Simultaneous Immobilization Research Articles

The effect of entropy on the structure and aqueous durability of nanocrystalline rare-earth zirconate ceramics

A series of compositionally complex A2Zr2O7 nanocrystalline ceramics were successfully prepared using sol-gel and co-precipitation methods. The resultant ceramics possess a cubic defect fluorite structure, with the sol-gel method yielding an average grain size of approximately 50–70 nm, while the co-precipitation method result in an average grain size of about 40–60 nm. Leaching tests revealed that the smaller grain sizes are correlated with higher leaching rates. Furthermore, for ceramics with similar grain sizes, those with higher entropy values exhibited higher leaching rates. The increase in grain boundaries was found to reduce the leaching performance of the rare earth zirconate ceramics, and this effect became more pronounced with increasing entropy. This work provides insights into the selection of entropy values and grain sizes for the high-level radioactive waste matrices, which can be considered as a potential substrate for the simultaneous immobilization of multiple radionuclides.

Engineered biochars for simultaneous immobilization of as and Cd in soil: Field evidence

Agricultural soil contamination by potentially toxic elements (PTEs) such as arsenic (As) and cadmium (Cd) poses a serious threat to food security. Immobilization serves as a widely used approach for the remediation of PTEs contaminated soils, nevertheless, the long-term effectiveness for the simultaneous immobilization of both cations and oxyanions remains a challenge. In order to effectively enhance the synergistic immobilization effect of soil As and Cd contaminated by multiple elements and improve the ecological environment of farmland. In this study, a typical polluted tailings area farmland was selected for situ immobilization experiments, and biochar was prepared from cow manure (CMB), rice straw (RSB), and pine wood (PWB) as raw materials. On this basis, the pristine biochar was modified with ferric chloride (F), potassium permanganate (K), magnesium chloride (M), and aluminum chloride (A), respectively. Furthermore, the immobilization effect of modified biochar on As-Cd and the stress effect on soil respiration were investigated. The results showed that CMB and RSB reduced the bioavailability of heavy metals, potassium permanganate has strong oxidizing properties, and the strong oxidability of potassium permanganate stimulated the generation of more oxygen-containing functional groups on the surface of biochar, thereby enhancing the adsorption and complexation effect of modified materials on As and Cd. Among them, the extracted Cd concentration of Diethylenetriamine pentaacetic acid (DTPA) in KCMB and KRSB in 2020 decreased by 8.23–43.12% and 9.67–35.29% compared to other treatments, respectively. Meanwhile, the KCMB and KRSB treatments also reduced the enrichment of As and Cd in plant tissues. In addition, the dissolved organic carbon (DOC) content in KCMB treatment was relatively high, and the carbon stability of the material was weakened. Simultaneously, the soil respiration emission of KCMB treatment was increased by 5.63% and 11.93% compared to KRSB and KPWB treatments, respectively. In addition, the structural equation also shows that DOC has a large positive effect on soil respiration. In summary, the KRSB treatment effectively achieve synergistic immobilization of As-Cd and provide important guiding significance for green and low-carbon remediation of polluted farmland.

Breaking the Passivation Effect for MnO2 Catalysts in Li−S Batteries by Anion‐Cation Doping

AbstractTransition metal oxides (TMOs) are recognized as high‐efficiency electrocatalyst systems for restraining the shuttle effect in lithium‐sulfur (Li−S) batteries, owing to their robust adsorption capabilities for polysulfides. However, the sluggish catalytic conversion of Li2S redox and severe passivation effect of TMOs exacerbate polysulfide shuttling and reduce the cyclability of Li−S batteries, which significantly hinders the development of TMOs electrocatalysts. Here, through the anion‐cation doping approach, dual incorporation of phosphorus and molybdenum into MnO2 (P,Mo‐MnO2) was engineered, demonstrating effective mitigation of the passivation effect and allowing for the simultaneous immobilization of polysulfides and rapid redox kinetics of Li2S. Both experimental and theoretical investigations reveal the pivotal role of dopants in fine‐tuning the d‐band center and optimizing the electronic structure of MnO2. Furthermore, this well‐designed configuration processes catalytic selectivity. Specifically, P‐doping expedites rapid Li2S nucleation kinetics by minimizing reaction‐free energy, while Mo‐doping facilitates robust Li2S dissolution kinetics by mitigating decomposition barriers. This dual‐doping approach equips P,Mo‐MnO2 with robust bi‐directional catalytic activity, effectively overcoming passivation effect and suppressing the notorious shuttle effect. Consequently, Li−S batteries incorporating P,Mo‐MnO2‐based separators demonstrate favorable performance than pristine TMOs. This design offers rational viewpoint for the development of catalytic materials with superior bi‐directional sulfur electrocatalytic in Li−S batteries.

Breaking the Passivation Effect for MnO2 Catalysts in Li-S Batteries by Anion-Cation Doping.

Transition metal oxides (TMOs) are recognized as high-efficiency electrocatalyst systems for restraining the shuttle effect in lithium-sulfur (Li-S) batteries, owing to their robust adsorption capabilities for polysulfides. However, the sluggish catalytic conversion of Li2S redox and severe passivation effect of TMOs exacerbate polysulfide shuttling and reduce the cyclability of Li-S batteries, which significantly hinders the development of TMOs electrocatalysts. Here, through the anion-cation doping approach, dual incorporation of phosphorus and molybdenum into MnO2 (P,Mo-MnO2) was engineered, demonstrating effective mitigation of the passivation effect and allowing for the simultaneous immobilization of polysulfides and rapid redox kinetics of Li2S. Both experimental and theoretical investigations reveal the pivotal role of dopants in fine-tuning the d-band center and optimizing the electronic structure of MnO2. Furthermore, this well-designed configuration processes catalytic selectivity. Specifically, P-doping expedites rapid Li2S nucleation kinetics by minimizing reaction-free energy, while Mo-doping facilitates robust Li2S dissolution kinetics by mitigating decomposition barriers. This dual-doping approach equips P,Mo-MnO2 with robust bi-directional catalytic activity, effectively overcoming passivation effect and suppressing the notorious shuttle effect. Consequently, Li-S batteries incorporating P,Mo-MnO2-based separators demonstrate favorable performance than pristine TMOs. This design offers rational viewpoint for the development of catalytic materials with superior bi-directional sulfur electrocatalytic in Li-S batteries.

Efficient and simultaneous immobilization of fluoride and lead in water and tea garden soil by bayberry tannin foam loaded zirconium

Nowadays, human activities intensified the combined pollution of fluoride and lead in acidic tea garden soil. The key to eliminating this combined pollution is to immobilize pollutants simultaneously, thus preventing their migration from tea garden soil to tea trees. In this paper, the natural product bayberry tannin was employed as raw material to fabricate functional materials (TF-Zr) for simultaneous adsorption of fluorine (F) and lead (Pb) in water and soil by the reactivity of tannin with Pb2+ and the affinity of Zr with F. SEM-Mapping, EDS, FT-IR, XPS were utilized to probe the immobilization mechanisms. The results showed that TF-Zr could simultaneously and efficiently adsorb F– and Pb2+ from water with the adsorption capacity of 5.02 mg/g (Pb) and 4.55 mg/g (F). The adsorption processes were both in accordance with the proposed secondary kinetic adsorption model. Besides, the presence of F– promoted the adsorption of Pb2+ by TF-Zr. The materials were applied into tea garden soil to explore its effect on the variation of F and Pb forms in the soil. It was found that the proportion of water-soluble fluorine, exchangeable fluorine and exchangeable lead in the tea garden soil decreased significantly, while the proportion of residual fluorine and lead increased evidently, illustrating TF-Zr possessed eximious fixation effect on the highly reactive fluorine and lead in the soil and facilitated their conversion to the more stable residue state. Therefore, TF-Zr can be used for the efficient and simultaneous immobilization of fluorine and lead in water and tea garden soil.

Plasma and radiation mediated green synthesis of gold Nanoparticles-immobilized bio-template based catalytic reactor ‘AuNICaR’: Mechanistic insights, catalytic performance and reusability analysis

The present work reports a green, non-thermal plasma-based approach for efficient synthesis of a gold nanoparticles (Au NPs) Immobilized Catalytic Reactor “AuNICaR” via a novel, efficient, indigenously developed process termed “Plasma Assisted Synthesis and Simultaneous Immobilization (PASSI)”, using isopropanol to enhance the reducing plasma environment. Au NPs were synthesized and simultaneously immobilized onto a cellulose based bio-template pre-functionalized via radiation induced grafting of 2,3-epoxypropylmethacrylate (EPMA) onto a nonwoven cellulose (NWC) substrate. The process entails minimal wastage of expensive gold precursor and eliminates use of external chemicals (reducing and stabilizing agents). Samples were characterized by 13C NMR, FTIR, XPS, TGA, DSC, SEM-EDS, BET, and EDXRF analysis. Catalytic activity was assessed by spectrophotometrically monitoring the reduction of p-nitroaniline (PNA) in presence of NaBH4. DFT calculations established the interaction between Au NPs and EPMA groups of the bio-template to be occurring in ratios of 1:1 and 1:2, with 1:1 being more stable. ANN modelling was also invoked to investigate the effect of simultaneous variation of plasma process parameters on the catalytic performance. AuNICaR was demonstrated for catalytic reduction of pollutants: PNA, p-nitrophenol (PNP) and methyl orange (MO) azo dye in both batch and continuous flow mode. Over 25000 mL of cumulative pollutant feed with concentrations ranging from 0.06 mM − 2 mM was treated at a flow rate of 540 mL.h−1, using a single catalyst batch after intermittent washing with water. With excellent storage stability of > 12 months and > 92 % retention in catalytic activity post multiple cycles, AuNICaR certifies as a potentially inexhaustible catalytic system for cost-effective pollutant treatment.

Simultaneous Immobilization of Heavy Metals from Multi-metal Contaminated Soil Amended with Chrysopogon Zizanioides Root Micro Powder

Simultaneous Immobilization of Heavy Metals from Multi-metal Contaminated Soil Amended with Chrysopogon Zizanioides Root Micro Powder

The performance and mechanism of sulfidated nano-zero-valent iron for the simultaneous stabilization of arsenic and cadmium

Co-contamination of soil and groundwater with arsenic (As) and cadmium (Cd) is widespread. Sulfidized Nanoscale Zero-Valent Iron (S-nZVI) is effective in removing As and Cd from contaminated environments. However, the mechanisms governing As and Cd removal from systems containing both species are still unclear. This study investigated the effectiveness of S-nZVI in the simultaneous removal of Cd(II) and As(III) from contaminated solutions and their interaction mechanisms. Adsorption experiments were conducted under aerobic conditions to investigate the effect of Cd(II) and As(III) on their co-immobilisation at different As(III) and Cd(II) concentrations. S-nZVI was characterised before and after the reaction to elucidate the mechanism of its simultaneous immobilisation of As(III) and Cd(II). Batch experiments revealed that the presence of Cd(II) and As(III) together considerably promotes the passivation of S-nZVI. The adsorption of Cd(II) at Cd:As = 1:3 was 198.37 mg/g, which was 27.6 % higher than that in Cd(II)-only systems, and the adsorption of As(III) at As:Cd = 1:3 was 204.05 mg/g, which was 175 % higher than that in As(III)-only systems. The results of X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy indicated that the removal of Cd(II) and As(III) by S-nZVI involves electrostatic adsorption, complexation and oxidation reactions, amongst which electrostatic adsorption and ternary-complex generation are responsible for the synergistic effect. As and Cd ions can form two types of surface complexes with FeOH or FeS on the outer layer of S-nZVI: anionic bridging to form Fe–As–Cd and cationic bridging to form Fe–Cd–As. This investigation elucidates the synergistic action of Cd(II) and As(III) during their removal using S-nZVI. Thus, S-nZVI is a promising material for the combined removal of Cd(II) and As(III), which can mitigate environmental pollution.

Tailor-Made Bioactive Papers by Site-Specific and Orthogonal Covalent Immobilization of Proteins.

A strategy for the bioorthogonal immobilization of proteins onto commercially available filter paper is presented. Recently, a two-step approach has been described that relies on covalent immobilization of a linker molecule to paper, followed by enzyme-mediated conjugation of a protein of interest containing an enzyme-recognition tag. Here, this strategy was expanded by evaluating four different chemical and chemoenzymatic reactions and investigating paper loading efficiency and orthogonality. Enhanced green fluorescent protein (EGFP) was used as a model protein to allow quantification of protein loading via fluorescence imaging. Two approaches were identified that showed significantly increased loading efficiencies compared with the previously applied conjugation strategy. Additionally, all four methods were proven orthogonal to each other, allowing simultaneous immobilization of a mixture of proteins to a premodified assembly of two paper sheets.

Layered double hydroxides for simultaneous and long-term immobilization of metal(loid)s in soil under simulated aging

Soil contamination by toxic metals and metalloids poses a grave threat to food security and human well-being. Immobilization serves as an effective method for the remediation of soils contaminated by metal(loid)s. Nevertheless, the ability of soil amendments for simultaneous immobilization of cations and oxyanions, and the long-term effectiveness of immobilization need substantial improvements. In this study, we used a series of layered double hydroxides (LDHs), including Mg-Al LDH and Ca-Al LDH fabricated from pure chemicals, and one waste-derived LDH synthesized using granulated ground blast furnace slag (GGBS), for the immobilization of Cu, Zn, As, and Sb in a historically contaminated soil obscured from a mining-affected region. The LDHs were first subjected to iron (Fe) modification to enhance their short-term immobilization performances toward metal(loid)s. Furthermore, the long-term effectiveness of Fe-modified LDHs was examined via two sets of experiments, including column experiments simulating 2-year water leaching, and accelerated aging experiments simulating 100-year proton attack. It was observed that Fe-modified LDHs, either made from pure chemicals or GGBS, demonstrated promising long-term immobilization performances toward metal(loid)s. Results from this study are encouraging for the future use of LDHs for simultaneous and long-term immobilization of metal(loid)s in soil.

Construction of direct Z-scheme Co9S8/CdS with tubular heterostructure through the simultaneous immobilization and in-situ reduction strategy for enhanced photocatalytic Cr(VI) reduction under visible light

Tubular Co9S8/CdS heterostructures have been successfully synthesized by in-situ growing CdS onto Co9S8 nanotubes through a simultaneous immobilization and in-situ reduction strategy. It turned out that the so-obtained heterostructure with Co9S8/CdS molar ratio of 1/10 can display a broad light absorption edge and especially much enhanced capacity for photocatalytic reduction of Cr(VI) under visible light. The characterization analysis and experimental results suggested that an interfacial electrostatic field between Co9S8 and CdS elements in the heterostructure could be constructed due to their different Fermi levels, allowing for more quantities of highly reductive electrons to participate in the photocatalytic reaction. Therefore, the so-obtained Co9S8/CdS (1/10) heterostructures could achieve the photocatalytic reduction efficiency of 100% within 20 min, which was more than two and four times larger than that of pristine CdS and Co9S8, respectively. Moreover, the possible photocatalytic reaction mechanism for reducing Cr(VI) was investigated and found to follow the direct Z-scheme charge transfer pathway. This novel fabrication route for composite photocatalysts with tubular heterostructures could lead to the widespread implementations for the elimination of various harmful pollutants in the process of environmental governance.

Physicochemical and Adsorption Properties of Nanoporous Activated Biocarbons from Thermochemical Treatment of Horsetail Herb.

In this study, the adsorption characteristics of novel activated biocarbons prepared from horsetail herb (a popular and troublesome weed) by physical activation (using carbon dioxide) and chemical one (using phosphoric(V) acid) in the process of simultaneous proteins immobilization in multicomponent solutions were examined. The carbon materials were characterized in terms of their porous structure, acidic-basic properties, and surface morphology. The binding mechanisms of such proteins as bovine serum albumin (BSA) and lysozyme (LSZ), differing in internal stability, were determined alone and in their blends. This was done based on the comprehensive analysis of the results of adsorption/desorption, surface, electrokinetic and stability measurements. These experiments were carried out over a wide pH range of 3-11. They included the following issues: (1) determination of the protein adsorbed/desorbed amounts on/from a surface of activated biocarbons; (2) study of the kinetics of these processes; (3) examination of the macromolecules impact on the surface charge density and zeta potential of the carbon materials; and (4) determination of the suspension stability and size of aggregates formed in the examined systems. The analysis of the obtained results indicated the differences in the binding mechanism of both proteins that is of key importance for their simultaneous immobilization on activated biocarbons surface in the soil environment.

The influence of carbonate on the adsorption performance and mechanism of LDHs toward Cd and As

The excellent adsorption performance of layered double hydroxides (LDHs) toward heavy metals (HMs) had been demonstrated. The carbonate contamination was one of the inherent problems for LDHs whether during the synthesis or application procedure, which significantly affected the adsorption performance of LDHs toward HMs. However, a few studies investigated the mutual effect and mechanism between HMs on LDHs with carbonate interference, especially for the coexistence system of cationic and anionic HMs. In this study, cadmium (Cd) and arsenate (As) were selected as typical cationic and anionic HMs to study the influences of carbonates on their adsorption performance on LDHs. The carbonate intercalated LDHs (CLDH) promoted Cd adsorption but inhibited As adsorption in single system. The adsorption capacity of Cd increased by ∼ 50 % while As adsorption decreased by half. CdCO3 precipitation contributed to ∼ 40 % of the adsorbed Cd whereas weaker electrostatic adsorption inhibited As adsorption due to lower surface zeta potentials of CLDH than LDH. In contrast, both adsorption capacities and rates of Cd and As on CLDH were promoted in binary system (the co-existence of Cd and As) compared with single system. The surface potentials of CLDH turned from positive to negative with As rapid occupation, facilitating Cd entrance into the interlayers. And then the opening of the interlayer space and rearrangement of CLDH enhanced CdCO3 precipitation and isomorphic substitution. With the increase of surface zeta potentials and rearrangement of CLDH, in turn, the adsorption of As was promoted via electrostatic adsorption (∼65 %) and surface complexation (∼35 %). The adsorption capacity of Cd increased by ∼ 15 % whereas As adsorption decreased by half with increasing pH from 4 to 9 in binary system. In contrast, temperature (15–35 ℃) had negligible influence on the adsorption of CLDH toward Cd and As. Herein, this study illustrated the influence mechanism of carbonate intercalation on the simultaneous immobilization of Cd and As on LDHs, providing an understanding for fates of Cd and As with LDHs in more realistic scenes.

A comparison of Vie Scope and standard Macintosh laryngoscopes in a simulated condition of an entrapped trauma patient with simultaneous cervical spine immobilisation - A randomised, controlled manikin trial

BackgroundTracheal intubation remains the gold standard in the management of the injured. Airway management of trauma patients, especially in pre-hospital settings is often challenging and may be associated with serious complications. In the current practice, standard laryngoscopes are being superseded by new generation devices such as video laryngoscopes. One of the recently-introduced airway devices is the Vie Scope. It is an illuminated intubating device with a design similar to Miller's straight intubating blade. The intubation technique using the Vie Scope requires the use of a bougie, which is inserted first and then after removing the scope the endotracheal tube is railroaded over the introducer. AimThe aim of this study was to evaluate the Vie Scope for intubation in a simulated condition of an entrapped trauma patient with simultaneous cervical spine immobilisation. MethodsAn intubation manikin with the cervical collar on was placed on and secured to the driver's seat of a passenger car. The car was then positioned on its left side. The time required to insert the device and achieve a successful glottic visualisation as well as the intubation and successful ventilation time were recorded. The glottic view was assessed using the Cormack-Lehane classification. The first attempt success rate of intubation and the ease of use by the operator were also assessed. ResultsFifty fully qualified and experienced paramedics participated in the study. The standard Macintosh laryngoscope required shorter mean time to obtain the glottic view 12.7 s (±4.64) vs. 18.8 s (±5.86), p < 0.0001, however, better view of the glottis was obtained with the Vie Scope. The time to intubation and successful ventilation was significantly shorter when the Macintosh laryngoscope was used 35.03 s (±5.27) vs. 51.1 s (±6.28), p = 0.02. There were no failed intubation attempts when the Macintosh laryngoscope was used. ConclusionAlthough the Vie Scope provided better glottic visualisation, because of the specific technique, the Macintosh laryngoscope was superior in terms of the time required to visualise the glottis, the time to intubation and successful ventilation. Moreover, the Macintosh laryngoscope was found to be easier and more convenient to use.

Recent Advances in the Strategies of Simultaneous Enzyme Immobilization Accompanied by Nanocarrier Synthesis

In recent years, with advancements in nanotechnology and materials science, new enzyme immobilization strategies based on nanomaterials have continuously emerged. These strategies have shown significant effects on enhancing enzyme catalytic performance and stability due to their high surface area, good chemical stability, and ease of enzyme binding, demonstrating tremendous potential for industrial applications. Those methods that can rapidly synthesize nanocarriers under mild conditions allow for the one-step synthesis of nanocarriers and enzyme complexes, thereby exhibiting advantages such as simplicity of process, minimal enzyme damage, short processing times, and environmental friendliness. This paper provides an overview of simultaneous enzyme immobilization strategies accompanied by nanocarrier synthesis, including organic–inorganic hybrid nano-flowers (HNFs), metal–organic frameworks (MOFs), and conductive polymers (CPs). It covers their preparation principles, post-immobilization performance, applications, and existing challenges.

Efficient co-stabilization of arsenic and cadmium in farmland soil by schwertmannite under long-term flooding-drying condition

Simultaneously stabilizing of arsenic (As) and cadmium (Cd) in co-contaminated soil presents substantial challenges due to their contrasting chemical properties. Schwertmannite (Sch) is recognized as a potent adsorbent for As pollution, with alkali modification showing promising results in the simultaneous immobilization of both As and Cd. This study systematically investigated the long-term stabilization efficacy of alkali-modified Sch in Cd–As co-contaminated farmland soil over a 200-day flooding-drying period. The results revealed that As showed significant mobility in flooded conditions, whereas Cd exhibited increased soil availability under drying phases. The addition of Sch did not affect the trends in soil pH and Eh fluctuations; nonetheless, it led to an augmentation in the levels of amorphous iron oxides and SO42− concentration in soil pore water. At a dosage of 0.5% Sch, there was a notable decrease in the mobility and soil availability of As and Cd under both flooding (34.5% and 53.6% at Day 50) and drying conditions (27.0% and 29.4% at Day 130), primarily promoting the transformation of labile metal(loid) fraction into amorphous iron oxide-bound forms. Throughout the flooding-drying treatment period, Sch maintained stable mineral morphology and mineralogical phase, highlighting its long-term stabilization effect. The findings of this study emphasize the promising application of Sch-based soil remediation agents in mitigating the challenges arising from As–Cd co-contamination. Further research is warranted to explore their application in real farmland settings and their impact on the uptake of toxic metal(loid)s by plants.

Enhanced multi-metals stabilization: Synergistic insights from hydroxyapatite and peroxide dosing strategies

Sediment contamination by heavy metals is a pressing environmental concern. While in situ metal stabilization techniques have shown promise, a great challenge remains in the simultaneous immobilization of multi-metals co-existing in contaminated sediments. This study aims to address this challenge by developing a practical method for stabilizing multi-metals by hydroxyapatite and calcium peroxide (HAP/CaO2) dosing strategies. Results showed that dosing 15.12 g of HAP/CaO2 at a ratio of 3:1 effectively transformed labile metals into stable fractions, reaching reaction kinetic equilibrium within one month with a pseudo-second-order kinetic (R2 > 0.98). The stable fractions of Nickel (Ni), Chromium (Cr), and lead (Pb) increased by approximately 16.9 %, 26.7 %, and 21.9 %, respectively, reducing heavy metal mobility and ensuring leachable concentrations complied with the stringent environmental Class I standard. Mechanistic analysis indicated that HAP played a crucial role in Pb stabilization, exhibiting a high rate of 0.0176 d−1, while Cr and Ni stabilization primarily occurred through the formation of hydroxide precipitates, as well as the slowly elevated pH (>8.5). Importantly, the proposed strategy poses a minimal environmental risk to benthic organisms exhibits almost negligible toxicity towards Vibrio fischeri and the Chironomus riparius, and saves about 71 % of costs compared to kaolinite. These advantages suggest the feasibility of HAP/CaO2 dosing strategies in multi-metal stabilization in contaminated sediments.

Preparation and performance of a coal gasification slag-based composite for simultaneous immobilization of Cd and As

Preparation and performance of a coal gasification slag-based composite for simultaneous immobilization of Cd and As

Biochar accelerated Fenton process for roxarsone oxidation, inorganic arsenic adsorption and simultaneous immobilization of arsenic-iron sludge

Complete remediation of organoarsenics from environmental matrix hits the bottleneck, that is, the sluggish efficiency of oxidative degradation towards organoarsenics and unsatisfying immobilization performance towards generated inorganic arsenic. Herein, we establish a biochar accelerated Fenton (BA-Fenton) process to decontaminate water from roxarsone (ROX). In comparison with Fe2+/H2O2 process (10 μΜ/0.2 mM), the incorporation of 0.5 g L-1 biochar promoted ROX degradation from 48.2% to 98.2% and total arsenic elimination from 67.6% to 97.3%, respectively. In BA-Fenton process, •OH as the dominant reactive oxygen species (ROS), exhibited a cumulative concentration of 0.42 mM, three times higher than that in classical Fenton process. Crucially, the presence of biochar in Fenton process significantly enhanced the stability of arsenic-iron sludge, whereas the secondary leaching of total arsenic decreased from 433.8 μg-As L-1 to 13.9 μg-As L-1, meeting the prescribed environmental quality standards for surface water in China (50 μg-As L-1, GB 3838-2002). Mechanistic studies unveiled ROX remediation mechanism by BA-Fenton process, highlighting the dual functionality of biochar. On one hand, biochar efficiently reduced Fe3+ to Fe2+ with a rate constant of 0.225 min-1, overcoming the rate-determining step of classical Fenton process for •OH production, consequently promoting the transformation of ROX to As(V). On the other hand, molecular spectroscopy analysis elucidated that in-situ formed As(V) was adsorbed by ferric hydroxides with the formation of arsenic-iron sludge. Subsequently, biochar immobilized arsenic-iron sludge through hydrogen bonds, electrostatic attraction and surface complexation. Furthermore, real water studies demonstrated the effective remediation of organoarsenics by BA-Fenton process in tap water, lake water and chicken manure leachate. This “Two Birds with One Stone” strategy with low-cost, environmental-friendly and sustainable biochar holds great promise for the ultimate disposal of industrial wastewater containing organoarsenics.

Simultaneous immobilization of V and Cr availability, speciation in contaminated soil and accumulation in ryegrass by using Fe-modified pyrolysis char

In this study, municipal waste pyrolytic char (PEWC) was prepared by pyrolysis from municipal solid waste extracted in landfills, and Fe-based modified pyrolytic char (Fe-PEWC) was prepared by modification. Focusing on the evaluation of the stabilization capacity of Fe-PEWC for vanadium (V) and chromium (Cr) in soils, the effects of PEWC addition on soil properties, bioavailability and morphological distribution of V and Cr, ryegrass growth, and V and Cr accumulation were thoroughly investigated. The results of pot experiment showed that the application of PEWC and Fe-PEWC significantly (P < 0.05) improved soil properties (such as pH, EC, total nitrogen, available phosphorus, available potassium, and organic matter). After 42 days of cultivation, Fe-PEWC has a better fixation effect on heavy metals, and the bioavailable V and Cr of 3% Fe-PEWC decreased by 14.96% and 19.48%, respectively. The exchangeable state and reducible state decreased, while the oxidizable state and residual state increased to varying degrees. The Fe-PEWC can effectively reduce the accumulation of V and Cr in ryegrass by 71.25% and 76.43%, respectively, thereby reducing their toxicity to plants. In summary, modified pyrolytic char can effectively solidify heavy metals in soil, improve soil ecology and reduce the toxicity to plants. The use of excavated waste as a raw material for the preparation of soil heavy metal curing agent has the significance of resource recycling, low price, and practical application.