Volatile Carboxylic Acids Research Articles

Gas chromatography-mass spectrometry characterization of the aroma of Ossetian cheeses

The aim of the study was the qualitative and quantitative determination of volatile aroma compounds and their formation pathways in brine Ossetian cheeses. Volatile components of cheeses were isolated by steam distillation and extraction with dichloromethane, with their subsequent determination and quantification by gas chromatography-mass spectrometry. The results of the analysis are presented according to the structural classes of the main chemical components and the corresponding microbial metabolic processes. Four processes were found to be the main contributors to flavor formation: lipolysis, proteolysis, glycolysis, and a number of oxidative enzymatic transformations. Lipolysis of the fatty fraction of cheeses is a source of formation of volatile carboxylic acids and their esters. Proteolysis of the casein fraction yields branched alcohols, aldehydes, and a number of aromatic and heteroaromatic compounds. Glycolysis of the carbohydrate fraction is a source of ethanol formation, which is the main cause of the dominance of ethyl esters in the ester fraction. Redox enzymatic transformations mainly determine the biosynthesis of unbranched aldehydes, ketones and lactones. A clear distinction between retail and homemade cheeses was observed, due to the different technological approaches to the cheese preparation. The structuralchemical and quantitative evolution of the volatile composition of the studied cheese samples during ripening is tentatively shown. From the authors’ point of view, the aromatic composition of the Tib cheese sort is the most consistent with the Ossetian cheese standard. This study represents the first gas chromatographic study of Ossetian cheeses and aims to create objective criteria for controlling technological processes and product quality during production and storage in the food industry.

Hierarchically porous bacterial cellulose nanofibrous membranes for selective adsorption and real-time colorimetric monitoring of volatile carboxylic acids

Hierarchically porous bacterial cellulose nanofibrous membranes for selective adsorption and real-time colorimetric monitoring of volatile carboxylic acids

A Simple, Rapid and Validated Method for the Determination of Free Volatile Carboxylic Acids in Cheese by GC-FID

A Simple, Rapid and Validated Method for the Determination of Free Volatile Carboxylic Acids in Cheese by GC-FID

Amorphous RuO2 Catalyst for Medium Size Carboxylic Acid to Alkane Dimer Selective Kolbe Electrolysis in an Aqueous Environment.

The catalytic transformation of biomass-derived volatile carboxylic acids in an aqueous environment is crucial to developing a sustainable biorefinery. To date, Kolbe electrolysis remains arguably the most effective means to convert energy-diluted aliphatic carboxylic acids (carboxylate) to alkane for biofuel production. This paper reports the use of a structurally disordered amorphous RuO2 (a-RuO2 ) that is synthesized facilely in a hydrothermal method. The a-RuO2 is highly effective towards electrocatalytic oxidative decarboxylation of hexanoic acid and is able to produce the Kolbe product, decane, with a yield 5.4 times greater than that of commercial RuO2 . A systematic study of the reaction temperature, current intensity, and electrolyte concentration reveals the enhanced Kolbe product yield is attributable to the more efficient oxidation of the carboxylate anions for the alkane dimer formation. Our work showcases a new design idea for establishing an efficient electrocatalysts for decarboxylation coupling reaction, providing a new electrocatalyst candidate for Kolbe electrolysis.

Classification of cheese varieties from Switzerland using machine learning methods: Free volatile carboxylic acids

In the first two decades of the 21st century, a wide range of analyses, including free volatile carboxylic acids (FVCAs), endeavoured to describe 10 different cheese varieties from Switzerland. The aim of the present work was to investigate whether these 10 cheese varieties could be classified by means of supervised machine learning (ML) techniques, as well as to analyse the importance of the features FVCAs in order to understand their role in characterising cheese varieties. Special emphasis was placed on SHAP values (SHapley Additive exPlanations). In total, 241 cheese samples were classified using different ML algorithms with the help of the PyCaret library; at least 90% were correctly classified with two ensemble algorithms: Extra Trees and Random Forest. The fewest misclassifications were observed for Emmentaler AOP, Raclette du Valais AOP, and Formaggio d’Alpe Ticinese DOP, whereas most misclassifications occurred between Le Gruyère AOP and Berner Alpkäse AOP. The most important feature was C1, followed by C3, C6, and iso-C4, with iso-C6 being the least important after C2 and C4. By means of the interpretation of SHAP values applied as a differentiating feature, key FVCAs were identified for most cheese varieties. This study represents a first step towards improved differentiation of cheese varieties.

Human scent guides mosquito thermotaxis and host selection under naturalistic conditions

The African malaria mosquito Anopheles gambiae exhibits a strong innate drive to seek out humans in its sensory environment, classically entering homes to land on human skin in the hours flanking midnight. To gain insight into the role that olfactory cues emanating from the human body play in generating this epidemiologically important behavior, we developed a large-scale multi-choice preference assay in Zambia with infrared motion vision under semi-field conditions. We determined that An. gambiae prefers to land on arrayed visual targets warmed to human skin temperature during the nighttime when they are baited with carbon dioxide (CO2) emissions reflective of a large human over background air, body odor from one human over CO2, and the scent of one sleeping human over another. Applying integrative whole body volatilomics to multiple humans tested simultaneously in competition in a six-choice assay, we reveal high attractiveness is associated with whole body odor profiles from humans with increased relative abundances of the volatile carboxylic acids butyric acid, isobutryic acid, and isovaleric acid, and the skin microbe-generated methyl ketone acetoin. Conversely, those least preferred had whole body odor that was depleted of carboxylic acids among other compounds and enriched with the monoterpenoid eucalyptol. Across expansive spatial scales, heated targets without CO2 or whole body odor were minimally or not attractive at all to An. gambiae. These results indicate that human scent acts critically to guide thermotaxis and host selection by this prolific malaria vector as it navigates towards humans, yielding intrinsic heterogeneity in human biting risk.

Shelf-life extension of leavened bakery products by using bio-protective cultures and type-III sourdough

Physicochemical and microbiological alteration of processed foods limits their shelf-life. To extend the shelf-life of two different types of bakery products, we evaluated the effectiveness of a type-III sourdough (tIII-SD) combined with a mixture of probiotics (Lactobacillus acidophilus, L. casei, Bifidobacterium spp, Bacillus coagulans) that were used as bioprotective-cultures (BCs). This innovative (I) dough was used to produce fresh base-pizza (BP) and focaccia (FO) that were inspected by a multi-omics approach aimful at monitoring features at different time-points of the shelf-life. Differences in physicochemical, protein, microbiological and volatile profiles were also investigated after 10-days of extended shelf-life. The addition of BCs and tIII-SD left unchanged the proximate composition. This, together with the absence of detected microbial contaminations, indicated the suitability of both I-BP and I-FO despite the shelf-life extension. Both I-samples accounted for a more stable and heterogeneous microbiota during the storage phase and showed lower scores of Alternaria infectoria and A. alternata. In I-samples, volatilomics showed an increased relative concentration of volatile carboxylic acids. Therefore, without resorting to chemical preservatives, the addition of BCs and tIII-SD led to specific microbiological and metabolite improvements in both BP and FO products, whose shelf-life was extended by 10-days under MAP.

Validated method for the determination of free volatile carboxylic acids in cheese and bacterial cultures by GC-FID after esterification in aqueous extract and headspace injection

A simple, rapid, sensitive and robust gas chromatographic method was developed for the simultaneous determination of free volatile carboxylic acids (FVCA) in cheese and bacterial cultures. The target analytes were extracted and converted directly from the aqueous phase to their ethyl esters using headspace. The lower detection limits for the volatile carboxylic acids in the cheese samples were less than 0.3 and less than 0.6 µmol kg−1 in the bacterial culture samples. The lower limits of quantitation in cheese were better than 0.001 mmol kg−1 for all analytes. The upper limits of quantitation varied from 39 to 136 mmol kg−1 in cheese and 78 to 272 mmol kg−1 in bacterial cultures depending on the analyte. The Horwitz ratio showed good precision for all analytes (less than 0.77). The proposed method is suitable for the determination of target metabolites directly from aqueous extracts and can also be validated for other matrices.

Gas‐Phase Models for the Nickel‐ and Palladium‐Catalyzed Deoxygenation of Fatty Acids

AbstractUsing fatty acids as renewable sources of biofuels requires deoxygenation. While a number of promising catalysts have been developed to achieve this, their operating mechanisms are poorly understood. Here, model molecular systems are studied in the gas phase using mass spectrometry experiments and DFT calculations. The coordinated metal complexes [(phen)M(O2CR)]+ (where phen=1,10‐phenanthroline; M=Ni or Pd; R=CnH2n+1, n≥2) are formed via electrospray ionization. Their collision‐induced dissociation (CID) initiates deoxygenation via loss of CO2 and [C,H2,O2]. The CID spectrum of the stearate complexes (R=C17H35) also shows a series of cations [(phen)M(R’)]+ (where R’ < C17) separated by 14 Da (CH2) corresponding to losses of C2H4‐C16H32 (cracking products). Sequential CID of [(phen)M(R’)]+ ultimately leads to [(phen)M(H)]+ and [(phen)M(CH3)]+, both of which react with volatile carboxylic acids, RCO2H, (acetic, propionic, and butyric) to reform the coordinated carboxylate complexes [(phen)M(O2CR)]+. In contrast, cracking products with longer carbon chains, [(phen)M(R)]+ (R>C2), were unreactive towards these carboxylic acids. DFT calculations are consistent with these results and reveal that the approach of the carboxylic acid to the “free” coordination site is blocked by agostic interactions for R > CH3.

Phytochemical Research and Antimicrobial Properties of Lipophylic Extracts of Some Species of Salix L. Genus from Ukraine

Background: Willows are indispensable for the creation of anti-erosion plantations, preliminary soil-improving crops in the reclamation of disturbed lands, as well as for energy plantations designed to produce the biomass suitable for biofuels. In the process of care and thinning of these plantations, there are a huge amount of waste remains - young willow branches and leaves, which would be advisable to use in medical and pharmaceutical practice to create new supplements and medicines. They are known to possess antimicrobial, antifungal, and antiviral properties. Objective: The aim of the current paper is to determine the chemical composition of lipophylic extracts of some species of Salix L. genus and to study their antimicrobial properties. Methods: The lipophylic extracts from Salix cinerea L., S. incana Schrank, S. cаprea L., S. sachalinensis F. Schmidt, S. acutifolia L., S. fragilis L., S. caspica Pall., S. rosmarinifolia L. and S. myrsinifolia Salisb. fresh shoots were obtained using chloroform in the Soxhlet apparatus. The composition of volatile components and carboxylic acids was determined using quantitative content of chlorophylls and carotenoids was measured spectrophotometrically. The antibacterial activity was studied by the agar diffusion method. Results: The methods used allowed identifying 46 volatile compounds in the lipophylic extracts from the shoots of the plants of Salix L. genus, where eugenol and squalene dominated; as well as 42 organic acids, among which benzoic, methoxybenzoic, salicylic acids prevailed, and palmitic, linoleic and linolenic acids were found to prevail among fatty acids. All lipophylic extracts studied showed antimicrobial activity against Staphylococcus aureus, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. Conclusion: The results obtained indicate the possibility of the creation of a novel antimicrobial agent using the lipophylic extracts from the shoots of Salix L. genus rich in different biologically active substances.

Examining the unique retention behavior of volatile carboxylic acids in gas chromatography using zwitterionic liquid stationary phases

For the first time, gas chromatographic (GC) stationary phases consisting of zwitterionic liquids (ZILs) possessing sulfonate functional groups were utilized for the analysis of volatile carboxylic acids (VCAs). The highly polar and acidic nature of VCAs significantly limits the number of currently available GC stationary phases, which are all largely based on acid-modified polyethylene glycol. In this study, it is shown that this class of ZILs exhibit strong retention of VCAs with excellent peak symmetry. Unique chromatographic selectivity toward VCAs is also demonstrated by tuning the structural features of the ZILs. The solvation properties of the three ZILs as well as a structurally similar conventional monocationic IL were characterized using the Abraham solvation parameter model.

Changes in volatile compounds of living Pacific oyster Crassostrea gigas during air-exposed storage

The changes in volatile compounds of living oysters Crassostrea gigas with shells under air-exposed storage for 7 days at 5 and 20 °C were investigated using an electronic nose system and a gas chromatography–mass spectrometer (GC/MS) with headspace solid-phase microextraction (SPME). Principal component analysis of a data matrix obtained from the electronic nose response and sensory evaluation showed deterioration of oyster odor during the storage period. Headspace SPME–GC/MS analysis revealed that 1-penten-3-one decreased to undetectable levels, and volatile carboxylic acids derived from anaerobic end-products and 1-propanol increased during air-exposed storage. The detection of trimethylamine was observed only in living oysters stored at 20 °C. Amounts of 1-penten-3-ol and 1-octen-3-ol showed few changes through the storage periods. These data suggested that most of aldehydes decreased, whereas trimethylamine and volatile carboxylic acids such as propanoic acid accumulated in deteriorated living oysters stored under air-exposed conditions. Consequently, detection of trimethylamine and volatile carboxylic acids would be useful indices for suitable storage conditions of living oysters.

Organics in soda-anthraquinone black liquors from hot-water-extracted non-wood feedstocks

ABSTRACT The chemical compositions of black liquors (BLs) obtained from the soda-anthraquinone (AQ) pulping of untreated and hot-water-extracted non-wood feedstocks (okra stalk, miscanthus stalk, and wheat straw) were determined. These under-utilized renewable and widely available feedstocks could provide a cheaper source for producing fiber and precursors for manufacturing green chemicals. These BLs were mainly characterized in terms of carbohydrate-derived volatile carboxylic acids (acetic and formic acids) and non-volatile carboxylic acids (hydroxy acids) as well as lignin. Additionally, in each case, the average molar mass and molar mass distribution of the dissolved lignin were measured. Results indicated typical effects of hot-water extraction; for example, in the case of hot-water-extracted feedstocks, compared to untreated feedstocks, more aliphatic carboxylic acids were formed, whereas in both cases the removal of lignin was similar. The maximum total amounts of aliphatic carboxylic acids were in the following order: okra/150 °C/P200 (39 g L−1) > miscanthus/150 °C/P200 (31 g L−1) > wheat/150 °C/P200 (15 g L−1). On the other hand, the total dissolved lignin was in the following order: wheat/150 °C/P200 (45 g L−1) > miscanthus/150 °C/P200 (35 g L−1) ≈ okra/140 °C/P50 (35 g L−1). The hot-water extraction also affected weight average molar mass (w) values of the dissolved lignin in BLs. When the pre-treatment conditions became harsher, the w values increased; the lowest value detected was 4160 g mol−1 for lignin in the okra BL from the untreated feedstock, and the highest value, 8730 g mol−1, was obtained for lignin in the wheat BL from pre-treated feedstock (150 °C/P200). All the data obtained are of importance when planning the overall strategy for recovering the non-wood-derived aliphatic carboxylic acids and lignin formed in this kind of integrated biorefinery approach.

Formation of odorous and hazardous by-products from the chlorination of amino acids

The formation of odorous aldehydes and N-chloraldimines, and also nitriles, which are potentially hazardous to human health, was investigated in studies of the chlorination of amino acids (AAs) in both operational drinking water treatment plants and laboratory-based experiments. In the drinking water treatment plants studied, the concentration of total free AAs did not significantly change after treatment, even though good removal of DOC was observed. However, free AAs still contributed less than 3% of total nitrogen in the treated drinking waters, and no aldehydes, N-chloraldimines or nitriles of interest were detected in the treated waters, presumably due to the low concentrations of the precursor AAs in these water samples. Laboratory formation potential experiments showed that carboxylic acids can form from the degradation of aldehydes and nitriles. Volatile carboxylic acids could result in odour issues and some carboxylic acids may be of potential health concern. Therefore, carboxylic acids should also be considered as potential by-products of interest in distribution systems with long contact times of ≥ 7days. A higher proportion of nitrile formation, and promotion of carboxylic acid formation, was observed when the chlorine to AA ratio was greater than 4 compared to when this ratio was 2.8, indicating that the Cl:AA ratio is an important factor in DBP formation pathways. This suggests that results from laboratory formation studies undertaken at these low Cl:AA ratios cannot be directly applied to ‘real’ water systems, which typically have Cl:AA ratios that are orders of magnitude higher than 4. Laboratory formation potential experiments also showed that the short-term rate of formation of aldehydes and N-chloraldimines was reduced in the presence of ammonia, although formation over longer timescales (e.g. 7 days) was not significantly different between chlorination and chloramination experiments. Therefore, the use of chloramination instead of chlorination does not appear to reduce the formation of these by-products from AAs.

Real-time quantification of emissions of volatile organic compounds from land spreading of pig slurry measured by PTR-MS and wind tunnels

Volatile organic compounds (VOC) and hydrogen sulfide are emitted from land spreading of manure slurry to the atmosphere and contribute to odour nuisance, particle formation and tropospheric ozone formation. Data on emissions is almost non-existing partly due to lack of suitable quantitative methods for measuring emissions in full scale. Here we present a method based on application of wind tunnels for simulation of air exchange combined with the use of online mass spectrometry (PTR-MS). The focus was on odorous VOC but all relevant VOC were included. A method for quantification of VOC emission based on calculated proton-transfer reaction rate constants was validated by comparison to reference concentrations for typical VOC emitted from pig manure slurry. Wall losses of volatile sulfur compounds in the wind tunnels were assessed to be insignificant and recoveries >95% were observed for these compounds. An influence of air exchange rate was clearly observed highlighting the need to identify realistic air exchange rates for future application of the method. Emission data was obtained for spreading of pig manure slurry as an example of an important source of gases. Emissions were monitored for ~37 h following land spreading and time-resolved emission data was presented for the first time. Highest emissions were observed for short-chain volatile carboxylic acids (C2–C6) with acetic acid being the most abundant compound. Emission peaks were observed immediately following application and were followed by declining emissions until the second day at which emissions reached a second peak for several compounds. This second emission peak was speculated to be caused by a temperature-induced diurnal effect. Emissions of volatile sulfur compounds occurred on a short time-scale and ceased shortly after application. Odour activity values were dominated by C4–C5 carboxylic acids and 4-methylphenol with a less pronounced influence of 4-methylphenol on day 2.

Carbonate-Promoted Hydrogenation of Carbon Dioxide to Multicarbon Carboxylates.

CO2 hydrogenation is a potential alternative to conventional petrochemical methods for making commodity chemicals and fuels. Research in this area has focused mostly on transition-metal-based catalysts. Here we show that hydrated alkali carbonates promote CO2 hydrogenation to formate, oxalate, and other C2+ carboxylates at elevated temperature and pressure in the absence of transition-metal catalysts or solvent. The reactions proceed rapidly, reaching up to 56% yield (with respect to CO32–) within minutes. Isotope labeling experiments indicate facile H2 and C–H deprotonations in the alkali cation-rich reaction media and identify probable intermediates for the C–C bond formations leading to the various C2+ products. The carboxylate salts are in equilibrium with volatile carboxylic acids under CO2 hydrogenation conditions, which may enable catalytic carboxylic acid syntheses. Our results provide a foundation for base-promoted and base-catalyzed CO2 hydrogenation processes that could complement existing approaches.

Preparation of molecularly imprinted polymer nanobeads for selective sensing of carboxylic acid vapors

The detection and discrimination of volatile carboxylic acid components, which are the main contributors to human body odor, have a wide range of potential applications. Here, a quartz crystal microbalance (QCM) sensor array based on molecularly imprinted polymer (MIP) nanobeads is developed for highly sensitive and selective sensing of typical carboxylic acid vapors, namely: propionic acid (PA), hexanoic acid (HA) and octanoic acid (OA). The MIP nanobeads were prepared by precipitation polymerization with methacrylic acid (MAA) as a functional monomer, trimethylolproane trimethacrylate (TRIM) as a crosslinker, and carboxylic acids (PA, HA and OA) as the template molecules. The precipitation polymerization resulted in nano-sized (150–200 nm) polymer beads with a regular shape. The polymerization conditions were optimized to give a functional monomer, crosslinker, and template ratio of 1:1:2. We investigated the imprinting effect using both QCM and GC/MS measurements comparing vapor absorption characteristics between the imprinted and non-imprinted (NIP) nanobeads. A four-channel QCM sensory array based on the NIP and the three types of MIP nanobeads was fabricated for sensing the three types of carboxylic acid vapor at concentrations on the ppm level. The output of the sensor array was analyzed by both a non-supervised method (principle component analysis: PCA) and supervised method (linear discrimination analysis: LDA). LDA showed a better discrimination ability than PCA. A 96%-classification rate was achieved by applying leave-one-out cross-validation to the LDA model. The high sensitivity and selectivity of the sensor array was attributed to the imprinting effect of the nano-sized polymer beads. The developed MIP nanobeads, together with other types of MIPs, show promise as materials for artificial receptors in vapor and odorant sensing.

Characterizing decomposition odor from soil and adipocere samples at a death scene using HS-SPME-GC×GC-HRTOFMS

Using decomposition odor as forensic evidence remains highly controversial despite well-established gas chromatography – mass spectrometry (GC–MS) techniques. Although extensive research characterizing decomposition odor has been conducted, its use in court has been publicly debated due to its admission in the trial The State of Florida vs. Casey Marie Anthony, largely due to the perception that it was too untested. Since this case, a shift from conventional GC–MS to comprehensive two-dimensional gas chromatography – mass spectrometry (GC×GC–MS) has occurred for analyzing decomposition odor. It has become apparent that GC×GC coupled with time-of-flight mass spectrometry (TOFMS), and high-resolution TOFMS (HRTOFMS), is valuable for the analysis of volatile organic compounds (VOCs) from decomposing cadavers as a higher number of VOCs can be detected and identified confidently. This was the first application of GC×GC-HRTOFMS analyzing decomposition VOCs in a forensic case. From a decomposition site, soil from different locations around the body, and adipocere samples were collected. The main objective was to investigate the heterogeneity of the samples using GC×GC–MS. Future challenges anticipated in case scenarios were also interpreted using the generated data. VOCs identified in the soil samples reflected those identified in previous studies, while the profile of adipocere was demonstrated for the first time by GC×GC-HRTOFMS and was dominated by volatile carboxylic acids and acid esters. The power of GC×GC images in court testimony was considered to be of high potential. This case study will strengthen the reliability and evidentiary value of decomposition odor as a valid forensic field.

Impact of ion-pairs for the determination of multiclass antimicrobials residues in honey by LC-MS/MS

ABSTRACTThis study examines the behaviour of volatile perfluorinated carboxylic acids used as ion-pairing reagents for the separation of multiclass antimicrobial residues in honey (tetracyclines, sulphonamides, macrolides, and aminoglycosides). Heptafluorobutanoic acid and pentafluoropentanoic acid were compared as mobile phase additives at concentrations of 0–20 mmol.L−1 using reversed-phase chromatography. Our objective was to find optimal conditions that enable the separation of antimicrobials with a minimum loss in sensitivity and efficiency. The influence of ion pairing on chromatographic performance was examined. Results showed that heptafluorobutanoic acid was able to separate aminoglycosides faster and more efficiently than pentafluoropentanoic acid, but at low concentrations of heptafluorobutanoic acid between 2.5 and 5 mM, tetracyclines showed poor chromatographic efficiency. A concentration of 10 mM was found to be optimal for all studied veterinary drugs. The method was then applied to determine multiclass antimicrobial residues in honey. Based on validation data, the mean recoveries of analytes ranged between 93% and 104%, and the intermediate precisions were <21%. The decision limit (CCα) and detection capability (CCβ) were in the ranges of 5–25 and 7–33 μg kg–1, respectively. The method was found to be suitable for use in analysis of veterinary drugs with a broader group of compounds found in food-producing animals.

Production and Characterization of Energy Materials with Adsorbent Properties by Hydrothermal Processing of Corn Stover with Subcritical H2O

This work aims to investigate the effect of temperature on the process performance of hydrothermal processing (HTC) of corn Stover with subcritical H2O and on the morphology of solid products. The experiments were carried out at 200, 225 and 250 ºC, reaction time of 240 minutes, heating rate of 2.0 ºC/min, and biomass to water ratio of 1:10, using a pilot scale stirred tank reactor (STR) of 5 gallon, operating in batch mode. The process performance analyzed by computing the yields of solid and liquid reaction products (RLP). The aqueous phase (H2O + RLP) was physicochemical analyzed for pH and total carboxylic acids, expressed as total acetic acid content. The chemical compositions of carboxylic acids, furfural, and hydroxymethylfurfural (HMF) in the aqueous phase determined by GC-MS and HPLC. The results showed solid yields ranging from 57.39 to 35.82% (wt.), and liquid reaction products (RLP) yields ranging from 39.53 to 54.59% (wt.). The solid phase products were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The chemically activated (2.0 M NaOH) solid phase energy material obtained by HTC at 250 °C, applied as adsorbent to investigate the capacity and/or efficiency to adsorb acetic acid from 1.0 to 4.0 g/L model solutions at 25 °C. The solid phase yield decreases along with the temperature, showing an inflection region between 200 and 225 °C, whereas a drastic change takes place, while that of liquid phase increases, showing also a drastic change between 200 and 225 °C. The total acetic acid content of aqueous phase varied from 4064 to 5387 mg/L, while the pH from 3.77 to 3.91. The GC analysis identified the presence of volatile carboxylic acids, particularly acetic acid, in concentrations between 4020 and 5040 mg/L. HPLC identified the presence of furfural and hydroxymethylfurfural, whose concentrations decrease exponentially and linearly along with the temperature between 686.7 and 0.0, and 443.9 and 0.0 mg/L, respectively, being both compounds not detectable at 250 °C. The elemental/ultimate analysis of solid products shows that carbon content increases, while the oxygen and hydrogen contents decrease, along with the temperature. The H/C and O/C ratios decrease linearly as process temperature increases, and the high heating value (HHV) of solid reaction products, an energy densified material, changes sharply between 200 and 225 °C, showing an increase with temperature. The SEM, EDX, and XDR indicates a change on the morphology and mineralogical phases present in solid reaction products with temperature, particularly at 250 °C. The activated solid phase has proven to be very selective to adsorb acetic acid, showing that recovery of acetic acid from hydrothermal carbonization/liquefaction aqueous solutions is feasible by using a multistage-stage adsorption process in series.