Removal Of Aqueous Phenol Research Articles

Removal of aqueous phenol and phenol derivatives by immobilized potato polyphenol oxidase

Phenols containing halogens, which tend to deactivate the aromatic nuclei, constitute a significant category of highly toxic and difficult-to-degrade pollutants, which arise from a wide variety of industries. The main purpose of this study was to obtain an inexpensive immobilized enzyme for the removal of phenols. Partially purified potato polyphenol oxidase (PPO) was immobilized onto different commercial and laboratory produced carriers. Three of the obtained biocatalysts, with the highest PPO activities, namely Eupergit C250L-PPO; Celite-PPO and Cellulose M-PPO, were tested in a batch reactor for the removal of phenol, 4-chlorophenol and 4-bromophenol. In the case of 2.5 mM substrates with Eupergit C250L-PPO, an around 45% removal of 4-bromophenol was achieved, while the removals 4-chlorophenol and phenol were 35% and 20%, respectively. The reusability of Eupergit C250L-PPO for the removal of 4-chlorophenol was tested. After eight repeated tests, the efficiency of 4-chlorophenol removal by Eupergit C250L-PPO immobilizate had decreased to 55%.

Removal of Aqueous Phenol by Adsorption and Oxidation with Doped Hydrophobic Cryptomelane-Type Manganese Oxide (K−OMS-2) Nanofibers

Molecular adsorption and oxidation at manganese oxide/liquid interfaces has attracted increased interest due to its importance in the development of heterogeneous catalysts, microbial fuel cells, and selective adsorption materials. Here we report the adsorption and oxidation of phenolic compounds on Cu2+, Co3+, and Ce4+ doped K−OMS-2 nanofibers. Different metal ion doped K−OMS-2 catalysts show distinct adsorption and oxidation ability. The structure and compositions of doped K−OMS-2 catalysts were characterized by X-ray diffraction and atomic absorption analyses. The relationships of catalyst structure-catalytic properties were discussed. The adsorbed polymeric nanospheres on doped K−OMS-2 nanofibers were investigated by field emission scanning electron microscopy, Fourier transform infared spectroscopy, transmission electron microscopy, and energy dispersive X-ray analyses. These nanospheres were totally oxidized to CO2 in oxygen or air at 553−603 K catalyzed by doped and undoped K−OMS-2 itself. OMS-2 wa...

Enhancement effect of carbon adsorbent on ozonation of aqueous phenol

Removal of aqueous phenol was examined by the simultaneous use of ozone and porous carbon adsorbents possessing different porous structures and surface properties. The removal efficiency of aqueous phenol was higher with the simultaneous use of ozone and carbon adsorbents than the use of ozone alone, due to the adsorptive-concentration effect of the adsorbents. The enhancement effect of macroporous carbon cryogel beads (CCB) on the ozonation of aqueous phenol was confirmed to be greater than in microporous activated carbon beads. Introduction of acidic functional groups to CCB by liquid-phase oxidation significantly diminished the adsorptive-concentration effect of CCB, since the interaction of aqueous phenol with the surface of CCB decreased.

Immobilization of polyphenol oxidase on alginate–SiO2 hybrid gel: stability and preliminary applications in the removal of aqueous phenol

AbstractAn organic/inorganic hybrid gel of alginate–SiO2 (ALG–SiO2) was used to immobilize the partially purified potato polyphenol oxidase (PPO) for the treatment of phenolic wastewater. The influences of alginate concentration, quantity of both enzyme and tetramethoxysilane (TMOS) on immobilization were investigated. The Michaelis constant for immobilized PPO was determined as 14.7 mmol L−1 at 25 °C, and the highest activity of immobilized PPO was achieved at pH 7.0. The ALG–SiO2 immobilized PPO was more stable than the free PPO or ALG(alone) immobilized PPO. This study suggests that ALG–SiO2 immobilized PPO might be a potential tool for the removal of phenolic compounds from industrial wastewater. Copyright © 2008 Society of Chemical Industry

Removal of aqueous organic pollutants by adsorption-catalytic process using mesoporous carbon beads loaded with metal oxides

Removal of aqueous organic pollutants using an adsorption-catalytic process was examined using metal-loaded carbon cryogel beads (CCBs) which possess numerous mesopores of controlled size. Adsorption isotherms of phenol, as a model organic pollutant, on CCBs could be interpreted based on the Langmuir model, indicating the preferable adsorption of phenol on micropores rather than on mesopores. Removal of aqueous phenol was examined using metal oxide-loaded CCBs in the presence of ozone. Due to the adsorptive-concentration effect of CCBs, it proved possible to increase the phenol removal efficiency by the simultaneous use of ozone with CCBs as compared with ozone only. Of the support materials for loading metal oxides, CCBs showed the highest removal efficiency. The enhancement effect of CCBs in the removal of aqueous phenol was examined with regard to the metal species loaded, the amount of loaded metal, the size of the mesopores, and the carbonization temperature used in the preparation of CCBs.

Screening of Coprinus Species for the Production of Extracellular Peroxidase and Evaluation of the Enzyme for the Treatment of Aqueous Phenol

The production of extracellular peroxidase by twenty-five strains of Coprinus species was investigated for the purpose of its application to the removal of phenolic and other aromatic compounds from industrial waste streams. After initial screening experiments, the production of peroxidase by three superior strains of C. cinereus UAMH 4103, UAMH 7907 and IFO 30116 was monitored over a 15-day period. Peroxidase activity was detected after 3 days of growth and had reached its peak another 6 days later. The peroxidase activity appeared to increase with a corresponding depletion of glucose concentration and rapidly declined immediately after the exhaustion of glucose. The effectiveness of the cultivated C. cinereus peroxidase (CIP) for the removal of aqueous phenol was evaluated in the presence and in the absence of additives including polyethylene glycol (PEG) and chitosan, and compared with those of purified horseradish peroxidase (HRP) and Arthromyces ramosus peroxidase (ARP). The addition of PEG and chitosan enhanced the efficiency of phenol transformation catalyzed by CIP by the factor of 1.5 and 1.3, respectively. Although the efficiency of phenol transformation was higher with CIP than those with purified HRP and ARP in the absence of additives, its superiority diminished in the presence of PEG. This suggests that the by-products of fungal culture in the crude CIP solution, presumably polycarbohydrates and proteins, have protective effects on the enzyme against inactivation during catalytic transformation of phenol, and the addition of PEG provides small effects on further protection.

Removal of aqueous phenol by Arthromyces ramosus peroxidase

The removal of aqueous phenol by Arthromyces ramosus peroxidase (ARP), in the presence of high molecular weight polyethylene glycol (PEG) as a protective additive, was investigated to study (i) the stoichiometry between phenol removal and peroxide consumption, (ii) enzyme inactivation in the presence of excess hydrogen peroxide, and (iii) the effect of reactor operating mode on phenol removal. The stoichiometry was observed to increase with increasing phenol conversion, and reached a maximum value of 0.9 mol phenol/mol peroxide when nearly complete phenol conversion was achieved. Spectral scans indicated that P-670 did not form with ARP in the presence of high concentrations of peroxide and in the absence of a reducing substrate. As long as phenol concentration was not limiting, the turnover capacity varied by approximately 3% of its average value of 76 400. This indicates that only marginal improvement in the efficiency of enzyme use would be achieved by stepped addition of enzyme. Similarly, sequential addition of hydrogen peroxide over an extended period of time yielded only a slight improvement in phenol removal from the reaction mixture. Key words: Arthromyces ramosus peroxidase, enzyme inactivation, phenol removal, reactor operation, stoichiometry.

Oxidation of aqueous phenol by ozone and peroxidase

Aqueous phenol was ozonated for the first time at pH over 12. Results obtained under conditions favoring rapid generation of radicals completely eliminated the possibility deduced from the absorption theory that the indirect radical reaction might be one of the reaction pathways. Meanwhile, it was found in this study that the apparent first-order rate constant of phenol ozonation decreased logarithmically with increasing initial phenol concentration. On the other hand, despite the phenomenological resemblance between the two oxidation processes (the removal of aqueous phenol by ozone and horseradish peroxidase (HRP)), the mechanisms of the two processes were proved to be quite different. Results of this study also indicate that the integration of ozone and HRP did not improve the efficiency of phenol removal.

Removal of aqueous phenol and 2-chlorophenol with purified soybean peroxidase and raw soybean hulls

In this study, the removal of phenol and 2-chlorophenol using soybean seed-hulls in the presence of hydrogen peroxide is demonstrated. The performance of a stirred membrane reactor containing soluble purified SBP was compared with a batch stirred reactor containing raw soybean seed-hulls. The purified enzyme reactor proved to be ineffective while excellent results were obtained with the crude seed-hulls for the removal of phenol and 2-chlorophenol. Four sequential batch reactors containing raw seed-hulls achieved greater than 96% removal of phenol with a retention time of 20min in each reactor. A single batch reactor containing raw seed-hulls was effective in removing greater than 98.5% of 2-chlorophenol (initially at 1000 ppm) in less than 15 min. The performance of these reactors is comparable to existing HRP-based technology. The stability of the soybean peroxidase (SBP) enzyme was also examined in the presence of detergents (SDS, Tween 20 and Triton X-100). Low concentrations of the detergents significantly increased the enzyme activity and higher concentrations of detergents (up to 20% w/v) did not inactivate the SBP enzyme. These results demonstrate that SBP has good potential for the treatment of phenol contaminated solutions.

Methods in aquatic bacteriology Austin, B 1 vol. (15,5?sx23,5 cm), 425 + xix pages. John Wiley & Sons, New York, Chichester, 1988.

Aqueous phenol was ozonated for the first time at pH over 12. Results obtained under conditions favoring rapid generation of radicals completely eliminated the possibility deduced from the absorption theory that the indirect radical reaction might be one of the reaction pathways. Meanwhile, it was found in this study that the apparent first-order rate constant of phenol ozonation decreased logarithmically with increasing initial phenol concentration. On the other hand, despite the phenomenological resemblance between the two oxidation processes (the removal of aqueous phenol by ozone and horseradish peroxidase (HRP)), the mechanisms of the two processes were proved to be quite different. Results of this study also indicate that the integration of ozone and HRP did not improve the efficiency of phenol removal.