisms. As a result, H₃PO₄ activated biochar was beneficial for the transformation of Fe⁰ to Fe₃C. Fe₃C-AB exhibited a significantly higher removal rate and removal capacity for BPA than that of Fe⁰-BC within a wide pH range of 5.0–11.0, and its performance was maintained even under extremely high salinity and different water sources. Moreover, X-ray photoelectron spectra and density functional theory calculations confirmed that hydrogen bonds were formed between the COOH groups and BPA. ¹O₂ was the major reactive species, constituting 37.0% of the removal efficiency in the degradation of BPA by Fe₃C-AB. Density functional reactivity theory showed that degradation pathway 2 of BPA was preferentially attacked by ROS. Thus, Fe₃C-AB with low cost and excellent recycling performance could be an alternative candidate for the efficient removal of contaminants.

Herein, magnetic porous pinecone-derived hydrochar (MPHCMW) co-activated by KHCO₃ and K₂FeO₄ through one-step microwave-assisted pyrolysis was innovatively synthesized for hexavalent chromium (Cr(VI)) and anthracene (ANT) removal from water. The analyses of characterization consequences and co-activation mechanisms not merely proved the high specific surface area (703.97 m²/g) and remarkable microporous structures of MPHCMW caused by the synergistic chemical activation of KHCO₃ and K₂FeO₄, but also testified successful loading of Fe⁰ and Fe₃O₄ on MPHCMW by the process of carbothermal reduction between K₂FeO₄ and carbon matrix of hydrochar. The resultant MPHCMW possessed pH-dependence for Cr(VI), while adsorption for ANT was hardly impacted by the pH of solution. Moreover, the adsorption processes of MPHCMW could attain equilibrium within 60 min for Cr(VI) and 30 min for ANT with multiple kinetics, and the corresponding adsorption capacity for Cr(VI) and ANT was 128.15 and 60.70 mg/g, respectively. Additionally, the adsorption percentages of MPBCMW for Cr(VI)/ANT was maintained at 87.87/82.64% after three times of adsorption-desorption cycles. Furthermore, pore filling, complexation, electrostatic interaction, reduction and ion exchange were testified to enhance the removal of Cr(VI), while the ANT removal was achieved via π-π stacking, complexation, pore filling and hydrogen bonding force.

The narrow acid pH range and the nonselectivity of the dominant •OH limit the Fenton systems to remediate the organic wastewater. Inspired by the role of heme in physiological processes, we employed iron porphyrin as a novel homogeneous catalyst to address this issue. Multiple active species are identified during the activation of H₂O₂, including high-valent iron porphyrin ((por)Fe(IV)) species ((por)Fe(IV)–OH, (por)⁺•Fe(IV)=O) and oxygen-centered radicals (•OH, HO₂•/•O₂⁻), as well as atomic hydrogen (*H) and carbon-centered radicals. With the cooperation of these active species, the degradation of pollutants could be resistant to the interference of concomitant ions and proceed over a wide pH range. This cooperative behavior is further verified by intermediates identified from bisphenol A degradation. Specifically, the presence of *H could facilitate the cleavage of the C–C bond and the addition of unsaturated or aromatic molecules. (Por)⁺•Fe(IV)=O could hydroxylate substrates with an oxygen rebound mechanism. Hydrogen atom abstraction of contaminants could be performed by (por)Fe(IV)–OH to form desaturated products by attacking oxygen-centered radicals. The ecotoxicity of bisphenol A could be significantly decreased through degradation. This study would provide a new approach to wastewater treatment and shed light on the interaction between metalloporphyrin and peroxide in an aqueous solution.

Bank filtration (BF) has been employed for more than a century for the production of water with a better quality, and it has been showing satisfactory results in diclofenac attenuation. Considered the most administered analgesic in the world, diclofenac has been frequently detected in water bodies. Besides being persistent in the environment, this compound is not completely removed by the conventional water treatments, drinking water treatment plants (DWTPs) and wastewater treatment plant (WWTPs). BF has a high complexity, whose efficiency depends on the characteristics of the observed pollutant and on the environment where the system in installed, which is why this is a topic that has been constantly studied. Nevertheless, studies present the behavior of diclofenac during the BF process. In this context, this research performed the evaluation of the factors and the biogeochemical processes that influence the efficiency of the BF technique in diclofenac removal. The aerobic conditions, higher temperatures, microbial biomass density, hydrogen potential close to neutrality and sediments with heterogeneous fractions are considered the ideal conditions in the aquifer for diclofenac removal. Nonetheless, there is no consensus on which of these factors has the greatest contribution on the mechanism of attenuation during BF. Studies with columns in laboratory and modeling affirm that the highest degradation rates occur in the first centimeters (5–50 cm) of the passage of water through the porous medium, in the environment known as hyporheic zone, where intense biogeochemical activities occur. Research has shown 100% removal efficiency for diclofenac persistent to compounds not removed during the BF process. However, half of the studies had removal efficiency that ranged between 80 and 100%. Therefore, the performance of more in-depth studies on the degradation and mobility of this compound becomes necessary for a better understanding of the conditions and biogeochemical processes which act in its attenuation.

Carbendazim (CBZ), a broad-spectrum pesticide frequently detected in fruits and vegetables, could trigger potential toxic risks to mammals. To facilitate the assessment of health risks, this study aimed to characterize the cytochrome P450 (CYPs)-mediated metabolism profiles of CBZ by a combined experimental and computational study. Our results demonstrated that CYPs-mediated region-selective hydroxylation was a major metabolism pathway for CBZ in liver microsomes from various species including rat, mouse, minipig, dog, rabbit, guinea pig, monkey, cow and human, and the metabolite was biosynthesized and well-characterized as 6-OH-CBZ. CYP1A displayed a predominant role in the region-selective hydroxylation of CBZ that could attenuate its toxicity through converting it into a less toxic metabolite. Meanwhile, five other common pesticides including chlorpyrifos-methyl, prochloraz, chlorfenapyr, chlorpyrifos, and chlorothalonil could significantly inhibit the region-selective hydroxylation of CBZ, and consequently remarkably increased CBZ exposure in vivo. Furthermore, computational study clarified the important contribution of the key amino acid residues Ser122, and Asp313 in CYP1A1, as well as Asp320 in CYP1A2 to the hydroxylation of CBZ through hydrogen bonds. These results would provide some useful information for the metabolic profiles of CBZ by mammalian CYPs, and shed new insights into CYP1A-mediated metabolic detoxification of CBZ and its health risk assessment.