In situ activation of peroxymonosulfate with bioelectricity for sulfamethoxazole sustainable removal.

Conventional electrochemical activation of peroxymonosulfate (PMS) is not very cost-effective and practical by the excessive input of energy. The electricity generated by photosynthetic microalgae fuel cells (MFCs) is utilized to activate PMS, which would achieve the combination of green bioelectricity and advanced oxidation processes for sustainable pollutants degradation. In this study, a novel dual-chamber of MFCs was constructed by using microalgae as anode electron donor and PMS as cathode electron acceptor, which was operating under both close-circuit and open-circuit conditions. Under close-circuit condition, 1-12 mM PMS in cathode was successfully in situ activated, where 32.00%-99.83% of SMX was removed within 24 h, which was about 1.21-1.78 times of that in the open-circuit of MFCs. Meanwhile, a significant increase in bioelectricity generation in MFCs was observed after the accumulation of microalgae biomass (4.65-5.37 mg/L), which was attributed to the efficient electron separation and transfer. Furthermore, the electrochemical analysis demonstrated that SMX or its products were functioned as electronic shuttles, facilitating the electrochemical reaction and altering the electrical capacitance. The quenching experiments and voltage output results reflected that complex active radical (SO4⋅-, ⋅OH, and 1O2) were involved in SMX removal. Seven degradation products of SMX were detected and S-N bond cleavage was the main degradation pathway. Predicted toxicity values calculated by ECOSAR program showed that all the products were less toxic or nontoxic. Finally, the density functional theory (DFT) calculations revealed that the O and N atoms on SMX were more susceptible to electrophilic reactions, which were more vulnerable to be attacked by reactive species. This study provided new insights into the activation of PMS by bioelectricity for SMX degradation, proposing the mechanisms for PMS activation and degradation sites of SMX.

Facile synthesis of ball-milling and oxalic acid co-modified sludge biochar to efficiently activate peroxymonosulfate for sulfamethoxazole degradation: 1O2 and surface-bound radicals.

A novel approach of ball milling and oxalic acid was employed to modify sludge-based biochar (BOSBC) to boost its activation performance for peroxymonosulfate (PMS) towards efficient degradation of sulfamethoxazole (SMX). 98.6% of SMX was eliminated by PMS/BOSBC system within 60 min. Furthermore, PMS/BOSBC system was capable of maintaining high removal rates for SMX (>88.8%) in a wide pH range from 3 to 9, and displayed a high tolerance to background electrolytes including inorganic ions and humic acid (HA). Quenching experiments, electron paramagnetic resonance (EPR) analysis, in-situ Raman characterization and PMS decomposition experiments confirmed that the non-radicals of 1O2 and surface-bound radicals were the main contributors to SMX degradation by PMS/BOSBC system. The results of ecotoxicity assessment illustrated that all transformed products (TPs) generated in PMS/BOSBC system were less toxic than that of SMX. After five reuse cycles, PMS/BOSBC system still maintained a high removal rate for SMX (77.8%). Additionally, PMS/BOSBC system exhibited excellent degradation performance for SMX in various real waters (Yangtze River water (76.5%), lake water (74.1%), tap water (86.5%), and drinking water (98.1%)). Overall, this study provided novel insights on non-metal modification for sludge-based biochar and non-radical mechanism, and offered a feasible approach for municipal sludge disposal.

A Phosphine-Amine-Linked Covalent Organic Framework with Staggered Stacking Structure for Lithium-Ion Conduction.

In-plane ionic conduction over two-dimensional (2D) materials is desirable for flexible electronics. Exfoliating 2D covalent organic frameworks (COFs) towards a few layers is highly anticipated, whereas most examples remain robust via π-stacking against the interlayered dislocation. Herein, we synthesize a phosphine-amine-linked 2D COF by a nucleophilic substitution reaction of phosphazene with amines. The synthesized COF is crystalline, and stacks in an AB-staggered fashion, wherein the AB dual layers are interlocked by embedding P-Cl bonds from one to another layer, and the non-interlocked layers are readily delaminated. Therefore, in situ post-quaternization over phosphazene can improve the ionization of backbones, accompanied by layered exfoliation. The ultrathin nanosheets can decouple lithium salts for fast solid-state ion transport, achieving a high conductivity and low activation energy. Our findings explore the P-N substitution reaction for COF crystallization and demonstrate that the staggered stacking 2D COFs are readily exfoliated for designing solid electrolytes.

Efficient degradation of sulfamethoxazole in various waters with peroxymonosulfate activated by magnetic-modified sludge biochar: Surface-bound radical mechanism.

First time, this study synthesized a magnetic-modified sludge biochar (MSBC) as an activator of peroxymonosulfate (PMS) to eliminate sulfamethoxazole (SMX). The removal efficiency of SMX reached 96.1% at t = 60 min by PMS/MSBC system. The larger surface area and magnetic Fe3O4 of MSBC surface enhanced its activation performance for PMS. The PMS decomposition, premixing and reactive oxygen species (ROS) identification experiments combined with Raman spectra analysis demonstrated that the degradation process was dominated by surface-bound radicals. The transformed products (TPs) of SMX and the main degradation pathways were identified and proposed. The ecotoxicity of all TPs was lower than that of SMX. The magnetic performance was beneficial for its reuse and the removal efficiency of SMX was 83.3% even after five reuse cycles. Solution pH, HCO3- and CO32- were the critical environmental factors affecting the degradation process. MSBC exhibited environmental safety for its low heavy metal leaching. PMS/MSBC system also performed excellent removal performance for SMX in real waters including drinking water (88.1%), lake water (84.3%), Yangtze River water (83.0%) and sewage effluent (70.2%). This study developed an efficient PMS activator for SMX degradation in various waters and provided a workable way to reuse and recycle municipal sludge.

Experimental study on tailings cementation by MICP technique with immersion curing.

The filling mining method is an effective method for controlling ground stress and preventing surface subsidence in the mining field during exploitation of underground resources. Tailings can be utilized as the filling material, so as to realize the reuse of industrial waste. However, utilization of the traditional Portland cement as the cementing material for tailings leads to groundwater pollution. In addition, production of Portland cement results in consumption of a great amount of ore and air pollution. In this paper, a tailings cementation method by using the microbial induced calcite precipitation (MICP) technique with immersion curing is proposed. Tailings are cemented by the MICP technique with aerobic bacteria (Sporosarcina pasteurii) under a soaked curing environment. The variable control method is applied to investigate the factors influencing the cementation effects by the MICP technique with Sporosarcina pasteurii, including the bacterial solution concentration, the cementing solution concentration, the particle size of tailings, and the curing temperature. The results indicate that: when OD600 of the Sporosarcina pasteurii solution is 1.6, the urea concentration in the cementing solution is 0.75 mol/L, the tailings are raw materials without grinding, and the curing temperature is 30°C, the cementation effect is the best. In view of uneven calcification during MICP with Sporosarcina pasteurii, mixed Sporosarcina pasteurii and Castellaniella denitrificans are used for tailings cementation. Higher strength of cemented tailings is achieved. It is proved that the MICP technique with mixed aerobic bacteria and facultative anaerobes is an effective method for tailings cementation.

Insights on ball milling enhanced iron magnesium layered double oxides bagasse biochar composite for ciprofloxacin adsorptive removal from water.

Both ciprofloxacin (CIP) and sugarcane bagasse have brought enormous pressure on environmental safety. Here, an innovative technique combining Fe-Mg-layered double oxides and ball milling was presented for the first time to convert bagasse-waste into a new biochar adsorbent (BM-LDOs-BC) for aqueous CIP removal. The maximum theoretical adsorption capacity of BM-LDOs-BC reached up to 213.1 mg g-1 due to abundant adsorption sites provided by well-developed pores characteristics and enhanced functional groups. The results of characterization, data fitting and environmental parameter revealed that pore filling, electrostatic interactions, H-bonding, complexation and π-π conjugation were the key mechanisms for CIP adsorptive removal. BM-LDOs-BC exhibited satisfactory environmental safety and outstanding adsorption capacity under various environmental situations (pH, inorganic salts, humic acid). Moreover, BM-LDOs-BC possessed excellent reusability. These superiorities illustrated that BM-LDOs-BC was a promising adsorbent and created a new avenue for rational placement of biowaste and high-efficiency synthesis of biochar for antibiotic removal.

A Mussel-Inspired Polydopamine-Filled Cellulose Aerogel for Solar-Enabled Water Remediation.

A solar steam generation method has been widely investigated as a sustainable method to achieve seawater desalination and sewage treatment. However, oil pollutants are usually emitted in real seawater or wastewaters, which can cause serious fouling problems to disturb the solar evaporation performance. In this work, a mussel-inspired, low-cost, polydopamine-filled cellulose aerogel (PDA-CA) has been rationally designed and fabricated with both superhydrophilicity and underwater superoleophobicity. The resulting PDA-CA device could also achieve a high solar evaporation rate of 1.36 kg m-1 h-1 with an 86% solar energy utilize efficiency under 1 sun illumination. In addition, the PDA-CA not only exhibited promising antifouling capacity for long-term water evaporation but also engaged in the effective adsorption of organic dye contaminants. These promising features of PDA-CA may offer new opportunities for developing multifunctional photothermal devices for solar-driven water remediation.

Physiological and transcriptomic analyses of brassinosteroid function in moso bamboo (Phyllostachys edulis) seedlings.

MAIN CONCLUSION: This study demonstrates that brassinosteroid is essential for seedling and shoot growth in moso bamboo. The shoot of moso bamboo is known to grow extremely fast. The roles of phytohormones in such fast growth of bamboo shoot remain unclear. Here we reported that endogenous brassinosteroid (BR) is a major factor promoting bamboo shoot internode elongation. Reducing endogenous brassinosteroid level by its biosynthesis inhibitor propiconazole stunted shoot growth in seedling stage, whereas exogenous BR application promoted scale leaf elongation and the inclination of lamina joint of leaves and scale leaves. Genome-wide transcriptome analysis identified hundreds of genes whose expression levels are altered by BR and propiconazole in shoots and roots of bamboo seedling. The data show that BR regulates cell wall-related genes, hydrogen peroxide catabolic genes, and auxin-related genes. Our study demonstrates an essential role of BR in fast growth bamboo shoots and identifies a large number of BR-responsive genes in bamboo seedlings.