Degradation Of Hydroquinone Research Articles

Stoichiometry and kinetic of the aerobic oxidation of phenolic compounds by activated sludge

The aerobic degradation of phenol (PH), catechol (CA), resorcinol (RE), pyrogallol (PY), and hydroquinone (HY) by phenol-acclimated activated sludge was investigated. A Haldane-type dependence of the respiration rate on PH, RE, and HY was observed; CA and PY exhibited a biphasic respiration pattern. According to the initial biodegradation rate, tested compounds were ordered as follows: CA>PH>>PYRE>HY. Also, they exhibited the following degree of toxicity to their own degradation: PY>>CARE>>PH>HY. Oxidation coefficients for PH, PY, RE, and HY were constant as a function of the consecutive additions of the compound. Conversely, an increase of YO/S from 1 to 1.5molO2molCA−1 was observed during repeated additions of CA. The role of some enzymes involved in the aerobic degradation pathways of the tested compounds is discussed and related to the obtained results.

Degradation of Hydroquinone by Pulsed Corona Discharge Combined with Ozone Process

Owing to toxicity of pharmacy wastewater to microbe, commonly used biodegradation is often limited in application; accordingly exploiting new ways of the wastewater treatment with high efficiency is a hot topic. As a new efficient advanced oxidation, pulsed corona discharge combining with ozone is attracting more and more attention. In this study, a special reactor was designed, in addition, the removal of TOC(Total Organic Carbon) and COD (Chemical Oxygen Demand)of simulant pharmacy wastewater containing hydroquinone (500mg/L) by pulsed corona discharge combining with ozone were investigated . It was showed that the TOC and COD removal (53.8% and 72.3%) by the combined technology was much higher than by using the two techniques in series when all the samples were treated 40mins.The two methods in combination have a synergistic effect. TOC and COD removal could be improved obviously when NaCl feed concentration increased from 0 to1000 mg/L, yet further increase in NaCl feed led to a markedly decrease removal efficiency of TOC and COD.

Photocatalytic degradation of hydroquinone using HFO supported polymeric material

Photocatalytic degradation of hydroquinone (HQ) has been investigated using polystyrene-divinyl benzene polymeric hybrid ion exchange (HIX) resin. The polymeric material was modified with iron cations and thermally treated at 60°C to produce nano FeOOH species (HFO) supported on the HIX polymer and denoted as Fe-HIX. The obtained material was characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). The data obtained for the degradation of HQ indicate that the addition of Fe-HIX material to the degraded HQ solution greatly enhance the rate of degradation in the presence of H2O2. Since the rate of degradation was found to be governed by the adsorption mechanism, so the adsorption isotherms were established in dark at different pH values and different doses from resin correlated with the obtained data of degradation.

Cloning and characterization of a gene cluster involved in the catabolism of p-nitrophenol from Pseudomonas putida DLL-E4

A 9.2-kb DNA fragment encoding the enzymes of a p-nitrophenol (PNP) catabolic pathway from Pseudomonas putida DLL-E4 was cloned and sequenced. Ten open reading frames (ORFs) were found and five ORFs were functionally verified. The pnpA and pnpC gene products were purified to homogeneity by Ni-NTA chromatography. PnpA is a flavin adenine dinucleotide-dependent single-component PNP 4-monooxygenase which converts p-nitrophenol to para-benzoquinone in the presence of NADH and FAD. PnpC is a 1,2,4-trihydroxybenzene (BT) 1,2-dioxygenase which converts BT to maleylacetate. The hydroquinone (HQ) dioxygenase (PnpC1C2) multi-component protein complex was expressed in Escherichia coli via plasmid pET-pnpC1C2 containing pnpC1 and pnpC2. This complex converts HQ to γ-hydroxymuconic semialdehyde. pnpR is a lysR-type regulator gene. PnpR is a positive regulator involved in HQ degradation in pnp gene cluster. These results demonstrate that a pathway encoded by the pnp gene cluster is involved in degradation of HQ and BT in P. putida DLL-E4.

Comparative evaluation of polymer surface functionalization techniques before iron oxide deposition. Activity of the iron oxide-coated polymer films in the photo-assisted degradation of organic pollutants and inactivation of bacteria

The preparation of iron oxide-coated polymer films and their photocatalytic activity in organic pollutants degradation and bacterial inactivation is described. Polyvinyl fluoride (PVF), polyethylene (PE) and polyethylene terephtalate (PET) films were used as catalyst supports. Polymer surfaces were functionalized by vacuum-UV radiation (V-UV) and radio-frequency plasma (RF-P); and also by photo-Fenton oxidation (P-FO) and TiO 2 photocatalysis (Ti-PC) in solution. These pre-treatments were performed to improve iron oxide adhesion on the commercial polymer surface. The functionalized polymers films (P f) were afterward immersed in an aqueous solution for the deposition of iron oxide layer by hydrolysis of FeCl 3. The photocatalytic activities of iron oxide-coated functionalized polymers films (P f-Fe oxide) prepared by different methods were compared during hydroquinone degradation in presence of H 2O 2. RF-P and Ti-PC pre-treated polymers showed significantly higher photocatalytic activity and long-term stability during processes leading to pollutant abatement, if compared with not treated ones (NT), although similar leaching of iron was observed for all the materials. PET bottles (PET b) were used as reactor and catalyst supports. The produced PET b f-Fe oxide surfaces were efficient in photo-assisted bacterial inactivation in the presence of H 2O 2, and no dissolved iron species were detected in solution.

Selection of the Mutants with High Hydroquinone Degradation Ability of Serratia Marcesscen by Plasma Mutation

In this study, an efficient way by plasma induced mutation was applied to improve the hydroquinone degradation capacity of Serratia marcescens AB 90027 (SM27). The results showed that combined with the selection of hydroquinone tolerance, the mutant with high hydroquinone degradation ability induced by plasma could be achieved. The best dose for plasma mutation was 15 s, which showed a 47.0% higher positive mutation ratio. Besides, the aimed mutant was markedly different from the parent strain (SM27) in colonial traits while cultivated on Kings media. Finally, the hydroquinone degradation ratio reached 70.5% using the induced mutant strain with 1500 mg/L hydroquinone (HQ) after 15 days of cultivation as the selective conditions; however, it was only 46.7% for SM27. The improvement of the degradation capacity by the induced mutant with a high concentration of HQ selection was attributed to its faster growth and higher hydroquinone tolerance compared with that of the parent strain.

ZnO activation by using activated carbon as a support: Characterisation and photoreactivity

The effect of the mixing ZnO with different portions of activated carbon (AC) has been studied. The resulting catalysts were characterised and evaluated in the photocatalytic decomposition of aqueous pollutants. Changes in the catalyst colour and in the FTIR vibration bands of the surface hydroxyl groups were recorded. νOH vibrations were shifted to lower wavenumbers as AC loading increased, demonstrating modification of the acid-base character of the catalysts. Laser scattering studies showed that AC loading leads to smaller ZnO particles. BET surface area measurements and scanning electron micrograph (SEM) analysis showed agglomeration of ZnO particle pores in the AC structure. Results showed that in addition to a synergistic effect of the AC-ZnO combination, AC content modifies the ZnO particle properties and consequently photocatalytic behaviour. This was evident in phenol degradation experiments where changes in the concentration profiles of the catechol and hydroquinone degradation intermediates, were observed. However, the AC-ZnO catalysts were less efficient than pure ZnO in the degradation of 2,4-dichlorophenol (DCP). This seems to be due to the strong adsorption of the DCP molecule on AC, resulting in lower diffusion to the catalytic ZnO and thus a lower rate of photocatalysis.

Synergistic effect of TiO2 and iron oxide supported on fluorocarbon films: Part 2: Long-term stability and influence of reaction parameters on photoactivated degradation of pollutants

The degradation of hydroquinone (HQ) and nalidixic acid (NA) mediated by TiO2 and iron oxide immobilized on functionalized polyvinyl fluoride films (PVFf–TiO2–Fe oxide) in the presence of H2O2 under simulated solar light has been examined. The results show that the contribution of homogeneous photo-Fenton oxidation to the initial mineralization process was low. The degradation rates were not dependant of initial pH. Heterogeneous photocatalytic activity of PVFf–TiO2–Fe oxide was enhanced by increasing temperature, NaCl addition and by long-term utilization.The PVFf–TiO2–Fe oxide surface was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) at different states of utilization. Correlations between the catalyst surface composition and degradation kinetics are discussed. Long-term stability evaluated by repetitive pollutant degradations was outstanding. The presence of TiO2 seems to (i) limit contact between polymer film and highly reactive radicals in the solution and (ii) act as a charge trap. Moreover, during the photocatalysis mediated by PVFf–TiO2–Fe oxide, some leaching of supported iron increased the amount of the top TiO2 layer exposed to the light increasing the synergistic effects between the two oxides leading to enhanced pollutant degradation.

Identification and Characterization of Catabolicpara-Nitrophenol 4-Monooxygenase andpara-Benzoquinone Reductase fromPseudomonassp. Strain WBC-3

Pseudomonas sp. strain WBC-3 utilizes para-nitrophenol (PNP) as a sole source of carbon, nitrogen, and energy. In order to identify the genes involved in this utilization, we cloned and sequenced a 12.7-kb fragment containing a conserved region of NAD(P)H:quinone oxidoreductase genes. Of the products of the 13 open reading frames deduced from this fragment, PnpA shares 24% identity to the large component of a 3-hydroxyphenylacetate hydroxylase from Pseudomonas putida U and PnpB is 58% identical to an NAD(P)H:quinone oxidoreductase from Escherichia coli. Both PnpA and PnpB were purified to homogeneity as His-tagged proteins, and they were considered to be a monomer and a dimer, respectively, as determined by gel filtration. PnpA is a flavin adenine dinucleotide-dependent single-component PNP 4-monooxygenase that converts PNP to para-benzoquinone in the presence of NADPH. PnpB is a flavin mononucleotide-and NADPH-dependent p-benzoquinone reductase that catalyzes the reduction of p-benzoquinone to hydroquinone. PnpB could enhance PnpA activity, and genetic analyses indicated that both pnpA and pnpB play essential roles in PNP mineralization in strain WBC-3. Furthermore, the pnpCDEF gene cluster next to pnpAB shares significant similarities with and has the same organization as a gene cluster responsible for hydroquinone degradation (hapCDEF) in Pseudomonas fluorescens ACB (M. J. Moonen, N. M. Kamerbeek, A. H. Westphal, S. A. Boeren, D. B. Janssen, M. W. Fraaije, and W. J. van Berkel, J. Bacteriol. 190:5190-5198, 2008), suggesting that the genes involved in PNP degradation are physically linked.

Oxidative degradation and associated mineralization of catechol, hydroquinone and resorcinol catalyzed by birnessite

Abiotic degradation and mineralization of catechol, hydroquinone, and resorcinol catalyzed by birnessite (δ-MnO 2) was investigated. Studies were carried out by monitoring changes of pE versus time and pH versus time of the reaction systems during the initial 10 h reaction period and release of CO 2 and associated reactions at the end of a 90 h reaction period. The reactions under anoxic condition were compared with aeration condition. The reactions were carried out in suspensions at initial pH of 6.0 under air and N 2 atmosphere at room temperature and free of microbial activity. These results indicated that kinetic-related changes of pE versus time and pH versus time were dependent on structural characteristics of phenolic compound and aeration or anoxic condition in the reaction system. The sequence of the mineralization of phenolic compounds catalyzed by δ-MnO 2 in presence of air expressed by CO 2 release was catechol > hydroquinone ⩾ resorcinol and the differences were significant. However, under an N 2 atmosphere the amounts of CO 2 released were drastically reduced with insignificant differences among the three reaction systems. Further, phenolic compound degradations, dissolved and adsorbed Mn, and oxidation state of Mn in δ-MnO 2 were also determined to elucidate the catalytic efficacy mediated by both O 2 and δ-MnO 2 in the reaction systems.

Bacterial inactivation and organic oxidation via immobilized photo-Fenton reagent on structured silica surfaces

A woven inorganic silica fabric loaded with Fe-ions (EGF-Fe) was tested under simulated solar light during hydroquinone degradation. The abatement of hydroquinone was observed to attain about ∼80% within 3h. The photo-catalyst was also tested to inactive Escherichia coli K12 at “natural” pH and in the presence of a low concentration of H2O2. Addition of H2O2 (10mgL−1) did not by itself to bacterial inactivation. Total bacterial inactivation was mediated by EGF-Fe fabrics in the presence of H2O2 (10mgL−1) under solar light irradiation. A sample containing active (culturable) bacteria (∼105CFUmL−1) decreased to values <1CFUmL−1 within 3h reaction. Fe-mediated homogeneous process decreased the bacterial CFU content by about two orders of magnitude within 4h. During the degradation of hydroquinone only a small amount of iron ions were found in solution of about 1.2mgL−1, within 90min decreasing to values ≤0.5mgL−1 after 180min. The leaching of Fe-ions did not affect the photo-catalyst performance since EGF-Fe fabric did not deactivate after five or more cycles. The Fe-ions founds in solution mineralized hydroquinone to levels below 37% of its initial content. The present study presents the first report on the beneficial role of a heterogeneous iron supported catalyst leading to efficient bacterial inactivation in aqueous solution with iron leaching <0.1mgL−1, the detection limit for Fe-analysis in solution. No bacterial re-growth was observed during a post-irradiation period up to 24h in the dark.

Investigation into NanoTiO2/ACSPCR for Decomposition of Aqueous Hydroquinone

The suspended TiO2 powder enjoys free contact with pollutant molecule in a photocatalytic reactor; it can generally achieve better efficiency than the immobilized TiO2 catalysts. However, the separation and reuse of this catalyst powder from treated water often limit its application in practice. An adsorptive activated carbon-supported titanium dioxide photocatalyst TiO2/AC was prepared using nanosized titanium dioxide (anatase) immobilized on activated carbon powder by a novel preparation technique with polyacrylic ester emulsion. Meanwhile, the heterogeneous photocatalytic decomposition of aqueous hydroquinone over the ultraviolet irradiated TiO2/AC photocatalyst was carried out with high decomposition efficiencies in a slurry photocatalytic reactor (SPCR), which provided the effective contact of TiO2/AC photocatalyst and reactant. The pH value, the ratio of TiO2/hydroquinone, the aerating, and the concentration of H2O2 on photocatalytic decomposition of hydroquinone were discussed in detail. Experimental results showed that not only did the photocatalyst have a high adsorption performance and a good photocatalytic activity for hydroquinone but also the catalyst was easily separated from SPCR and recycled as well. Moreover, it was found that the reaction kinetic fixed the pseudo-first-order kinetic equation, which provided a detailed kinetic understanding of photocatalytic degradation of hydroquinone in SPCR.

Comparison of Antioxidant Activity of Green Tea Extract to Commercial Antioxidants in 2% Hydroquinone Cream

ABSTRACT Powdered dry leaves of green tea were extracted with methanol. Green tea extract was tested for antioxidative activity in comparison with antioxidants (sodium metabisulfite and butylated hydro-xytoluene) at 0.1,0.5,1.0, and 2.0% w/w in 2% w/w hydroquinone cream. The systems were incubated in a dark room at 25°C ± 0.5°C and 45°C ± 0.5°C for 3 months. The physical stability and the percentages of hydroquinone remaining after 2 weeks and 1, 2, and 3 months were determined by UV spectrophotometry at 294 nm according to official standard procedures. The experiment revealed that oxidation degradation of hydroquinone was accelerated by heat even with existence of antioxidants. The green tea extract at 1.0 and 2.0% can be used as a double action (both water- and oil-soluble) antioxidant, having 77 and 81% (at 25°C), and 58 and 62% (at 45°C) hydroquinone remaining, respectively, after 3 months. These results suggested the possibility of using the green tea extract as an effective natural antioxidant for substances that are oxidation-susceptible.

Degradation of phenolic compounds with hydrogen peroxide catalyzed by enzyme from Serratia marcescens AB 90027

In this paper, the degradation of phenolic compounds using hydrogen peroxide as oxidizer and the enzyme extract from Serratia marcescens AB 90027 as catalyst was reported. With such an enzyme/H2O2 combination treatment, a high chemical oxygen demand (COD) removal efficiency was achieved, e.g., degradation of hydroquinone exceeded 96%. From UV–visible and IR spectra, the degradation mechanisms were judged as a process of phenyl ring cleavage. HPLC analysis shows that in the degradation p-benzoquinone, maleic acid and oxalic acid were formed as intermediates and that they were ultimately converted to CO2 and H2O. With the enzyme/H2O2 treatment, vanillin, hydroquinone, catechol, o-aminophenol, p-aminophenol, phloroglucinol and p-hydroxybenzaldehyde were readily degraded, whereas the degradation of phenol, salicylic acid, resorcinol, p-cholorophenol and p-nitrophenol were limited. Their degradability was closely related to the properties and positions of their side chain groups. Electron-donating groups, such as –OH, –NH2 and –OCH3 enhanced the degradation, whereas electron-withdrawing groups, such as –NO2, –Cl and –COOH, had a negative effect on the degradation of these compounds in the presence of enzyme/H2O2. Compounds with −OH at ortho and para positions were more readily degraded than those with –OH at meta positions.

Investigation of 2-ethylanthraquinone degradation on palladium catalysts

The hydrogenation of 2-ethylanthraquinone (eAQ) was performed over alumina, silica and carbon supported palladium catalysts. Present research is concentrated on the process of eAQ degradation and especially a role of the type of catalyst is examined. Degradation of eAQ in the catalytic experiments has been discussed on the basis of reaction pattern reported for the reduction of carbonyl groups in anthraquinone by standard procedures (Zn, Sn, NaBH 4). Various by-products formed by degradation of hydroquinone (eAQH 2) have been identified by GC–MS. They are the product of C O hydrogenolysis such as 2-ethylanthrone (eAN, two isomers), 2-ethylanthracene (eANT) and the products of eAN hydrogenation (H 4eAN, two isomers). Tautomerization of partially and fully saturated hydroquinones produces OXO-isomers [two isomers OXO-H 4(1,2) and OXO-H 8(1,2)]. Reduction of eAQ with NaBH 4 gives 2-ethyl-9,10-dihydroxy-9,10-dihydroanthraquinone, intermediate product in the consecutive reactions occurring during the hydrogenolysis of C O and resulting in eAN. A difference in performance of 0.5% Pd/C, 0.5% Pd/SiO 2 and 0.5% Pd/Al 2O 3 catalysts is related with their reactivity in degradation of eAQH 2. Much higher reactivity in the whole degradation process and especially in the formation of intermediate product exhibits alumina-supported catalyst.

Decomposition of phenol by hybrid gas/liquid electrical discharge reactors with zeolite catalysts

Application of hybrid gas/liquid electrical discharge reactors and a liquid phase direct electrical discharge reactor for degradation of phenol in the presence and absence of zeolites have been investigated. Hybrid gas/liquid electrical discharges involve simultaneous high voltage electrical discharges in water and in the gas phase above the water surface leading to the additional OH radicals in the liquid phase and ozone formation in the gas phase with subsequent dissolution into the liquid. The role of applied zeolites, namely NH 4ZSM5, FeZSM5 and HY, were also studied. Phenol degradation and production of primary phenol by-products, catechol and hydroquinone, during the treatment were monitored by HPLC measurements. The highest phenol removal results, 89.4–93.6%, were achieved by electrical discharge in combination with FeZSM5 in all three configurations of corona reactors. These results indicate that the Fenton reaction has significant influence on overall phenol removal efficiency in the electrical discharge/FeZSM5 system due to the additional OH radical formation from hydrogen peroxide generated by the water phase discharge.

Biodegradation of resorcinol and catechol by denitrifying enrichment cultures

AbstractWe examined the anaerobic degradation of catechol (1,2‐dihydroxybenzene), resorcinol (1,3‐dihydroxybenzene), and hydroquinone (1,4‐dihydroxybenzene), which are widely used industrial reagents and central intermediates in the biodegradation of numerous aromatic compounds. Anaerobic denitrifying enrichments were established with sediments from an estuarine tidal strait in New Jersey, USA. The three dihydroxybenzene isomers were provided as a sole carbon source in separate enrichment series. Resorcinol‐ and catechol‐degrading consortia used their respective substrates over repeated feedings. Initial loss of hydroquinone was observed, but activity could not be maintained. The degradation of resorcinol and catechol was coupled to denitrification and was dependent on nitrate or nitrite as an electron acceptor. Nitrate consumption and N2 production corresponded to the stoichiometric values predicted for the oxidation of dihydroxybenzenes to CO2.

Isolation and Characterization of Tn5-Induced Mutants ofSphingomonas paucimobilisDefective in 2,5-Dichlorohydroquinone Degradation

Sphingomonas paucimobilis UT26 uses γ-hexachlorocyclohexane (γ-HCH) as a sole source of carbon and energy. In UT26, γ-HCH is converted to 2,5-dichlorohydroquinone (2,5-DCHQ). To clone a gene that is involved in the degradation of 2,5-DCHQ, a Tn5 mutation was introduced into UT26, and three mutants (UT102, UT103, and UT116) defective in 2,5-DCHQ degradation were visually selected by spraying γ-HCH solution on the colonies. 2,5-DCHQ and hydroquinone (HQ) degradation activities of these three mutants and UT26 were analyzed using resting cells. The three mutants had different phenotypes. It was also demonstrated that 2,5-DCHQ and HQ degradation activities were inducibly expressed in UT26 in the presence of 2,5-CHQ.

Formation of hydroxyl radicals, hydrogen peroxide and aqueous electrons by pulsed streamer corona discharge in aqueous solution

The initiation reaction rate constants for the formation of hydroxyl radicals, hydrogen peroxide, and aqueous electrons using a pulsed streamer corona discharge in aqueous solutions are determined in the present study. The free radical scavenging property of carbonate ions was used to determine the initiation rate constants for the formation of hydroxyl radicals and hydrogen peroxide from the pulsed streamer corona discharge. The effects of average current, voltage, and power input on the initiation rate constants were also studied. A reactor model including known chemical reaction kinetics was developed for the degradation of phenol, and the initiation rate constant for aqueous electrons was determined by fitting the experimental data of phenol degradation to the model. Transient concentration profiles predicted by the model were compared to those of experiments for the formation of hydrogen peroxide in deionized water and for the degradation of hydroquinone. It was observed that the model results match experimental results satisfactorily for the formation of hydrogen peroxide and qualitatively follow the experimental results for the degradation of hydroquinone. The model was improved by considering that the reaction rate constants vary with the current in the reactor. The current was observed to vary with time for the cases where no salts were added to the reactor. It was observed that the improved model follows the experimental results satisfactorily for high initial concentrations (> 5.4 × 10 −5 M) of hydroquinone.

Complete anaerobic oxidation of hydroquinone by Desulfococcus sp. strain Hy5: indications of hydroquinone carboxylation to gentisate

The sulfate-reducing strain Hy5 was able to grow with hydroquinone as sole source of carbon and energy. In experiments with dense cell suspensions, several indications were found that gentisate was the first intermediate in anaerobic degradation of hydroquinone: (1) degradation of hydroquinone was accelerated by addition of bicarbonate; (2) cell suspensions grown with hydroquinone oxidized gentisate at a rate similar to that of suspensions grown with gentisate, whereas the latter were not able to degrade hydroquinone in the presence of chloramphenicol; (3) in SDS-PAGE analysis of cell-free extracts of strain Hy5, two additional protein bands were found after growth with hydroquinone that were not detected in cells grown with gentisate, probably representing a hydroquinone carboxylating enzyme. A corresponding enzyme activity could not be detected. In cell-free extracts of hydroquinone-grown strain Hy5, the specific acyl-CoA ligase activity with gentisate as substrate was detected at 70 nmol x mg-1 x min-1. Gentisyl-CoA was enzymatically reduced to several unidentified nonaromatic products in the presence of dithionite-reduced methyl viologen.