China
Africa
Explore chapters and articles related to this topic
Bacterial Biodegradation of Phenolics and Derivatives of Phenolics
Published in M.H. Fulekar, Bhawana Pathak, Bioremediation Technology, 2020
Many industries are releasing highly aromatic compounds as waste. Thus, industrial effluent contains phenolics and their derivatives (El-Ashtoukhy et al., 2013). All these aromatic compounds accumulate in the environment—some of these compounds are naturally degraded from environmental flora, and the remaining materials are deposited in the natural environment (Chakraborty et al., 2010). These deposited compounds are hazardous to human, animal, and flora. Some aromatic compounds are carcinogenic, mutagenic, and teratogenic (Olaniran and Igbinosa, 2011). Nonbiodegradable aromatic compounds must be treated by biodegradable compounds or less toxic compounds (El-Nass et al., 2009. Aromatic pollutants such as phenolics and their derivatives are polluting the surface water, underground water, and soil. It causes a big concern worldwide (Krastanov et al., 2013). Phenolics and their derivatives such as phenol, o-cresol, m-cresol, p-cresol, nitrophenol, and resorcinol are highly toxic to human, animal, aquatic life, and others (Gonzalez et al., 2016). Some of these compounds are highly toxic and difficult to remove from the environment (El-Naas et al., 2010).
Organic Compounds
Published in Epstein Eliot, The Science of Composting, 2017
Sawhney and Kozloski (1984) reported on toxic organics in landfill leachates. Although it is difficult and wrong to extrapolate their data to potential leachate from compost, their study does provide a perspective. Five landfills in Connecticut were studied. One town had considerably higher levels of volatile organic compounds than the others. The volatile organic compounds detected included acetone, isopropyl alcohol, methyl ethyl ke-tone, 2-butyl alcohol, benzene, toluene, and methyl isobutyl ketone. Nonvolatile compounds detected were toluene, phenol, m-cresol, p-cresol, m-ethyl phenol,p-ethyl phenol, and Cx-acids. The authors indicated that the presence of 0.1 to 1.5 mg/L of the substituted phenols in the leachate was probably the result ofleaching through the soil under anaerobic conditions. In a previous paper, Isaacson and Sawhney (1983) found that under aerobic conditions, sorption by clays and soil of organic compounds was irreversible.
Biopolymers as Supports for Heterogeneous Catalysis: Focus on Chitosan, a Promising Aminopolysaccharide
Published in Arup K. SenGupta, Ion Exchange and Solvent Extraction, 2007
Eric Guibal, Thierry Vincent, Francisco Peirano Blondet
The hydrogenation of phenol and cresols has been investigated by Tang et al. using SiO2-chitosan-Pd catalyst.324,362 They observed that the conversion of phenol is very selective for cyclohexanone, preventing further hydrogenation of the product to cyclohexanol, as it may occur in conventional systems involving Pt catalysts; more specifically, the hydrogenation of cyclohexanone, described by Shen et al. using SiO2-casein-Fe (see above),257 is not observed. The conversion reaches a maximum with the chitosan:Pd molar ratio close to 8, at 70°C in cyclohexane as the solvent. A progressive deactivation of the catalyst is observed, though the conversion maintains its selectivity over five cycles. The reactivity is compared for phenol and cresols; the reactivity is controlled by the substituents and their position on the phenolic cycle: phenol > m-cresol > p-cresol ≫ o-cresol.
Photodeoxygenation of phenanthro[4,5-bcd]thiophene S-oxide, triphenyleno[1,12-bcd]thiophene S-oxide and perylo[1,12-bcd]thiophene S-oxide
Published in Journal of Sulfur Chemistry, 2019
Satyanarayana M. Chintala, John T. Petroff II, Andrew Barnes, Ryan D. McCulla
Sulfoxides 6O–8O oxidized toluene to benzaldehyde, benzyl alcohol, o-cresol, m-cresol and p-cresol. The ratios of CH3:ring oxidation obtained for DBTO and 6O–8O were 1:3, 1:4, 1:2 and 1:2, respectively. Although the ratios of CH3:ring oxidation obtained for 6O–8O are similar to the CH3:ring oxidation ratio obtained for DBTO, the total product yields of 6O–8O were lower to that of DBTO. The total product yields of toluene oxidation obtained for DBTO and 6O–8O were 42 ± 6%, 27 ± 2%, 15 ± 4%, and 28 ± 2%, respectively. This is because the yields of cresols (ring oxidation) obtained for 6O–8O were lower compared to DBTO. The ratios of the oxidized products obtained for 6O–8O suggests O(3P) formation. However, the lower total product yields suggest other photodeoxygenation pathways that do not generate O(3P).
Multisubstrate specific flavin containing monooxygenase from Chlorella pyrenoidosa with potential application for phenolic wastewater remediation and biosensor application
Published in Environmental Technology, 2018
The activity of the enzyme towards a broad range of phenolics (unsubstituted and substituted phenols) would be beneficial for its application in remediation technologies of phenol. Apart from this, broad substrate specificity for a variety of phenolics would further highlight its potential application for developing phenolic biosensors. This makes the study of multisubstrate specificity of phenol hydroxylase important. In addition to phenol, the purified enzyme has broad substrate specificity acting on 4-nitrophenol; isomeric diphenols such as catechol and resorcinol, isomeric methylphenols such as o-cresol, m-cresol and p-cresol; halogen-substituted phenol such as 2-chlorophenol, 4-chlorophenol, 2,4-chlorophenol and p-bromophenol; amino-substituted phenols such as 2-aminophenol and 3-aminophenol; m-hydroxybenzaldehyde and p-hydroxybenzaldehyde and p-hydroxylbenzoic acid (Figure 14). Neujhar and Gall [10] reported similar substrate specificity of phenol hydroxylase from Trichosporon cutaneum against phenol, isomeric diphenols, halogen-substituted phenol, amino-substituted phenol and, to lesser extent, on cresols and hydroxybenzoates. Figure 13 shows that the purified enzyme shows higher activity (38.34%) with 4-chlorophenol as substrate when compared to 2-chlorophenol. This is in accordance with the findings of Neujhar and Gall [10]. Purified phenol hydroxylase from Trichosporon cutaneum showed higher activity for 4-chlorophenol (29%) over 2-chlorophenol (10%). The purified enzyme had comparatively lower activity against 2,4-dichlorophenol since higher chlorinated phenols are degraded less rapidly than lower chlorinated phenols [52]. As evident from Figure 13, the activity of the purified enzyme against three isomers of cresol was in the order: o-cresol > p-cresol > m-cresol. Ahmad and Kunhi [53] reported similar difference in cresol isomer degradation rates in Pseudomonas sp. CP4. Similarly, the activity of the purified enzyme against 2-aminophenol was higher by 12.12% than that of 3-aminophenol, as seen in Figure 13. The activity of purified enzyme against isomeric diphenols is of the order: quinol > resorcinol > catechol, which is in accordance to catalytic activity of phenol hydroxylase from Trichosporon cutaneum against isomeric diphenols [10].
Separation of m-cresol and p-cresol by NaZSM-5 with different Si/Al ratios
Published in Environmental Technology, 2023
Jiaying Zhu, Yanyang Wu, Bin Wu, Kui Chen, Lijun Ji
Cresols generally refer to a mixture of o-cresol, m-cresol, and p-cresol, which are mainly found in crude oil and coal tar. Cresol isomers are in high demand in the production of antioxidants [1], phenolic resins [2], colourants [3], preservatives [4], and disinfectants [5]. o-Cresol can be obtained from cresols by normal distillation. However, it’s hard to separate m-cresol and p-cresol due to the similarities in both boiling points (202.9℃/ 202.5℃) and molecular size (0.70 nm/0.58 nm) [6]. The most commonly used separation methods of m-cresol and p-cresol include alkylation [7–9], extraction [10–13], crystallization [14–19], and adsorption [20, 21]. The first three showed limitations such as equipment erosion, environmental pollution, and high energy consumption. While adsorption has gained increasing concerns due to its less environmental pollution and energy consumption. Li [20] separated m-cresol and p-cresol through HPLC by MIL-53(Al), the purity of 96.26% and 93.23% and the yield of 96.93% and 96.59% for m-cresol and p-cresol were obtained, respectively. Xu et al. [21] investigated the adsorption of m-cresol and p-cresol on the molecularly imprinted material p-MIM-BC. The adsorption capacities were 44.9 and 7.6 mg/g for p-cresol and m-cresol, respectively, and the selectivity was greater than 5.0. Vijayakumar et al. [22] studied adsorption of m-cresol and p-cresol on Zn-Al hydroxide (Zn/Al = 0.17), where 70 mg/g m-cresol and 160 mg/g p-cresol were adsorbed and the selectivity was 2.2 with toluene as solvent. Neuzil et al. [23] modified 13X zeolite by Ba2+ and K+ ions, with which the selectivity of m-cresol and p-cresol was about 1.8. Zinnen et al. [24] studied the effect of water content (LOI) on the adsorption of m-cresol and p-cresol by X zeolite modified with Ba2+ and K + . The selectivity for p-cresol/m-cresol was 1.94 when LOI was 3.42%. Seitaro [25] separated m-cresol and p-cresol by HZSM-5 modified with Mg, P, B, Li, Na, or K ions. The percentage of adsorption capacity for p-cresol was 82%. Yue et al. [26] studied the adsorption of m-cresol and p-cresol on HZSM-5(Si/Al = 26) modified by SiCl4. m-Cresol was not adsorbed and the adsorption capacity of p-cresol was only 4.25 mg/g. Thereafter, Lee [27] used modified HZSM-5(Si/Al = 26) particles, which were filled into HPLC, to separate m-cresol and p-cresol at 373 K and 3.45 MPa. The purity of monophenol was greater than 98%. Lv et al. [6] evaluated the performance of HZSM-5(Si/Al = 470) modified by ammonium hexafluoro silicate through competitive breakthrough experiments, wherein the adsorption capacities of m-cresol and p-cresol were 8.5 and 36.7 mg/g, respectively.