Adsorption Of Phenol Research Articles

Biochar as an electron shuttle loaded with Fe/Ni bimetallic nanoparticles for efficient removal of 2,4-dichlorophenols: Performance, degradation pathway and mechanism

Biochar can be served as a substrate for immobilizing bimetallic particles and applied in the pollutant removal, however, its specific role and mediated electron shuttle mechanism against 2,4-dichlorophenol (2,4-DCP) have not been elucidated. In this study, biochar loaded with Fe/Ni bimetallic nanoparticles (BC@Fe/Ni) was optimally synthesized, and its dechlorination performance, pathway and mechanism towards 2,4-DCP were investigated. The results showed that BC@Fe/Ni was more effective compared to Fe/Ni nanoparticles in the 2,4-DCP removal due to its well-dispersed Fe/Ni nanoparticles and increased electron-shuttling capability. The optimal parameters for 2,4-DCP removal by BC@Fe/Ni were assessed, the highest removal efficiency equivalent to 50 mg L−1 of 2,4-DCP was achieved at pH 4.0 with a dosage of 2 g L−1. The 2,4-DCP removal was an adsorption-dechlorination-adsorption pathway, primarily through para-Cl elimination, ortho-Cl elimination and finally phenol adsorption. The removal mechanism of 2,4-DCP by BC@Fe/Ni may involve the 2,4-DCP reductive dechlorination by nZVI, atomic hydrogen and biochar-mediated electron transfer, and final adsorption by biochar. In summary, this study demonstrates that biochar is a promising electron shuttle for immobilizing bimetallic particles and serves as a reference for the dechlorination mechanism of chlorinated organic pollutants by biochar-based bimetallic nanomaterials.

Enhancing Phenol Adsorption on Hydrophobic Pd/SiO2 to Achieve Faster and More Selective Hydrogenation

Enhancing Phenol Adsorption on Hydrophobic Pd/SiO2 to Achieve Faster and More Selective Hydrogenation

Sustainable removal of phenol from wastewater using a biopolymer hydrogel adsorbent comprising crosslinked chitosan and κ-carrageenan

A biopolymer-based adsorbent comprising chitosan (CS) and κ-carrageenan (κ-Carr) was synthesised and evaluated to treat phenolic-contaminated water. The developed CS/κ-Carr hydrogel demonstrated excellent performance with a phenol adsorption uptake of 80 %. The morphologies of CS/κ-Carr hydrogels with different ratios of CS to κ-Carr ranging from 1:2 to 7:3 were characterised using scanning electron microscopy and atomic force microscopy; their chemical structures were investigated by spectral analyses using Fourier-transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry; their adsorption characteristics were determined using tests for swelling, chemical stability, hygroscopic moisture content, and hydrophilicity. Finally, a batch-type evaluation method demonstrated adsorption performance at 25 °C and pH 6.9. Adsorption isotherms and kinetic data were successfully obtained using the Freundlich and pseudo-second-order models, respectively. The results indicate that one-pot synthesis of an insoluble CS/κ-Carr hydrogel adsorbent exhibits considerable potential for the removal of phenol from aqueous solutions, providing an environmentally friendly technology enhancing the phenol adsorption performance of CS.

Nanoporous carbons based on coordinate organic polymers as an efficient and eco-friendly nano-sorbent for adsorption of phenol from wastewater

The major part of water pollutants includes of organic such as phenolic pollutant, thus there are every hazardous to environment. Present work is a comparative onto surface chemistry and adsorptive characteristics of coordinate organic polymer (Cop-150) and nanoporous carbon (NPC) prepared using solvothermal method. New NPC was successfully synthesized to remove of phenol. FT-IR, XRD, XPS, SEM, TGA, and BET techniques have been used to characterization and confirm physicochemical variation during preparing Cop-150 and NPC. Box–Behnken response surface methodology (BBRSM) was used to optimize four important factors of the pH (2–10), contact time (1–40 min), temperature (25–60 °C), and initial concentration of phenol (5–50 mg L−1). To analyze the data obtained from the adsorption of phenol by synthesized adsorbents, four linear, 2FI, quadratic and cubic models were examined, which the quadratic model was recognized as the best model. To the NPC the equal adsorption capacity 500 mg g−1 is achieved at the initial concentration of phenol = 49.252 mg L−1, contact time = 15.738 min, temperature = 28.3 °C, and pH 7.042. On the other hand, the adsorption capacity for Cop-150 in pH 4.638, the contact time = 19.695 min, the temperature = 56.8 °C, and the initial concentration of phenol = 6.902 mg L−1 was equal to 50 mg g−1. The experimental data at different conditions were investigated by some famous kinetic and isotherm models, which among them, were corresponded to the pseudo-second-order kinetic model and the Langmuir isotherm. Moreover, based to result of thermodynamics to the both Cop-150 and NPC, the adsorption process is exothermic and spontaneous. According to results the Cop-150 and NPC could be used for up to four and five cycles without significantly reducing their performance, respectively.

Role of Maillard reactions in co-pyrolysis of lignite and spent coffee grounds: Fixation of nitrogen in semicoke and improved adsorption of phenols

Semicoke derived from lignite and biomass has been utilized in soil remediation and activated sludge treatment. Nitrogen-doping treatment has been utilized to improve adsorption capacity of semicoke for phenols (such as humic acids). Known as nitrogen-rich biomass residue, spent coffee grounds (SCG) may serve as nitrogen resources when co-pyrolyzed with lignite. But impacts of SCG on structure and adsorption capacity of semicoke in co-pyrolysis have not been confirmed. In consideration of proteins in SCG, nitrogen fixation and the impacting mechanism have not been sufficiently confirmed. In this work, nitrogen fixation between lignite and SCG during co-pyrolysis were investigated by thermogravimetric analysis (TG) and pyrolysis experiments. Corresponding mechanism were speculated and confirmed by in-situ diffuse reflectance infrared Fourier transformation spectra (DRIFT) and mass spectrum (MS). Impacts of nitrogen fixation on adsorption of phenols on semicoke were investigated by X-ray photoelectron spectroscopy (XPS), adsorption kinetics analysis and density functional theory (DFT) calculations. Compared to theoretical values, higher contents of N have been obtained in co-pyrolyzed semicoke (N: 2.89%; pyridinic N: 44.86%), which implied N fixation and cyclization reactions. Fixation mechanism can be explained by formation of Amadori/Heyns intermediates in Maillard reactions. Release of volatiles and capture of NH3 are crucial in 340–440 °C range, which result in nitrogen fixation. Then formation of pyrrolic and pyridinic N can be explained by cyclization reactions and decomposition of Amadori/Heyns intermediates in 550 °C pyrolysis. Enrichment of pyridinic N, pyrrolic N and CO might enhance adsorption of phenols by offering binding sites for formation of hydrogen bonds. Both C, N fixation and improved adsorption capacity (27.80 mg/g) have been realized for 7:3–550 semicoke. Consequently, doping treatment with typical nitrogen-rich biomass (SCG) may be feasible to enhance adsorption of phenols onto semicoke, based on selection of raw materials and pyrolysis conditions.

Strategies for promoting the degradation of phenol by electro-Fenton: Simultaneously promoting the generation and utilization of H2O2

The use of the electro-Fenton process to continuously generate H2O2 and efficiently degrade organic pollutants is considered a promising technology. The ratio of generation of H2O2 is usually regarded as the critical step; however, how the H2O2 is utilized is also of particular importance. Herein, activated carbon was activated at different temperatures and used to explore the effect of nitrogen doping on the production and utilization of H2O2 in the electro-Fenton-based degradation of organic pollutants. The experimental results indicate that nitrogen-doped activated carbon simultaneously promotes the generation and utilization of H2O2, which is attributed to the regulation of the competition between phenol and O2 adsorption by the doped nitrogen. Nitrogen doping not only improves 2e−ORR selectivity but also aggregates phenol near the cathode to balance the concentrations of phenol and ·OH. Density functional theory (DFT) calculations further confirmed that pyrrole-N as a dopant promoted the adsorption of phenol, while pyridine-N was more favorable for O2 adsorption. The unique balance of nitrogen types possessed by modified activated carbon NAC-750 permits the efficient synergistic generation and utilization of H2O2 in a balanced manner during the degradation of phenol. This work provides a new direction for the rational nitrogen-doping modification of activated carbon for the electro-Fenton-based degradation of organic pollutants.

Adsorption of Phenols on Carbonaceous Materials of Various Origins but of Similar Specific Surface Areas

The adsorption of phenol (Ph), 4-chlorophenol (CP), and 4-cresol (MP) from aqueous solutions on three carbonaceous materials of diverse origins but similar specific surface areas was investigated. Vulcan XC72 carbon black (CB), AKP-5 activated coke (AC), and activated tire pyrolysis char (AP) were examined as adsorbents. The kinetics and equilibrium adsorption, as well as the influence of pH and ionic strength of each solution on the adsorption process, were studied. The results revealed that the adsorption was pH-dependent and preferred an acidic environment. The presence of an inorganic salt in the solution (ionic strength) did not affect the adsorption processes of the three adsorbates. The pseudo-first- and pseudo-second-order equations, as well as the Weber–Morris and Boyd kinetic models, were used to describe the adsorption kinetics. It was found that equilibrium was reached for all adsorbates after approximately 2–3 h. Adsorption kinetics followed a pseudo-second-order model, and the adsorption rate was determined by film diffusion. The adsorption isotherms were described using the Langmuir and Freundlich equations. The results revealed that the adsorption processes of Ph, CP, and MP on all three adsorbents from the water were better described by the Langmuir model. The adsorption of CP was the most efficient, the adsorption of MP was slightly weaker, and the adsorption of phenol was the least efficient.

Synthesis of silica from rice husk as coating material on magnetic nanoparticle for efficient adsorption of phenol from water samples

Silica (SiO2) from rice husk was coated with magnetic nanoparticles (MNPs) as an adsorbent to adsorb phenol from river water. The structure of SiO2 and SiO2-MNPs were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) showed a rod shape, with a rough surface area in the range of 2 to 3 µm. Transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDX) were used to examine the resulting spherical shape of the synthesized SiO2-MNP. The results showed a range of 1.3 to 1.5 nm for SiO2 and 4.2 to 6.4 nm for SiO2-MNP. Vibrating-sample magnetometer (VSM) showed an Fe value of 45.1% in SiO2-MNP (VSM); for MNP, SiO2, SiO2-MNP 104.12, 4.72, and 8.01 emu/g, respectively. Response surface methodology (RSM) was used to study the parameters and responses to obtain an optimized condition in SiO2-MNPs usage. The optimized parameters were extraction time selected at 5 min, pH 8, 8 mL acetonitrile as solvent and 15 min as sonication time. The application of SiO2-MNPs was applied to real water samples, with recovery of 84% of phenol. Thus, the synthesized adsorbent, SiO2-MNPs, was developed successfully for phenol removal from water samples.

Conversion of agricultural waste to porous hydrochar for non-metallic activation of persulfate to phenol degradation via non-radical-dominated processes: Singlet oxygen and electron transfer

Recently, non-radical oxidation was served as an efficient approach during pollutant degradation due to its excellent environmental applicability. However, designing a green and low-cost non-metallic catalyst to activate persulfate (PS) for removal of hazardous organic contaminants via non-radical-dominated processes is still challenging. Herein, porous hydrochar (PHC) was synthesized with agricultural waste of corn straw (CS) as precursor and KHCO3 as pore-forming agent, which contained mesoporous structures with defects, thus facilitating phenol adsorption (117.14 mg/g). Moreover, 20 mg/L of phenol could achieve 100% removal at a wide pH range (7.0–11.0) within 10 min by PHC/PS system. The radical pathways induced by O·H and O2·− had certain effect on phenol removal, while non-radical pathways (1O2 and electron transfer process) played dominant contributions. Among them, 1O2 was produced from the reaction between surface functional groups on PHC and PS, and electron transfer process occurred from phenol to PS via PHC as the conductor. Whether under the interference of co-existing substances or in different water matrixes, the degradation efficiency of phenol could reach above 80%, exhibiting the excellent adaptability of PHC/PS system. This study proposed a potential resource utilization method of agricultural waste to prepare non-metallic catalyst for effective water remediation.

One-step hydrothermal generation of oxygen-deficient N-doped blue TiO2–Ti3C2 for degradation of pollutants and antibacterial properties

In this study, TiO2 was generated in situ on the surface of Ti3C2 by a hydrothermal process, and urea was added to form N-doped TiO2–Ti3C2. The surface morphology and functional group properties of the prepared materials were analyzed by SEM, TEM, XRD, XPS, etc. The results showed that anatase TiO2 formed on the surface of the Ti3C2 monolayer. Nitrogen-doped nanomaterials show good phenol degradation and good recyclability under visible light. At a urea content of 0.5 g, the photocatalytic degradation of phenol under visible light is best, reaching 88.9% in 3 h, with ·OH and ·O2− holes playing the leading role. However, at lower pH and higher ion concentration, the degradability of N–TiO2–Ti3C2 for phenol is reduced. Furthermore, the material prepared in this work is a two-dimensional layered material, and the adsorption of phenol best fits the Langmuir adsorption isotherm model and the pseudo-second-order kinetic equation. In terms of the antibacterial performance of the material, the N-doped TiO2–Ti3C2 nanomaterial made with 0.2 g of urea has an Escherichia coli scavenging efficiency of about 97.86%, which is an excellent antibacterial material. This study shows that the N–TiO2–Ti3C2 produced in this experiment can be used for environmental applications.

Removal of Phenols by Highly Active Periodate on Carbon Nanotubes: A Mechanistic Investigation.

Carbon nanotubes (CNTs) and their derivatives have been widely exploited to activate various oxidants for environmental remediation. However, the intrinsic mechanism of CNTs-driven periodate (PI) activation remains ambiguous, which significantly impedes their scientific progress toward practical application. Here, we found that CNTs can strongly boost PI activation for the oxidation of various phenols. Reactive oxygen species analysis, in situ Raman characterization, galvanic oxidation process experiments, and electrochemical tests revealed that CNTs could activate PI to form high-potential metastable intermediates (CNTs-PI*) rather than produce free radicals and 1O2, thereby facilitating direct electron transfer from the pollutants to PI. Additionally, we analyzed quantitative structure-activity relationships between rate constants of phenols oxidation and double descriptors (e.g., Hammett constants and logarithm of the octanol-water partition coefficient). The adsorption of phenols on CNT surfaces and their electronic properties are critical factors affecting the oxidation process. Besides, in the CNTs/PI system, phenol adsorbed the CNT surfaces was oxidized by the CNTs-PI* complexes, and products were mainly generated via the coupling reaction of phenoxyl radical. Most of the products adsorbed and accumulated on the CNT surfaces realized phenol removal from the bulk solution. Such a unique non-mineralization removal process achieved an extremely high apparent electron utilization efficiency of 378%. The activity evaluation and theoretical calculations of CNT derivatives confirmed that the carbonyl/ketonic functional groups and double-vacancy defects of the CNTs were the primary active sites, where high-oxidation-potential CNTs-PI* were formed. Further, the PI species could achieve a stoichiometric decomposition into iodate, a safe sink of iodine species, without the generation of typical iodinated byproducts. Our discovery provides new mechanistic insight into CNTs-driven PI activation for the green future of environmental remediation.

Regenerable carbon honeycomb monoliths directly prepared from brown coal: A novel carbon product

A novel, straightforward and efficient method for preparing electrically regenerable carbon honeycomb monoliths (CHMs) directly from brown coal is described. Soft brown coal, which inherently contains relatively high oxygen functional group concentrations and high moisture contents, was kneaded with NaOH or KOH to achieve homogenised and smooth dough with plasticine consistency. This method of alkali salt addition leads to a high level of ion-exchange. The exchanged cations form a strong electrostatic network, strengthening the coal structure such that the dough can be directly extruded into high cell density CHMs (e.g., 227 cells/in2) which maintain their structural integrity throughout drying¸ carbonisation and activation processes.It was found that a modest temperature increase (to above 50 °C) enabled by the kneading, played an important role in developing the dough quality via an apparent irreversible, exothermic cross-linking reaction.The fabricated CHMs are structurally robust with high compressive strength (e.g., 40 MPa). They exhibit good electrical conductivity (e.g. 150 S/m) and high surface areas (e.g., 1175 m2/g), which can both be tailored for specific applications. The used CHM was fully regenerated by in-situ resistive heating after liquid adsorption in a short time (30 min) under atmospheric air, thanks to its optimal electrical conductivity and stable structure. These characteristics along with its low material and production cost make this CHM a promising material for a variety of applications, such as methane storage and phenol adsorption.

Thermodynamics and Kinetics Studies of Phenol Adsorption on to Anchote Peel Activated Carbon Adsorbent

Thermodynamics and Kinetics Studies of Phenol Adsorption on to Anchote Peel Activated Carbon Adsorbent

Adsorption of phenol by a Moroccan clay/ Hematite composite: Experimental studies and statistical physical modeling

Water pollution by phenolic compounds is considered a primary environmental concern. The adsorption of phenol on iron-modified clay and its mechanism were evaluated in this study. A new hybrid material, “Clay-Iron oxide,” has been synthesized for its possible use in phenol removal from wastewater. Textural and chemical properties of this new composite have also been assessed using a variety of techniques such as XRD, XRF, SEM-EDX, FTIR, and BET. On the other hand, phenol adsorption performance has been studied in terms of pH, temperature, and initial concentration. Theoretically, the phenol adsorption onto modified clay was satisfactorily modeled with pseudo-second-order kinetics and the Langmuir isotherm; the maximum phenol adsorption capacities, obtained with the Langmuir model, are 15.24, 17.55, 20.24, and 20.10 mg/g at 303, 313, 323, and 333 K, respectively. Furthermore, five advanced statistical physics models were adopted to understand the adsorption mechanism better. The combination of experimental and modeling approaches revealed that: i) the present material is competitive compared to other adsorbents, ii) phenol molecules interact with clay/iron oxide functional groups via several mechanisms, iii) the number of phenol molecules adsorbed per site increases with temperature, iv) phenol adsorption process is spontaneous, physisorption and endothermic, and v) Iron increases the phenol removal efficiency. Thus, the novelty of this research paper lies in the phenol adsorption mechanism study based on the spatial and energetic properties, the determination of the adsorption process effect on the adsorbent, and finally, the assessment of the iron-modified clay’s efficiency in removing phenol from wastewater.

Adsorption of Phenol Using Hydrochar Modified Layered Double Hydroxide – Kinetic, Isotherm, and Regeneration Studies

Adsorption of Phenol Using Hydrochar Modified Layered Double Hydroxide – Kinetic, Isotherm, and Regeneration Studies

Potential of agro-industrial residues from the Amazon region to produce activated carbon

Thousands of tons of residual lignocellulosic biomass are produced and discarded by agroindustries in the Amazon. These biomasses could be harnessed and used in the preparation of activated carbon, in view of the growing demand for this product with high added value, however, little is known about their characteristics, in addition to their potential as precursors of activated carbon. Therefore, the aim of this work was to evaluate the potential of four different biomasses in the preparation and quality of activated carbon. Residues from the processing of the fruits of acai, babassu, Brazil nut, and oil palm were collected, characterized, carbonized, physically activated with CO2, and characterized. The contents of the total extractives, insoluble lignin, minerals, holocellulose, and elemental (CHNS–O) were analyzed. The surface area and surface morphology were determined from the AC produced, and adsorption tests for methylene blue and phenol were performed. The four biomasses showed potential for use in the preparation of CA; the residues presented high contents of lignin (21.83–55.76%) and carbon (46.49–53.79%). AC were predominantly microporous, although small mesopores could be observed. The AC had a surface area of 569.65–1101.26 m2 g−1, a high methylene blue (93–390 mg g−1), and phenol (159–595 mg g−1) adsorption capacities. Babassu-AC stood out compared to the AC of the other analyzed biomasses, reaching the best results.

Thermodynamics and kinetics studies of Phenol adsorption on to Anchote peel activated carbon adsorbent

Thermodynamic and kinetics (pseudo first, pseudo second) of phenol adsorption were investigated. Anchote peel (coconia Abysinica peel) was carbonized and activated by treating with KOH solution followed by heating in an electrical furnace at 800 for 2 hrs. Kinetic studies of the data showed that the adsorption follows the pseudo-second-order kinetic model. Thermodynamic parameters showed that adsorption on the surface of APAC was feasible, spontaneous in nature, and exothermic. The equilibrium data better fitted the Freundlich isotherm model. Maximum adsorption efficiencies of Phenol were 97% at optimum pH 6 and optimum contact time 210 min., adsorbent dose 0.25 g and initial conc. 0.025 mg/l respectively. Maximum adsorption capacity of APAC was observed to 43.75 mg/g of Phenol at 25 and 5 mg/L. Key words:

Towards experimental and theoretical understanding of the adsorption behavior of phenol on a new activated carbon prepared from oak wood

Although phenol is frequently used in various industrial applications, it is a very dangerous pollutant; thus, wastewater containing this pollutant must be properly treated before being released into the environment. In this sense, a new activated carbon (AC), prepared from Atlas oak, has been successfully used to remove phenol from aqueous solutions. The new material has been characterized by Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (SEM/EDX), X-Ray Diffraction (XRD), and Fourier-Transform Infrared spectroscopy (FTIR); its textural properties have been also examined by nitrogen adsorption/desorption measurements. By using H3PO4 acid as an activator, the activated carbon's ability to adsorb phenol was assessed under various conditions. Indeed, the adsorption process follows the pseudo-second-order kinetics, and the isotherm data were best fitted with the Langmuir model. Thereby, the highest adsorption capacity, which has a value of 250 mg g‐−1, was achieved for an equilibration time of 2 h, an initial concentration of 10−2 mol L−1, an adsorbent mass of 100 mg, and a pH value of 4; this capacity exceeds that of other adsorbents. On the theoretical level, statistical physics modeling of the experimental data shows that the monolayer with two energy sites model (M2) was found to be the best model to describe the phenol adsorption phenomenon. Indeed, steric parameters indicate that the phenol molecules tend to be vertically adsorbed to the surface of the new material. The thermodynamic data reveal that phenol adsorption is physical, spontaneous, and endothermic in nature as well as it depends on electrostatic interactions, hydrogen bonds, and potential interactions. Finally, the present work may open the way for the development of new low-cost, effective, and natural adsorbents in order to remove pollutants from wastewater.

Activated carbon from sugarcane as an efficient adsorbent for phenol from petroleum refinery wastewater: Equilibrium, kinetic, and thermodynamic study

Abstract The adsorption method may be one of the environmentally friendly, economical, and effective techniques to remove phenol from wastewater using low-cost adsorbent activated carbon (AC). The effects of the initial concentration of phenol, temperature, and time of the adsorption on the phenol removal percent were studied. The maximum removal percentage of phenol was 63.73% of the initial 150 mg/l concentration obtained at 25°C. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models have been applied to study the adsorption equilibrium. The results show that both Langmuir and Freundlich isotherms fitted the equilibrium data better with a high correlation coefficient (R 2) and a maximum adsorption capacity of 108.70 mg/g. Thorough fitting of adsorption kinetics data followed the pseudo-second-order model. Thermodynamic parameters were calculated in the temperature range of 25–50°C. The results show that the adsorption process of phenol on AC is more favorable at low temperatures.

Removal behaviors of phenol from aqueous solution using industrial coal sludge-derived porous carbon sorbent

Porous activated carbon was prepared from industrial coal sludge (CS) by one-step pyrolysis and KHCO3 activation, and applied to remove phenol from aqueous phase. The effects of activation parameters on the characteristics of activated carbon and phenol adsorption performance were investigated. CSAC-900 (obtained at 900 °C) has abundant pores and shows three-dimensional porous structure. The adsorption process of phenol on CSAC-900 are controlled by various mechanisms, such as π-π interaction, hydrogen bond and pore filling. The isotherm fitting agrees with Langmuir model. The maximum adsorption capacity of phenol on CSAC-900 is 305.83 mg/g. The positive ΔH and negative ΔG illustrate the adsorption of phenol onto CSAC-900 is a spontaneous endothermic reaction. Compared with commercial activated carbon materials, the adsorption of phenol by CSAC-900 exhibits significant advantages in adsorption capacity and adsorption rate, and it can also be regenerated and recycled.