Acyl chloride-mediated synthesis of rhodanine-modified UiO-66 for high-efficiency silver recovery.

Silver (Ag) recovery is essential for ecological protection, human health and economic benefits. Effective capture of Ag(I) from wastewater is still challenging due to insufficient accessible sites of adsorbents. Herein, an acyl chloride-mediated strategy is developed to synthesize rhodanine (Rd) modified UiO-66 derivatives for Ag(I) adsorption. Benefitting from the high grafting density of Rd, the optimal Rd-modified UiO-66-NH2 (UiO-66-NH2@20Rd) features an ultra-high uptake capacity (maximum capacity of 923.9 mg·g-1) and selectivity (maximum selectivity coefficient of 1665.52) for Ag(I). Almost 90 % of Ag(I) could be captured in one minute over UiO-66-NH2@20Rd and maintained a removal rate of 98.9 % even after six cycles. Moreover, a fixed-bed column test demonstrates that approximately 21,780 bed volumes of Ag(I) simulated wastewater can be effectively treated, indicating great promise for practical application. Mechanism investigation illustrates that outstanding performance can be attributed to the synergistic effect of Ag(I) adsorption and reduction on dense rhodanine sites. This study highlights that such a general strategy can provide a valuable avenue toward various functional adsorption materials.

A new microalgal negative carbon technology for landfill leachate treatment: Simultaneous removal of nitrogen and phosphorus.

Replete with ammonia nitrogen and organic pollutants, landfill leachate typically undergoes treatment employing expensive and carbon-intensive integrated techniques. We propose a novel microalgae technology for efficient, low-carbon simultaneous treatment of carbon, nitrogen, and phosphorus in landfill leachate (LL). The microbial composition comprises a mixed microalgae culture with Chlorella accounting for 82.58 %. After seven days, the process with an N/P ratio of approximately 14:1 removed 98.81 % of NH4+-N, 88.62 % of TN, and 99.55 % of TP. Notably, the concentrations of NH4+-N and TP met the discharge standards, while the removal rate of NH4+-N was nearly three times higher than previously reported in relevant studies. The microalgae achieved a removal efficiency of 64.27 % for Total Organic Carbon (TOC) and 99.26 % for Inorganic Carbon (IC) under mixotrophic cultivation, yielding a biomass of 1.18 g/L. The treatment process employed in this study results in a carbon emissions equivalent of -8.25 kgCO2/kgNremoved, representing a reduction of 33.56 kgCO2 compared to the 2AO + MBR process. In addition, shake flask experiments were conducted to evaluate the biodegradability of leachate after microalgae treatment. After microalgae treatment, the TOCB (Biodegradable Total Organic Carbon)/TOC ratio decreased from 56.54 % to 27.71 %, with no significant improvement in biodegradability. It establishes a fundamental foundation for further applied research in microalgae treatment of leachate.

Selective exposure of (111) crystal plane in Pd49Ag30Te4 by Tb doping to weaken Pd - C bond and promote electroreduction of CO2 to CO.

Employing electric energy to convert carbon dioxide (CO2) into valuable small molecules is a potentially practical method in energy storage and greenhouse gas alleviation. A huge challenge for electrocatalytic CO2 reduction is to reduce overpotential to improve energy efficiency. Herein, we demonstrate that doping alloy Pd49Ag30Te4 (PAT) with rare-earth element Tb is beneficial for selective exposure of (111) crystal plane, which is a highly active crystal plane for producing carbon monoxide (CO). The as-prepared Tb2.9PAT exhibited high electrocatalytic performance with 95.7 % CO faradic efficiency at - 0.8 V (vs RHE), far exceeding that of PAT, and coupled with good durability. In situ spectral study and theoretical calculations disclose that the introduction of Tb regulates the d-band center of PAT alloy, weakens the Pd - C bonding ability, and promotes the desorption of *CO in the rate-determining step. This study provides a method for doping induced selective exposure of crystal face, which provides new idea for improving catalytic performance.

Enhancing the Lewis acidity of single atom Tb via introduction of boron to achieve efficient photothermal synergistic CO2 cycloaddition.

Nowadays, it is becoming increasingly urgent to lower the escalating carbon dioxide (CO2) to reduce greenhouse effect. Fortunately, it is an ideal strategy by using the inexhaustible solar energy as the driving force to manipulate the cycloaddition reaction, the atomic efficiency of which is 100 %. This work represents the first attempt on utilization of rare-earth metal Tb with atomic dispersion, and the structure of Tb coordinated with 4 N-atoms and 2B-atoms was constructed on interconnected carbon hollow spheres. The introduction of electron-deficient B reduces the electron density of Tb, thereby boosting Lewis acidity and promoting the occurrence of ring-opening reaction. The mechanism exploration enunciates that TbN4B2/C is a photothermal synergistic catalyst, the combined action of photogenerated electrons and strong Lewis acidic site of Tb reduces the free energy of the rate-determining step, and then improving the yield of cyclic carbonate up to 739 mmol g-1h-1.

Integrated influence of sulfide modification on the reactivity of nanoscale zero-valent iron towards decabromodiphenyl ether under an electromagnetic field.

Individual application of sulfide modification and electromagnetic field (EMF) can enhance the reactivity of nanoscale zero-valent iron (nZVI), yet the potential of both in combination is not clear. This work found that the reactivity of nZVI towards decabromodiphenyl ether was significantly enhanced by the combined effect of sulfidation and EMF. The specific reaction rate constant of nZVI increased by 7 to 10 times. A series of characterization results revealed that the sulfidation level not only affects the inherent reactivity but also the magnetic-induced heating (MIH) and corrosion (MIC) of nZVI. These collectively influence the degradation efficiency of nZVI under EMF. Sulfidation generally diminished the MIH effect. The low degree of sulfidation (S/Fe = 0.1) slightly reduced the MIC effect by 21.4%. However, the high degree of sulfidation (S/Fe = 0.4) led to significantly enhanced MIC effect by 107.1%. For S/Fe = 0.1 and 0.4, the overall enhancement in the reactivity resulting from EMF was alternately dominated by the contributions of MIH and MIC. This work provides valuable insights into the MIH and MIC effects about the sulfidation level of nZVI, which is needed for further exploration and optimization of this combined technology.

Direct Regeneration of Spent Lithium-Ion Battery Cathodes: From Theoretical Study to Production Practice.

Direct regeneration method has been widely concerned by researchers in the field of battery recycling because of its advantages of in situ regeneration, short process and less pollutant emission. In this review, we firstly analyze the primary causes for the failure of three representative battery cathodes (lithium iron phosphate, layered lithium transition metal oxide and lithium cobalt oxide), targeting at illustrating their underlying regeneration mechanism and applicability. Efficient stripping of material from the collector to obtain pure cathode material has become a first challenge in recycling, for which we report several pretreatment methods currently available for subsequent regeneration processes. We review and discuss emphatically the research progress of five direct regeneration methods, including solid-state sintering, hydrothermal, eutectic molten salt, electrochemical and chemical lithiation methods. Finally, the application of direct regeneration technology in production practice is introduced, the problems exposed at the early stage of the industrialization of direct regeneration technology are revealed, and the prospect of future large-scale commercial production is proposed. It is hoped that this review will give readers a comprehensive and basic understanding of direct regeneration methods for used lithium-ion batteries and promote the industrial application of direct regeneration technology.

A Novel Polyfunctional Polyurethane Acrylate Derived from Castor Oil-Based Polyols for Waterborne UV-Curable Coating Application.

Because of its unique molecular structure and renewable properties, vegetable oil has gradually become the focus of researchers. In this work, castor oil was first transformed into a castor oil-based triacrylate structure (MACOG) using two steps of chemical modification, then it was prepared into castor oil-based waterborne polyurethane acrylate emulsion, and finally, a series of coating materials were prepared under UV curing. The results showed that with the increase in MACOG content, the glass transition temperature of the sample was increased from 20.3 °C to 46.6 °C, and the water contact angle of its surface was increased from 73.85 °C to 90.57 °C. In addition, the thermal decomposition temperature, mechanical strength, and water resistance of the samples were also greatly improved. This study not only provides a new idea for the preparation of waterborne polyurethane coatings with excellent comprehensive properties but also expands the application of biomass material castor oil in the field of coating.

Salinity-mediated enhancement of quaternary ammonium compounds resistance and removal in endophytic bacteria LSE01.

The widespread usage of quaternary ammonium compounds (QACs) as disinfectants during the COVID-19 pandemic poses significant environmental risks, such as toxicity to organisms and the emergence of superbugs. In this study, different inorganic salts (NaCl, KCl, CaCl2, MgCl2) were used to induce endophytes LSE01 isolated from hyperaccumulating plants. After five generations of cultivation under 80 g/L NaCl, the minimum inhibitory concentration (MIC) of LSE01 to QACs increased by about 3-fold, while its degradation extent increased from 8% to 84% for C12BDMA-Cl and 5%-89% for C14BDMA-Cl. Transmission electron microscopy (TEM) and three-dimensional fluorescence spectra indicated that the cells induced by high concentration of salt caused plasmolysis and secreted more bound extracellular polymeric substances (B-EPS); these changes are likely to be an important reason for the observed increased resistance and enhanced degradation extent of LSE01 to QACs. Our findings suggest that salt-induction could be an effective way to enhance the resistance and removal of toxic organic pollutants by functional microorganisms.

Bidirectional Enhancement of Nitrogen Removal by Indigenous Synergetic Microalgal-Bacterial Consortia in Harsh Low-C/N Wastewater.

Conventional microalgal-bacterial consortia have limited capacity to treat low-C/N wastewater due to carbon limitation and single nitrogen (N) removal mode. In this work, indigenous synergetic microalgal-bacterial consortia with high N removal performance and bidirectional interaction were successful in treating rare earth tailing wastewaters with low-C/N. Ammonia removal reached 0.89 mg N L-1 h-1, 1.84-fold more efficient than a common microalgal-bacterial system. Metagenomics-based metabolic reconstruction revealed bidirectional microalgal-bacterial interactions. The presence of microalgae increased the abundance of bacterial N-related genes by 1.5- to 57-fold. Similarly, the presence of bacteria increased the abundance of microalgal N assimilation by 2.5- to 15.8-fold. Furthermore, nine bacterial species were isolated, and the bidirectional promotion of N removal by the microalgal-bacterial system was verified. The mechanism of microalgal N assimilation enhanced by indole-3-acetic acid was revealed. In addition, the bidirectional mode of the system ensured the scavenging of toxic byproducts from nitrate metabolism to maintain the stability of the system. Collectively, the bidirectional enhancement system of synergetic microalgae-bacteria was established as an effective N removal strategy to broaden the stable application of this system for the effective treatment of low C/N ratio wastewater.

Resourceful application and mechanism of oyster shell-microalgae synergistic system：Sustainable treatment of harsh low carbon nitrogen ratio actual wastewater.

Microalgal technology holds great promise for both low C/N wastewater treatment and resource recovery simultaneously. Nevertheless, the advancement of microalgal technology is hindered by its reduced nitrogen removal efficiency in low C/N ratio wastewater. In this work, microalgae and waste oyster shells were combined to achieve a total inorganic nitrogen removal efficiency of 93.85% at a rate of 2.05 mg L-1 h-1 in low C/N wastewater. Notably, over four cycles of oyster shell reuse, the reactor achieved an average 85% ammonia nitrogen removal extent, with a wastewater treatment cost of only $0.092/ton. Moreover, microbial community analysis during the reuse of oyster shells revealed the critical importance of timely replacement in inhibiting the growth of non-functional bacteria (Poterioochromonas_malhamensi). The work demonstrated that the oyster shell - microalgae system provides a time- and cost-saving, environmental approach for the resourceful treatment of harsh low C/N wastewater.

Exceptional anti-toxic growth of water spinach in arsenic and cadmium co-contaminated soil remediated using biochar loaded with Bacillus aryabhattai.

Functionalized biochars are crucial for simultaneous soil remediation and safe agricultural production. However, a comprehensive understanding of the remediation mechanism and crop safety is imperative. In this work, the all-in-one biochars loaded with a Bacillus aryabhattai (B10) were developed via physisorption (BBC) and sodium alginate embedding (EBC) for simultaneous toxic As and Cd stabilization in soil. The bacteria-loaded biochar composites significantly decreased exchangeable As and Cd fractions in co-contaminated soil, with enhanced residual fractions. Heavy metal bioavailability analysis showed a maximum CaCl2-As concentration decline of 63.51% and a CaCl2-Cd decline of 50.96%. At a 3% dosage of composite, rhizosphere soil showed improved organic matter, cation exchange capacity, and enzyme activity. The aboveground portion of water spinach grown in pots was edible, with final As and Cd contents (0.347 and 0.075 mg·kg⁻¹, respectively) meeting food safety standards. Microbial analysis revealed the composite's influence on the rhizosphere microbial community, favoring beneficial bacteria and reducing plant pathogenic fungi. Additionally, it increased functional microorganisms with heavy metal-resistant genes, limiting metal migration in plants and favoring its growth. Our research highlights an effective strategy for simultaneous As and Cd immobilization in soil and inhibition of heavy metal accumulation in vegetables.

Metal element-based adsorbents for phosphorus capture: Chaperone effect, performance and mechanism.

Excessive phosphorus (P) enters the water bodies via wastewater discharges or agricultural runoff, triggering serious environmental problems such as eutrophication. In contrast, P as an irreplaceable key resource, presents notable supply-demand contradictions due to ineffective recovery mechanisms. Hence, constructing a system that simultaneously reduce P contaminants and effective recycling has profound theoretical and practical implications. Metal element-based adsorbents, including metal (hydro) oxides, layered double hydroxides (LDHs) and metal-organic frameworks (MOFs), exhibit a significant chaperone effect stemming from strong orbital hybridization between their intrinsic Lewis acid sites and P (Lewis base). This review aims to parse the structure-effect relationship between metal element-based adsorbents and P, and explores how to optimize the P removal properties. Special emphasis is given to the formation of the metal-P chemical bond, which not only depends on the type of metal in the adsorbent but also closely relates to its surface activity and pore structure. Then, we delve into the intrinsic mechanisms behind these adsorbents' remarkable adsorption capacity and precise targeting. Finally, we offer an insightful discussion of the prospects and challenges of metal element-based adsorbents in terms of precise material control, large-scale production, P-directed adsorption and effective utilization.

Insight into the Alkali Resistance Mechanism of FeMoTiOx Catalysts for NH3 Selective Catalytic Reduction of NO: Self-Defense Effects of MoOx for Alkali Capture.

The deactivation of selective catalytic reduction (SCR) catalysts caused by alkali metal poisoning remains an insurmountable challenge. In this study, we examined the impact of Na poisoning on the performance of Fe and Mo co-doped TiO2 (FeaMobTiOx) catalysts in the SCR reaction and revealed the related alkali resistance mechanism. On the obtained Fe1Mo2.6TiOx catalyst, the synergistic catalytic effect of uniformly dispersed FeOx and MoOx species leads to remarkable catalytic activity, with over 90% NO conversion achieved in a wide temperature range of 210-410 °C. During the Na poisoning process, Na ions predominantly adsorb on the MoOx species, which exhibit stronger alkali resistance, effectively safeguarding the FeOx species. This preferential adsorption minimizes the negative effect of Na poisoning on Fe1Mo2.6TiOx. Moreover, Na poisoning has little influence on the Eley-Rideal reaction pathway involving adsorbed NHx reacting with gaseous NOx. After Na poisoning, the Lewis acid sites were deteriorated, while the abundant Brønsted acid sites ensured sufficient NHx adsorption. As a benefit from the self-defense effects of active MoOx species for alkali capture, FeaMobTiOx exhibits exceptional alkali resistance in the SCR reaction. This research provides valuable insights for the design of highly efficient and alkali-resistant SCR catalysts.

Functionally responsive hydrogels with salt-alkali sensitivity effectively target soil amelioration.

The long-standing crisis of soil salinization and alkalization poses a significant challenge to global agricultural development. High soil salinity-alkalinity, water dispersion, and nutrient loss present major hurdles to soil improvement. Novel environmentally friendly gels have demonstrated excellent water retention and slow-release capabilities in agricultural enhancement. However, their application for improving saline-alkali soil is both scarce and competitive. This study proposes a new strategy for regulating saline-alkali soil using gel-coated controlled-release soil modifiers (CWR-SRMs), where radical-polymerized gels are embedded on the surface of composite gel beads through spray coating. Characterization and performance analysis reveal that the three-dimensional spatial network structure rich in hydrophilic groups exhibits good thermal stability (first-stage weight loss temperature of 257.7 °C in thermogravimetric analysis) and encapsulation efficiency for fulvic acid­potassium (FA-K), which can enhance soil quality in saline-alkali environments. The molecular chain relaxation under saline-alkali conditions promotes a synergistic effect of swelling and slow release, endowing it with qualifications as a water reservoir, Ca2+ source unit, and slow-release body. The results of a 6 weeks incubation experiment on 0-20 cm saline-alkaline soil with different application gradients showed that the gradient content had a significant effect on the soil improvement effect. Specifically, the T2 (the dosage accounted for 1 % of soil mass) treatment significantly increases water retention (30 % ~ 90 %), and nutrient levels (30 % ~ 50 %), while significantly decreasing soil sodium colloid content (30 % ~ 60 %) and soil pH (10 % ~ 15 %). Furthermore, PCA analysis indicates that the addition of 1 % CWR-SRMs as amendments can significantly adjust the negative aspects of soil salinity and alkalinity. This highlights the excellent applicability of CWR-SRMs in improving saline-alkali agricultural ecosystems, demonstrating the potential value of novel environmentally friendly gels as an alternative solution for soil challenges persistently affected by adverse salinity and alkalinity.

Response of tomatoes to inactivated endophyte LSE01 under combined stress of high-temperature and drought.

Endophytes can assist crops in adapting to high temperatures and drought conditions, thereby reducing agricultural losses. However, the mechanism through which endophytes regulate crop resistance to high temperatures and drought stress remains unclear, and concerns regarding safety and stability exist with active endophytes. Thus, heat-treated endophytic bacteria LSE01 (HTB) were employed as a novel microbial fertilizer to investigate their effects on plant adaptation to high temperatures and drought conditions. The results indicated that the diameter and weight of tomatoes treated with HTB under stress conditions increased by 23.04% and 71.15%, respectively, compared to the control. Tomato yield did not significantly decrease compared to non-stress conditions. Additionally, the contents of vitamin C, soluble sugars, and proteins treated with HTB increased by 18.81%, 11.54%, and 99.75%, respectively. Mechanistic research revealed that HTB treatment enhances tomato's stress resistance by elevating photosynthetic pigment and proline contents, enhancing antioxidant enzyme activities, and reducing the accumulation of MDA. Molecular biology research demonstrates that HTB treatment upregulates the expression of drought-resistant genes (GA2ox7, USP1, SlNAC3, SlNAC4), leading to modifications in stomatal conductance, plant morphology, photosynthetic intensity, and antioxidant enzyme synthesis to facilitate adaptation to dry conditions. Furthermore, the upregulation of the heat-resistant gene (SlCathB2-2) can increases the thickness of tomato cell walls, rendering them less vulnerable to heat stress. In summary, HTB endows tomatoes with the ability to adapt to high temperatures and drought conditions, providing new opportunities for sustainable agriculture.

Selective recycling of lithium from spent LiNixCoyMn1-x-yO2 cathode via constructing a synergistic leaching environment.

The global response to lithium scarcity is overstretched, and it is imperative to explore a green process to sustainably and selectively recover lithium from spent lithium-ion battery (LIB) cathodes. This work investigates the distinct leaching behaviors between lithium and transition metals in pure formic acid and the auxiliary effect of acetic acid as a solvent in the leaching reaction. A formic acid-acetic acid (FA-AA) synergistic system was constructed to selectively recycle 96.81% of lithium from spent LIB cathodes by regulating the conditions of the reaction environment to inhibit the leaching of non-target metals. Meanwhile, the transition metals generate carboxylate precipitates enriched in the leaching residue. The inhibition mechanism of manganese leaching by acetic acid and the leaching behavior of nickel or cobalt being precipitated after release was revealed by characterizations such as XPS, SEM, and FTIR. After the reaction, 90.50% of the acid can be recycled by distillation, and small amounts of the residual Li-containing concentrated solution are converted to battery-grade lithium carbonate by roasting and washing (91.62% recovery rate). This recycling process possesses four significant advantages: i) no additional chemicals are required, ii) the lithium sinking step is eliminated, iii) no waste liquid is discharged, and iv) there is the potential for profitability. Overall, this study provides a novel approach to the waste management technology of lithium batteries and sustainable recycling of lithium resources.

Evaluating the Role of Functional Groups in the Selective Capture of Ag(I) onto UiO-66-Type Metal-Organic Frameworks.

UiO-66-type metal-organic frameworks have been considered as promising adsorbents for capturing Ag(I) from wastewater. However, uncertainties persist regarding the specific absorptivity of individual functional groups to the UiO-66 framework structure. In this study, UiO-66-type metal-organic frameworks (UiO-66-X), featuring diverse functional groups (X = -(OH)2, -(COOH)2, -NO2, -NH2, -SO3H, -(SH)2), were synthesized in situ for Ag(I) capture. The findings revealed that functionalization significantly enhanced the adsorption capacity of Ag(I). Notably, quantitative analysis showed that 1 mol of -SH functional group onto the UiO-66 framework structure can adsorb 0.73 mol of Ag(I) ions, surpassing those of -COOH, -OH, -NH2, -SO3H, and -NO2 by 2.4-, 3.5-, 3.8-, 9.1-, and 24.3-fold, respectively. This represents the first assessment of the adsorption capacity of functionalized UiO-66 for Ag(I) based on each effective functional group, addressing limitations in traditional unit mass calculations. Further, the adsorption mechanism of UiO-66-X for selectively capturing Ag(I) was elucidated through experimental and theoretical analyses. Additionally, selectivity and practical applications confirm that UiO-66-(SH)2 exhibits strong anti-interference ability, whether in natural water bodies with complex compositions or in industrial wastewater under harsh conditions. We anticipate that this study will enhance our understanding of structure-performance dependencies of multivariate MOFs for designing novel adsorbents for Ag(I) capture.

Mineralization versus polymerization pathways in heterogeneous Fenton-like reactions.

Fenton reaction has been widespread application in water purification due to the excellent oxidation performances. However, the poor cycle efficiency of Fe(III)/Fe(II) is one of the biggest bottlenecks. In this study, graphite (GP) was used as a green carbon catalyst to accelerate Fenton-like (H2O2/Fe3+ and persulfate/Fe3+) reactions by promoting ferric ion reduction and intensifying diverse peroxide activation pathways. Significantly, the carboxyl group on GP anchors iron ions to form GP-COOFe(III) which promote persulfate adsorption to form surface complexes and induce an electron transfer pathway (ETP). While the electron-rich hydroxyl and carbonyl groups will combine to from GP-COFe(II), a reductive intermediate to activate peroxide to generate free radicals (from H2O2 and PDS) or high-value iron [Fe(IV)] (from PMS). Consequently, different pathways lead to distinct degree of oxidation: i) radicals in H2O2/Fe3+/GP prefer to mineralize bisphenol A (BPA) with no selectivity; ii) Fe(IV) in PMS/Fe3+/GP partially oxidizes BPA but cannot open the aromatic ring; iii) ETP in PMS/ or PDS/Fe3+/GP drives coupling reactions to form polymeric products covered on catalyst surface. Thus, rational engineering surface functionality of graphite and selecting proper peroxides can realize on-demand selectivity and oxidation capacity in Fenton-like systems.

Regulating steric hindrance in difunctionalized porous aromatic frameworks for the selective separation of Pb(II).

Efficient and selective removal of Pb(II) from wastewater with complex matrix remains a challenging task. Porous aromatic frameworks (PAFs) with predesigned functional building blocks provide a favorable platform for the selective separation of Pb(II). Herein, the bifunctional SPAFs with the introduction of -OH and -SO3H were synthesized through rationally optimizing their steric hindrance. As a result, the SPAF-0.75 exhibits favorable adsorption capacity of Pb(II) (212.34 mg g-1), which is 22 times larger than pristine framework. Competition experiment indicates that SPAF-0.75 possess the selective removal of Pb(II) without interfering from co-existing metal ions. The removal rate of SPAF-0.75 still retain at 100% after six successive cycles. The DFT calculation illustrates that -OH and -SO3H are co-participate in the process of capturing Pb(II), revealing SPAF-0.75 preferred removal of Pb(II) owing to the lowest adsorption energy (ΔEab = -3.99 eV). This study extend the understanding of the structure-property relationship and facilitate new possibilities for PAFs.