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.

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.

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.

Integrated effect of bulk cations on nano-confined reactivity of clay-intercalated subnanoscale zero-valent iron in water-tetrahydrofuran mixtures.

Smectite clay-intercalated subnanoscale zero-valent iron (CSZVI) exhibits superior reactivity toward contaminants due to the small iron clusters (∼0.5 nm) under nano-confinement, which however is significantly influenced by the solution chemistry e.g., various cations, of polluted soil and water. This work was undertaken to elucidate the mechanisms of solution chemistry effects on dehalogenation ability of CSZVI in water-tetrahydrofuran solution using decabromodiphenyl ether as a model contaminant. By combined spectroscopic characterization and molecular dynamics simulation, it was revealed that bulk cations, i.e., Na+, K+, Mg2+ and Ca2+ collectively affected the interlayer distance, water content and Brønsted acidity of CSZVI and thus its degradation efficiency. Although causing inter-particle aggregation, Mg2+ induced optimal nano-confined interlayers at concentration of 20 mM, exhibiting a superior debromination efficiency with rate constant 9.84 times larger than that by the common nano-sized ZVI. Conversely, K+ rendered the interlayers less reactive, but protected CSZVI from corrosion loss with higher electron utilization efficiency, which was 1.7 times higher than CSZVI in presence of Mg2+. The findings provide new strategies to manipulate the reactivity of nano-confined CSZVI for effective wastewater and contaminated soil remediation.

Effect of soil pH on thermally enhanced desorption of m-xylene by zero-valent iron particles under an electromagnetic field.

This study, for the first time, evaluates a novel method for the desorption of contaminants from soil that uses the heat generated by zero-valent iron (ZVI) under low-frequency electromagnetic fields (EMF), and elucidates the specific effects of soil pH upon the process. It was found that the temperature of soil mixed with ZVI could reach up to ∼60 °C within 20 min under the applied EMF, and after 60 min the residual fraction of m-xylene in soil decreased by 86.4% compared to no-ZVI soil. The most efficient desorption of m-xylene occurred at a soil of pH 5. Desorption was related to the net heating capacity of the ZVI particles, which was defined by pH-dependent formation of surface corrosion products. The preservation of metal iron and formation of Fe(II) species was favored for heat generation. Soil pH also affected m-xylene retention and the local thermal conduction from ZVI to m-xylene by regulating the surface properties of fulvic acid and ZVI. This study provides valuable information regarding the impact of pH on the thermal desorption of soil contaminants by ZVI coupled with EMF and illustrates the potential of the method in the remediation of contaminated sites.

Defect-rich porous carbon with anti-interference capability for adsorption of bisphenol A via long-range hydrophobic interaction synergized with short-range dispersion force.

Wastewater features-directed design of an adsorbent is promising but challenging strategy for sustainable remediation of actual bisphenol A (BPA)-polluted water. Herein, we report that the discarded cigarette butt-derived porous carbon (AC-800) exhibit high capacity (865 mg/g), rapid reaction rate (186.9 mg/g/min) and outstanding durability for adsorption of BPA. Different from the most reported carbon-based adsorbents, quantitative structure-activity relationship studies unveil that graphitic defect plays a crucial role in the improvement of adsorptivity. Further studies illuminate that π-π interactions, electrostatic attraction and hydrogen-bond interaction play a negligible role whereas long-range hydrophobic interaction synergized with short-range dispersion force make a substantial contribution to BPA adsorption on AC-800. Benefited from this unique adsorption mechanism, AC-800 features a remarkable anti-interference capability and realizes the efficient clean-up of BPA from actual wastewater with complex backgrounds. This work sheds new light on mechanistic insight into the BPA adsorption on carbon-based materials and develops a fit-for-purpose designed adsorbent toward green remediation of practical wastewater.

Synergistic removal of cadmium and organic matter by a microalgae-endophyte symbiotic system (MESS): An approach to improve the application potential of plant-derived biosorbents.

Plant-derived materials as environmentally friendly biosorbents to remove heavy metals from wastewater have been extensively studied. However, the chemical oxygen demand (COD) increase caused by the plant-derived biosorbent has not been considered previously. In this study, water hyacinth was used as biosorbent to remove Cd(II) from wastewater. About 66% of Cd(II) was removed by the biosorbent with a maximum biosorption capacity (qmax) of 21.6 mg g-1. However, the COD of the filtrate increased from 0 to 292 mg L-1 during this process. Subsequently, endophytes, microalgae and the microalgae-endophyte symbiotic system (MESS) were assessed for the simultaneous Cd(II) and COD removal. Among these three systems, the MESS achieved the best performance. After 3 d of inoculation, the extent of total Cd(II) removal increased to 99.2% while COD decreased to 77 mg L-1. This study provides a new insight into the application of a plant-derived biosorbent in combination with microalgae and endophytes for the effective treatment of heavy metal-bearing wastewater.

One-step reductive synthesis of Ti3+ self-doped elongated anatase TiO2 nanowires combined with reduced graphene oxide for adsorbing and degrading waste engine oil.

A sustainable photocatalyst of Ti3+ self-doped elongated anatase nanowires combined with reduced graphene oxide (TiO2 NWs@rGO) was prepared via a facile one-step reductive synthesis process using NaBH4 as reductant for the first time. The obtained optimal TiO2 NWs@rGO composite has a large surface area,182 m2  g-1, which demonstrates strong adsorption capacity due to the multilayered structure built by highly crystallized nanowires of TiO2 and ultrathin rGO layers. When the photocatalyst was applied in removing waste engine oil (100 mL, 50 mg L-1), it exhibited outstanding performance with up to COD 98.6% removal extent (from 145 initial to 2 mg L-1 final COD) after 5 h, which is 34.1% higher than that of TiO2 NWs (64.5% COD removal extent). Gas chromatography-mass spectrometry analyses of residual waste engine oil after photocatalysis shows significant reductions of C6-C19 chemicals as well as total disappear of C15,C16, C17, C18 chemicals. The outstanding photocatalytic activity of TiO2 NWs@rGO benefits from sensitive response to visible light, improved surface reactivity and high electron flux enabled by rGO and Ti3+ in TiO2. In addition, this composite catalyst can be self-cleaned, and recycled for reuse, which suggests promising potential for waste engine oil treatment.

Building electrode with three-dimensional macroporous interface from biocompatible polypyrrole and conductive graphene nanosheets to achieve highly efficient microbial electrocatalysis.

Bioelectrochemical systems (BESs) possess a great potential for simultaneous wastewater treatment and energy recovery. Rational construction of electrode materials could significantly improve the BESs performance. Three-dimensional macroporous electrode interface with high conductivity is highly desirable but challenging. In this work, we report a hierarchically nanostructured reduced graphene oxide nanosheets-polypyrrole (rGO@PPy) electrode via one-step electrodeposition technique. The prepared electrode was comprehensively studied by scanning/transmission electron microscopy, Raman spectroscopy, X-ray diffraction and electrochemical measurements, which showed that the rGO@PPy possessed a three-dimensional macroporous interconnecting scaffold with superior conductivity. The rGO@PPy electrode was utilized in Geobacter sulfurreducens inoculated BESs, and the maximum current density was 4.10 ±â€¯0.02 mA cm-2, which is 8-fold higher than that of a rGO electrode (0.51 ±â€¯0.03 mA cm-2), and is among the best performance reported for two-dimensional electrodes. The improved performance is ascribed to ultrahigh biomass concentration induced by "best match scale" between rGO@PPy and microbes, excellent extracellular electron transfer, as well as enhanced microbial affinity through the adequate exposure of biocompatible PPy layers. This work demonstrated a synergistic effect between rGO and PPy for the BESs performance improvement, and provided a new insight to design and fabricate a high-performance bioelectrode.

Visible-light photocatalytic degradation performances and thermal stability due to the synergetic effect of TiO2 with conductive copolymers of polyaniline and polypyrrole.

Conductive polypyrrole-polyaniline/TiO2 nanocomposites (PPy-PANI/TiO2) were prepared by in situ oxidative copolymerization of pyrrole and aniline monomers in the presence of TiO2. For comparison studies, polypyrrole/TiO2 (PPy/TiO2) and polyaniline/TiO2 (PANI/TiO2) were also prepared. The samples were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, zeta potential analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis and photocurrent tests. In contrast to PPy/TiO2 and PANI/TiO2, PPy-PANI/TiO2 exhibits obvious absorption in the visible-light range, and is much superior to PPy/TiO2 and PANI/TiO2 in thermal stability. It is found that PPy-PANI/TiO2 performs well in the visible-light photocatalytic degradation of 4-nitrophenol. The optimized pyrrole : aniline : TiO2 molar ratio for best performance is 0.75 : 0.25 : 100. The efficacy of PPy-PANI/TiO2 is attributed to its conductivity, conjugated structure, as well as to the synergy amidst polypyrrole, polyaniline and TiO2.