Phenol In Aqueous Solution Research Articles

Zeolitic imidazolate frameworks in mixed matrix membranes for boosting phenol/water separation: Crystal evolution and preferential orientation

The treatment of phenolic wastewater has become a critical but challenging issue for growing concerns over human health and the environment. In this study, the highly permeable mixed matrix membranes (MMMs) were fabricated by embedding structure- and morphology-tailored zeolitic imidazolate frameworks (ZIFs) in poly(ether-block-amide) (PEBA) bulk for pervaporation (PV) separation of phenol/water mixture. The crystal evolution from rhombic dodecahedral ZIF-8 particles to anisotropic ZIF-L nanosheets (ZLNs) was achieved by varying precursor concentration in aqueous system, and the morphology of ZIFs was precisely adjusted. Using a spin-coating method, the horizontally-oriented ZLNs constructed a typical brick-and-mortar architecture in the polymer matrix, suggesting their excellent interfacial compatibility. The high aspect-ratio ZLNs created preferential pathways for phenol but limited water transport in the membrane. Notably, the ZLNs/PEBA MMMs exhibited ultra-high phenol permeance of 4.96 × 105 GPU and phenol/water selectivity of 32.5 in separation of 1000 ppm phenol aqueous solution at 60 °C, which surpassed the overall performance of other phenol-selective membranes. Besides, the presence of ZLNs endowed the MMMs with good thermal and mechanical properties, guaranteeing long-term stability in realistic conditions. These findings of regulating morphology and preferential orientation of two-dimensional metal-organic framework fillers might have significant implications in designing high-performance membranes for various applications.

Visible light active Fe-Pr co-doped TiO2 for water pollutants degradation

Fe–Pr co-doped TiO2 photocatalysts are synthetized by sol–gel method using titanium tetraisopropoxide, praseodymium nitrate and iron acetylacetonate as precursors of titania, praseodymium and iron, respectively. The chemical-physical properties of all prepared samples are analysed by X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) spectroscopy and N2 adsorption at −196 °C. XRD patterns show the main peaks of anatase phase in all photocatalysts and evidence that Fe and Pr ions are effectively introduced into the TiO2 lattice. UV–vis DRS spectra indicate the reduction of the band gap value of Fe-Pr co-doped TiO2 with respect to TiO2 and Pr-doped TiO2 thank to co-doping of TiO2 with Pr and Fe ions. The photocatalytic performances of all prepared samples are investigated for the degradation of Acid Orange 7 azo dye (AO7) and also of phenol under visible light irradiation. Photocatalytic efficiency obtained using Fe–Pr co-doped TiO2 markedly increases compared to un-doped TiO2, Pr-doped TiO2 and Fe-doped TiO2 photocatalysts. Fe-Pr co-doped TiO2 prepared with 8.5 mg of praseodymium nitrate gave the best photocatalytic activity. The enhanced photocatalytic activity should be associated with the simultaneous doping of TiO2 with Pr3+ and Fe3+ ions that induces a marked decrease of band gap value together with an enhanced generation of oxygen vacancies, which can trap electrons, and therefore reducing their recombination with photogenerated positive holes. Indeed, using the optimized Fe-Pr co-doped TiO2, the dye discoloration and mineralization is about 87 and 80 %, respectively, after 60 min of LEDs visible light irradiation, underlining the best performances of the optimized Fe–Pr co-doped TiO2 in terms of treatment time. Finally, the optimized Fe-Pr co-doped TiO2 is tested for visible light degradation of phenol in aqueous solution, confirming the absence of possible sensitization phenomena of photocatalyst surface by the AO7 dye.

New composite material based on Kaolinite, cement, TiO2 for efficient removal of phenol by photocatalysis

Photocatalysis is one of the most important process and was used to eliminate various organic pollutants as phenol in water. In this research study, a new composite containing Kaolinite, cement, and wood fibers modified by titanium oxide TiO2 was elaborated in order to be used in addition of building materials, as photocatalyst for the degradation of phenol. Different kinds and amounts of TiO2 (PC500, P90, and C-TiO2) were immobilized by a simple method inside the composite materials based. The matrix of the hybrid materials was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), N2 adsorption-desorption (BET), and scanning electron microscope (SEM). These investigations confirmed the dispersion of titania in the new composite materials. The FTIR result has shown that clay particles were successfully treated before their insertion in the composite, by the appearance of two peaks at 2921-2851 cm-1. The XRD results reveal the identification of crystalline phase of TiO2 as anatase. The photocatalytic activity of the composite materials was investigated towards degradation of phenol in aqueous solution under UV light irradiation (369 nm). It has been found that photocatalytic efficiency was significantly enhanced when TiO2 is added. The highest photocatalytic activity has been shown by 3% P90-comp of 41.65% in comparison with 3% PC500 and 3% C-TiO2 which are 29.88% and 22.64 %, respectively. It was shown that the experimental data of kinetic reaction are well fitted by first-order model.

Nitrogen-doped char as a catalyst for wet oxidation of phenol-contaminated water

Catalytic wet oxidation (CWO) of aqueous effluents rich in organic compounds is a very promising technology for the treatment of liquid wastes from biomass conversion processes. CWO reactions occur through the formation of free radical species, produced in the presence of an oxidant, which act on organic contaminates in the effluent. Although the reaction is well known, there exists a lack of affordable catalysts to conduct this process at the lower temperatures and pressures in novel bioenergy processes. This study assessed the catalytic effect of nitrogen-doped chars as such an option. Phenol in aqueous solution was used as a model waste effluent. Treatment was conducted at moderate temperatures (190 to 260 °C), oxygen partial pressure of 1 MPa, and reaction times of 15, 30, and 45 min in stainless steel and glass-lined tube reactors. High pressure liquid chromatography (HPLC) analyses of the products quantified phenol and by-product concentrations used in the calculation of reaction activation energy. The char catalyst was studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) in order to gain insight into its structure and surface composition. The results indicate that nitrogen-doped char catalysts accelerate the oxidation of phenol by decreasing its reaction activation energy from 82.2 kJ/mol (non-catalyzed) to 40.4 kJ/mol (catalyzed). An analysis from first principles using density functional theory (DFT) was conducted to ascertain which N functional group has the most significant impact on free radical formation in the presence of oxygen. Among all the N functional groups studied, the dipyridinic functional groups showed the most promising characteristics to facilitate the formation of hydroxyl free radicals.

Regulating Electron-Hole Separation to Promote the Photocatalytic Property of BiOBr<sub>1&#8722x</sub>I<sub>x</sub>/BiOBr Local Distorted Hierarchical Microspheres

In this work, hierarchical BiOBr1&#8722xIx/BiOBr heterojunction photocatalyst with a microsphere morphology was synthesized by a facile solvothermal process. It demonstrated that the local structure of the photocatalysts was highly distorted due to the substitution of bromide ions by iodine ions. The photocatalytic properties were evaluated by the photodecomposition of aqueous phenol solution under visible-light irradiation. The results indicated that all the composite photocatalysts exhibited high photocatalytic activity. In particularly, the BiOBr1&#8722xIx/BiOBr (x = 0.25) sample exhibited over 92% degradation efficiency of phenol within 150 min, which is 24.6 and 3.08 fold enhancement in the photocatalytic activity over the pure phased BiOBr and BiOI, respectively. Moreover, this excellent photocatalytic property can be expanded to other colorless organic contaminants, verifying the common applicability of BiOBr1&#8722xIx/BiOBr (x = 0.25) as an excellent visible-light photocatalyst for organics decomposition. The significant improvement in the photocatalytic activity can be explained by the high efficiency of charge separation due to the enhancement in the internal electric fields and band match that comes from the local structure distortion. This work provides valuable information for the design of highly active photocatalysts toward the environmental remediation.

Hydrodechlorination of 4-Chlorophenol on Pd-Fe Catalysts on Mesoporous ZrO2SiO2 Support.

A mesoporous support based on silica and zirconia (ZS) was used to prepare monometallic 1 wt% Pd/ZS, 10 wt% Fe/ZS, and bimetallic FePd/ZS catalysts. The catalysts were characterized by TPR-H2, XRD, SEM-EDS, TEM, AAS, and DRIFT spectroscopy of adsorbed CO after H2 reduction in situ and tested in hydrodechlorination of environmental pollutant 4-chlorophelol in aqueous solution at 30 °C. The bimetallic catalyst demonstrated an excellent activity, selectivity to phenol and stability in 10 consecutive runs. FePd/ZS has exceptional reducibility due to the high dispersion of palladium and strong interaction between FeOx and palladium, confirmed by TPR-H2, DRIFT spectroscopy, XRD, and TEM. Its reduction occurs during short-time treatment with hydrogen in an aqueous solution at RT. The Pd/ZS was more resistant to reduction but can be activated by aqueous phenol solution and H2. The study by DRIFT spectroscopy of CO adsorbed on Pd/ZS reduced in harsh (H2, 330 °C), medium (H2, 200 °C) and mild conditions (H2 + aqueous solution of phenol) helped to identify the reasons of the reducing action of phenol solution. It was found that phenol provided fast transformation of Pd+ to Pd0. Pd/ZS also can serve as an active and stable catalyst for 4-PhCl transformation to phenol after proper reduction.

Гибридный фотокатализатор нано-диоксид титана/диатомит для удаления токсичных органических загрязнителей из воды с помощью эффективных окислительных процессов (АОPs)

В статье представлены результаты изучения фотокаталитической активности гибридной каталитической системы диатомит/диоксид титана, представляющей собой композит на основе наноразмерного диоксида титана, привитого на поверхность диатомита, которая была применена для разложения фенола в водном растворе под действием УФ излучения, как пример эффективных окислительных процессов типа AOPs (Advanced Oxidation Processes). Катализатор был синтезирован методом модифицированного гетерогенного гидролиза в присутствии диатомита с использованием четыреххлористого титана в качестве прекурсора диоксида титана. Фотокатализатор показал высокую активность в разложении фенола в водном растворе: так, степень деградации фенола достигала 90% в течение 180 мин процесса в зависимости от исходной концентрации загрязняющего вещества. Кинетика процесса фоторазложения хорошо описывается моделью адсорбции Ленгмюра-Хиншельвуда. Полученный композитный катализатор при дозе 2 г/л и исходном содержании фенола 10 г/л удаляет загрязнитель из водного раствора, достигая значений ПДК по фенолу в сточных водах (~5 мг/л) в течение 54 мин фотокатализа. Photocatalytic activity of the hybrid photocatalyst (diatomite/titanium dioxide, DTD) based on nano-sized titanium dioxide grafted on the diatomite surface was tested in advanced oxidation processes (AOPs) by measuring degradation of phenol in model contaminated aqueous solutions under UV illumination. The hybrid catalytic system was synthesized via a modified heterogeneous hydrolysis procedure in the presence of diatomite by using titanium tetrachloride as titania precursor. The photocatalyst showed high activity in photocatalytic decomposition of phenol in aqueous solution. The degradation degree was up to 90% in 180 min depending on initial phenol concentration. The experimental results obtained for the photodegradation kinetics of phenol showed a good agreement with the Langmuir-Hinshelwood model of adsorption with the external diffusion as the determining step of the process. The prepared DTD composite at a loading of 2g/L was able to mineralize phenol under UV irradiation in aqueous solution at initial phenol concentration of 10g/L within 54 min of photocatalytic process up to the maximum allowable concentration level (MAC) for phenol in wastewater (~5 mg/L).

Synthesis, characterization, optoelectronic and photocatalytic properties of Sr2Bi2O5/SrCO3 and Sr3Bi2O6/SrCO3 heterostructures with varying SrCO3 content

We report on the structure and properties of novel Sr2Bi2O5/SrCO3 and Sr3Bi2O6/SrCO3 heterostructures with SrCO3 content varying from 10 wt% to 90 wt%. Formation of the heterostructures is succeeded via sintering technique and according to XRD, SEM, and EDX studies has resulted in highly crystalline materials with well-defined carbonate-bismuthate interfaces. In the reaction of photodegradation of phenol in aqueous solution the heterostructures demonstrated photocatalytic activity exceeding that of TiO2. It is demonstrated that their photocatalytic action is due to the presence of type II semiconductor heterojunctions. The content of SrCO3 ensuring utmost photocatalytic activity is explained based on numerical modeling of the heterostructures’ formation using ‘Unity’ development platform. In addition, the heterostructures show photoluminescence. Its mechanism proposed here implies permeability of the materials’ heterojunctions to electrons. This work describes new materials that can be used for photodegradation of organic pollutants. Besides, it extends available principles of design of photocatalytically active heterostructures.

Tailoring phenol photomineralization pathway over polymeric carbon nitride with cyano group multifunctional active sites

The electronic and interfacial properties of catalysts play vital roles in tailoring catalytic performance. Here, we report that the modification of polymeric carbon nitride (PCN) with cyano group (CN) can achieve excellent catalytic performance in mineralization of phenol. The CN site not only enhances the adsorption and activation of molecular O2 for efficient H2O2 production, but also improves the absorption capability of PCN for phenol in aqueous solution by tuning surface charge states. Subsequently, the surficial adsorbed phenol acts as holes scavenger which promotes the separation efficiency of photogenerated carriers in PCN and in turn facilitates the in-situ decomposition of H2O2 to OH. This reduces the uncontrollable decomposition of H2O2 to OH and inhibits the polymerization of phenolic compounds. The active sites of catalyst, O2 transformation state and pathway on the catalyst surface as well as the firstly attacked sites of phenol are confirmed respectively by in-situ DRIFT spectra, scavengers and Bader charge analysis.

Solvation of Ethanol, Phenol, and o-Methoxyphenol in Dilute Aqueous Solutions under Normal and Supercritical Conditions

The structure of 2 wt % aqueous solutions of ethanol, phenol, and o-methoxyphenol (guaiacol) was modeled in NVT ensemble using the classical molecular dynamics method at densities of 0.997 and 0.133 g/cm3 corresponding to the normal (298 K, 0.1 MPa) and supercritical (673 K, 23.0 MPa) conditions. The self-diffusion coefficients were calculated for individual components in solutions; the radial distribution functions were calculated for the oxygen atoms of water molecules, oxygen atoms of hydroxyl groups, and centers of mass in phenol molecules. The possibility of clusterization of solute molecules was analyzed. The data obtained suggest heterogeneity of solutions, in which clusters of different compositions and structures can exist. Clusterization of up to seven ethanol and phenol molecules can occur under normal conditions, and dimerization was detected under SC conditions. The structural features of solutions under normal and SC conditions were compared. The difference in the formation of hydration shells of ethanol and phenols molecules was demonstrated. Stable shells of water molecules form around ethanol molecules under normal conditions. For phenols, the solvation shells are unstable, with a pronounced tendency toward clusterization of organic molecules.

Screening of Activated Carbons for the Treatment of Highly Concentrated Phenol Solutions Using Catalytic Wet Peroxide Oxidation: The Effect of Iron Impurities on the Catalytic Activity

Activated carbons (ACs) have been used as metal supports for catalytic wet peroxide oxidation (CWPO) of organic compounds. A shortcoming is that added metals can undergo leaching, leading to catalyst deactivation and secondary contamination of the treated water. In the present study, CWPO of phenol aqueous solutions was investigated in the presence of five commercial ACs without added metals yet containing different extents of iron impurities resulting from their industrial preparation procedures (ROX 0.8, RX 3-Extra, C-Gran and PK 0.25-1 from Cabot Norit and HYDRAFFIN AS 12/450 from Degussa). Application of as-received ROX 0.8 leads to the best compromise between removals of phenol (79%) and total organic carbon (TOC; 50%) and iron leaching (0.22 mg L−1). In-house-modified ROX 0.8 materials, obtained by thermal treatment under inert atmosphere followed by activation under oxidative atmosphere, were also tested. The activity of ROX 0.8 oxidized at 673 K (ROXN673) was the highest among these materials (92% and 57% of phenol and TOC removals, respectively) and with iron leaching (0.67 mg L−1) well below the limits established by European regulations for discharge of treated waters. This enhanced performance was mainly explained by the more developed porous structure and higher specific surface area (SBET) of ROXN673, thus promoting better accessibility to iron impurities, which act as active sites for CWPO at the surface of the catalyst.

RP – HPLC method for the determination of removal phenol as a pollutant in aqueous solution

An efficient, rapid, sensitive, and reproducible methods for the removal phenol determination of in aqueous solution was developed. UV- Spectroscopy methods and reverse phase high performance liquid chromatographic (RP - HPLC) were used. The phenol removal from the aqueous solution was carried out by prepared activated carbons (ACs) from the wheat plant waste as a natural material. The remains phenol was determined using RP – HPLC and UV- Spectroscopy. The elution was done using a mobile phase consisting of acetonitrile (ACN): water in the ratio of 10:90 on HPLC Shimadzu LC–20 A, Japan and Phenomenex C18 column (250 × 4.6 mm, 5μm). The separation was monitored for 15 min at 270 nm using a UV-visible detector and 1.5 ml/min flow rate. UV-VIS spectrophotometric measurement for quantitative of phenol was carried out at 272.6 nm. The optimum conditions such as the composition of the mobile phase, flow rate, temperature, size, time and pH were studied. The obtained results revealed that the values of R2 are (0.9996 and 0.9991), the detection limit (0.02 and 0.01), the quantitative limit (0. 066 and 0.033), the linear ranges (0.2 – 25 and 0.1 – 30) μg / mL for UV and HPLC respectively. The removal percentages of phenol using the treated wheat plant waste were found 98.76 and 98.85 using UV and HPLC measurements respectively. Compared to the other methods, the current method is rapid, simple and economical for the removal and determination of phenol in aqueous solution.

The Photocatalytical Properties of RGO/TiO2 Coated Fabrics

The aim of this work was to immobilize reduced graphene oxide (RGO) and titanium dioxide (TiO2) on the surface of selected fibrous structures. Textile fabrics made of cotton (CO) and polyamide (PA) were used as a carrier. The following modification methods were applied: coating for modification of PA and dip-coating for modification of CO. In the dip-coating method, no auxiliaries were used, which is a huge advantage. The RGO/TiO2 coated fabrics were characterized using several techniques: ultraviolet–visible (UV–VIS) spectroscopy, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The obtained results showed the immobilization of RGO and TiO2 on the fabrics. Raw fabrics absorb much less radiation than coated ones, which is associated with strong absorption of radiation by applied modifiers (RGO and TiO2). Photocatalytic activity of functionalized textiles was determined using aqueous phenol solutions. Phenol removal efficiency obtained for RGO/TiO2 coated CO and RGO/TiO2 coated PA was 51% and 46%, respectively. The hydroxyl radicals play a major role in the phenol photocatalytic degradation. The phenol removal efficiency in the fifth cycle was higher (about 14% and 8% for RGO/TiO2 coated CO and RGO/TiO2 coated PA, respectively) compared to the first cycle.

Sodium Lignosulfonate Modified Polystyrene for the Removal of Phenol from Wastewater.

An eco-friendly and novel water treatment material was synthesized using sodium lignosulfonate modified polystyrene (SLPS), which can be used to eliminate phenols in aqueous solution. SLPS was characterized by BET, FTIR, SEM, and EDS. The effect of the initial pH value, phenol content, adsorption time, and temperature on the absorbability of phenol in SLPS was investigated through adsorption experiments. It was found that SLPS could efficiently adsorb phenol in aqueous solution at a pH value of about 7. The test results revealed that the kinetic adsorption and isotherm adsorption could be successfully described using the pseudo second-order and Langmuir models, respectively. It was illustrated that the phenol adsorption on SLPS was dominated by chemisorption and belonged to monolayer adsorption. The max. phenol adsorption value of SLPS was 31.08 mg/g at 30 °C. Therefore, SLPS displayed a great potential for eliminating phenol from polluted water as a kind of novel and effective adsorbent.

Peroxidase from waste cabbage (Brassica oleracea capitata L.) exhibits the potential to biodegrade phenol and synthetic dyes from wastewater

Peroxidases are well known for their ability to biodegrade some recalcitrant organic pollutants like phenol and their derivatives resulting in a reduction in their toxicity. The present study was designed to extract, characterize, and evaluate the potential of partially purified peroxidase from discarded and decaying waste cabbage leaves in the biodegradation of phenol and some common synthetic azo dyes. This was done by first partially purifying the crude extract of waste cabbage peroxidase (WCP) using ammonium sulfate precipitation, dialysis, and gel filtration chromatography. Thereafter, the experimental determination of protein concentration, peroxidase activity, and biodegradation of phenol and azo dyes was done spectrophotometrically. The results showed a purification fold of 87.65 with a 34.92% yield. The partially purified peroxidase had its optimum activity at temperature 30 °C, pH 5.5 while showing broad substrate preference with ABTS been the substrate. The stability studies also showed that WCP was stable over a wide range of pH (4.0–7.0) and 41% of its original activity was retained at 80 °C indicating that it is a thermostable enzyme. The kinetic data of WCP showed Km values of 1.24, 17.89, and 19.24 mM and Vmax values of 1111.11, 909.09, and 588.24 mM /minutes for ABTS, guaiacol, and o-dianisidine respectively. Three metal ions, Hg2+, Cu2+, Ni2+, organic solvent (acetone), EDTA, and urea inhibited peroxidase activity; whereas Mn2+ and Zn2+ showed slight activation. The partially purified WCP exhibited high efficiency for the biodegradation of synthetic azo dyes and phenol at the lab-scale. After 48 h incubation, the waste cabbage peroxidase efficiently catalyzed the decolorization of tested azo dyes at varying degrees; azo blue 5, azo purple, azo yellow 6, and citrus red 2, with a percentage decolorization of 85.1, 69.1, 46.2 and 42.9%, respectively. The waste cabbage peroxidase also shows up to 91.1% efficiency for degradation of phenol in aqueous solution after 60 min. Findings from this study provide promising evidence on the possibility of utilizing/recycling a readily abundant waste cabbage to useful bioproducts like peroxidase enzyme with the ability to biodegrade azo dyes and phenol at a small scale in the laboratory. Moreover, the findings from this study increase the prospect of waste cabbage peroxidase for the treatment of industrial effluents containing dyes and phenolic pollutants. The approach of transforming waste from one source into a useful biocatalyst that can potentially be exploited to treat waste pollutants from a different source offers a chain of green technology.

Performance of TiO2/Graphene (cocoPAS) Composite as Photocatalyst for Removal of Phenols in Aqueous Solution

As one of the hazardous industrial wastes, an excessive amount of phenol in the environment can cause damage to the biological ecosystem and nutrient cycle. Phenol removal can be done by photocatalysis process using photocatalyst materials such as titanium dioxide (TiO2). The photocatalysis activity of TiO2 can be improved by making TiO2-graphene (cocoPAS) composite. The obtained TiO2-graphene (cocoPAS) composite was characterized by Scanning Electron Miscroscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared absorption spectroscopy (FTIR), and Breneur Emmet Teller (BET). The performance of the TiO2-graphene (cocoPAS) composite in phenol degradation was tested in a photocatalysis process with variation are the concentration of phenol (10, 20, and 30 ppm, respectively) and photocatalysis temperature (30, 40, and 50 °C, respectively). TiO2 particle loaded on the graphene sheet and Ti-O-C bond was formed at 719 cm−1. The size of anatase and rutile crystals are 26.39 nm and 27.39 nm with the fraction of anatase and rutile are 57% and 43%. The surface area of the TiO2-graphene (cocoPAS) composite is 40.9 m2/g. The highest efficiency of phenol degradation was achieved when the concentration of phenol is 10 ppm and photocatalysis temperature is 50°C which efficiency of phenol degradation is 96.9%. The higher concentration of phenol will decrease the efficiency of degradation but the degradation efficiency of phenol increases with an increase in photocatalysis temperature.

Enhancing the pervaporation performance of PEBA/PVDF membrane by incorporating MAF-6 for the separation of phenol from its aqueous solution

Phenol is highly toxic and carcinogenic even at low concentrations. This study focused on preparing high-performance mixed matrix membranes (MMMs) for the pervaporation separation of phenol from its aqueous solution. A highly-efficient zeolitic metal azolate framework, RHO-[Zn(Heim)2] (MAF-6, Heim = 2-ethylimidazole) was incorporated into the polyether block amide (PEBA-2533) supported on the polyvinylidene fluoride (PVDF) ultrafiltration membrane. The MAF-6 was chosen as the filler due to its inherent hydrophobic surfaces and aperture size (7.6 Å), which is larger than the molecular kinetic diameter of phenol (6.6 Å). Effects of the casting solution concentration, active layer thickness, MAF-6 loading, operating temperature, and phenol concentration were systematically investigated. With the increase of the MAF-6 loading ratio X from 0 to 7, the phenol flux of the membrane was gradually enhanced, but the water flux was reduced. For 1000 ppm phenol aqueous solution at 80 °C, MAF-6–7@MMM displayed the optimal separation factor of 25.9 with a phenol flux of 89.2 g∙m−2∙h−1. The pervaporation separation index (PSI) of the MAF-6–7@MMM was 1317.7 kg∙µm∙m−2∙h−1 at 80 °C, which was much higher than the PEBA/PVDF membrane (787 kg∙µm∙m−2∙h−1). Impressively, an increasing feed temperature enhanced the phenol flux more prominently than water, owing to the hydrophobicity and porosity of MAF-6. Consequently, the resultant MAF-6-X@MMMs broke the trade-off limitation between phenol permeability and selectivity. The as-prepared membrane also exhibited exceptional long-term stability, suggesting its prospect of industrial application.

Characterization and Kinetic Studies on Photocatalytic Degradation of Phenol in Aqueous Solution

Recently, many researchers tend to study the performance of hybrid polyoxometalates (HPOM) as photocatalyst due to its greater performance in photocatalytic degradation. The process that based on the light enhanced generation of reactive OH radical that plays an important role in order to convert organic compound completely into water, CO2 and inorganic compounds. In this research, the photocatalytic degradation of phenol was studied using HPOM as photocatalyst. The HPOM was synthesized and used to study its effect on photocatalytic degradation of phenol. The synthesized HPOM were characterized using SEM and FTIR. It was found that the surface morphology of the synthesized HPOM le displayed an irregular spherical-like shape, granular structure with different size and least distribution of non-agglomerated rod-like nanoparticles. The present of WO6 octahedral and PO4 octahedral indicated that Keggin type structure of synthesized hybrid polyoxometalates. The kinetics of photocatalytic degradation of phenol via hybrid polyoxometalates follows pseudo first order kinetic reaction.

Olive Mill Wastewater (OMW) Polyphenols Adsorption onto Polymeric Resins: Part I—Batch Anaerobic Digestion of OMW

Adsorption experiments using pure aqueous phenol solutions (in the range of 200 to 1000 ppm) were performed in the presence of different adsorbent resins (namely XAD 4, XAD 16, FPX 66) at 1% w/v (ratio of resin weight to phenol solution volume) at constant temperature (25 °C) and ionic strength (0.1 M NaCl). Langmuir and Freundlich isotherm models were used to describe the adsorption kinetics of all tested resins. The experimental equilibrium data were very well fitted to both Langmuir and Freundlich models (R2 > 0.900). FPX 66 exhibited the best efficiency among the tested resins. Regeneration of adsorbent resins thus recovery experiments of pure phenol solutions were also performed. Adsorbent tested resins were further examined in different mass ratios (10, 15, 20%) for phenolics removal from olive mill wastewater (OMW). A reduction of 75% of the soluble phenolic content was observed when 20% of FPX 66 was applied. Finally batch anaerobic digestion experiments of resin-pretreated OMW were carried out under mesophilic conditions (37 °C). Augmentation of methane production was measured during anaerobic digestion of resin-pretreated OMW compared to raw OMW. Polyphenols in OMW were proved to inhibit OMW fermentation and thus methane production.

Polyarylate membrane with special circular microporous structure by interfacial polymerization for gas separation

Microporous polymer membranes have received extensive attention in the membrane separation field based on the advantage of high gas permeance and low cost. However, there are a few reports of microporous polyacrylate membranes fabricated by interfacial polymerization (IP), and the formation mechanism and influence factor of the microporous structure is rarely illuminated. In this work, thin-film polyacrylate membrane with circular microporous morphology were prepared by IP method with cyclodextrin and acyl chloride as the aqueous and oil phase monomer respectively for effective gas separation. The effects of the aqueous and organic phase monomer structure and concentration, the concentration and type of alkali in the aqueous solution on the membrane morphology and gas separation performance were investigated in detail. As a result, the polyacrylate membrane fabricated by β-cyclodextrin (β-CD) and trimesoyl chloride (TMC) with optimal content of NaOH in the aqueous phase formed the special circular microporous structure by the scanning electronic microscope (SEM) characterization. The resulting membrane showed CO2 permeance of 200 GPU with CO2/N2 ideal separation selectivity of 10.53. This work provides an effective strategy to fabricate high performance polyacrylate membrane by regulating the monomer structure and the alkali concentration in the aqueous phenol solution with IP method, which would inspire the exploration of other phenolic monomer for the assembly of microporous polymer membranes for gas separation or seawater desalination.