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Carnation-like CuS nanoflowers were prepared by a mildly hydrothermal method without any surfactants or templates and further evolved into CCN-CuS p–n heterojunctions. And the as-prepared samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis absorption spectroscopy, Brunauer–Emmett–Teller (BET), photoluminescence (PL) and the photocurrent response. The results show that the appropriate load content of CCN is conducive to form well-morphology CCN-CuS heterojunctions. And the formation of CCN-CuS p–n heterojunctions is both beneficial to achieve higher charge separation efficiency and promote its photocatalytic performance to RhB dye without the existence of H 2 O 2 , which is commonly used as the sources of hydroxyl radicals to assist photocatalytic process. Besides, the as-synthesized 5CCN-CuS NFs show good stability and no obvious inactivation occurred after five degradation cycles runs. [ABSTRACT FROM AUTHOR]

Recently, highly efficient activation of peroxymonosulfate (PMS) by S-doped cobalt-based catalysts are receiving increased attention. The effect of S is worth exploring since it has a great influence on PMS activation performance. In this work, dimethyl sulfoxide was adopted as an S source and loaded on bamboo biochar (BB) with Co to form CoS/BBC, which served as an efficient catalyst for PMS activation to degrade sulfamethoxazole (SMX). The experiment results showed that CoS/BBC exhibits an excellent catalytic activity and the SMX (20 mg/L) can be completely degraded under the attack of species of · OH, SO 4 - · , 1O 2 and electron transfer. The SMX degradation conformed to pseudo first-order kinetics with rate constant reaching 0.442 min−1 in 10 min under the optimal conditions (a catalyst dose of 0.02 g/L, a PMS dose of 0.3 g/L and an initial pH = 7.0). The electrochemical experiments and density functional theory (DFT) calculation revealed that the introduction of S can accelerate electron transfer and promote the decomposition of PMS while facilitating Co(III)/Co(II) redox cycling. Furthermore, liquid chromatograph-mass spectrometer (LC-MS) and ecological structure activity relationships (ECOSAR) proved that the degradation process of SMX in CoS/BBC/PMS system has low ecotoxicity and is harmless to the environment. This work provides a new strategy for enhancing electron transfer by S-doped metal materials and the synthesis of efficient catalysts for SMX removal. [Display omitted] • CoS/BBC/PMS system presented > 99% removal efficiency within 10 min. • S accelerated electron transfer and promoted Co(III)/Co(II) redox cycling. • Effects of anions and dissolved organic matters on PMS activation were studied. • SMX degradation pathways were proposed and verified by LC-MS and DFT. • Sulfamethoxazole degradation in this system was a toxicity-attenuation process. [ABSTRACT FROM AUTHOR]

Bi/BiVO 4 photoelectrode was prepared on FTO glass by the combination of electrochemical deposition, heating treatment and photo-assisted reduction method at room temperature. All of the samples were characterized by X-ray diffraction spectrum (XRD), scanning electron microscope (SEM) and UV–vis diffuse reflectance spectrum (DRS), respectively. The results indicated that metallic Bi particles were well deposited on porous BiVO 4 film during the deposition process of photo-assisted reduction, resulting in a greatly broadened visible light absorption edge than that of BiVO 4 alone. The optimized photoelectrochemical (PEC) performance of Bi/BiVO 4 -60 was further verified by linear scan voltammetry (LSV), current-time (I-t) and incident photon-to-current efficiency (IPCE), respectively. It was conjectured the broadened visible light response range of Bi/BiVO 4 PEC system and the increased counteraction against positive charge both were caused by the electron transferred from BiVO 4 to Bi, and thus effectively facilitated the separation and transfer of photo-generated carriers and thus promote the PEC water splitting performance. [ABSTRACT FROM AUTHOR]

• OA-ZVIbm/H 2 O 2 removed TAP efficiently at pH 3.5–9.5 for more than 13 cycles. • OA-ZVIbm/H 2 O 2 self-adapted the solution pH to weak acidic conditions. • The highly proton-conductive FeC 2 O 4 ·2H 2 O shell enabled H+ transfer to Fe0 core. • Effective H+ cycle of OA-ZVIbm/H 2 O 2 drove Fe(II) production and Fenton reaction. Heterogeneous Fenton reactions of zero-valent iron (ZVI) requires the sufficient release of Fe(II) to catalyze the H 2 O 2 decomposition. However, the rate-limiting step of proton transfer through the passivation layer of ZVI restricted the Fe(II) release via Fe0 core corrosion. Herein we modified the shell of ZVI with highly proton-conductive FeC 2 O 4 ·2H 2 O by ball-milling (OA-ZVIbm), and demonstrated its high heterogeneous Fenton performance of thiamphenicol (TAP) removal, with 500 times enhancement of the rate constant. More importantly, the OA-ZVIbm/H 2 O 2 showed little attenuation of the Fenton activity during 13 successive cycles, and was applicable across a wide pH range of 3.5–9.5. Interestingly, the OA-ZVIbm/H 2 O 2 reaction showed pH self-adapting ability, which initially reduced and then sustained the solution pH in the range of 3.5–5.2. The abundant intrinsic surface Fe(II) of OA-ZVIbm (45.54% vs. 27.52% in ZVIbm, according to Fe 2p XPS profiles) was oxidized by H 2 O 2 and hydrolyzed to generate protons, and the FeC 2 O 4 ·2H 2 O shell favored the fast transfer of protons to inner Fe0, therefore, the consumption-regeneration cycle of protons were accelerated to drove the production of Fe(II) for Fenton reactions, demonstrated by the more prominent H 2 evolution and nearly 100% H 2 O 2 decomposition by OA-ZVIbm. Furthermore, the FeC 2 O 4 ·2H 2 O shell was stable and slightly decreased from 1.9% to 1.7% after the Fenton reaction. This study clarified the significance of proton transfer on the reactivity of ZVI, and provided an efficient strategy to achieve the highly efficient and robust heterogeneous Fenton reaction of ZVI for pollution control. The proton-conductive FeC 2 O 4 ·2H 2 O shell accelerates the cycle of H + and the heterogeneous Fenton reaction of OA-ZVIbm/H 2 O 2. [Display omitted] [ABSTRACT FROM AUTHOR]

• Cl modified Cu foam electrode was used to efficiently reduce nitrate. • The O–H···Cl hydrogen-bonds accelerated water dissociation to generate atomic H*. • A novel device was designed for nitrate conversion and in-situ ammonia recovery. • A stable NH 3 yield rate of 420 μg h−1 cm−2 could be achieved over 100 h. Green ammonia production from wastewater via electrochemical nitrate reduction contributes substantially to the realization of carbon neutrality. Nonetheless, the current electrochemical technology is largely limited by the lack of suitable device for efficient and continuous electroreduction nitrate into ammonia and in-situ ammonia recovery. Here, we report a flow-through coupled device composed of a compact electrocatalytic cell for efficient nitrate reduction and a unit to separate the produced ammonia without any pH adjustment and additional energy-input from the circulating nitrate-containing wastewater. Using an efficient and selective Cl-modified Cu foam electrode, nearly 100% NO 3 − electroreduction efficiency and over 82.5% NH 3 Faradaic efficiency was realized for a wide range of nitrate-containing wastewater from 50 to 200 mg NO 3 −-N L−1. Moreover, this flow-through coupled device can continuingly operate at a large current of 800 mA over 100 h with a sustained NH 3 yield rate of 420 μg h−1 cm−2 for nitrate-containing wastewater treatment (50 mg NO 3 −-N L−1). When driven by solar energy, the flow-through coupled device can also exhibit exceptional real wastewater treatment performance, delivering great potential for practical application. This work paves a new avenue for clean energy production and environmental sustainability as well as carbon neutrality. [Display omitted] [ABSTRACT FROM AUTHOR]

• Pharmaceutical sludge biochar (PSBC) was used to activate peroxymonosulfate (PMS). • PSBC/PMS removed 4-CP effectively with high rate constants of 0.42–1.70 min−1. • Rising pyrolysis temperature shifted reactive species from FeIVO2+ to SO 4 ·−/·OH. • FeN x and Fe x N in PSBC were active sites of PMS to produce FeIVO2+ and SO 4 ·−/·OH. Pyrolysis of pharmaceutical sludge (PS) is a promising way of safe disposal and to recover energy and resources from waste. The resulting PS biochar (PSBC) is often used as adsorbent, but has seldom been explored as catalyst. Herein we demonstrate that PSBC (0.4 g/L) could efficiently activate peroxymonosulfate (PMS) to 100% degrade 4-chlorophenol (4-CP) with rate constants of 0.42–1.70 min−1, outperforming other reported catalysts. Interestingly, the PMS activation pathway highly depended on PSBC pyrolysis temperature, which produced dominantly high-valent iron species (e.g., FeIVO2+) at low temperature but more sulfate radical (SO 4 ·−) and hydroxyl radical (·OH) at higher temperature, e.g., 0.17, 0.23, 0.12 mmol/L of FeIVO2+ and 0.009, 0.038, 0.102 mmol/L of SO 4 ·−/·OH were produced within 10 min by PSBC-600/PMS, PSBC-800/PMS, and PSBC-1000/PMS, respectively. Characterization, density functional theory (DFT) simulation and Pearson correlation analysis revealed that along with the increase of pyrolysis temperatures, the active sites of PSBC gradually shifted from atomically dispersed N-coordinated Fe moieties (FeN x) to iron nitrides (Fe x N), which activated PMS to produce FeIVO2+ and SO 4 ·−/·OH, respectively. This study clarifies the structure-activity relationships of PSBC for PMS activation, and opens a new avenue for the treatment and utilization of PS as high value-added resources. [Display omitted] [ABSTRACT FROM AUTHOR]

• ZVI/H2O2 delivers a controllable reduction-oxidation coupling process for CNBs remediation. • ZVI pre-reduction significantly accelerates CNBs mineralization rate by ·OH. • The performance of ZVI/H2O2 based reduction-oxidation process is controlled by the addition time of H2O2. • The efficiency of this controllable reduction-oxidation process has been validated in remediating real site contaminated by CNBs. Chloronitrobenzenes (CNBs) are typical refractory aromatic pollutants. The reduction products of CNBs often possess higher toxicity, and the electron-withdrawing substituent groups are detrimental to the ring-opening during the oxidation treatment, leading to ineffective removal of CNBs by either reduction or oxidation technology. Herein we demonstrate a controllable reduction-oxidation coupling (ROC) process composed of zero-valent iron (ZVI) and H 2 O 2 for the effective removal of CNBs from both water and soil. In water, ZVI first reduced p-CNB into 4-chloronitrosobenzene and 4-chloroaniline intermediates, which were then suffered from the subsequent oxidative ring-opening by ·OH generated from the reaction between Fe(II) and H 2 O 2. By controlling the addition time of H 2 O 2 , the final mineralization rate of p-CNB reached 6.6 × 10−1 h−1, about 74 times that of oxidation alone (9.0 × 10−3 h−1). More importantly, this controllable ROC process was also applicable for the site remediation of CNBs contaminated soil by either ex-situ treatment or in-situ injection, and, respectively decreased the concentrations of p-CNB, m-CNB, and o-CNB from 1105, 980, and 94 mg/kg to 3, 1, and < 1mg/kg, meeting the remediation goals (p-CNB: < 32.35 mg/kg, o-CNB and m-CNB: < 1.98 mg/kg). These laboratory and field trial results reveal that this controllable ROC strategy is very promising for the treatment of electron-withdrawing groups substituted aromatic contaminates. [Display omitted] [ABSTRACT FROM AUTHOR]

Persulfate (PS) is widely used for environmental remediation, but its organic contaminant removal performance strongly depends on its activation. In this study, we demonstrate that pyrite (FeS 2) can more effectively activate PS than the commonly used FeSO 4 for atrazine degradation. When 3.0 mM of PS and 4.2 mM of iron salts were used, the atrazine degradation efficiency of FeS 2 /PS was 1.4 times that of FeSO 4 /PS, while the amount of consumed PS in case of FeS 2 was only 53% of that by FeSO 4. The better PS activation performance of FeS 2 could be attributed to its slow and sustainable release of dissolved Fe(II), inhibiting the quenching reaction between •SO 4 −/•OH and Fe(II) ions, and thus producing more reactive oxygen species for the atrazine degradation. More importantly, the surface bound Fe(II) of FeS 2 could activate molecular oxygen to generate superoxide radical (•O 2 −), which could further promote the effective decomposition of PS by accelerating the Fe(III)/Fe(II) redox cycle. This study unravels the roles of dissolved Fe(II) and surface bound Fe(II) on the persulfate activation, and provides a promising heterogeneous persulfate activator for pollutant control and environmental remediation. Image 1 • Pyrite (FeS 2) could more effectively activate persulfate (PS) than FeSO 4 for atrazine degradation. • The slow and sustainable release of dissolved Fe(II) from FeS 2 inhibited the quenching reaction between SO 4 −/ OH and Fe(II) ions. • The surface Fe(II) of FeS 2 could activate molecular oxygen to generate O 2 −, which could promote the effective decomposition of PS by accelerating the Fe(III)/Fe(II) cycle. • The TOC removal efficiency of FeS 2 /PS was 26% within 7 h, much higher than that (4%) of FeSO 4 /PS. [ABSTRACT FROM AUTHOR]