Synthesis, characterization and catalytic application for wet oxidation of phenol of iron-containing clays

High-surface-area pillared clays (PILC) were prepared from naturally occurring montmorillonites by exchanging interlayer ions to polyoxocations containing (i) aluminum (Al₁₃-PILC), (ii) iron adsorpted onto Al₁₃-PILC, and (iii) iron and aluminum located within the same complex (Fe_0.8Al_12.2-PILC). The obtained Fe_0.8Al_12.2-PILCs were characterized by DR–UV–vis and IR spectroscopy, XRD, ESR, scanning electron microscopy and low temperature N₂ adsorption measurements. Important factors affecting catalyst activity and phenol removal efficiencies have been studied, i.e. the effect of pH, temperature, catalyst concentration and stability of the catalyst.     

PHENOL RECOVERY WITH SLM USING “CYANEX 923”

The study of the phenol separation-concentration process with the hollow fiber supported liquid membrane technology has been performed. Mixtures of kerosene and CYANEX 923 were used as liquid membrane. The extractant CYANEX 923 is characterized by a high phenol selectivity and an extremely low solubility in the aqueous phase. The introduction of CYANEX 923 in the membrane composition decreases the extractant losses from the pores of the support.

The phenol separation and simultaneous concentration process has been checked. The influences of the initial concentration of phenol in the feed solution and sodium hydroxide in the stripping phase and the membrane composition on the separation rate have been investigated in a single-pass mode. The analysis of the membrane composition influence has been performed according to the steady-state mass transfer conservation equation and the associated boundary conditions, leading to the mass transfer parameters of the process     

Study of the copper leaching in the wet oxidation of phenol with CuO-based catalysts: Causes and effects

Catalytic wet oxidation of phenol as a model pollutant has been performed in a three phase fixed-bed reactor (FBR) by using a commercial catalyst based on copper oxide in order to analyze the variables affecting significantly the copper leaching. It has been found that temperature has an almost negligible influence in the range studied (70–160 °C). On the contrary, an important effect of the pH value was noticed. The copper leaching reduces when the pH of the solution fed to the reactor increases, being almost negligible at pH ≥ 5. Moreover, the composition of the reaction media also influences the leaching. Higher copper concentrations than those expected by the effect of the acid aqueous media have been measured in the reactor effluent when phenol, catechol, hydroquinone, p-benzoquinone and maleic acid are present in the reaction media. On the contrary, oxalic acid has a negative influence on the leaching, since it captures the copper in solution to form copper oxalate which precipitates on the catalyst surface. For a previously acidified medium, the acetic and formic acids do not have any other effect on the copper leaching. It has been also demonstrated that as copper in solution decreases, so does phenol conversion, because the homogeneous catalysis contributes significantly to the oxidation reactions even in fixed-bed reactors.     

Electrochemical pre-treatment of effluents containing chlorinated compounds using an adsorbent

Electrochemical pre-treatment of industrial wastewater to remove refractory and/or toxic organic components, making them more amenable to biological treatment, is likely to be more cost-effective than using a physical or chemical process for complete organic removal. This paper demonstrates the use of a carbon-based adsorbent material that preferentially removes chlorinated organic compounds. Electrochemical regeneration of the adsorbent is shown to be a quick, easy and cheap process, because the adsorbent is both highly electrically conducting and non-porous. High regeneration rates over a number of cycles were obtained by passing a charge of 25 C g⁻¹ through a bed of adsorbent particles, at a current density of 20 mA cm⁻² for 10 min. The energy required to remove a kg of COD from an industrial wastewater was calculated to be 27 kWh.     

Synthesis, characterization of bimetallic Sn-Zn-MCM41 and its catalytic performance in the hydroxylation of phenol

A series of Sn-Zn modified-MCM41 has been synthesized by direct hydrothermal method and characterized using ICP, XRD, TG/DTA, FT-IR, HRTEM and N_2-adsorption techniques. Catalytic performances of the obtained materials were evaluated in the hydroxylation of phenol with H₂O₂. Results indicated that all the samples exhibited typical hexagonal arrangement of mesoporous structure with high surface area and the heteroatoms were probably incorporated into the framework of MCM41. Catalytic tests revealed that the bimetallic incorporated materials were effective catalysts in the hydroxylation of phenol. The conversion of phenol could be reach to 56.8% for the catalysts with Sn: Zn: Si = 2.69: 4.57: 100 (molar ratio) under the optimized reaction conditions. Moreover, the materials containing Sn and Zn exhibited higher catalytic activity than monometallic Sn and Zn modified MCM41.     

HT-730改性酚醛-丁腈胶粘剂的研制

对酚醛-丁腈胶粘剂进行改性，添加5．0％的硅烷偶联剂，改善了酚醛-丁腈胶粘剂的工艺性能，提高了粘接强度，特别是降低了酚醛-丁腈胶对环境湿度的敏感性。研制的HT-730胶在环境湿度90％时仍有很高的粘接强度，同时老化性能和适用期并没有受到影响。     

Modeling of batch phenol biodegradation in internal loop airlift bioreactor with gas recirculation by Candida tropicalis

A mathematical model for simulating the dynamic behaviors of batch phenol biodegradation processes in internal loop airlift bioreactor (ILAB) with gas recirculation using free cells of the yeast Candida tropicalis was established by coupling the fluid dynamic model and the mass balance model. Based on the coupling arithmetic, the program for evaluating batch phenol biodegradation processes was achieved. The predicted results of linear liquid velocities, gas holdups, linear gas velocities, cell and phenol concentration profiles in the riser and the downcomer of the ILAB with gas recirculation agreed very well with the corresponding experimental data, and the applicability and reliability of this proposed model were validated.     

Iron species incorporated over different silica supports for the heterogeneous photo-Fenton oxidation of phenol

Iron-containing catalysts have been prepared following different synthesis routes and silica supports (amorphous, zeolitic and mesostructured materials). Activity and stability of these materials were assessed on the photo-Fenton degradation of phenolic aqueous solutions using near UV irradiation (higher than 313 nm) at room temperature and initial neutral pH. Their catalytic performance was monitored in terms of phenol and total organic carbon (TOC) conversions. Aromatic compounds and carboxylic acids as by-products coming from incomplete mineralization of phenol as well as the efficiency of each catalytic system in the use of the oxidant were also studied. Stability of the materials throughout the photo-Fenton reaction was evaluated in terms of metal leachibility. Activity and stability depend on the environment of iron species and features of silica support. The evolution of pH with the reaction time and their relationship with TOC degradation and leaching degree has been discussed. A nanocomposite material of crystalline iron oxides supported over mesostructured SBA-15 material is shown the most successful catalyst for degradation of phenolic aqueous solutions by photo-Fenton processes, achieving an outstanding overall catalytic performance accompanied with a noteworthy stability.     

Phenolic epoxidised polyurethane coating for petroleum tanks from available raw materials

Summary  Linseed oil was epoxidised by 60% per acetic acid to produce epoxidised linseed oil. By this process, two new groups entered the molecule (epoxy group and hydroxyl group). These groups were detected by using infrared (IR) analysis. Product (I) reacted with phenol in different ratios by weight percent to produce Phenolic epoxidised resin (II). Product (II) reacted with toluene diisocyanate to produce product (III), Phenolic epoxidised polyurethane, which had an excellent adhesion character. Product (III) was examined chemically and physically according to ASTM-API standard methods. The results provide encouragement for their use as a petroleum tank coating material. They can be used as a one-layer coating which combines the properties of more than coating of two layers because it combines more than one function group.     

Adsorption properties of tetradecyl- and hexadecyl trimethylammonium bentonites

This study concerns the adsorption properties of organo-bentonites obtained through the modification performed at 25%, 50% and 100% of the cation exchange capacity (CEC) using tetradecyl trimethylammonium bromide (TDTAB) and hexadecyl trimethylammonium bromide (HDTAB). According to the XRD measurements, TDTAB and HDTAB form bilayers between the silicate layers when the montmorillonite surface is modified by 100% CEC. At 25% and 50% CEC, a random interstratification of monolayer and bilayer structures is observed. The surface area of bentonite decreases upon modification. The adsorption properties of organo-bentonites were tested using phenol as a model pollutant. Batch kinetic and isotherm studies were conducted over the concentration range from 50 to 1000 ppm at pH of 5.5. The adsorption excess isotherms of bentonites show different regions. A considerable increase was observed in the adsorption efficiency of montmorillonite modified with HDTAB at 100% CEC.