Adsorption Of Phenolic Compounds Research Articles

A first-principles study on the hydrodeoxygenation mechanism of the lignin-derived phenolic compounds over MoS2 catalysts

Understanding the hydrodeoxygenation (HDO) mechanism of phenolic compounds is crucial for advancing catalytic upgrading techniques of bio-oil. Herein, a comprehensive theoretical study of the HDO of lignin-derived phenolic compounds (phenol, cresols, and guaiacol) on the MoS2 surface was carried out using periodic density functional theory (DFT) calculations. Adsorption of phenolic compounds on different crystal faces was first compared. The MoS2 (100) crystal face is more favorable for the adsorption of phenolic compounds which show the horizontal adsorption configurations. Three kinds of HDO patterns were explored for the phenolic compounds. Phenol tends to transform into benzene via stepwise deoxygenation and hydrogenation under the induction of active hydrogen. For cresol isomers, their HDO mechanisms differ from each other due to the influence of the methyl group on the dehydroxylation process. Specifically, o-cresol follows a synergistic process of deoxidation and hydrogenation, m-cresol undergoes a two-step reaction involving direct dehydroxylation and hydrogenation, and p-cresol involves the identical HDO pathway as phenol. With regard to guaiacol, the preferred HDO route involves successive dehydroxylation and demethoxylation to benzene with the anisole intermediate. In addition, the adsorption of phenolics over transition metal-doped MoS2 catalysts was further explored to examine the potential of metal doping for the HDO of phenolics. The doping of Ta and W increases the adsorption capacity, which shows the potential to enhance the HDO activity of the catalyst theoretically.

Enhanced adsorption of phenolic compounds using biomass-derived high surface area activated carbon: Isotherms, kinetics and thermodynamics.

The progress of industrial and agricultural pursuits, along with the release of inadequately treated effluents especially phenolic pollutant, has amplified the pollution load on environment. These organic compounds pose considerable challenges in both drinking water and wastewater systems, given their toxicity, demanding high oxygen and limited biodegradability. Thus, developing an eco-friendly, low-cost and highly efficient adsorbent to treat the organic pollutants has become an important task. The present investigation highlights development of a novel adsorbent (CFPAC) by activation of Cassia fistula pod shell for the purpose of removing phenol and 2,4-dichlorophnenol (2,4-DCP). The significant operational factors (dosage, pH, concentration, temperature, speed) were also investigated. The factors such as pH = 2 and T = 20°C were found to be significant at 1.6g/L and 0.6g/L dosage for phenol and 2,4-DCPrespectively. Batch experiments were further conducted to study isotherms, kinetic and thermodynamics studies for the removal of phenol and 2,4-DCP. The activated carbon was characterised as mesoporous (specific surface area 1146 m2/g, pore volume = 0.8628cc/g), amorphous and pHPZC =6.4. At optimum conditions, the maximum sorption capacity for phenol and 2,4-DCP were 183.79mg/g and 374.4mg/g respectively. The adsorption isotherm was better conformed to Redlich Peterson isotherm (phenol) and Langmuir isotherm (2,4-DCP). The kinetic study obeyed pseudo-second-order type behaviour for both the pollutants with R2 > 0.999. The thermodynamic studies and the value of isosteric heat of adsorption for both the pollutants suggested that the adsorption reaction was dominated by physical adsorption (ΔHx < 80kJ/mol). Further, the whole process was feasible, exothermic and spontaneous in nature. The overall studies suggested that the activated carbon synthesised from Cassia fistula pods can be a promising adsorbent for phenolic compounds.

Investigation of phenolic compounds recovery from brewery wastewater with coupled membrane and adsorption process

Recovery of phenolic compounds from food-processing by-products represents an interest for various industrial sectors. The potential of a coupled ultrafiltration and adsorption or ion exchange resin process was analyzed to recover phenolic compounds from a brewery liquid residue. Ultrafiltration yielded a 95% removal of turbidity-causing compounds without significant modification of the chemical composition of brewery by-products. After a pH optimization step, ten different macroporous resins, including MN202, SP700, HP2MGL, LXA8302, LWT510, XAD16N, FPX66, WA20, WA30 and SCAV4, were screened for phenolic compounds sorption. Resins were selected through a multi-step batch test procedure according to their performance in phenolic compounds adsorption capacity, phenolic compounds selectivity compared to carbohydrates and price. The strong base resin SCAV4 with OH- counter ion showed the highest adsorption capacity, 35.4 ± 0.8 mg·gdryresin−1, with selective sorption of phenolic compounds. Higher temperatures of 48 °C improved the adsorption and desorption performances of LXA8302 and SCAV4 resins, compared to 25 °C. Up to 70% of phenolic compounds were desorbed from adsorption resin with adequate solvent.

A sustainable bioprocess to produce bacterial cellulose (BC) using waste streams from wine distilleries and the biodiesel industry: evaluation of BC for adsorption of phenolic compounds, dyes and metals

BackgroundThe main challenge for large-scale production of bacterial cellulose (BC) includes high production costs interlinked with raw materials, and low production rates. The valorization of renewable nutrient sources could improve the economic effectiveness of BC fermentation while their direct bioconversion into sustainable biopolymers addresses environmental pollution and/or resource depletion challenges. Herein a green bioprocess was developed to produce BC in high amounts with the rather unexplored bacterial strain Komagataeibacter rhaeticus, using waste streams such as wine distillery effluents (WDE) and biodiesel-derived glycerol. Also, BC was evaluated as a bio-adsorbent for phenolics, dyes and metals removal to enlarge its market diversification.ResultsBC production was significantly affected by the WDE mixing ratio (0–100%), glycerol concentration (20–45 g/L), type of glycerol and media-sterilization method. A maximum BC concentration of 9.0 g/L, with a productivity of 0.90 g/L/day and a water holding capacity of 60.1 g water/g dry BC, was achieved at 100% WDE and ≈30 g/L crude glycerol. BC samples showed typical cellulose vibration bands and average fiber diameters between 37.2 and 89.6 nm. The BC capacity to dephenolize WDE and adsorb phenolics during fermentation reached respectively, up to 50.7% and 26.96 mg gallic acid equivalents/g dry BC (in-situ process). The produced BC was also investigated for dye and metal removal. The highest removal of dye acid yellow 17 (54.3%) was recorded when 5% of BC was applied as the bio-adsorbent. Experiments performed in a multi-metal synthetic wastewater showed that BC could remove up to 96% of Zn and 97% of Cd.ConclusionsThis work demonstrated a low-carbon approach to produce low-cost, green and biodegradable BC-based bio-adsorbents, without any chemical modification. Their potential in wastewater-treatment-applications was highlighted, promoting closed-loop systems within the circular economy era. This study may serve as an orientation for future research towards competitive or targeted adsorption technologies for wastewater treatment or resources recovery.

Development of new effective activated carbon supported alkaline adsorbent used for removal phenolic compounds

Phenolic (phenol) compounds are the major contaminates in wastewater, which can have a considerable negative influence on the environment and health of human. Adsorption is an efficient process that is widely applied in order to eliminate phenol in wastewater. In recent, Adsorption process has acquired a lot of attentiveness owing to its relative moderate operating conditions. However, adsorption process needs considerable ameliorations in terms of adsorbent modification, process type, productivity, and conversion rate. This work studies the development of a fast and effective adsorption process in a fixed bed adsorption column (FBAC) in order to reach safe and continuous elimination of phenolic compounds. Several adsorption parameters (reaction temperature, adsorbent bed height, feed flow rate and kind of adsorbent) were studied to achieve the highest removal of phenolic compounds. The adsorption process was conducted in the presence of two type of adsorbents (activated carbon (AC), and KOH/AC), 73% and 94% of phenol elimination were attained, respectively, at 10 cm bed height, 1 ml/s feed flow rate, and 75 °C reaction temperature. The adsorbents activity was investigated after six consecutive adsorption cycles at the best process conditions, and the adsorbents show high stability in terms of phenolic compounds adsorption. After that, the spent adsorbents were regenerated by utilizing various solvents (methanol, ethanol and iso-octane), and the results show that iso- octane achieved highest regeneration efficiency. The adsorption process was implemented in the adsorption column that the performance is possibly to be adjusted at an industrial scale since it can be scaled up predictably.

Regulation of SiO2 Nanoparticles on the Adsorptive Fractionation of Dissolved Organic Matter by Goethite.

SiO2 nanoparticles (SiO2NPs) are most widely available and coexisting with DOM at the mineral-water interface; however, the role of SiO2NPs in DOM fractionation and the underlying mechanisms have not been fully understood. Using Fourier transform ion cyclotron resonance mass spectrometry, combined with Fourier transform infrared spectroscopy and X-ray adsorption fine structure spectroscopy, was employed to investigate the adsorptive fractionation of litter layer-derived DOM on goethite coexisting with SiO2NPs under different pH conditions. Results indicated that the inhibitory effect of the coexisting SiO2NPs on OM sorbed by goethite was waning as environmental pH increased due to the reduced steric interactions and the concurrent elevated hydrogen bonding/hydrophobic partitioning interactions on the goethite surface. We observed the coexisting SiO2NPs inhibited the adsorption of high carboxylic-containing condensed aromatic/aromatics compounds on goethite under different pH conditions while improving the adsorption of highly unsaturated aliphatic/phenolic and carbohydrate-like compounds in an alkaline and/or circumneutral environment. More nitrogen-containing structures may favor the adsorption of phenolic and nonaromatic compounds to goethite by counteracting the negative effect of SiO2NPs. These findings suggest that DOM sequestration may be significantly regulated by the coexisting SiO2NPs at the mineral-water interface, which may further influence the carbon-nitrogen cycling and contaminant fate in natural environments.

Adsorption of Phenols from Aqueous Solution with A pH-Sensitive Surfactant-Modified Bentonite

The presence of organic pollutants in wastewater remains a prominent environmental concern due to the related ecological and health hazards. In response, this study employs an adsorptive methodology to address the removal of phenol and catechol, utilizing an organo-bentonite material modified with a pH-responsive switchable surfactant, dodecyldimethylamine oxide (C12DAO). The synthesized organo-bentonite (C12DAO-Bt) manifests commendable thermostability resulting from thermogravimetric analyses. The adsorption capacities of C12DAO-Bt concerning phenol and catechol intensify with the augmentation of the C12DAO/bentonite mass ratio. The utmost adsorption capacities of 150C12DAO-Bt, deduced through a pseudo-second-order kinetic model, stand at 5.72 mg·g−1 for phenol and 5.55 mg·g−1 for catechol, respectively. Subject to modification by a pH-responsive surfactant, conditions leaning towards weakly acidic and neutral conditions (pH = 6~7) are conducive to the adsorption of phenolic compounds. Conversely, alkaline conditions (pH = 8~9) facilitate the dissociation of adsorbates from adsorbents. The augmentation of cationic strength within the examined scope incites the adsorption procedure while impeding the desorption efficacy. In the case of cationic species with comparable ionic strengths, Na+ exhibited a superior effect on the adsorption–desorption dynamics of phenol, while Ca2+ exerts a more pronounced effect on those of catechol. Moreover, even following five consecutive acid–base regulation cycles, C12DAO-Bt retains a relatively high adsorption capacity and desorption efficacy, which underscores its exceptional regenerative capacity for removing phenolic compounds from wastewater.

Fining strategies for quercetin deposit prevention in sangiovese wines

A strategy aimed at decreasing the content of quercetin (Q) and quercetin glycosides (QG) was applied to prevent future quercetin precipitation in wines. Different oenological fining agents were tested: polyvinylpolypyrrolidone (PVPP), a vegetable protein (VP), four yeast lysate (YLs) and a polyfunctional product (MIX) obtained by mixing PVPP, vegetable protein and a yeast lysate selected among the four tested. For each fining agent the adsorption isotherms were obtained; based on Freundlich model, PVPP and MIX showed the best adsorption of Q and QG. The MIX determined also a contemporary lower adsorption of other phenolic compounds. The treatment carried out with MIX on the Sangiovese wines determined a decrease of Q (from −27 to −47% with respect to the initial values) and of QG (−17%) preserving wine anthocyanins.

Alkaline Prehydrolysis Prolongs Resin Life and Enhances the Adsorption of Phenolic Compounds

Phenolic compounds in oil wastewater are highly toxic and refractory. Hydrolysis at pH 12 for 12 h makes these compounds more vulnerable to attack and destruction. Under the binding and precipitation of polyaluminum chloride (PAC) at pH 8, the chemical oxygen demand (COD) was significantly reduced by 38%. The simulation found that hydrolysis + flocculation was a complex multistep process. The COD removal rate was mainly controlled by the prehydrolysis process. The metabolic pathway suggested that the m-cresol produced in the factory was oxidized to low water-soluble aldehyde. Alkaline hydrolysis converted the aldehyde into m-toluene-methanol, which was conducive to being captured by the PAC. Fourier transform infrared spectroscopy (FTIR) showed that the alkaline dehydrogenation of two m-methylphenyl carbinols produced a molecule that was removed by the resin. Generally, the particle size of the residue after alkaline hydrolysis was 6.4–8.3 nm, which was included in the pore size range of the resin. Therefore, the resin adsorption capacity for the hydrolyzed substances increased to 47,000 mg L−1, with 93% renewability. In short, hybrid technology reduces the concentration burden of the resin inflow and controls the molecular size of adsorbed substances for repurification. It strengthens the treatment effect of high COD wastewater and provides innovative ideas for extending the service life of resin.

Chemically versus thermally reduced graphene oxide: effects of reduction methods and reducing agents on the adsorption of phenolic compounds from wastewater

Chemically versus thermally reduced graphene oxide: effects of reduction methods and reducing agents on the adsorption of phenolic compounds from wastewater

Dairy-Protein-Based Aggregates as Additives Enriched with Tart Cherry Polyphenols and Flavor Compounds.

Nowadays, the development of innovative food products with positive health effects is on the rise. Consequently, the aim of this study was a formulation of aggregates based on tart cherry juice and dairy protein matrix to investigate whether different amounts (2% and 6%) of protein matrix have an impact on the adsorption of polyphenols as well as on the adsorption of flavor compounds. Formulated aggregates were investigated through high-performance liquid chromatography, spectrophotometric methods, gas chromatography and Fourier transform infrared spectrometry. The obtained results revealed that with an increase in the amount of protein matrix used for the formulation of aggregates, a decrease in the adsorption of polyphenols occurred, and, consequently, the antioxidant activity of the formulated aggregates was lower. The amount of protein matrix additionally affected the adsorption of flavor compounds; thus the formulated aggregates differed in their flavor profiles in comparison with tart cherry juice. Adsorption of both phenolic and flavor compounds caused changes in the protein structure, as proven by recording IR spectra. Formulated dairy-protein-based aggregates could be used as additives which are enriched with tart cherry polyphenols and flavor compounds.

Resin Adsorption of Phenolic Compounds from Olive Leaf and Coffee Residue Extracts: Batch and Packed Column Adsorption Experimental Investigation and Mathematical Modeling

Phenolic compounds are important secondary metabolites often found in nature, and most prominently in plants. Plant biomass residues can be a sustainable source of this high-added-value group of compounds that can be used in the food and cosmetics industries due to their antioxidant properties. Olea europaea is a widely studied source of phenolic compounds, with olive leaves being an untapped solid residue with high phenolic content. Coffee residues after coffee extraction is another biomass residue stream rich in phenols. In this work, phenolic extracts of these two substrates, alongside different fractions produced through ultrafiltration and nanofiltration, were examined in resin adsorption experiments. Amberlite XAD16N was used as adsorbent in both batch and packed column experiments, with the experimental results being fitted with mathematical models for batch kinetics, adsorption isotherms, and column adsorption. The tested adsorbent proved capable of separating the target compounds, exhibiting a capacity of 72 mg of olive leaf phenols from nanofiltration retentate per g of resin in batch adsorption experiments, second order kinetics better described the batch adsorption process, while the use of the Thomas model sufficiently described the continuous adsorption process in packed columns (R2 &gt; 0.9).

Efficient phenolic compounds adsorption by immobilization of copper-based metal-organic framework anchored polyacrylonitrile/chitosan beads

The application of newly formulated beads from copper-benzenetricarboxylate (Cu-BTC), polyacrylonitrile (PAN), and chitosan (C), Cu-BTC@C-PAN, C-PAN, and PAN, for the removal of phenolic chemicals from water, is described in the current paper. Phenolic compounds (4-chlorophenol (4-CP) and 4-nitrophenol (4-NP)) were adsorbed using beads and the adsorption optimization looked at the effects of several experimental factors. The Langmuir and Freundlich models were used to explain the adsorption isotherms in the system. A pseudo-first and second-order equation is performed for describing the kinetics of adsorption. The obtained data fit (R2 = 0.999) supports the suitability of the Langmuir model and pseudo-second-order kinetic equation for the adsorption mechanism. Cu-BTC@C-PAN, C-PAN, and PAN beads' morphology and structure were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FT-IR). According to the findings, Cu-BTC@C-PAN has very high adsorption capacities of 277.02, and 324.74 mg g−1, for 4-CP and 4-NP, respectively. The Cu-BTC@C-PAN beads showed 2.55 times higher adsorption capacity than PAN in the case of 4-NP, but in the case of 4-CP, it was higher by 2.64 times.

Adsorption of phenolic compounds from olive mill wastewaters on spent coffee grounds: isotherms, kinetics, and pure phenol adsorption

Adsorption of phenolic compounds from olive mill wastewaters on spent coffee grounds: isotherms, kinetics, and pure phenol adsorption

Phenolic compounds removal in table olive processing wastewater by column adsorption: conditions' optimization.

The annual production of wastewater from the olive table industry poses a serious problem owing to its high organic matter load, which is highly concentrated in phenolic compounds (PCs) and inorganic materials. This research used adsorption to recover PCs from table olive wastewater (TOWW). Activated carbon was employed as a novel adsorbent. The activated carbon was obtained from olive pomace (OP) and activated using a chemical agent (ZnCl2). Fourier transform infrared spectroscopy analysis (FTIR), Brunauer-Emmett-Teller analysis (BET), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were applied to characterize the activated carbon sample. To optimize the biosorption conditions of PCs (adsorbent dose (A), temperature (B), and time (C)), a central composite design (CCD) model was used. An adsorption capacity was 1952.34mgg-1 for optimal conditions with an activated carbon dose of 0.569g L-1, a temperature of 39°C, and a contact time of 239min. The pseudo-second-order and Langmuir models as kinetic and isothermal mathematical models were proved to be more appropriate for the interpretation of the adsorption phenomenon of PCs. PC recovery was performed in fixed-bed reactors. The results of the adsorption of PCs from TOWW by activated carbon could be an effective process at a low cost.

Kinetic study of adsorption of phenolic compounds from olive oil mill wastewater on activated carbon

Kinetic study of adsorption of phenolic compounds from olive oil mill wastewater on activated carbon

Effects Sequential Usage of Coagulations (Ferric Chloride or Alum) and Fenton's Solution or Biochar on Removal Phenolic Compounds and Organic Load from Olive Mill Wastewater

The chemical properties of the wastewater of 17 olive mills in the area between Al-Dafniyah into Qaraboli in the west of Libya were studied and chemical coagulants such as alum, ferric chloride, chemical oxidation, and biochar were used to remove the organic load and phenolic compounds from this water. The results showed that the wastewater of the olive mill is highly acidic with an average pH of 5.15 and its high content of solids reached 192 g/L, while the average of dissolved solids was 63.5 g/L and the organic solids were about 90% of the total solids and the average of chemical oxygen demand is 104.9 g O2/L, and the concentration of phenolic compounds is high and it was 1.86 g /L. In addition, the results showed that the usage of Ferric chloride as a coagulant gave higher removal percentage of phenolic compounds, dissolved solids, and chemical oxygen demand in comparison with Alum in the pH range of 6-9. The removal percentage was higher in alkaline pH, especially for phenolic compounds. Moreover, increasing the amount of the coagulant from 2 to 16 g/L enhanced the removal of phenolic compounds and chemical oxygen demand, while the removal efficiency of dissolved solids was weak, which required the use of chemical oxidation and adsorption on biochar to improve the efficiency of the removal. Although sequential treatments by coagulants and chemical oxidation by Fenton solution or biochar improved the percentage of removal in biochar treatments compared to chemical oxidation, the concentration of pollutants is still high for disposal, especially phenolic compounds. As a result of that, these methods need more studies to improve them. Langmuir and Freundlich’s models gave a good describing the adsorption of phenolic compounds on the surface of biochar. However, the adsorption capacity is low compared to the scientific literature, because this study uses raw olive mill wastewater with a high organic load, which causes competition between these substances on the adsorption sites or inhibits adsorption by depositing them on the surface of the biochar.

Mesoporous carbon material prepared from sewage sludge hydrochar using Pluronic F127 as template for efficient removal of phenolic compounds: Experimental study and mechanism interpretation via advanced statistical physics model

Mesoporous carbon material (MCM) with rich ether surface group was prepared from sewage sludge hydrochar using Pluronic F127 as template under pyrolysis activation, which provided an energy-efficient method to promote the resource utilization of sewage sludge as adsorbents for phenols removal from water. The MCM possessed high surface area (549 m2/g), abundant mesopores (average width 3.81 nm) and well-developed graphite structure. Acidic conditions and low temperatures favored the adsorption of phenolic compounds. The quick adsorption process of reaching over 85% of the capacity in the first 10 min and intraparticle diffusion as primary rate-limiting step were observed for all phenolic compounds. Advanced statistical physics analysis was used successfully to interpret the adsorption mechanism of phenols onto MCM and revealed a multi-molecular monolayer adsorption process primarily through negative charge-assisted hydrogen bond interaction where the ether functional group contributed to the predominant active sites. The adsorption capacity of phenolic compounds depended upon the number of molecules adsorbed per ether active site and the available density of ether bond group on the surface of MCM. 2,4,6-trichlorophenol showed a highest adsorption priority to occupy the limited ether active sites and its adsorption capacity reached 0.49 mmol/g, while p-nitrophenol exhibited a maximum number of molecules adsorbed on the single ether active site, showing an adsorption capacity of 0.42 mmol/g. The synergistic effect of multi-interactions mechanisms resulted in phenolic compounds removal with adsorption energies lower than 30 kJ/mol. This prepared MCM adsorbent is promising for application in treatment of water polluted by phenols.

Facile synthesis of aryl-triazine linked two-dimensional covalent organic frameworks via “two-in-one” strategy for phenolic compounds adsorption

We report the synthesis of aryl-triazine linked two-dimensional covalent organic frameworks (2D-COFs) via trifluoromethanesulfonic acid-catalyzed trimerization, employing 4-acetylbenzonitrile as a “two-in-one” type monomer in COFs synthesis for the first time. It enables the simple and scalable synthesis of COFs with outstanding thermal stability and lamellar structure at >90 % yield via convenient operations. 2D-COFs have been applied for the adsorption of phenol, bisphenol A and 1-naphthol, exhibiting a pseudo-second-order kinetics. Calculations demonstrated that the incorporation of triazines into aromatic 2D-COFs benefit the adsorption process. The facile synthesis and aryl-triazine-linked architecture should broaden opportunities toward more 2D-COFs and facilitate potential applications.

Argentinian Sugar Cane Vinasse: Characterization of Phenolic Compounds and Evaluation of Adsorption as a Possible Remediation Technique

Chemical composition of sugar cane vinasse (Tucumán, Argentina) was studied finding high concentration of organic compounds. Phenolic compounds were partially characterized, finding mostly flavonoids, anthocyanins, as well as resorcinol and ferulic acid derivatives. Adsorption isotherms of phenolic compounds and total organic compounds were measured on four commercial activated carbons with different physical and chemical properties at two temperatures. The isotherm shape depends on the type of carbon and the adsorption capacity is enhanced as temperature increases. Enthalpies of the adsorption process were estimated, revealing that the adsorption of organic compounds is a chemisorption process, while the adsorption of phenolic compounds is a physisorption process on three of the tested carbons and a chemisorption process on the other one (CONCARBO).