A dopant-assisted iodide-adduct chemical ionization time-of-flight mass spectrometer based on VUV lamp photoionization for atmospheric low-molecular-weight organic acids analysis.

Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry. In iodine-adduct chemical ionization mass spectrometry (CIMS), the low utilization efficiency of methyl iodide and humidity interference are two major issues of the vacuum ultraviolet (VUV) lamp initiated CIMS for on-line gaseous formic and acetic acids analysis. In this work, we present a new CIMS based on VUV lamp, and the ion-molecular reactor is separated into photoionization and chemical ionization zones by a reducer electrode. Acetone was added to the photoionization zone, and the VUV photoionization acetone provided low-energy electrons for methyl iodide to generate I-, and the addition of acetone reduced the amount of methyl iodide by 2/3. In the chemical ionization zone, a headspace vial containing ultrapure water was added for humidity calibration, and the vial changes the sensitivity as a function of humidity from ambiguity to well linear correlation (R2 > 0.95). With humidity calibration, the CIMS can quantitatively measure formic and acetic acids in the humidity range of 0%-88% RH. In this mode, limits of detection of 10 and 50 pptv are obtained for formic and acetic acids, respectively. And the relative standard deviation (RSD) of quantitation stability for 6 days were less than 10.5%. This CIMS was successfully used to determine the formic and acetic acids in the underground parking and ambient environment of the Shandong University campus (Qingdao, China). In addition, we developed a simple model based formic acid concentration to assess vehicular emissions.

Rational Strategies for Preparing Highly Efficient Tin-, Bismuth- or Indium Based Electrocatalysts for Electrochemical CO2 Reduction to Formic acid.

Electrochemical carbon dioxide reduction reaction (CO2RR) is an environmentally friendly and economically viable approach to convert greenhouse gas CO2 into valuable chemical fuels and feedstocks. Among various products of CO2RR, formic acid/formate (HCOOH/HCOO-) is considered the most attractive one with its high energy density and ease of storage, thereby enabling widespread commercial applications in chemical, medicine, and energy-related industries. Nowadays, the development of efficient and financially feasible electrocatalysts with excellent selectivity and activity towards HCOOH/HCOO- is paramount for the industrial application of CO2RR technology, in which Tin (Sn), Bismuth (Bi), and Indium (In)-based electrocatalysts have drawn significant attention due to their high efficiency and various regulation strategies have been explored to design diverse advanced electrocatalysts. Herein, we comprehensively review the rational strategies to enhance electrocatalytic performances of these electrocatalysts for CO2RR to HCOOH/HCOO-. Specifically, the internal mechanism between the physicochemical properties of engineering materials and electrocatalytic performance is analyzed and discussed in details. Besides, the current challenges and future opportunities are proposed to provide inspiration for the development of more efficient electrocatalysts in this field.

Conversion of Cellobiose to Formic Acid as a Biomass-Derived Renewable Hydrogen Source Using Solid Base Catalysts.

Formic acid is considered a promising hydrogen carrier. Biomass-derived formic acid can be obtained by oxidative decomposition of sugars. This study explored the production of formic acid from cellobiose, a disaccharide consisting of d-glucose linked by ß-glycosidic bonds using heterogeneous catalysts under mild reaction conditions. The use of alkaline earth metal oxide solid base catalysts like CaO and MgO in the presence of hydrogen peroxide could afford formic acid from cellobiose at 343 K. While CaO gave 14 % yield of formic acid, the oxide itself was converted to a harmful metal peroxide, CaO2 after the reaction. In contrast, MgO could produce formic acid without the formation of the metal peroxide. The difficulty in selectively synthesizing formic acid from cellobiose using these solid base catalysts was due to the poor conversion of cellobiose to glucose. Using a combination of solid acid and base catalysts, a high formic acid yield of 33 % was obtained under mild reaction conditions due to the quantitative hydrolysis of cellobiose to glucose by a solid acid followed by the selective decomposition of glucose to formic acid by a solid base.

An Effective Strategy to Boost Formic Acid Dehydrogenation over Pd/AC-NH2 Catalyst through Pd Size Control.

Formic acid (FA, HCOOH) is regarded as one of the most promising carriers for hydrogen storage. However, the catalyst design for FA dehydrogenation into H2 with high efficiency is not clear. Here, we elucidate the rationale of size effect over the most commonly used Pd-based catalyst through supporting different Pd species, including single atoms, nanoclusters, and nanoparticles, on amine-functionalized active carbon (Pd/AC-NH2). The activity test presents that Pd/AC-NH2 with Pd nanoclusters exhibits the best turnover frequency (TOF) value of 40856 h-1 for 1 M FA at 328 K and even 1504 h-1 for neat FA at 308 K, which is comparable to the homogeneous catalysts and has been the first heterogeneous catalyst used in neat FA dehydrogenation under mild conditions. The comprehensive characterizations reveal that the size of Pd species affects the ratios of Pd0/Pd2+ and hydrogen spillover effect, which is crucial for the C-H cleavage and H2 desorption. Besides, the influences of amine groups on catalytic performance were further examined. This work provided an ingenious guideline to design efficient and practical catalysts for hydrogen storage under ambient conditions.

State-of-the-Art Light-Driven Hydrogen Generation from Formic Acid and Utilization in Enzymatic Hydrogenations.

A concept of combining photocatalytically generated hydrogen with green enzymatic reductions is demonstrated. The developed photocatalytic formic acid (FA) dehydrogenation setup based on Pt(x)@TiO2 shows unprecedented hydrogen generation activity, which is two orders of magnitude higher than reported values of state-of-the-art systems. Mechanistic studies confirm that hydrogen generation proceeds via a photocatalytic pathway, which is entirely different from purely thermal reaction mechanisms previously reported. The viability of the presented approach is demonstrated by the synthesis of value-added compounds 3-phenylpropanal and (2R, 5S)-dihydrocarvone at ambient pressure and room temperature, which should be applicable for many other hydrogenation processes, e.g., for the preparation of flavours and fragrance compounds, as well as pharmaceuticals.

A Two-Phase Hydrogenation Membrane for Contaminants Reduction at High Hydrogen Reagent Utilization Efficiency.

Heterogeneous hydrogenation is surging as a promising strategy for selective removal of water pollutants, yet numerous efforts rely on catalyst design to advance catalytic activity. Herein, we enhanced the mass transfer and the utilization of hydrogen reagent through construction of a two-phase flow-through membrane reaction device (Pd/SiC-MR). Pd/SiC-MR displays high efficiency and selectivity toward removal of multiple pollutants. For instance, rapid (∼0.35 s) and exclusive hydrogenation (>99%) of carbon-chlorine bond in organohalogens were realized at high water flux (220 L/m2/h). More importantly, the two-phase Pd/SiC-MR reaction system achieved 31.4% utilization of hydrogen reagent, 1-3 orders of magnitude higher than those by classical slurry or fixed-bed reactor. The high hydrogenation performance is attributed to the close proximity of the hydrogen source, reactive hydrogen atom, and pollutant under high molecular collision frequency in membrane pores. Our study opens an approach for improved hydrogen reagent utilization while reserving the high pollutant removal efficiency through altering operating conditions, beyond complex material design limitations in hydrogenation water purification.

Formic Acid-Intensified Photoreduction of NOx on Iron Minerals Triggers Daytime HONO Formation through Active Hydrogen.

Nitrous acid (HONO) is crucial in atmospheric chemistry as a precursor to morning peak hydroxyl radicals and significantly affects urban air quality by forming secondary pollutants, yet the mechanisms of its daytime formation is not fully understood. This study investigates the role of formic acid (HCOOH), a prevalent electron and proton donor, in the transformation of nitrogen oxides (NOx) and the formation of HONO on photoactive mineral dust. Exploiting hematite (Fe2O3) as an environmental indicator, we demonstrate that HCOOH significantly promotes the photoreduction of NO2 to HONO, while suppressing nitrate accumulation. This occurs through the formation of a surface ≡Fe-OOCH complex, where sunlight activates the C-H bond to generate and transfer active hydrogen, directly converting NO2 to HONO. Additionally, HCOOH can trigger the photolysis of nitrates as predeposited on Fe2O3, further increasing HONO production. These findings show that HCOOH-mediated photochemical reactions on iron minerals may contribute to elevated atmospheric HONO levels, highlighting a crucial pathway with broad effects on atmospheric chemistry and public health.

Efficient hydrogen production from formic acid dehydrogenation over ultrasmall PdIr nanoparticles on amine-functionalized yolk-shell mesoporous silica.

Developing heterogeneous catalysts with exceptional catalytic activity over formic acid (HCOOH, FA) dehydrogenation is imperative to employ FA as an effective hydrogen (H2) carrier. In this work, ultrasmall (1.4 nm) and well-dispersed PdIr nanoparticles (NPs) immobilized on amine-functionalized yolk-shell mesoporous silica nanospheres (YSMSNs) with radially oriented mesoporous channels have been synthesized by a co-reduction strategy. The optimized catalyst Pd4Ir1/YSMSNs-NH2 (Pd/Ir molar ratio = 4:1) exhibited a remarkable turnover frequency (TOF) of 5818 h-1 and remarkable stability at 50 °C with the addition of sodium formate (SF), resulting in complete FA conversion and H2 selectivity, exceeding most of the solid heterogeneous catalysts in previous reports under similar circumstances. Kinetic isotope effect (KIE) exploration indicates the cleavage of the CH bond is regarded as the rate-determining step (RDS) during the FA dehydrogenation process. Such excellent catalytic properties arise from the ultrafine and well-dispersed PdIr NPs supported on the nanosphere support YSMSNs-NH2, the electronic synergistic effect of PdIr alloy NPs, and the strong metal-support interaction (MSI) effect between the introduced PdIr NPs and YSMSNs-NH2 support. This work offers a new paradigm for exploiting the highly effective silica-supported Pd-based heterogeneous catalysts over the dehydrogenation of FA.

Transition metal pincer catalysts for formic acid dehydrogenation: a mechanistic perspective.

The storage and transportation of hydrogen gas, a non-polluting alternative to carbon-based fuels, have always been challenging due to its extreme flammability. In this regard, formic acid (FA) is a promising liquid organic hydrogen carrier (LOHC), and over the past decades, significant progress has been made in dehydrogenating FA through transition metal catalysis. In this review, our goal is to provide a detailed insight into the existing processes to expose various mechanistic challenges associated with FA dehydrogenation (FAD). Specifically, methodologies catalyzed by pincer-ligated metal complexes were chosen. Pincer ligands are preferred as they provide structural rigidity to the complexes, making the isolation and analysis of reaction intermediates less challenging and consequently providing a better mechanistic understanding. In this perspective, the catalytic activity of the reported pincer complexes in FAD was overviewed, and more importantly, the catalytic cycles were examined in detail. Further attention was given to the structural modifications, role of additives, reaction medium, and their crucial effects on the outcome.

Ozone-Assisted Cu-Based Catalysts for the Efficient Electro-Reforming Glycerol to Formic Acid.

Glycerol electrooxidation reaction (GOR) to produce value-added chemicals, such as formic acid, could make more efficient use of abundant glycerol and meet future demand for formic acid as a fuel for direct or indirect formic acid fuel cells. Non-noble metal Cu-based catalysts have great potential in electro-reforming glycerol to formic acid. However, the high activity, selectivity and stability of Cu based catalysts in GOR cannot be achieved simultaneously. Here, we used ozone-assisted electrocatalyst to convert glycerol to formic acid under alkaline conditions, the onset potential was reduced by 60 mV, the Faraday efficiency (FE) reached 95%. The catalyst has excellent stability within 300 h at the current density of 10 mA cm-2. The electron spin resonance proved that ozone produced superoxide anion during the GOR. In situ Raman spectroscopy, electrochemical studies showed that glycerol can be activated with ozone in GOR, and the C-C bond can be broken to reduce the polymerization of glycerol on the catalyst surface, so as to produce more formic acid at a lower voltage. Moreover, the removal of dissolved O3 from water can be up to 100% after 30 minutes of GOR reaction at a solubility of 50 mg L-1 as measured by UV-VIS spectrophotometry.

Effect of dietary calcium source, exogenous phytase, and formic acid on inositol phosphate degradation, mineral and amino acid digestibility, and microbiota in growing pigs.

The choice of the calcium (Ca) source in pig diets and the addition of formic acid may affect the gastrointestinal inositol phosphate (InsP) degradation and thereby, phosphorus (P) digestibility in pigs. This study assessed the effects of different Ca sources (Ca carbonate, Ca formate), exogenous phytase, and chemical acidification on InsP degradation, nutrient digestion and retention, blood metabolites, and microbiota composition in growing pigs. In a randomized design, 8 ileal-cannulated barrows (24 kg initial BW) were fed 5 diets containing Ca formate or Ca carbonate as the only mineral Ca addition, with or without 1,500 FTU/kg of an exogenous hybrid 6-phytase. A fifth diet was composed of Ca carbonate with phytase but with 8 g formic acid/kg diet. No mineral P was added to the diets. Prececal InsP6 disappearance and P digestibility were lower (P ≤ 0.032) in pigs fed diets containing Ca formate. In the presence of exogenous phytase, InsP5 and InsP4 concentrations in the ileal digesta were lower (P ≤ 0.019) with Ca carbonate than Ca formate. The addition of formic acid to Ca carbonate with phytase diet resulted in greater (P = 0.027) prececal InsP6 disappearance (87% vs. 80%), lower (P = 0.001) InsP5 concentration, and greater (P ≤ 0.031) InsP2 and myo-inositol concentrations in the ileal digesta. Prececal P digestibility was greater (P = 0.004) with the addition of formic acid compared to Ca carbonate with phytase alone. Prececal amino acid (AA) digestibility of some AA was greater with Ca formate compared to Ca carbonate but only in diets with phytase (P ≤ 0.048). The addition of formic acid to the diet with Ca carbonate and phytase increased (P ≤ 0.006) the prececal AA digestibility of most indispensable AA. Exogenous phytase affected more microbial genera in the feces when Ca formate was used compared to Ca carbonate. In the ileal digesta, the Ca carbonate diet supplemented with formic acid and phytase led to a similar microbial community as the Ca formate diets. In conclusion, Ca formate reduced prececal InsP6 degradation and P digestibility, but might be of advantage in regard to prececal AA digestibility in pigs compared to Ca carbonate when exogenous phytase is added. The addition of formic acid to Ca carbonate with phytase, however, resulted in greater InsP6 disappearance, P and AA digestibility values, and changed ileal microbiota composition compared to Ca carbonate with phytase alone.

The study aimed to investigate the effects of dietary calcium sources, exogenous phytase, and formic acid on inositol phosphate (InsP) degradation and nutrient digestibility in ileal-cannulated growing pigs. It also evaluated the concentrations of phosphorus, calcium, and myo-inositol in the blood, the composition of the microbiota in the ileal digesta and feces, and the concentrations of volatile fatty acids in the feces. Replacing calcium carbonate with calcium formate in the feed reduced prececal InsP6 disappearance and phosphorus digestibility. However, adding formic acid to a diet containing calcium carbonate and phytase enhanced prececal InsP6 disappearance and phosphorus digestibility, and increased InsP2 and myo-inositol concentrations in the ileal digesta. The dietary treatments resulted in more pronounced alterations of the microbiota in the feces than the ileal digesta. In ileal digesta, the shifts in relative abundance were primarily evident among low-abundant genera, while in feces, changes were observed in a larger number among genera with higher levels of abundance. The findings of this study suggest that calcium formate is not a suitable alternative to calcium carbonate for phosphorus digestibility in growing pigs. The release of phosphorus from InsP by exogenous phytase can be increased by adding formic acid.

Molecular Iridium Catalyzed Electrochemical Formic Acid Oxidation: Mechanistic Insights.

Electrochemical formic acid oxidation reaction (FAOR) is a pivotal model for understanding organic fuel oxidation and advancing sustainable energy technologies. Here, we present mechanistic insights into a novel molecular-like iridium catalyst (Ir-N4-C) for FAOR. Our studies reveal that isolated sites facilitate a preferential dehydrogenation pathway, circumventing catalyst poisoning and exhibiting high inherent activity. In-situ spectroscopic analyses elucidate that weakly adsorbed intermediates mediate the FAOR and are dynamically regulated by potential-dependent redox transitions. Theoretical and experimental investigations demonstrate a parallel mechanism involving two key intermediates with distinct pH and potential sensitivities. The rate-determining step is identified as the adsorption of formate via coupled or sequential proton-electron transfer, which aligns well with the observed kinetic properties, pH dependence, and hydrogen/deuterium isotope effects in experiments. These findings provide valuable insights into the reaction mechanism of FAOR, advancing our understanding at the molecular level and potentially guiding the design of efficient catalysts for fuel cells and electrolyzers.

Catalyst-Free Transformation of Carbon Dioxide to Small Organic Compounds in Water Microdroplets Nebulized by Different Gases.

A straightforward nebulized spray system is designed to explore the hydrogenation of carbon dioxide (CO2) within water microdroplets surrounded by different gases such as carbon dioxide, nitrogen, oxygen, and compressed air. The collected droplets are analyzed using water-suppressed nuclear magnetic resonance (NMR). Formate anion (HCOO-), acetate anion (CH3COO-), ethylene glycol (HOCH2CH2OH), and methane (CH4) are detected when water is nebulized. This pattern persisted when the water is saturated with CO2, indicating that CO2 in the nebulizing gas triggers the formation of these small organics. In a pure CO2 atmosphere, the formate anion concentration is determined to be ≈70 µm, referenced to dimethyl sulfoxide, which has been introduced as an internal standard in the collected water droplets. This study highlights the power of water microdroplets to initiate unexpected chemistry for the transformation of CO2 to small organic compounds.

Optimizing Cr(VI) reduction to Cr(III) using Pd-CNTs nanocatalyst: kinetic Monte Carlo simulation and experimental design insights.

In this investigation, we explored the kinetics of Cr(VI) reduction to Cr(III) on carbon nanotube decorated with palladium (Pd-CNTs) nanocatalyst, using formic acid as the reducing agent. This study has been bone utilizing kinetic Monte Carlo simulation and experimental design methods. The mechanism and kinetic parameters of this reaction are provided. The effect various factors such as reaction time, pH level, dichromate (Cr2O72-) concentration, and formic acid concentration on Cr(VI) reduction was studied. Concentrations of HCOOH and Cr2O72- were identified as the crucial variables, while the HCOOH concentration has the most significant impact. Positive influences on Cr(VI) reduction were observed with increasing pH level and HCOOH concentration. Reaction time positively affects on Cr(VI) reduction efficiency. However, the concentration of Cr2O72- showed an increasing effect up to a threshold, negatively impacting the efficiency. The optimal conditions (Reaction time = 60 min, pH = 4.5, [Cr2O72-] = 5.05 × 10-3 M, and [HCOOH] = 0.95 M) for Cr(VI) reduction. At optimal conditions, the Cr(VI) reduction efficiency was obtained to be 100%.

A hybrid FeOx/CoOx/Pt ternary nanocatalyst for augmented catalysis of formic acid electro-oxidation.

Platinum-based catalysts that have long been used as the anodes for the formic acid electro-oxidation (FAO) in the direct formic acid fuel cells (DFAFCs) were susceptible to retrogradation in performance due to CO poisoning that impaired the technology transfer in industry. This work is designed to overcome this challenge by amending the Pt surface sequentially with nanosized cobalt (nano-CoOx, fibril texture of ca. 200 nm in particle size) and iron (nano-FeOx, nanorods of particle size and length of 80 and 253 nm, respectively) oxides. This enriched the Pt surface with oxygenated groups that boosted FAO and mitigated the CO poisoning. The unfilled d-orbitals of the transition metals and their tendency to vary their oxidations states presumed their participation in a faster mechanism of FAO. Engineering the Pt surface in this FeOx/CoOx/Pt hierarchy resulted in a remarkable activity toward FAO, that exceeded four times that of the Pt catalyst with up to ca. 2.5 times improvement in the catalytic tolerance against CO poisoning. This associated a ca. - 32 mV shift in the onset potential of FAO which increased to - 40 mV with a post-activation of the same catalyst at - 0.5  in 0.2 mol L-1 NaOH, displaying the catalyst's competitiveness in reducing overpotentials in DFAFCs. It also exhibited a favorable amelioration in the catalytic durability in long-termed chronoamperometric electrolysis. The electrochemical impedance spectroscopy and the CO stripping voltammetry were employed to elucidate the origin of enhancement.

Death Following Methyl Alcohol Intoxication: Gross Autopsy and Histological Findings.

Methanol, or wood alcohol, is a clear liquid with a weak odor, slightly sweeter than ethanol, which is easily accessible. The last makes it a product of choice for intentional self-harm, severe intoxication, or even suicide. Accidental ingestion and homicidal usage are not exclusions. We present and discuss the case of a man in his 20s who was in continuous alcoholic intoxication until he finally abused with methanol and was admitted to a hospital, where he died six days later. When it comes to intoxication, there are often no apparent findings that could help in determining the cause and manner of death. The last is especially important in cases of delayed death when the toxicology results are negative.

An environmentally friendly deep eutectic solvent for CO2 capture.

A leading cause of global warming is the increase of carbon dioxide (CO2) emissions due to anthropogenic activities which prompts an urgent need for substantial reduction. Recently, CO2 absorption in deep eutectic solvents (DESs) has attracted scientific attention, because of their adaptability compared to traditional ionic liquids and aqueous amine solutions. This study employs the heating method to synthesize DESs using tetrapropylammonium bromide (TPAB) and formic acid (Fa) with molar ratios of TPAB-Fa (1:1) and TPAB-Fa (1:2). Absorption experiments by static method quantified CO2 solubility in the DESs under varied pressures and temperatures. TPAB-Fa (1:2) at 25.0 °C was the most efficient with the CO2 solubility of 0.218. Thermodynamic modeling was performed by employing the nonrandom two liquids activity coefficient model and the Peng-Robinson equation of state for the liquid and gas phases, respectively. The Henry's law constant was determined from experimental data. CO2 physical absorption was confirmed via nuclear magnetic resonance (NMR) and Fourier-transform infrared (FT-IR) analyses. TPAB-Fa (1:2), as the superior DES, exhibited regeneration efficiency of 99% after five absorption/desorption cycles.

Formate Salt as a Bifunctional Reagent for Hydroxylation and Carbonylation Reactions Under Photochemically Driven Nickel Catalysis.

In this study, we disclose for the first time that formate salt can be used as a bifunctional reagent for the synthesis of phenol derivatives and as a CO source for carbonylative cross-coupling processes using the COware gas reactor under activation free conditions. Key to this success is the in-situ synthesis of aryl formate via an unprecedented nickel/organophotocatalyst system under blue LED irradiation. This developed system demonstrated high applicability to various aryl iodide substrates for synthesizing phenol derivatives. Moreover, the generated CO could be utilized in a range of carbonylative C-heteroatom and C-C processes. Notably, commercially available H13COONa salt can serve as a bifunctional reagent for both synthesizing phenols and generating 13CO.

Dietary concoction of formic acid and thymol and its effects on zoo-technical performance, immunity, jejunal architecture and gut health in Turkey.

With increasing demand for improved protein-rich food, diverse poultry birds like turkey are gaining popularity in India. However, with the rising concerns of antibiotic residues and drug resistance, safe alternatives like formic acid (FA) and thymol (TH) have attracted the attention of researchers as effective replacer of antibiotic growth promoters (AGP). This experiment investigated the effects of combinations of FA and TH on growth performance, immunity, gut microflora and jejunal microstructures in turkey. A total of 240 turkey poults were reared in 6 treatment groups for a period of 16 weeks with standard management and feeding: T1 (basal diet only); T2 (AGP); T3 (FA@2.5 ml + TH@240 mg/kg); T4 (FA@2.5 ml + TH@360 mg/kg); T5 (FA@7.5 ml + TH@240 mg/kg) and T6 (FA@7.5 ml + TH@360 mg/kg). The results revealed that T5 group had the highest final body weight and best FCR while the feed consumption across the groups was comparable. The immune status of the turkey improved (p ≤ 0.05) in treatment groups compared to control with T4 and T5 group showcasing the best CBH response, antibody titres and relative immune organ weight index. A significant improvement (p ≤ 0.05) in jejunal microstructures was observed at 16th week in T5 group over control and AGP fed group. There was significant (p ≤ 0.001) reduction in total plate and coliform counts, but a positive shift was seen in Lactobacillus population in T5 group as compared to control and AGP fed group. In conclusion, the concoction of formic acid (7.5 ml/kg) + thymol (240 mg/kg) in-feed supplement improved the performance, immune status and gut health in turkey as an efficient alternative to AGPs.

Hierarchically porous and flexible chitin-fiber/melamine-sponge composite filter with high-loading of PdAu nanoparticles for effective hydrodechlorination of chlorophenols.

Hydrodechlorination has emerged as a promising technique for detoxifying chlorophenols (CPs) in wastewater, but it suffers from sluggish reaction kinetics and limited durability due to the lack of effective and stable catalysts. Herein, a composite filter consisting of melamine-sponge (MS), chitin fiber (CF) and ultrafine PdAu nanoparticles (PdAu/CF-MS) has been designed for continuous hydrodechlorination of CPs by using formic acid as a H-donor and sodium formate as a promoter. Benefitting from the dense active sites, rich porosity, and synergetic interaction of Pd/Au, the PdAu/CF-MS filter exhibits excellent hydrodechlorination performance (∼ 100 % conversion) towards 4-chlorophenol (1 mM, fluxes below 6100 mL·h-1·g-1) and outstanding durability (over 500 h at 61 mL·h-1·g-1), surpassing most reported counterparts (usually deactivated within 200 h or several cycles). Moreover, other CPs can also be effectively dechlorinated by the PdAu/CF-MS filter. The catalytic system proposed herein will provide a promising candidate for the detoxification of wastewater containing toxic CPs.