Phenol Adsorption Capacity Research Articles

One-Step Fabrication of Magnetic Polymer/Montmorillonite Adsorbent for Highly Efficient Phenol Adsorption

AbstractPhenol contaminants are highly biotoxic and have become a global problem threatening the environment and human health. The objective of the present study was to develop a very efficient and easily recyclable adsorbent to remove phenol. A magnetic montmorillonite composite with organic co-intercalation was fabricated by a simple one-step co-precipitation method and exhibited excellent phenol removal. Two surfactants, cetyltrimethylammonium bromide (CTAB) and erucic acid amide (EA), were successfully co-intercalated into the interlayer of Ca-montmorillonite, and Fe3O4 nanoparticles were simultaneously decorated to obtain Fe3O4-CTAB/EA-montmorillonite composite (Fe3O4-C/E-Mnt). The morphology and structure of Fe3O4-C/E-Mnt composite were explored by using different techniques such as X-ray diffraction, Fourier-Transform infrared spectroscopy, X-ray photoelectron microscopy and so on. The adsorption capacity of Fe3O4-C/E-Mnt for phenol was investigated under various conditions including temperature, pH, contact time, various phenol concentrations, and adsorbent dosage. The results showed that Fe3O4-C/E-Mnt retained a lamellar structure of Ca-Mnt with mesopores. Its interlayer space, surface area, and pore volume were increased. The Fe3O4-C/E-Mnt composite exhibited a good adsorption capacity (31.45 mg·g–1) for phenol with a removal efficiency of 85.46% at optimized conditions. Moreover, the adsorbent still maintained 78.32% of the adsorption capacity after five cycles. The adsorption test data of Fe3O4-C/E-Mnt followed the pseudo-second order kinetic model and the Langmuir model. The adsorption was a spontaneous, exothermic, entropy-decreasing process, and a possible adsorption mechanism of Fe3O4-C/E-Mnt was finally proposed.

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.

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.

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.

Preparation, Characterization, and Chemically Modified Date Palm Fiber Waste Biomass for Enhanced Phenol Removal from an Aqueous Environment.

The date palm tree is extensively cultivated in Middle Eastern countries such as Saudi Arabia, generating a large amount of waste in the form of leaves, seeds, and fibrous materials. This study examined the feasibility of using raw date palm fiber (RDPF) and NaOH chemically modified date palm fiber (NaOH-CMDPF) obtained from discarded agricultural waste for the removal of phenol in an aqueous environment. The adsorbent characterization was performed by using different techniques, i.e., particle size analysis; elemental analyzer (CHN); and BET, FTIR, and FESEM-EDX analysis. The FTIR analysis revealed the presence of various functional groups on the surface of the RDPF and NaOH-CMDPF. The results showed that chemical modification by NaOH increased the phenol adsorption capacity that was well-fitted by the Langmuir isotherm. Higher removal was obtained with NaOH-CMDPF (86%) than with the RDPF (81%). The RDPF and NaOH-CMDPF sorbents' maximum (Qm) adsorption capacities were more than 45.62 mg/g and 89.67 mg/g and were comparable to the sorption capacities of various other types of agricultural waste biomass reported in the literature. The kinetic studies confirmed that the adsorption of phenol followed the pseudo-second-order kinetic process. The present study concluded that the RDPF and NaOH-CMDPF were eco-friendly and cost-effective in promoting sustainable management and the reuse of the Kingdom's lignocellulosic fiber waste material.

Phenol adsorption properties and microstructural changes of organically modified bentonite

Phenolic compounds are prevalent organic contaminants in aquatic and soil environments. To address the issue of phenolic waste water treatment, bentonite can be utilised as an effective adsorbent through organic modification. The present study focuses on using sodium bentonite, which was modified with cetyltrimethylammonium bromide (CTMAB), to remove phenol from an aqueous solution. The influence of various factors such as adsorption time, initial phenol concentration and CTMAB–bentonite dosage on phenol adsorption was thoroughly investigated. In addition, the microstructural changes during the adsorption process, adsorption kinetics and adsorption isotherms of the organically modified bentonite (OMB) were analysed. The results indicated that the adsorption equilibrium time of OMB was longer compared with that of sodium bentonite. The amount of phenol adsorbed by OMB was found to be positively correlated with the initial phenol concentration and CTMAB–bentonite dosage. The maximum phenol adsorption capacity and removal rate achieved were 3.00 mg/g and 43.74%, respectively. The study also revealed that a quasi-second-order kinetic model was appropriate for describing the phenol adsorption process of OMB, and the adsorption isotherm was found to conform with the Freundlich isotherm model. These findings demonstrate the potential of OMB as an efficient and effective adsorbent for phenolic waste water treatment.

Investigation of activated carbon derived from rice straw biomass for removal of phenol from aqueous solution

The rapidly developing of industry and population leads to various problems, such as an increase in the energy used and discharging of pollutants into the environment. Water pollution is a big issue in Vietnam as well as in the world. Therefore, finding the method for the treatment of water is urgent.This work investigated activated carbon derived from rice straw biomass (ACRS) for the adsorption of phenol. The surface morphology, surface functional group, and surface area of the ACRS were determined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer-Emmett-Teller (BET) analysis, respectively. ACRS had a porous structure along with a larger surface area of 216.3 m2/g, which effectively enhanced the adsorption performance of phenol. The removal performance of phenol increased with increasing the contact time (10-60 min), then reached equilibrium at 90 min. The maximum adsorption capacity of phenol using ACRS was 128.4 mg/g and the adsorption behaviour of the pollutant fit well to the Langmuir and Freundlich isotherms. Experimental results revealed that adsorption by surface area, activated sites, pores, and complexation between functional groups of the adsorbent and phenol were major mechanisms.

Effect of double carbon chains on enhanced removal of phenol from wastewater by amphoteric-gemini complex-modified bentonite

A novle amphoteric-gemini complex-modified bentonite was prepared with a gemini surfactant ethylene bis (tetradecyl dimethyl ammonium chloride) (EB) on the basis of the bentonite modified by amphoteric modifier dodecyldimethyl betaine (BS). The surface and structural characteristics of modified bentonite were characterized by X-ray diffraction (XRD), specific surface area (SBET), scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), total carbon (TC) and total nitrogen (TN). In addition to studying the enhanced effect of gemini surfactants on phenol adsorption by kinetics and equilibrium adsorption, the influences of modification ratio, pH, temperature and ionic strength were investigated. Results showed that BS + EB complex modification increased the interlayer spacing (IS), TC and TN of bentonite (BT), and SBET decreased with the increase in its total modification ratio. The adsorption of phenol on modified bentonite reached equilibrium in 20 min, and the adsorption capacities were in the order of BS+50 EB (BS+50% CEC EB)>BS+100 EB > BS+150 EB > BS+25 EB > BS > BT. The adsorption capacities of phenol on BS + EB complex modified bentonite (CMB) increased by 9.98–15.96 and 1.19–3.35 times compared with those on BT and BS single modified bentonite (SMB), respectively. The phenol adsorption capacities decreased with the increases in temperature and pH, while it increased with the augment in ionic strength. This study revealed that double carbon chains increased the organic carbon content more effectively than single carbon chains at low complex modification ratios, thus promoting the adsorption of phenol by hydrophobic partitioning on the bentonite surface.

Green synthesis of reduced graphene oxide and their use on column adsorption of phenol from olive mill wastewater

A novel reduced graphene oxide (RGO) synthesis using Verbena officinalis as a green, reducing agent was out-reaching. RGO was encapsulated in sodium alginate (SA) by cross-linking (SA-RGO beads). SA-RGO beads have been used to treat olive mill wastewater (OMWW). This effluent is rich in phenolic compounds that inhibit biological degradation and are toxic at high concentrations. The newly prepared SA-RGO beads were characterized by scanning electron microscopy (SEM),energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), BET surface area analyzer, and Fourier transforms infrared spectroscopy (FTIR). In addition, the organic compounds of Verbena officinalis were determined by HPLC to reveal the reduction mechanism of graphene oxide (GO). Finally, batch and fixed-bed column adsorption tests were performed to assess the performance of SA-RGO beads. The kinetics, isotherm models and adsorption thermodynamics show that the pseudo-second-order and Freundlich best present phenol adsorption and the endothermic reaction. Thomas and Yoon-Nelson's models satisfactorily described fixed-bed column adsorption. The optimized adsorption parameters were 3.68 g L−1 of adsorbent dosage, pH of 4.0, adsorption time of 135 min, and temperature of 25 °C. The reusability of SA-RGO beads and regeneration experiments with HCl (0.5 M) were performed in fixed-bed reactors. The results showed a phenol adsorption capacity of 994 mg g−1 for an initial concentration of 4000 mg L−1.

Comparative assessment of modified bentonites as retardation barrier: adsorption performance and characterization

Modified bentonites for the anti-seepage system have been attracting global attention. At the same time, the performances of modified bentonite containing retardation barrier exposed to organic–heavy metal pollutants have not been fully reported. In this study, the adsorption performances (one of the key evaluation indicators of retardation barrier) of nine kinds of commonly used modified bentonites on multiple contaminants were comparatively investigated. The x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses were also performed to unravel the adsorption mechanisms. Results show that the adsorption of modified bentonites on phenol and Pb(II) follows the order of SB-16 > PVA > CTAB > APAM > CTAB + PAC > PAC > CPAM > CTAB + PAC > CTAB + CPAM + APAM. Among all the samples, the bentonite modified with SB-16 showed the highest adsorption capacities for phenol and Pb(II). The surfactant molecules inserted in the interlayer space of montmorillonite increase the substrate spacing, which changes the structural properties of the bentonite from hydrophilic to hydrophobic and increases the adsorption of organic contaminants. On the other hand, the polymer has functional groups such as hydroxyl and carboxyl that can form a spatial three-dimensional cross-linking structure on the bentonite surface, providing more adsorption sites for heavy metal ions. These findings indicate the potential industrial applications of modified bentonite in a contaminant barrier system.

A comparative study of the pore characteristics and phenol adsorption performance of activated carbons prepared from oil-palm shell wastes by steam and combined steam-chemical activation

Oil-palm shell wastes were successfully converted into useful activated carbons in a systematic and novel approach by optimizing the pyrolysis conditions and subsequent steam activation conditions to maximize the BET surface area. The optimal activation conditions were a steam flow rate of 1.13 kg/h, hold time of 1.5 h and temperature of 950 °C, yielding BET areas of 1432.94 and 1382.95 m2/g for nitrogen-pyrolyzed and vacuum-pyrolyzed chars, respectively. In steam-chemical activation, one-step activation of oil-palm shell in steam with potassium carbonate (K2CO3), sodium carbonate (Na2CO3) or potassium chloride (KCl) was conducted, resulting in BET area output order of shell/K2CO3 (710.56 m2/g) > shell/KCl (498.55 m2/g) > shell (366.7 m2/g) > shell/Na2CO3 (326.62 m2/g). This study reported the first use of KCl and Na2CO3 as chemical reagents in one-step steam-chemical activation of biomass. KCl-activated carbon exhibited retardation of tar formation property, resulting in better pore development than pure steam activated carbon.Phenol adsorption of activated carbon is not only a function of the BET surface area but also the type of pyrolysis used prior to physical activation. Activated carbon (BET area of 1192.29 m2/g) pyrolyzed under vacuum could adsorb 87% more phenol than that pyrolyzed in nitrogen flow which had a higher BET area of 1432.94 m2/g. Phenol adsorption capacities of activated carbons are: shell pyrolyzed under vacuum (275.5 mg/g) > shell pyrolyzed in N2 flow (147.1 mg/g) > shell/K2CO3 (145.7 mg/g) > shell without pyrolysis (12.1 mg/g). These activated carbons would be highly suitable in industry processes to remove phenolic contaminants.

β-Cyclodextrin with Sodium Alginate based Nanosponges Preparation and Characterization in the Removal of Organic Toxin: p-Cresol in the Simulated Biological Fluids

Sodium alginate (SA)-based β-cyclodextrin(β-CD) can show an amazing adsorption capacity and are considered as secure and biocompatible frameworks for evacuating harmful particles from the body. Tyrosine, an amino acid which is found in certain nourishment and food constituents is changed over into p-Cresyl sulfate by intestine microbiota and on the off chance that this cannot be evacuated from the body, it will come-up as a dangerous uremic toxin in the body and rapid removal of this toxic molecule is relevant especially for patients affected by chronic kidney disease. Based on the necessity in the removal of this protein bound uremic toxin, Innovative cyclodextrin polymers were synthesized with different concentrations of sodium alginate to form nanosponges which are able to remove p-Cresol (Phenolic molecule), before it converted into the toxic form i,e,. p-Cresyl sulfate in the body. Furthermore, in vitro studies were carried out using optimal concentrations of sodium alginate with β-cyclodextrin-NS formulations by assessing physicochemical properties, stability, phenol adsorption capacity and in vitro toxicity. Nanosponges (NSs) were found to be of 1:2 proportion of β-cyclodextrin with sodium alginate respectively as NS2-formulation with an adsorption efficiency of in-vitro phenol toxin is 72%. In contrast, this subsidiary was more-steady in gastrointestinal media. In conclusion, this idea proposes that CD-NS details are secure and successful in expelling harmful atoms from the body. Their potential utilization in veterinary or human medication may diminish dialysis recurrence and lead to decreased phenol arrangement which concurrently decreases the cardiovascular and renal burden.

Adsorption and in-situ photocatalytic Fenton multifield coupled degradation of organic pollutants and coking wastewater via Fe[sbnd]BiOBr modification of three-dimensional graphene aerogel

Both adsorption and advanced oxidation processes can achieve rapid removal of organic pollutants. Based on this, FeBiOBr was modified on the surface of three-dimensional graphene aerogel (3D rGA) to construct FeBiOBr/rGA composites. Using the surface adsorption properties of graphene to quickly adsorb pollutants, combined with photocatalytic Fenton degradation by FeBiOBr catalysts, the adsorption and in-situ photocatalytic Fenton multifield coupled degradation system was constructed by the consistency of adsorption and catalytic degradation sites. Experimental results showed that FeBiOBr/rGA has a 2.92-fold increase in the adsorption capacity for phenol compared with bulk rGA. Meanwhile, the degradation rate constant was 2.7 times higher than that of FeBiOBr because of the excellent electrical conductivity of graphene. In addition, it also exhibited excellent COD and TOC removal performance for different phenolic and coking wastewaters. The effects of graphene content, catalyst dosage, H2O2 concentration and other factors on the adsorption-catalytic degradation activity of the synergistic system were further investigated. Based on the influence of active species, the mechanism of FeBiOBr/rGA composite adsorption and in-situ catalytic degradation multifield coupling removal of pollutants was proposed. In addition, the 3D rGA could effectively solve the problem of difficult recycling of powder catalysts and has significant practical application potential.

Biomass Novel Adsorbents for Phenol and Mercury Removal.

This paper reports the use of activated carbons made from novel agriculture and industrial wastes, namely sunflower, vine shoots, and coffee endocarp, to remove two high-priority contaminants: phenol and mercury species (under different forms) from aqueous solutions. The activated carbons were used as prepared and also modified with nitric acid and triethylenediamine in order to explore additional adsorption mechanisms. The results showed an interesting potential of the materials to be used for water decontamination as indicated by the mercury uptake up to 1104 mg/g for Hg2+, 771 mg/g for [HgCl4]2-, 966 mg/g for HgCl2 and the maximum phenol adsorption capacity of 190 mg/g. The modification with triethylenediamine led to a significant increase in the phenol and mercury adsorption reaching an increment of 85% for phenol and 250% for Hg2+.

Carbonized ZIF-8/chitosan biomass imprinted hybrid carbon aerogel for phenol selective removal from wastewater

In this work, carbonized ZIF-8/chitosan imprinted hybrid carbon aerogel (MIP@CZIF-8/CS) is constructed. The introduction of CZIF-8 effectively optimizes the specific surface area (664 m2 g−1) of imprinted matrix and further enhances the nitrogen atom doping, leading the increased adsorption sites and the formation of superhydrophilic surface. MIP@CZIF-8/CS exhibits a remarkable phenol adsorption capacity (246.6 mg g−1) at pH of 7 and shows excellent selective adsorption towards phenol against its structural analogues. The adsorption kinetics and isotherms of MIP@CZIF-8/CS follow pseudo-second-order and Langmuir–Freundlich models, respectively. Besides, MIP@CZIF-8/CS with monolithic structure can support about 4167 times its own weight. Thanks to its monolithic structure and excellent mechanical stability, MIP@CZIF-8/CS maintains 94 % adsorption capacity after 10 cycle tests and does not contaminate application system. In addition, MIP@CZIF-8/CS can realize the dynamic filtration of phenol in fixed bed column system. The effluent phenol concentration conforms to GB8978-1996, proving its practical application potential.

Adsorption characteristics of lead, copper, cadmium, methylene blue, phenol, and toluene in water using composite synthesized from titanium dioxides and carbon spheres through hydrothermal method

Titanium nanotubes (TNT) are commonly synthesized from TiO2 P25 under hydrothermal reaction (HTR) using 10 M NaOH). Composite adsorbents derived from TiO2 and carbon spheres (CS) were synthesized via a facile two-stage HTR process. CS was firstly synthesized from glucose through HTR. The mixture (CS, TiO2, and NaOH) was then transferred to a Teflon-lined autoclave for another HTC process to generate TNT/CS. The TNT/CS composite was calcined from 300 to 800 °C to evaluate the changes in its surface properties (functional group, morphology, and external charge), textural parameters, crystallinity, cation exchange capacity, and adsorption capacity. Results indicated that the Brunauer–Emmett–Teller surface area and total pore volume of composites were 25.0–131.9 m2/g and 0.099–0.33 cm3/g, respectively. The composites exhibited a negatively charged surface within pH 4.0–9.0, with their zeta potentials at pH 5.0 ranging from −54.60 to −31.1 mV. The result of X-ray photoelectron spectroscopy demonstrated that the main components (%atomic) in the composites were carbon (29.07%–60.75%), oxygen (29.09%–49.16%), titanium (2.93%–17.52%), and sodium (0.56%–9.48%). During the preparation of TNT/CS, CS (its negatively charged surface) can well absorb Na+ ions in the mixture. This phenomenon prevented the performance of tubular morphology in TNT/CS. The synthesized composites were regarded as multifunctional adsorbents for adsorbing various contaminants (Pb2+, Cd2+, Cu2+, cationic methylene blue dye, phenol, and toluene) in water. Equilibrium adsorption at pH 5.0 was carried out to estimate their adsorption capacities toward the selected contaminants. The Langmuir maximum adsorption capacities of Pb, Cd, Cu, methylene blue, phenol, and toluene were 534, 518, 514, 690, 329, 138 mg/g for TNT/CS and 334–523, 384–477, 297–453, 394–677, 303–416, 118–260 mg/g for the calcinated TNT/CS composites, and 26.3, 23.8, 21.4, 285, 239, 188 mg/g for commercial activated carbon, respectively. The adsorption mechanisms were elucidated based on the adsorption experiments and surface characteristics of TNT/CS. Ion exchange was the primary adsorption mechanism for the test cationic contaminants. The van der Waals force was an important adsorption mechanism for phenol and toluene. The developed TNT/CS composite can be employed as an effective adsorbent for adsorbing cationic and non-ionic contaminants in aqueous solutions.

The superior adsorption capacity of phenol from aqueous solution using Modified Date Palm Nanomaterials: A performance and kinetic study

This work investigates the prospective usage of dried Date palm fibers (DPF) and amino silica modified Date palm fibers nanomaterials (Si-DPF) for phenol removal from water. We studied the characteristics of both dried DPF and Si-DPF nanomaterials based on their composition and morphology. The characterization includes diverse types of instruments such as Fourier-transform infrared spectroscopy (FTIR), Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Batch mode experimentations were continued and studied utilizing various significant factors such as the dose of adsorbent, solution pH, contact time, and the initial quantity of phenol molecules as a pollutant. Under optimum conditions (pH: 7.00, adsorbent dose: 2.00 g/L, initial concentration of phenol: 100 ppm and contact time: 24 h), the maximum adsorption capacities were calculated to be 19.57 and 31.25 mg/g for DPF and Si-DPF respectively. Further, to study the mechanism of the adsorption process of the under-investigated toxic molecules on the active sites of the nanomaterials, we introduced kinetic models involving pseudo-first-order, pseudo-second-order, and models based on intra-particle diffusion. To study the equilibrium isotherms, the Langmuir and Freundlich isotherms were considered, and the Langmuir isothermal model (R 2 ≈ 0.997 and 0.984 for DPF and Si-DPF respectively) which largely deals with the results of the experiments achieved.

Highly efficient conversion of phenol to cyclohexanone on Pd-based catalysts by cobalt doping

Efficient catalysts are still the key to practical industrial applications. In this work, Pd-based catalyst was modified by doping metal Co to obtain Pd-Co@mSiO2 bimetallic core–shell catalyst. The modified bimetallic core–shell catalyst was used in the hydrogenation of phenol, and the catalytic results showed that the Co modification effectively improved the catalytic performance of the Pd-based catalyst, especially, it reduced the activation energy of the reaction and greatly improve the conversion of phenol. Combined with characterization, it was found that Co doping reduced the particle size of Pd metal particles and affected the adsorption capacity of substrate phenol on the surface of Pd metal. The conversion of phenol was close to 99.9 % within 1 h at 80 °C, while the selectivity of cyclohexanone reached 95.4 %. In addition, the core–shell structure provided a stable environment for the catalyst, which still maintained high activity after being recycled for 5 times.

Lignite-Based N-Doped Porous Carbon as an Efficient Adsorbent for Phenol Adsorption

The treatment of phenolic-containing wastewater has received increased attention in recent years. In this study, the N-doped porous carbons were prepared from lignite with tripolycyanamide as the N source, and their phenol adsorption behaviors were investigated. Results clearly showed that the addition of tripolycyanamide largely improved the surface area, micropore volume, N content and thus the phenol adsorption capacity of lignite-based carbons. The N-doped sample prepared at 700 °C showed a surface area of 1630 m2/g and a phenol adsorption capacity as high as 182.4 mg/g at 20 °C, which were 2.0 and 1.6 times that of the lignite-based carbon without N-doping. Pseudo-second order and Freundlich adsorption isotherm models could better explain the phenol adsorption behaviors over lignite-based N-doped porous carbon. Theoretical calculations demonstrated that phenol adsorption energies over graphitic-N (−72 kJ/mol) and pyrrolic-N (−74 kJ/mol) groups were slightly lower than that over the N-free graphite layer (−71 kJ/mol), supporting that these N-containing groups contribute to enhance the phenol adsorption capacity. The adsorption mechanism of phenol over porous carbon might be interpreted by the π–π dispersion interactions between aromatic-ring and carbon planes, which could be enhanced by N-doping through increasing π electron densities in the carbon plane.

Magnetic reed biochar materials as adsorbents for aqueous copper and phenol removal.

Organics and heavy metals are common pollutants in many wastewaters and water bodies. Adsorption processes by magnetic materials can rapidly remove these pollutants from water and effectively recycle adsorbent. In this study, magnetic analyzer, X-ray diffraction, Flourier transform infrared spectroscopy, and granulometry were used to characterize the synthesized magnetic reed biochar materials (ZnFe2O4/biochar). Influences of adsorption time, pH, temperature, initial solution concentration, and adsorption equilibrium concentration on adsorption performances were investigated for Cu2+ and phenol adsorption by ZnFe2O4/biochar. Adsorption kinetic and isotherm models were used to describe the adsorption processes. Adsorption of phenol and Cu2+ by ZnFe2O4/biochar reached saturation within 45min and increased slightly with the increase of temperature from 15 to 45°C. Adsorption of Cu2+ increased with the increase of pH, while the adsorption of phenol peaked at pH = 6. The adsorption processes fit the pseudo-second order kinetics model, and both conformed to the Langmuir model. The fitting results show that the maximum single-component adsorption capacity of phenol and Cu2+ by ZnFe2O4/biochar is 63.29 and 12.20mg/g, and the maximum bi-component adsorption capacity reaches 40.16 and 9.48mg/g, respectively. All the findings demonstrate that ZnFe2O4/biochar has good adsorption performance for phenol and Cu2+.