Removal Of Formic Acid Research Articles

Calcined Chitosan/Cellulous Aerogel Modified with Copper Oxide Nanoparticles as an Efficient Sorbent for the Optimized Removal of Formic Acid from Water.

A porous aerogel sorbent was prepared by the carbonization of a biohydrogel consisting of cellulose and chitosan (CS/CE) biopolymers. The adsorbent was also modified with copper oxide nanoparticles to effectively remove formic acid from water in batch mode. Characterization techniques, including scanning electron microscopy, Fourier transform infrared, Brunauer-Emmett-Teller, and X-ray diffraction, were employed to study the prepared sorbents. The concentration of formic acid in the solution was exactly determined by using liquid chromatography. To achieve maximum removal efficiency, important process variables were optimized using a central composite design data-based algorithm. Under optimal conditions, i.e., the initial concentration of 167.98 mg/L, the amount of sorbent equal to 75.28 mg, the contact time of 10.41 min, and the sample volume of 22.56 mL, a maximum acid removal efficiency of 84% was obtained. The Langmuir isotherm model was appropriately fitted to the experimental data, which indicates the chemical interaction of the sorbent active sites with formic acid. An adsorption capacity of 116.28 mg/g was also attained. The adsorption followed a pseudo-second-order kinetic pattern. According to the thermodynamic criteria, the adsorption of formic acid on the copper oxide-modified aerogel was exothermic, entropy-reducing, and favorable at temperatures lower than 290 K. Based on the results, CS/CE hydrogels comprising CuO nanoparticles are promising precursors for synthesizing carbonized aerogel sorbents that are successful in removing formic acid from aqueous environments.

Targeted Decomplexation of Metal Complexes for Efficient Metal Recovery by Ozone/Percarbonate

Traditional methods cannot efficiently recover Cu from Cu(II)-EDTA wastewater and encounter the formation of secondary contaminants. In this study, an ozone/percarbonate (O3/SPC) process was proposed to efficiently decomplex Cu(II)-EDTA and simultaneously recover Cu. The results demonstrate that the O3/SPC process achieves 100% recovery of Cu with the corresponding kobs value of 0.103 min-1 compared with the typical •OH-based O3/H2O2 process (81.2%, 0.042 min-1). The carbonate radical anion (CO3•-) is generated from the O3/SPC process and carries out the targeted attack of amino groups of Cu(II)-EDTA for decarboxylation and deamination processes, resulting in successive cleavage of Cu-O and Cu-N bonds. In comparison, the •OH-based O3/H2O2 process is predominantly responsible for the breakage of Cu-O bonds via decarboxylation and formic acid removal. Moreover, the released Cu(II) can be transformed into stable copper precipitates by employing an endogenous precipitant (CO32-), accompanied by toxic-free byproducts in the O3/SPC process. More importantly, the O3/SPC process exhibits excellent metal recovery in the treatment of real copper electroplating wastewater and other metal-EDTA complexes. This study provides a promising technology and opens a new avenue for the efficient decomplexation of metal-organic complexes with simultaneous recovery of valuable metal resources.

Evaluation of Preparation and Detoxification of Hemicellulose Hydrolysate for Improved Xylitol Production from Quinoa Straw.

Quinoa straw is rich in hemicellulose, and it could be hydrolyzed into xylose. It is a promising energy resource alternative that acts as a potential low-cost material for producing xylitol. In this study, quinoa straw was used as a substrate subjected to the hydrolysis of dilute sulfuric acid solution. Based on the production of xylose and inhibitors during hydrolysis, the optimal conditions for the hydrolysis of hemicellulose in quinoa straw were determined. Detoxification was performed via activated carbon adsorption. The optimal detoxification conditions were determined on the basis of major inhibitor concentrations in the hydrolysate. When the addition of activated carbon was 3% at 30 °C for 40 min, the removal of formic acid, acetic acid, furfural, and 5-HMF could reach 66.52%, 64.54%, 88.31%, and 89.44%, respectively. In addition to activated carbon adsorption, vacuum evaporation was further conducted to perform two-step detoxification. Subsequently, the detoxified hydrolysate was used for xylitol fermentation. The yield of xylitol reached 0.50 g/g after 96 h of fermentation by Candida tropicalis (CICC 1779). It is 1.2-fold higher than that obtained through the sole vacuum evaporation method. This study validated the feasibility of xylitol production from quinoa straw via a biorefinery process.

Formic acid, an organic acid food preservative, induces viable-but-non-culturable state, and triggers new Antimicrobial Resistance traits in Acinetobacter baumannii and Klebsiella pneumoniae.

Numerous human pathogens, especially Gram-negative bacteria, are able to enter the viable-but-non-culturable (VBNC) state when they are exposed to environmental stressors and pose the risk of being resuscitated and causing infection after the removal of the trigger. Widely used food preservatives like weak organic acids are potential VBNC inducers in food processing and packaging facilities but have only been reported for food-borne pathogens. In the present study, it is demonstrated for the first time that one such agent, formic acid (FA), can induce a VBNC state at food processing, storage, and distribution temperatures (4, 25, and 37°C) with a varied time of treatment (days 4-10) in pathogenic Gram-negative bacteria Acinetobacter baumannii and Klebsiella pneumoniae. The use of hospital-associated pathogens is critical based on the earlier reports that demonstrated the presence of these bacteria in hospital kitchens and commonly consumed foods. VBNC induction was validated by multiple parameters, e.g., non-culturability, metabolic activity as energy production, respiratory markers, and membrane integrity. Furthermore, it was demonstrated that the removal of FA was able to resuscitate VBNC with an increased expression of multiple virulence and Antimicrobial Resistance (AMR) genes in both pathogens. Since food additives/preservatives are significantly used in most food manufacturing facilities supplying to hospitals, contamination of these packaged foods with pathogenic bacteria and the consequence of exposure to food additives emerge as pertinent issues for infection control, and control of antimicrobial resistance in the hospital setting.

Tissue Fixation with a Formic Acid-Deprived Formalin Better Preserves DNA Integrity over Time

Introduction: Optimization of pre-analytic procedures and tissue processing is a basic requirement for reliable and reproducible data to be obtained. Tissue fixation in formalin represents the extensively favored method for surgical tissue specimen processing in diagnostic pathology; however, formalin fixation exerts a blasting effect on DNA and RNA. Methods: A formic acid-deprived formaldehyde solution was prepared by removing acids with an ion-exchange basic resin and the concentrated, acid-deprived formaldehyde (ADF) solution was employed to prepare a 4% ADF solution in 0.1 M phosphate buffer, pH 7.2–7.4. Human (n = 27) and mouse (n = 20) tissues were fixed in parallel and similar conditions in either ADF or neutral buffered formalin (NBF). DNAs and RNAs were extracted, and fragmentation analyses were performed. Results: Besides no significant differences in terms of extraction yield and absorbance ratio, ADF fixation reduced DNA fragmentation, i.e., the largest fragments (>5,000 bp) were significantly more prevalent in the DNAs purified from ADF-fixed tissues (p < 0.001 in both cohorts). Moreover, we observed that DNA preservation is more stable in ADF-fixed tissue compared to NBF-fixed tissues. Conclusion: Although DNA fragmentation in FFPE tissues is a multifactor process, we showed that the removal of formic acid is responsible for a significant improvement in DNA preservation.

Separation of Lignocellulose and Preparation of Xylose from Miscanthus lutarioriparius with a Formic Acid Method

Efficient component separation technology is one of the key ways to improve the efficiency of lignocellulose bioconversion. In this study, the formic acid method was used to separate the components of lignocellulose from Miscanthus lutarioriparius, hemicellulose was degraded into xylose simultaneously, and the composition and structure of the separated components were analyzed. Then, xylose was further purified with activated carbon for decolorization and resins for the removal of formic acid and other monosaccharide impurities. The results showed that formic acid could effectively separate the cellulose, hemicellulose, and lignin of lignocellulose with recoveries of 91.7%, 80.2%, and 85.3%, respectively. Structural analyses revealed that the cellulose and lignin underwent different degrees of formylation during the formic acid treatment, yet their primary structures remained intact, and the crystallinity of cellulose increased significantly. By GC–MS and HPLC analysis, xylose was the main component of hemicellulose extract, accounting for 74.90%. The activated carbon treatment decolorized the xylose extract more than 93.66% and gave a xylose recovery of 88.58%. D301 resin could effectively remove more than 99% of the formic acid residue in xylose. The xylose extract was further purified by removing arabinose and other monosaccharide impurities with Dowex 50wx4 resin, which increased the purity to 95%. The results demonstrated that the formic acid method is an effective method to separate lignocellulose and prepare xylose, and it has broad application prospects in the field of bio-refining lignocellulose resources such as Miscanthus lutarioriparius

Intensification of formic acid from dilute aqueous solutions using menthol based hydrophobic deep eutectic solvents

The fermentation of biomass and organic waste streams is the primary source of formic acid production. Formic acid is the hydrogen energy carrier and is used as a hydrogen storage medium in fuel cells. Sustainable production of formic acid makes the hydrogen-fuel cell entirely environmentally friendly and ensures the long-term storage of renewable energy. Therefore, green, economic, and sustainable production and recovery of formic acid are highly demanded. In this study, it was aimed to use a new generation, green, easily prepared, and designer hydrophobic deep eutectic solvents (HDES) for the removal of formic acid via reactive extraction. HDESs obtained by preparing binary mixtures of nonanoic acid, decanoic acid, dodecanoic acid (HBD), and menthol (HBA) were used as diluents; tri-n-octylamine (TOA) and Amberlite LA-2 (Amb.LA-2) were acted as extractants. Experiments were performed to investigate the effect of extractant type and concentration, initial acid concentration, and volume of the organic phase on extraction. Experimental data were presented by calculating the extraction efficiency (E%), distribution coefficient (D), and loading factor (Z). Results demonstrated that the extraction efficiency remained between 10 and 13% when performing physical extraction using M-NA, M-DA, and M-DDA, while TOA was diluted with the same HDESs reached around 90% and with Amb.LA-2 85%. The highest distribution coefficient was obtained that the organic phase consisting of TOA and M-DDA mixture was used. The efficiency of utilized HDESs was in the following order: M-DDA ​> ​M-DA ​> ​M-NA.

Modeling and optimization of formic acid adsorption by multiwall carbon nanotube using response surface methodology

Abstract Formic acid is extensively utilized in various chemical industries and applications. So, formic acid can be present in the wastewaters of these industries. It is widely produced in aqueous solutions by fermentation processes. And also, it forms as a by-product in the production of chemical processes. Thus, the removal of formic acid from waste streams and production medium is very significant topic. The objective of this study is to remove formic acid from its aqueous solutions by adsorption and to optimize the adsorption process. In this context, in this study, the optimal conditions for formic acid adsorption by multiwall carbon nanotube were investigated by using response surface methodology. Face-centered central composite design based on response surface methodology was applied to investigate the effects of the initial acid concentration (2–10%, w/w), amount of adsorbent (0.01–0.03 g) and temperature (25–45○C) on the adsorption capacity (qe, mg acid adsorbed/g adsorbent). The acquired experimental results were appraised by means of analysis of variance. A second-degree model equation for the adsorption capacity was obtained to explain adsorption characteristics of formic acid by multiwall carbon nanotube. The acquired model equation was well in agreement with the experimental results. The response surface plots were illustrated and they also supported the compatibility of the model equation. The design study also showed that MWCNT is an effective adsorbent for the removal of formic acid from aqueous solutions.

Experimental and modeling study for the removal of formic acid through bulk ionic liquid membrane using response surface methodology

In this study, formic acid removal from its aqueous solutions through bulk ionic liquid membrane (BILM) was investigated. Tributyl phosphate (TBP) as a carrier in imidazolium-based ionic liquids was used. D-optimal design based on response surface methodology has been applied to investigate the effect of various operating factors. Initial formic acid concentration, TBP concentration, and NaOH concentration were selected as numerical factors, and ionic liquid type was chosen as a categorical factor. The model equations were obtained to determine BILM process behavior. The removal efficiencies, represented by the extraction and stripping efficiencies, were calculated from the experimental data. The highest removal efficiencies were determined at higher concentration values of TBP and NaOH. All ionic liquids studied in this study had good transport selectivity for the removal of formic acid. The design study showed that BILM is an effective method for the removal of formic acid from the water.

Optimization of extractive removal of formic acid from water by tri-n-propyl amine and dibenzyl amine in mono and dibasic ester diluents: LSER modelling

Optimization of extractive removal of formic acid from water by tri-n-propyl amine and dibenzyl amine in mono and dibasic ester diluents: LSER modelling

Biosorption of formic and acetic acids from aqueous solution using activated carbon from shea butter seed shells

The efficiency of prepared activated carbon from shea butter seed shells (SB-AC) for the adsorption of formic acid (FA) and acetic acid (AA) from aqueous solution was investigated. The effect of optimization parameters including initial concentration, agitation time, adsorbent dosage and temperature of adsorbate solution on the sorption capacity were studied. The SB-AC was characterized for the following parameters: bulk density, moisture content, ash content, pH, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optimal conditions for the adsorption were established and the adsorption data for AA fitted Dubinin–Radushkevich (D–R) isotherm well, whereas FA followed Langmuir isotherm. The kinetic data were examined. It was found that pseudo-second-order kinetic model was found to adequately explain the sorption kinetic of AA and FA from aqueous solution. It was again found that intraparticle diffusion was found to explain the adsorption mechanism. Adsorption thermodynamic parameters were estimated and the negative values of ∆G showed that the adsorption process was feasible and spontaneous in nature, while the negative values of ∆H indicate that the adsorption process was exothermic. It is therefore established that SB-AC has good potential for the removal of AA and FA from aqueous solution. Hence, it should find application in the regular treatment of polluted water in aquaculture and fish breeding system.

Solid Molecular Phosphine Catalysts for Formic Acid Decomposition in the Biorefinery.

The co-production of formic acid during the conversion of cellulose to levulinic acid offers the possibility for on-site hydrogen production and reductive transformations. Phosphorus-based porous polymers loaded with Ru complexes exhibit high activity and selectivity in the base-free decomposition of formic acid to CO2 and H2 . A polymeric analogue of 1,2-bis(diphenylphosphino)ethane (DPPE) gave the best results in terms of performance and stability. Recycling tests revealed low levels of leaching and only a gradual decrease in the activity over seven runs. An applicability study revealed that these catalysts even facilitate selective removal of formic acid from crude product mixtures arising from the synthesis of levulinic acid.

Recovery of Formic Acid and Acetic Acid from Waste Water Using Reactive Distillation

Processing of biobased feedstock materials may lead to formation of multicomponent azeotropic mixtures. Reactive separations provide an opportunity to circumvent azeotropes by changing the substance properties through chemical reactions. Exemplarily several effluents from black liquor processing contain aqueous mixtures of low molecular weight fatty acids such as formic acid and acetic acid. These mixtures form inseparable azeotropes. Separation of the system formic acid–acetic acid–water by esterification with methanol was investigated. Reactive distillation experiments in batch and continuous mode confirmed complete removal of formic acid in a first step. Acetic acid may then be isolated by distillation or by reactive distillation.

Sorption behavior and mechanism investigation of formic acid removal by sorption using an anion-exchange resin

In this work, D-II07 resin was used to remove formic acid from aqueous solution. A series of operational conditions including solution pH, adsorbent dose, temperature and initial formic acid concentration on formic acid uptake was evaluated. D-II07 resin showed a good uptake at neutral pH. Removal of formic acid was rapid and equilibrium was reached within 2 h of contact. The results demonstrated that the sorption equilibrium data were well fitted by bi-Langmuir isotherm model and the maximum sorption capacity was negatively affected with increasing temperature. Thermodynamic studies performed indicated that the sorption process was spontaneous and exothermic in nature. Furthermore, the sorption kinetic of formic acid was simulated successfully by the macropore diffusion model. The effective pore diffusivity (Dp) was dependent on temperature, but independent of initial formic acid concentration, and was 1.846 × 10−10, 3.652 × 10−10, and 5.552 × 10−10 m2 s−1 at 298, 318, and 338 K, respectively. In summary, D-II07 resin is a promising valuable adsorbent to remove formic acid from the diluted wastewater streams or fermentation broth.

Synthesis of highly photoactive TiO2 and Pt/TiO2 nanocatalysts for substrate-specific photocatalytic applications

The relative activity of TiO2 photocatalysts depends to a large extent on the type of test substrate. With this in mind, phenol, formic acid, 2,4-dichlorophenoxyacetic acid (2,4-D) and methyl orange (MO) were selected as test substrates due to their different degradation mechanisms. In this work, the aim behind the synthesis and subsequent surface modification of the nanocatalysts was to obtain the most efficient material for removing these test substrates from water. A series of nanocatalysts with different average particle size, specific surface area and anatase phase content were synthesized by sol–gel method followed by calcinations at different annealing temperatures or hydrothermal treatment. Subsequently, platinization of certain samples was carried out using a photodeposition method. The most efficient catalyst for phenol photodegradation was found to be that with the largest average particle size as well as the highest anatase phase ratio. The photodeposition of platinum on this sample had detrimental effects on phenol photodegradation. The platinized sample and anatase TiO2 with the lowest average particle size were the most efficient catalysts for the removal of formic acid. Finally, the platinized material also showed the highest photoactivity in the removal of 2,4-D and in the methyl orange bleaching test.

Metabolic analysis of the removal of formic acid by unacclimated activated sludge

This paper investigates the removal of formic acid by unacclimated biomass from a municipal activated sludge wastewater treatment plant. The biomass was initially able to remove formic acid, but its removal rate and Oxygen Uptake Rate (OUR) decreased with time, until formic acid removal stopped before the formic acid had been exhausted. Formaldehyde was removed in a similar way, whereas the same biomass was simultaneously able to grow and store PHAs when acetic acid was used as substrate. Batch tests with glycine and 13C NMR analysis were performed, showing that unacclimated biomass was not able to synthesize all the metabolic intermediates from formic acid alone. At least glycine needed to be externally supplemented, in order to activate the serine synthesis pathway. A small amount of formic acid removal in the absence of growth was also possible through formaldehyde formation and its further conversion to formalin (1,2-formaldehyde dimer), whereas no PHAs were formed.

Role of biomass adaptation in the removal of formic acid in sequencing batch reactors

This study deals with formic acid removal in activated sludge processes, in particular in the processes carried out in sequencing batch reactors (SBRs). Formic acid removal has been investigated in a SBR fed with acetic and formic acids at equimolar concentrations. Biomass performance in the reactor has been investigated both by the analysis of the removal of the two substrates and by batch tests. Regarding SBR process, the obtained results show that a relevant difference occurred between formic and acetic acid profiles. Acetic acid was never found in the effluent and was always completely removed during the reaction phase. On the other hand, formic acid removal was determined by biomass acclimation, which is in turn determined by sludge age imposed to the system. Batch tests confirmed that formic acid removal occurs only if biomass is acclimated. It has been shown that the minimal sludge age to obtain complete formic acid removal is much higher than those predictable with the classical models of microbial growth in wastewater treatment processes. The advantages of SBRs over continuous-flow systems in the removal of formic acid have also been highlighted.

Catalytic wet-air oxidation of aqueous solutions of formic acid, acetic acid and phenol in a continuous-flow trickle-bed reactor over Ru/TiO2 catalysts

Catalytic wet-air oxidation of aqueous solutions of formic acid, acetic acid and phenol was carried out in a trickle-bed reactor at T=328–523K and total pressures up to 50bar over various Ru/TiO2 catalysts. Complete oxidation of formic acid was obtained at mild operating conditions, and no catalyst deactivation occurred that could be attributed to the dissolution of active ingredient material. It was observed that besides oxidation route thermal decomposition contributes significantly to the removal of formic acid; Ru/TiO2 catalysts could be thus efficiently used for transformation of HCOOH to H2 and CO2 in an inert atmosphere. Liquid-phase oxidation of acetic acid was found to be structure sensitive; the highest catalyst activity was obtained, when Ru phase on the catalyst surface prevailed in zero-valent state. Due to simultaneous oxidation of metallic Ru to RuO2 during the reaction course, correspondingly lower conversion of acetic acid was measured in the reactor outlet. The employed Ru/TiO2 catalysts enable complete removal of phenol and TOC at temperatures above 483K; at these conditions, no carbonaceous deposits were accumulated on the catalyst surface. Apparent catalyst deactivation observed at temperatures below 463K is attributed to strong adsorption of partially oxidized intermediates on the catalyst surface, which can be avoided by conducting the CWAO process at sufficiently high temperatures. The acute toxicity to Daphnia magna and Vibrio fischeri of end-product solutions compared with that of the feed solutions was significantly reduced by oxidative treatment over Ru/TiO2 catalysts.

&lt;i&gt;Technical note&lt;/i&gt; Biological treatment of industrial wastewater containing formaldehyde and formic acid

The biological treatment of wastewater from an aminoplastic resin-producing industry was studied in a pre-denitrification system. This study reports results on the removal of organic matter and nitrogen compounds from wastewater which contained high levels of formaldehyde and formic acid. The formaldehyde concentration in the feed varied between 2 087.0 and 2 200.0 mg/&#8467;, the mean removal being 99.9%. The mean efficiency of formic acid removal was 99.7%, and its concentration in the feed ranged between 1 384.6 and 1 513.9 mg/&#8467;. The total organic carbon (TOC) values in the feed varied from 1 423.0 to 1 599.5 mg/&#8467;, corresponding to an organic loading rate of about 0.20 kg TOC/m3·d. High TOC removal was achieved, around 92.0%. With regard to nitrogen compounds, the total Kjeldahl nitrogen (TKN) concentration in the feed ranged between 467.8 and 492.3 mg/&#8467;. The applied nitrogen loading rate was around 0.06 kg TKN/m3·d, and the mean percentage of TKN removal was 76.7%. Water SA Vol 32(1)pp:115-118

Carbon Dioxide Hydrogenation Catalyzed by a Ruthenium Dihydride: A DFT and High‐Pressure Spectroscopic Investigation

Reaction pathways during CO(2) hydrogenation catalyzed by the Ru dihydride complex [Ru(dmpe)(2)H(2)] (dmpe=Me(2)PCH(2)CH(2)PMe(2)) have been studied by DFT calculations and by IR and NMR spectroscopy up to 120 bar in toluene at 300 K. CO(2) and formic acid readily inserted into or reacted with the complex to form formates. Two formate complexes, cis-[Ru(dmpe)(2)(OCHO)(2)] and trans-[Ru(dmpe)(2)H(OCHO)], were formed at low CO(2) pressure (<5 bar). The latter occurred exclusively when formic acid reacted with the complex. A RuHHOCHO dihydrogen-bonded complex of the trans form was identified at H(2) partial pressure higher than about 50 bar. The trans form of the complex is suggested to play a pivotal role in the reaction pathway. Potential-energy profiles along possible reaction paths have been investigated by static DFT calculations, and lower activation-energy profiles via the trans route were confirmed. The H(2) insertion has been identified as the rate-limiting step of the overall reaction. The high energy of the transition state for H(2) insertion is attributed to the elongated Ru--O bond. The H(2) insertion and the subsequent formation of formic acid proceed via Ru(eta(2)-H(2))-like complexes, in which apparently formate ion and Ru(+) or Ru(eta(2)-H(2))(+) interact. The bond properties of involved Ru complexes were characterized by natural bond orbital analysis, and the highly ionic characters of various complexes and transition states are shown. The stability of the formate ion near the Ru center likely plays a decisive role for catalytic activity. Removal of formic acid from the dihydrogen-bonded complex (RuHHOCHO) seems to be crucial for catalytic efficiency, since formic acid can easily react with the complex to regenerate the original formate complex. Important aspects for the design of highly active catalytic systems are discussed.