Phenol In Aqueous Solution Research Articles

Novel Zr–Cu–Fe nanocomposite metal oxides: structural, magnetic and composition activity effects on photodegradation of phenols

Pure CuFe2O4 nanoparticles were synthesized using sol–gel method technique. Effect of Zr/Cu substitution (Cu1−xZrx, where x = 0.25, 0.50, 0.75, and 1.00) on the structural, morphological, and magnetic properties was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), infrared Fourier transform infrared (FTIR), and vibrating sample magnetometer (VSM). The photocatalytic behavior of pure CuFe2O4 as well Zr-substituted samples was investigated for degradation of phenol in aqueous solution in the presence of ultraviolet irradiation. The XRD results of pure CuFe2O4 confirmed the formation of single tetragonal structure phase, while introducing zirconium in the structural composition resulted in a decrease in the crystallinity and gradual disappearance of the cuprospinel phase accompanied with appearance of single metal oxides species (Fe2O3, ZrO2, Cu4O3). Based on the scanning (SEM–EDX), the samples consist of agglomerated particles with varying sizes and shapes related to their compositions. The magnetic hysteresis loops of all samples exhibited room temperature ferromagnetism with variable shapes, saturation magnetization, and coercivity values. All samples showed a significant photocatalytic activity when irradiated with ultraviolet light. The highest photocatalytic efficiency (92%) for phenol degradation was achieved through the 25% Zr-substituted sample under irradiation time of 150 min.

Photocatalytic degradation of phenol using ionic liquid stabilized TiO2 nanoparticles

This paper describes the successful synthesis of ionic liquid stabilized TiO2 and it was characterized by various instrumental techniques such as UV–vis, FT-IR, XRD and TEM analysis. The photocatalytic activity of ionic liquid stabilized TiO2 nanoparticles (TiO2 NPs) was evaluated by analyzing the degradation of aqueous phenol solution by UV irradiation. The effect of phase composition of TiO2 NPs namely, anatase and rutile, on photocatalytic activity was studied using chemical oxygen demand (COD) and fluorescence measurements. The results show that pure anatase phase shows lesser photocatalytic activity compared to a mixed anatase: rutile phase (80:20) and the degradation mechanism is also investigated. The remarkable point is that the ionic liquid tunes the phases of the TiO2 NPs and this work provides a promising approach to fabricate TiO2 based catalyst with efficient photocatalytic performance.

Pillared interlayered clays as catalyst for wastewater treatment: Cost-effective and sustainable materials

Metal oxide pillared interlayered clays (PILC) represent a novel class of materials that have attracted interests in catalytic oxidative removal of organic pollutants in wastewater. In this work, South African bentonite clay were modified by polymeric Al/Fe, Al/Zr and Al/Cr species, and the obtained pillared solids were characterized and as potential catalysts in catalytic wet air oxidation (CWAO) of phenol in aqueous solution. The placement of metal oxide pillars between bentonite clay sheets modifies their physicochemical properties (surface area and basal spacing) and catalytic activity. The Al/Zr pillared clay exhibited a higher activity compared to Al/Fe and Al/Cr for phenol oxidation. All the pillared clay catalysts allowed the total oxidation of phenol and significant removal for the total organic carbon. The metal leaching was very low in all catalysts studied.

Synthesis and Study on Photogenerated Charge Behavior of Novel Pt/CeO2/ZnO Ternary Composites with Enhanced Photocatalytic Degradation Activity

A novel Pt/CeO2/ZnO ternary composite is synthesized via two simple procedures of hydrothermal and photoreduction. The crystal structure, morphology, and composition of as-prepared samples are characterized by XRD, SEM, HRTEM, XPS and UV–Vis DRS. Because both ZnO and CeO2 are good photocatalytic semiconductors, photocatalytic activities of the samples are evaluated by the degradation of phenol aqueous solution (25 mg/L). Under the strong interaction among the Pt, CeO2 and ZnO, the maximum photocatalytic activity is observed in the Pt/CeO2/ZnO ternary composites and 91% phenol can be degraded in 60 min under UV light irradiation. The probable photocatalytic mechanism is discussed by active species trapping experiments along with SPV, TPV, PL and PA measurements. The enhanced photocatalytic activity is attributed to the redox cycle of Ce4+ ↔ Ce3+, the effective interface between ZnO and CeO2 as well as the electron transfer action of Pt nanoparticles. The photocatalytic activity almost unchanged after four cycles and proves excellent reusable photocatalysts. This work shows the synergistic effect of rare earth elements and noble metals in the photocatalytic process, which facilitates their practical application in toxic pollution abatement.

Study on stable mass transfer and enrichment of phenol by 1-octanol/kerosene/polyvinyl chloride polymer inclusion membrane

A polymer inclusion membrane (PIM) that contains a polyvinyl chloride (PVC) polymer matrix and 1-octanol (OCT) as specific carrier (PO-PIM) was prepared to investigate the mass transfer behaviour of phenol in aqueous solutions. Results showed that the mass transfer behaviour of the PO-PIM for phenol conformed to the first-order kinetics. In addition, the mass transfer efficiency for phenol reached the maximum when the OCT content was 82.8 wt%. The mass transfer activation energy (Ea) was 14.46 kJ mol−1, which indicated that intramembranous diffusion was the main controlling factor in the mass transfer process. The introduction of hydrophobic additives, such as kerosene, liquid paraffin and vegetable oil, into the PO-PIM could remarkably improve its stability. In an aqueous solutions of phenol ranging from 0 mg L−1 to 9000 mg L−1, the initial flux (J0) of kerosene/PVC/OCT-PIM (KPO-PIM) was positively correlated with the initial concentration of phenol. For a stripping solution with a feed solution pH of 2.0 and a sodium hydroxide concentration of 0.1 mol L−1, the maximum permeability coefficient during stable mass transfer reached 12.55 μm s−1. At a mass transfer area of 3.14 cm2, an enrichment factor (EF) of 3.5 for 200 mg L−1 of phenolic aqueous solution was achieved within 48 h through KPO-PIM.

Acidity of the chlorinated phenols: DFT study and experiential affirmation.

A quantum mechanical density functional theory (DFT) was successfully developed for the estimation of pKa values of chlorinated phenols in aqueous solution with a precision of 0.9 pKa units. The MP2/6-311++G(d,p)//B3LYP/6-31+G(d) level of theory was used for the gas phase calculation. For computation in the solution phase and to calculate the energy difference of the acid-base, the polarized continuum model (PCM) at the HF/6-31G(d,p) level was used. The pKa value was computed for each involved species using pentachlorophenol (PCP) as a reference molecule. Natural bond orbital (NBO) analysis considering the natural resonance theory (NRT) was carried out on an optimized geometry of studied compounds to give information about the nature of bonds. Graphical abstract Chlorinated phenols.

Effect of peroxydisulfate on the degradation of phenol under dielectric barrier discharge plasma treatment

The activation of peroxydisulfate (PDS) by gas/liquid dielectric barrier discharge (DBD) plasma in a flat plate configuration was assessed through phenol removal. The results indicated that PDS addition exhibited a significantly promoting effect on phenol removal and mineralization. In the reaction lacking PDS, phenol in aqueous solution was removed from the initial 10 mg L−1 to 4.75 mg L−1 (by 52.5%), whereas the addition of 1770 mg L−1 PDS increased the overall removal to 78.7%, as indicated by a one-fold increase in the pseudo-first-order kinetic constant. In addition, the corresponding total organic carbon (TOC) removal was increased from 27.5% to 48.4%. Furthermore, an increased input voltage was favourable for increases in phenol removal, the kinetic constant and PDS utilization, which were also influenced by the PDS dose, initial solution pH and water matrix. In addition, through the analysis of radical quenching experiments, the enhancement could be mainly attributed to the production of SO4•- and •OH by PDS activation by discharge plasma. The DBD system coupled with PDS exhibited a high removal efficiency for phenol, and thus, the overall findings could provide new insight into wastewater treatment.

Carbon nanotube-grafted chitosan and its adsorption capacity for phenol in aqueous solution

Chitosan was covalently grafted onto the surface of multi-walled carbon nanotubes to create a novel chitosan/multi-walled carbon nanotube. The structure of the new material was characterized using Fourier transform-infrared spectroscopy, cross polarization magic angle spinning 13C nuclear magnetic resonance, thermogravimetric analysis, XRD ray diffraction analysis, differential scanning calorimetry and scanning electron microscopy. The phenol adsorption capacity was determined and the Langmuir and Freundlich models were used to describe the adsorption isotherms. The adsorption capacity of the novel chitosan/multi-walled carbon nanotube material for phenol (86.96 mg/g) was improved compared to the original chitosan (61.69 mg/g). The kinetic studies showed rapid adsorption, exhibiting Lagergren second-order kinetics. Therefore, this study provides a reference for preparing functional materials from biological substrates that are able to remove toxic pollutants from an aqueous environment.

Molecular Dynamics Simulation of Phenol Aqueous Solution under the Impact of an External Electrostatic Field

Molecular dynamics simulations were carried out to study the influence of an external electrostatic field on phenol aqueous solution. The influence is examined in terms of some structural parameter...

Photochemical reflective optical fiber sensor for selective detection of phenol in aqueous solutions.

A photochemical fiber-optic sensor was developed by integrating a plastic optical fiber (POF), polymer membrane, gold mirror, and TiO2-based composite, and was shown to sensitively and selectively detect phenol in aqueous solution. The sensing element consisted of a thinned POF and visible-light-driven SiO2/N-doped TiO2 coating. The gold mirror was used to develop a reflective POF probe. The polymer membrane with high phenol permselectivity was employed to form a micro-channel between the membrane and probe. Our findings highlight the sensor's capability of phenol detection in aqueous solutions with high sensitivity of 0.294×10-3 (mg·L-1)-1, pH immunity ranging from 2.0 to 14.0, and high selectivity with a limit of detection of 30 μg·L-1.

Synthesis of Activated Carbon from Eichhronia Crassipes Plant as Adsorbent for the Removal of Phenol from Aqueous Solution

For a friendly environment, adsorbents are prepared from harmful natural sources to reduce their impact on the environment. The preparation of activated carbon from the Eichhornia crassipes was done by carbonization at 450C°, followed by activation step at 800C°. The adsorption processes were carried out by the batch system to determine the optimal conditions for the removal of phenol from the aqueous solutions. Different parameters were used in batch experiments such as initial concentrations of phenol (in the range from 10-100 ppm), pH (from 2-12), temperature (from 298-328k), AC dosage (from 0.09-0.4g). All the adsorption experiments were carried out in thermostat shaker at 150 rpm. The removal percentage of phenol on activated carbon was 98.2% at optimum conditions of 10 ppm initial phenol concentration, 25 minutes, pH=7, 308 k, 0.2 g of AC dosage). The thermodynamic functions of phenol adsorption were studied at different temperatures. The values of Gibbs free energy (∆G) at maximum removal with temperatures (298, 308, 318 and 328K) was (-5.17, -6.83, -8.22, -8.48) respectively and enthalpy ∆H, entropy ∆S values was 29.22 and 0.114. The activated carbon extracted from Eichhornia crassipes has a double benefit. first, to remove various organic pollutants such as phenols in aqueous solutions and the second, to create a clean water environment free of this plant found in Iraqi waters.

Metal-free graphene-based catalytic membrane for degradation of organic contaminants by persulfate activation

The persulfate (PS) activation can be successfully applied in water treatment and the use of carbon materials to activate PS has been thoroughly described in the literature. Nevertheless, the prospect of employing a metal-free catalytic membrane as the single activator of PS has to be better studied. In the present work, graphite oxide was prepared by the modified Hummers’ method and different nitrogen precursors (melamine, urea and gaseous ammonia) were investigated to produce N-doped graphene oxide catalysts. The material prepared with melamine presented the highest nitrogen content (23.78 wt%) and the highest catalytic activity for the degradation of phenol in aqueous solution. The membrane fabricated with this catalyst was applied in filtration experiments for the degradation of phenol and oxalic acid. The catalytic mechanism is governed by both the radical and the non-radical degradation of the pollutants, but a more notorious contribution of singlet oxygen species was observed. It was demonstrated that the membrane lost the N-pyridinic groups during the reaction and, as consequence, part of its catalytic activity, whereas N-quaternary species remained in the used membrane. An important advantage associated with the application of this metal-free catalytic membrane, instead of a catalyst in powder form, is to avoid the final catalyst separation step.

Mechanical milling: a sustainable route to induce structural transformations in MoS2 for applications in the treatment of contaminated water

Two-dimensional (2D) nanomaterials have received much attention in recent years, because of their unusual properties associated with their ultra-thin thickness and 2D morphology. Besides graphene, a new 2D material, molybdenum disulfide (MoS2), has attracted immense interest in various applications. On the other hand, ball-milling process provides an original strategy to modify materials at the nanometer scale. This methodology represents a smart solution for the fabrication of MoS2 nanopowders extremely-efficient in adsorbing water contaminants in aqueous solution. This work reports a comprehensive morphological, structural, and physicochemical investigation of MoS2 nanopowders treated with dry ball-milling. The adsorption performances of the produced nanopowders were tested using methylene blue (MB) dye and phenol in aqueous solution. The adsorption capacity as a function of ball-milling time was deeply studied and explained. Importantly, the ball-milled MoS2 nanopowders can be easily and efficiently regenerated without compromising their adsorption capacity, so to be reusable for dye adsorption. The eventual toxic effects of the prepared materials on microcrustacean Artemia salina were also studied. The present results demonstrate that ball-milling of MoS2 offers a valid method for large-scale production of extremely efficient adsorbent for the decontamination of wastewaters from several pollutants.

A highly sensitive photocatalytic plastic optic-fiber sensor for selective detection of phenol in aqueous solutions

We present a highly sensitive photocatalytic plastic optic-fiber (POF) sensor for the selective detection of phenol in aqueous solutions. To obtain high sensitivity and low limit of detection (LOD) of the sensor, part of the POF cladding was removed and replaced by a Canada balsam doped with GeO2 (CBG); a UV–vis-light-driven photocatalytic material, that is a CdS-sensitized Er3+YAlO3/SiO2/TiO2 (EYST) composite, was coated on the CBG film. To realize highly selective detection of phenol in water, a high phenol permselectivity and pH independence polymer membrane was fixed on the CdS-sensitized EYST-CBG-coated POF. Furthermore, a model was developed to show that the phenol concentration can be determined by measuring the change in transmitted light intensity of the POF sensor and the sensitivity of the sensors can be improved by employing the CdS-sensitized EYST film. The results showed that the proposed photocatalytic POF sensor has a high sensitivity of -0.39 (mg·mL−1)−1 and low LOD of 15 μg·L−1 for the selective detection of phenol in aqueous solutions with pH ranging from 2.0 to 14.0.

Influence of the Textural Parameters of LDH-TiO2 Composites on Phenol Adsorption and Photodegradation Capacities

Layered double hydroxides (LDH) M2+M3+CO32− were synthesized following the sol-gel methodology using Mg-Al, Mg-Fe, and Zn-Al as cation pairs for subsequent use in the preparation of TiO2/LDH materials. The samples were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM), and the Brunauer–Emmett–Teller (BET) technique to determine the surface area (SA); the results of which were used to determine the roughness of the samples in terms of surface fractal dimension (D). The prepared materials exhibited both adsorption and photocatalytic properties in the removal of phenol in aqueous solution under ultraviolet irradiation. This work studies the relationship between the textural parameters of the materials obtained in relation to their photocatalytic efficiency and adsorption capacity, finding that the surface of the solids, their structural heterogeneity, and roughness condition the photodegradation and adsorption processes, using phenol as reference organic pollutant. The results show that different cation in LDH influences in photocatalytic capacity; the TiO2/ZnAl was the best material in one test, but after 10 times of test, the TiO2/MgFe gave the better photodegradation material. In adsorption capacity, TiO2/ZnAl and TiO2/MgFe have a close rate for phenol adsorption and both were better than TiO2/MgAl. The differences in textural characteristics (surface area, surface roughness, and pore-size distribution) affected phenol adsorption and photodegradation efficiency.

Adsorption and Oxidation of Pnenol on Metal Oxide Electrodes

The article investigates kinetics of electrocatalytic oxidation of phenol in the solution of sodium sulfate on a platinum electrode in the presence of dispersed oxides of metals of varied valence. It is shown that the degree of phenol oxidation in the presence of oxides increase by 10–15%. The most active catalysts include oxides of cobalt, chromium, copper and titanium, whose catalytic activity diminishes in the series Co3O4 > Cr2O3 > Cr2O3 > TiO2 > CuO; the rate of electrooxidation of phenol increases at a decrease of anolyte. It was shown that a limiting stage of electrochemical oxidation of phenol in aqueous solutions with the concentration 50 mg/dm3 is a diffusion of the substance to the electrode.

Kinetic Study on Photocatalytic Degradation of Phenol Using Green Electrosynthesized TiO2 Nanoparticles

Abstract Various methods to prepare TiO2 photocatalyst loaded onto plant extract support have been developed over the last few decades. This experiment investigated the performance of the TiO2 photocatalyst against different concentration of phenol in aqueous solution with the help of hibiscus leaf crude extract as supporting new electrolyte. The experimental results showed the rate of degradation favoured in lower concentration by the prepared catalyst. The photocatalytic reaction followed pseudo first-order kinetics which were rationalized in terms of the Langmuir–Hinshelwood model, and provided nearly complete mineralization.

The Potential of ZrO2 Catalyst Toward Degradation of Dyes and Phenolic Compound

Abstract A ZrO2 catalyst was prepared through a simple electrochemical method which resulted in superior photoactivity toward dyes and phenolic compound degradation. An amount of 0.4 g L−1 of ZrO2 catalyst was found to be an optimum dosage for 10 mg L−1 dye and phenol solution, which resulted in nearly complete degradation of dyes and phenol solution (more than 80%) after 1 h of contact time at pH 9 under fluorescent light irradiation. The degradation followed pseudo first–order kinetic rationalized Langmuir–Hinshelwood model. An excellent photo-activity toward degradation of dyes and phenol in aqueous solution promises the ZrO2 catalyst to be used in textiles industry wastewater treatment and also other applications.

Advanced Oxidation Processes to the Remediation of Liquid Residue from the Thermal Treatment of Oily Sludge

This work reports the remediation of a liquid residue derived from the thermal treatment of petrochemical residues by advanced oxidation processes. Firstly, degradation studies of phenol aqueous solutions by heterogeneous photocatalysis, Fenton, and photo-Fenton were conducted. Fenton processes showed a higher efficiency, mainly in the UVA photo-assisted mode (94% in 3 min), and henceforward it was chosen for the remediation of the residue. However, the high organic load of the raw residue (6,000 mg L-1 of chemical oxygen demand (COD)) limited the efficiency of the Fenton processes. Hence, the raw liquid residue was diluted with the scrubber residue, produced during the thermal treatment of the petrochemical residues, reducing the COD to values close to 2,000 mg L-1. The photo-Fenton treatment allowed the removal of approximately 95% of the COD load, decreasing the residual concentration of phenolic compounds from 213 to 0.5 mg L-1. At the same time, the concentration of BTEXs (benzene, toluene, ethylbenzene and xylene) were reduced to values lower than the limit of quantification (LOQ) of the chromatographic technique. Therefore, the photo-Fenton process is an efficient alternative to the remediation of residues with high complexity and with high COD values, like the ones obtained in the petrochemical industry.

Assessing some advanced oxidation processes in the abatement of phenol aqueous solutions

Assessing some advanced oxidation processes in the abatement of phenol aqueous solutions