Optimization of sulfate reduction and methanogenesis via phase separation in a two-phase internal circulation reactor for the treatment of high-sulfate organic wastewater.

To enhance the performance of the internal circulation (IC) reactor when treating high-sulfate organic wastewater, a laboratory-scale two-phase IC reactor with distinct phase separation capabilities was designed, and the sulfate reduction and methanogenesis processes were optimized by segregating the reactor into two specialized reaction zones. The results demonstrated that the first and second reaction areas of the two-phase IC reactor could be maintained at 4.5-6.0 and 7.5-8.5, respectively, turning them into the specialized phase for sulfate reduction and methanogenesis. Through phase separation, the two-phase IC reactor achieved a COD degradation and sulfate reduction efficiency of more than 80% when the influent sulfate concentration exceeded 5,000 mg/L, which were 32.32% and 16.04% higher than that before phase separation. Functional analyses indicated a greater activity of both the dissimilatory and assimilatory sulfate reduction pathways in the acidogenic phase, largely due to a rise in the relative abundance of the genera Desulfovibrio, Bacteroides, and Lacticaseibacillus, the primary carriers of sulfate reduction functional genes. In contrast, all the acetoclastic, hydrogenotrophic, and methylotrophic methanogenesis pathways were inhibited in the acidogenic phase but thrived in the methanogenic phase, coinciding with shifts in the genus Methanothrix, which harbors the mcrA, mcrB, and mcrG genes essential for the final transformation step of all three methanogenesis pathways.

Relationship of widowhood with pulse pressure, fasting blood glucose, and mental health in older adults: a propensity matching score analysis.

Background: Transitioning from marriage to widowhood presents inevitable and significant challenges for many older adults. This study explored the impact of widowhood on a range of mental health outcomes, including pulse pressure and fasting blood glucose levels, among older adults in nursing homes. Methods: This cross-sectional study utilized cluster random sampling to recruit participants, with data analyzed from 388 older Chinese adults. Psychosocial traits were assessed using the Perceived Social Support from Family scale (PSS-Fa) for family support, the Generalized Anxiety Disorder 7-item scale (GAD-7) for anxiety symptoms, and the 9-item Patient Health Questionnaire (PHQ-9) for depressive symptoms and suicidal ideation. Propensity score matching (PSM) was employed to control for confounding factors. A multivariate linear regression analysis was performed to explore the relationship between widowhood, mental health outcomes, pulse pressure, and fasting blood glucose levels. Results: After applying PSM, the sample size was refined to 268 (N = 134 for both married and widowed groups) from the initial 388, excluding 120 unmatched cases. Widowed older adults were found to have notably lower family support (ß = -0.81, p = 0.002), increased depressive symptoms (ß = 1.04, p = 0.043), elevated pulse pressure (ß = 8.90, p < 0.001), and higher fasting blood glucose levels (ß = 3.22, p = 0.027). These associations exhibited greater beta values compared to pre-matching analysis. Conclusion: Our findings revealed that widowed participants had reduced family support, an increased risk of depressive symptoms, heightened pulse pressure, and elevated fasting blood glucose in comparison to their married counterparts. Interventions focusing on social support, mental health, and cardiovascular well-being could be advantageous for this at-risk group.

Molecular oxygen-assisted in defect-rich ZnO for catalytic depolymerization of polyethylene terephthalate.

Polyethylene terephthalate (PET) is the most produced polyester plastic; its waste has a disruptive impact on the environment and ecosystem. Here, we report a catalytic depolymerization of PET into bis(2-hydroxyethyl) terephthalate (BHET) using molecule oxygen (O2)-assisted in defect-rich ZnO. At air, the PET conversion rate, the BHET yield, and the space-time yield are 3.5, 10.6, and 10.6 times higher than those in nitrogen, respectively. Combining structural characterization with the results of DFT calculations, we conclude that the (100) facet of defect-rich ZnO nanosheets conducive to the formation of reactive oxygen species (∗O2-) and Zn defect, promotes the PET breakage of the ester bond and thus complete the depolymerization processed. This approach demonstrates a sustainable route for PET depolymerization by molecule-assisted defect engineering.

Enhanced denitrification using high-molecular-weight poly(lactic acid) blended with lactide as an effective carbon source.

The utilization of wasted Poly(lactic acid) (PLA) as low-cost carbon sources in solid-phase denitrification is hindered by its low biodegradability, which can be attributed to its high molecular weight. This study presents a new approach by blending high-molecular-weight PLA with a small amount of ʟ-lactide (PLA/LAx) to treat nitrate-contaminated wastewater. The addition of ʟ-lactide enhanced the release of carbon from high-molecular-weight PLA. An impressive denitrification efficiency of 96.7% was achieved, accompanied by extremely low levels of accumulated NO2--N (0.1 mg/L) and NH4+-N (0.4 mg/L). The quantity of ʟ-lactide used significantly impacted the bacterial community structure. A high abundance of the phyla Bacteroidota and Chloroflexi associated with polymer degradation was observed. The most dominant denitrifier was the genus unclassified_f__Rhodocyclaceae belonged to the phylum Proteobacteria. This study demonstrates that blending PLA with just 5 wt% lactide can transform it into a highly effective solid-phase carbon source to eliminate nitrates.

Oxygen Vacancy Promoted Generation of Monatomic Oxygen Anion over Ni2+ -Doped MgO for Efficient Glycolysis of Waste PET.

Developing efficient and eco-friendly catalysts for selective degradation of waste polyethylene terephthalate (PET) is critical to the circular economy of plastics. Herein, we report the first monatomic oxygen anion (O- )-rich MgO-Ni catalyst based on a combined theoretical and experimental approach, which achieves a bis(hydroxyethyl) terephthalate yield of 93.7 % with no heavy metal residues detected. DFT calculations and electron paramagnetic resonance characterization indicate that Ni2+ doping not only reduces the formation energy of oxygen vacancies, but also enhances local electron density to facilitate the conversion of adsorbed oxygen into O- . O- plays a crucial role in the deprotonation of ethylene glycol (EG) to EG- (exothermic by -0.6 eV with an activation barrier of 0.4 eV), which is proved effective to break the PET chain via nucleophilic attack on carbonyl carbon. This work reveals the potential of alkaline earth metal-based catalysts in efficient PET glycolysis.

Hydrophobic Biodegradable Hyperbranched Copolymers with Excellent Marine Diatom Resistance.

As the utilization of degradable polymer coatings increased, the accompanying trade-off between good degradability and high-efficiency antidiatom adhesion due to their hydrophobic nature remains unresolved. The study presents a new hydrophobic surface-fragmenting coating consisting of degradable hyperbranched polymers (hereafter denoted as h-LLAx) synthesized by reversible complexation-mediated copolymerization with isobornyl acrylate (IBOA) and divinyl-functional oligomeric poly(l-lactide) (OLLA-V2), both derived from biomass, that exhibited superior resistance (∼0 cell mm-2) to marine diatom Navicula incerta (N. incerta) attachment with higher OLLA content. The combined impact of the microscale hollow semisphere micelles that self-assembled degradable hyperbranched copolymers and hydrolysis-driven self-renewable surfaces following immersion in seawater may account for the remarkable resistance of h-LLAx coatings against N. incerta. Detailed investigations were conducted across multiple perspectives, from hydrolytic degradation to broad-spectrum antibacterial attachment to ecotoxicity assessment. The excellent features of high resistance to marine diatoms and bacterial attachment, degradability, and environmental friendliness make the as-prepared h-LLAx coatings widely sought after for antifouling coating applications.

Recent Advances on Synthesis of CoCO3 with Controlled Morphologies.

Cobalt carbonates and derivatives represent most promising cost-effective materials for energy storage, conversion and upgrading. Morphology determines the performances, as size, shape and electronic configuration are key factors for tunable properties in the area of batteries, catalysis, magnetics and plasmonics. However, there is lack of insights in literature on morphological control of cobalt carbonates during hydrothermal and solvothermal conditions. Therefore, this review provides detailed discussion on synthesis, formation mechanism and morphological control of nanosheets, wires, spheres and cubes of cobalt carbonates. Furthermore, the influence of experimental conditions and plausible mechanism which govern the growing processes were further discussed in details. The outcome of this short review will offer insights into rational design of inexpensive metal carbonates for numerous other energy and environment applications.

PLA-based core-shell structure stereocomplexed nanoparticles with enhanced loading and release profile of paclitaxel.

Purpose: In the present study, to achieve high paclitaxel (PTX) loading in a conjugated drug delivery system with minimal long-term side effects, we formulated a novel degradable stereocomplexed micelle-like particle with a core-shell structure. Materials and methods: In this system, methoxy polyethylene glycol (MPEG) acted as the hydrophilic shell, and the stereocomplex of polylactic acid with PTX (SCPLA-PTX) acted as the hydrophobic core. The MPEG-SCPLA-PTX micelle-like particles were synthesized via the self-assembly of a MPEG-poly L-lactic acid (PLLA) copolymer with a PTX-poly D-lactic acid-PTX copolymer. The resultant copolymers and their intermediates were characterized using 1H nuclear magnetic resonance and GPC. Micelle-like particles with different molecular weight ratios of MPEG and PLLA were synthesized to demonstrate the functions of both components. Results: PTX loading into MPEG2000Da-PLLA6000Da particles reached as high as 20.11%. At 216 h, the cumulative release from MPEG5000Da-PLLA6000Da, MPEG2000Da-PLLA6000Da, and MPEG5000Da-PLLA22000Da particles were 51.5%, 37.7%, and 52.0%, respectively. Conclusions: According to the cell uptake experiments, inhibition of tumor cell growth was satisfactory, indicating that the stereocomplexed particles developed in the present study can be employed as a promising nanocarrier for PTX delivery.

Oriented Assembly of Anisotropic Nanosheets into Ultrathin Flowerlike Superstructures for Energy Storage.

The hierarchical ultrathin nanostructures are excellent electrode materials for supercapacitors because of their large surface area and their ability to promote ion and electron transport. Herein, we investigated nine l-amino acids (LAs) as inductive agents to synthesize a series of CoNi-OH/LAs materials for energy storage. With the different amino acids, the assembled CoNi-OH/LAs form a lamellar, flower-shaped, and bulk structure. Among all materials, the ultrathin flowerlike CoNi2-OH/l-asparagine (CoNi2-OH/l-Asn) exhibits an excellent specific capacity of 405.4 mAh g-1 (2608 F g-1) and a 100% retention rate after 3000 cycles. We also assembled asymmetrical supercapacitor CoNi2-OH/l-Asn//N-rGO devices, which demonstrated an energy density of 64.9 Wh kg-1 at 799.9 W kg-1 and superlong cycling stability (82.4% at 10 A g-1) over 5000 cycles.

Removal of model dyes on charged UF membranes: Experiment and simulation.

Charged ultrafiltration (UF) membranes can repel electrically charged molecules that are smaller than the size of the membrane pores and display high rejection of solutes, high flux, and low operation pressures compared to uncharged UF, nanofiltration (NF) and reverse osmosis (RO). Here, a charged UF membrane composite (PANI/PVDF) was prepared and regulated via electrochemically reversible control in portions of amine/imine functional groups of PANI. As a result, the permeability and rejection ratios of CR2- on charged PANI/PVDF, with PVDF as a control, increased from 19.6 to a maximum of 183.3 L m-2 h-1 bar-1 and from 3.4% to 74%, which expands the trade-off confine benefited from surface potential change from -12.21 mV to -25.26 mV, furtherly, the rejection ratio of CR2- on PANI/PVDF reached up to 93% via the electrochemical regulation. Finally, a fixed-charge model was built that well describes the steric and electric repulsion effects on membrane performance and the important roles of the electrochemically controllable surface charge. Moreover, the contour map of rejection ratios containing the ratio of molecular size vs the average pore size of the membrane (r/R = 0.2-1.0) and the zeta potential (-10 to -60 mV) were taken into account, which can be used to visually understand the rejection performance of membranes. This model is also appropriate for varying molecular sizes and for molecules with different charges. Our work opens a new horizon for the design of electrochemically controllable charged membranes to remove charged compounds.

Adsorption and Reduction of Cr(VI) Together with Cr(III) Sequestration by Polyaniline Confined in Pores of Polystyrene Beads.

The simultaneous reduction and sequestration of Cr(VI) from wastewater is desirable as a cost-effective and environmentally friendly approach. In this study, we execute a one-step facile synthesis strategy on polyaniline (PANI) composites based on aniline adsorption and polymerization on pores of millimeter-scale polystyrene balls (PANI@PS). The well-defined PANI@PS increased the removal capacity of Cr(VI) by 5.4 times, going from 43.6 (bulky PANI) to 233.7 mg g-1 near neutral pH (6.0) instead of the pH 1-3 documented in other reports, which was higher than that of many reported adsorbents due to its porous structure, numerous interaction sites, and confinement effects in the polymer. Most importantly, PANI@PS could efficiently sequester positive Cr(III) after reducing Cr(VI) to Cr(III) due to its negative surface created by confinement effects confined to the nanopores of PS. Conversely, positively charged bulky PANI repelled electrostatically positive Cr(III); thus, additional precipitation or adsorption treatments were needed in practical applications. Moreover, a coating of PANI can protect PS, as a substrate and a composite, from irreversible damage due to the strong oxidation capacity of Cr(VI), which is another major concern in adsorbing strong oxidants using polymers. A novel strategy to regenerate the exhausted PANI@PS was efficiently executed based on the electrochemical redox reversibility of PANI. Finally, the comprehensive adsorption/reduction/sequestration of Cr on PANI@PS was elucidated in detail.

Enhanced fluoride removal by La-doped Li/Al layered double hydroxides.

In this study La intercalated Li/Al layered double hydroxide (LDH) was developed for efficient water defluoridation. The La-modified material, i.e., La doped Li/Al-LDH, exhibits more preferable fluoride adsorption than Li/Al-LDH in a broad pH range of 5-9, with the working capacity twice of the latter and seven times of magnitude higher than activated alumina. The fluoride removal kinetics is well fitted by pseudo-second order model, and the adsorption isotherm is well described by Freundlich model. Effect of pH and competing ions was examined during fluoride sequestration. The underlying mechanism for such enhanced adsorption of fluoride by La doped Li/Al-LDH was further revealed based on XPS and FTIR analysis. The presence of La and Al was found to be responsible for the satisfactory defluoridation of La doped Li/Al-LDH, and chloride replacement with fluoride occurred from both LDHs during fluoride adsorption. Also, the capacity of La doped Li/Al-LDH could be refreshed by alkaline solution (pH = 12) for cyclic runs. All the results implied that La doped Li/Al-LDH could serve asa potential adsorbent for efficient fluoride removal from water.

Efficient defluoridation of water using reusable nanocrystalline layered double hydroxides impregnated polystyrene anion exchanger.

Water decontamination from fluoride is still a challenging task of global concern. Recently, Al-based layered double hydroxides (LDHs) have been extensively studied for specific fluoride adsorption from water. Unfortunately, they cannot be readily applied in scaled-up application due to their ultrafine particles as well as the regeneration issues caused by their poor stability at alkaline pHs. Here, we developed a novel (LDH)-based hybrid adsorbent, i.e., LALDH-201, by impregnating nanocrystalline Li/Al LDHs (LADLH) inside a commercial polystyrene anion exchanger D201. TEM image and XRD spectra of the resultant nanocomposite confirmed that the LDHs particles were nanosized inside the pores of D201 of highly crystalline nature and well-ordered layer structure. After impregnation, the chemical and mechanical stability of LALDH were significantly improved against pH variation, facilitating its application at a wide pH range (3.5-12). Fluoride adsorption onto LALDH-201 was compared to D201 and activated alumina, evidencing the preferable removal fluoride of LALDH-201. Fluoride adsorption onto LALDH-201 followed pseudo-second-order model, with the maximum capacity (62.5 mg/g from the Sips model) much higher than the other two adsorbents. Fixed-bed adsorption run indicated the qualified treatable volume of the fluoride contaminated groundwater (4.1 mg/L initially) with LALDH-201 was about 11 times as much as with the anion exchanger D201 when the breakthrough point was set as 1.5 mg/L. The capacity of LALDH-201 could be effectively refreshed for continuous column operation without observable loss by using the mixed solution of 0.01 M NaOH + 1 M NaCl. The above results suggested that the hybrid adsorbent LALDH-201 is very promising for water defluoridation in scaled-up application.

Spherical polystyrene-supported chitosan thin film of fast kinetics and high capacity for copper removal.

In order to accelerate the kinetics and improve the utilization of the surface active groups of chitosan (CS) for heavy metal ion removal, sub-micron-sized polystyrene supported chitosan thin-film was synthesized by the electrostatic assembly method. Glutaraldehyde was used as cross-linking agent. Chitosan thin-film was well coated onto the surface of the polystyrene (PS) beads characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Their adsorption toward Cu(II) ions was investigated as a function of solution pH, degree of cross-linking, equilibrium Cu(II) ions concentration and contact time. The maximum adsorptive capacity of PS-CS was 99.8 mg/g in the adsorption isotherm study. More attractively, the adsorption equilibrium was achieved in 10 min, which showed superior properties among similar adsorbents. Continuous adsorption-desorption cyclic results demonstrated that Cu(II)-loaded PS-CS can be effectively regenerated by a hydrochloric acid solution (HCl), and the regenerated composite beads could be employed for repeated use without significant capacity loss, indicating the good stability of the adsorbents. The XPS analysis confirmed that the adsorption process was due to surface complexes with atoms of chitosan. Generally, PS beads could be employed as a promising host to fabricate efficient composites that originated from chitosan or other bio-sorbents for environmental remediation.

Iron-mediated oxidation of arsenic(III) by oxygen and hydrogen peroxide: dispersed versus resin-supported zero-valent iron.

The goal of this study is to assess the differences in As(III) removal kinetics and mechanisms between dispersed zero-valent iron (d-ZVI) and resin-supported zero-valent iron (D201-ZVI) in the presence of dissolved oxygen and hydrogen peroxide. Experimental results show that As(III) could be removed by all the studied systems (d-ZVI/O2, d-ZVI/H2O2, D201-ZVI/O2, D201-ZVI/H2O2). The d-ZVI/H2O2 system was more efficient than D201-ZVI/H2O2 for the oxidation of As(III). Similar trends were observed in O2 system for both solids. The kinetic behaviors as well as the influence of a hydroxyl radical scavenger (2-propanol) on the oxidation of As(III) at different pH suggest that the oxidation of As(III) in the d-ZVI/O2 and d-ZVI/H2O2 systems occurred mainly through Fenton-like reactions. The oxidation of As(III) in the D201-ZVI/O2 and D201-ZVI/H2O2 systems might be expected as follows: As(III) was firstly adsorbed onto the surface of the D201-ZVI, and then oxidation may proceed mainly through a non-Fenton mechanism that directly converts H2O2 into O2 and H2O. In addition, certain iron oxides in the D201-ZVI could also serve as oxidants for As(III) oxidation. The significant differences between the dispersed and supported ZVIs suggest that the supporting matrix interfered in the removal process, which deserves a further investigation.

Facile fabrication of magnetic chitosan beads of fast kinetics and high capacity for copper removal.

In this study, magnetic chitosan (CS) beads of ∼200 nm in diameter were successfully prepared by a facile one-step method. The resultant composite Fe3O4-CS was characterized using transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Its adsorption toward Cu(II) ions was investigated as a function of solution pH, CS dosage, Cu(II) concentration, and contact time. The maximum capacity of Fe3O4-CS was 129.6 mg of Cu(II)/g of beads (617.1 mg/g of CS). More attractively, the adsorption equilibrium could be achieved within 10 min, which showed superior properties among the available CS-based adsorbents. Continuous adsorption-desorption cyclic results demonstrated that Cu(II)-loaded Fe3O4-CS can be effectively regenerated by ethylenediaminetetraacetic acid (EDTA) solution, and the regenerated composite beads could be employed for repeated use without significant capacity loss. Additionally, Fe3O4-CS beads can be readily separated from water within 30 s under a low magnetic field (<0.035 T).

Enhanced removal of arsenic from a highly laden industrial effluent using a combined coprecipitation/nano-adsorption process.

Effective arsenic removal from highly laden industrial wastewater is an important but challenging task. Here, a combined coprecipitation/nano-adsorption process, with ferric chloride and calcium chloride as coprecipitation agents and polymer-based nanocomposite as selective adsorbent, has been validated for arsenic removal from tungsten-smelting wastewater. On the basis of operating optimization, a binary FeCl3 (520 mg/L)-CaCl2 (300 mg/L) coprecipitation agent could remove more than 93% arsenic from the wastewater. The resulting precipitate has proved environmental safety based on leaching toxicity test. Fixed-bed column packed with zirconium or ferric-oxide-loaded nanocomposite was employed for further elimination of arsenic in coprecipitated effluent, resulting in a significant decrease of arsenic (from 0.96 to less than 0.5 mg/L). The working capacity of zirconium-loaded nanocomposite was 220 bed volumes per run, much higher than that of ferric-loaded nanocomposite (40 bed volumes per run). The exhausted zirconium-loaded nanocomposite could be efficiently in situ regenerated with a binary NaOH-NaCl solution for reuse without any significant capacity loss. The results validated the combinational coprecipitation/nano-adsorption process to be a potential alternative for effective arsenic removal from highly laden industrial effluent.

Fabrication of a new hydrous Zr(IV) oxide-based nanocomposite for enhanced Pb(II) and Cd(II) removal from waters.

To overcome the technical bottleneck of fine hydrated Zr(IV) oxide particles in environmental remediation, we irreversibly impregnated nanosized hydrated Zr(IV) oxide inside a commercial cation exchange resin D-001 and obtained a new nanocomposite NZP. NZP exhibited efficient removal of lead and cadmium ions in a pH range of 2-6, where no Zr(IV) leaching was detected from NZP. As compared to D-001, NZP showed more preferable adsorption toward both toxic metals from the background Ca(II) solution at greater levels. The synthetic Pb(II) or Cd(II) solution containing other ubiquitous metal ions was employed as the feeding influent for column adsorption, and the results indicated that the treatable volume of NZP is around 3-4 times that of D-001 before reaching the breakthrough point set according to the effluent discharge standard of China. With respect to Pb(II) removal from an acidic mining effluent, the treatable volume of NZP was 13 times higher than that of D-001. The exhausted NZP could be effectively regenerated by HNO3-Ca(NO3)2 binary solution for repeated use without any significant capacity loss. The superior performance of NZP was attributed to the Donnan membrane effect exerted by the host D-001 as well as the impregnated HZO nanoparticles of specific interaction toward toxic metals, as confirmed by the comparative isothermal adsorption and X-ray photoelectron spectroscopic study.

Bifunctional resin-ZVI composites for effective removal of arsenite through simultaneous adsorption and oxidation.

Bifunctional resin-supported nanosized zero-valent iron (N-S-ZVI) composite was developed by combining the oxidation properties of nZVI/O2 with adsorption features of iron oxides and anion-exchange resin N-S. In batch culture experiments, N-S and the N-S-ZVI composite were examined for As(III) and As(V). The results reveal that ZVI in the composite played a key role in enhancing As(III) removal. The N-S-ZVI composites could oxidize more toxic As(III) to less toxic As(V) with high efficiency under ambient conditions without the need of noble metals. At the same time, the oxidized As(V) could be effectively removed by adsorption onto the surface of composites. The mechanisms for the oxidation of As(III) to As(V) and the simultaneous removal of As(V) are proposed. In order to investigate the potential performance of N-S-ZVI in practical use, the effects of solution pH and coexisting anions on arsenite removal and on fixed-bed column treatment of simulated waters were studied. All the results indicated that the bifunctional composites have a great potential for As(III) removal from contaminated waters.