Study on catalytic and non-catalytic supercritical water oxidation of p-nitrophenol wastewater

Dong, Xiuqin; Gan, Zhongdong; Lu, Xianlin; Jin, Wen-Zhu; Yu, Yingzhe; Zhang, Minhua

doi:10.1016/j.cej.2015.04.134

Cited by 64 publications

(13 citation statements)

References 32 publications

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“…Mn 2 O 3 supported on Ti-Al oxide composite, prepared by incipient wet impregnation using Mg(NO 3 ) 2 , has been tested as a catalyst for oxidation of p-nitrophenol-containing wastewater, using compressed air and H 2 O 2 as oxidants, in the temperature interval from 658 K to 718 K, at 260 bar and 1-2 s reaction time. Compared to the activity of unsupported MnO 2 and Mn 2 O 3 , the supported catalysts showed the highest removal efficiency, close to 100%, at the optimal temperature for the catalytic process of 693 K [130].…”

Section: Metal Oxides For Scw Processesmentioning

confidence: 92%

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Functional Materials for Waste-to-Energy Processes in Supercritical Water

et al. 2021

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In response to increasing energy demand, various types of organic wastes, including industrial and municipal wastewaters, or biomass wastes, are considered reliable energy sources. Wastes are now treated in supercritical water (SCW) for non-fossil fuel production and energy recovery. Considering that SCW technologies are green and energetically effective, to implement them on a large scale is a worldwide interest. However, issues related to the stability and functionality of materials used in the harsh conditions of SCW reactors still need to be addressed. Here we present an overview on materials used in the SCW technologies for energy harvesting from wastes. There are catalysts based on metals or metal oxides, and we discuss on these materials’ efficiency and selectivity in SCW conditions. We focus on processes relevant to the waste-to-energy field, such as supercritical water gasification (SCWG) and supercritical water oxidation (SCWO). We discuss the results reported, mainly in the last decades in connection to the current concept of supercritical pseudo-boiling (PB), a phenomenon occurring at the phase change from liquid-like (LL) to gas-like (GL) state of a fluid. This review aims to be a useful database that provides guidelines for the selection of the abovementioned functional materials (catalysts, catalyst supports, and sorbents) for the SCW process, starting from wastes and ending with energy-relevant products.

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Section: Metal Oxides For Scw Processesmentioning

confidence: 92%

“…Most of the experiments on the oxidative catalysis in SCW are performed starting from model solutions and using MnO 2 -based catalysts [25,98,108,130,134].…”

Section: Metal Oxides For Scw Processesmentioning

confidence: 99%

Functional Materials for Waste-to-Energy Processes in Supercritical Water

et al. 2021

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“…7,8 However, from the point of view of a practical application of SCWO, there still exist the three inevitable problems of corrosion, salt deposition, and high cost that significantly hinder the development of this technology on the industrial scale. 5,9,10 At present, in a commercial SCWO system those above issues are solved primarily by two ways: special reactor design and process control method, wherein the addition of auxiliary fuel into main streams was one of the effective solutions for the latter. The oxidation of cofuel compounds not only could provide the required energy for heating reaction streams, it also could facilitate the destruction of refractory components by the co-oxidation effect.…”

Section: Introductionmentioning

confidence: 99%

“…The supercritical water oxidation (SCWO), as an environmentally friendly management approach for aqueous wastes, can achieve effective and complete harmless disposal for organic wastes. − When both the temperature and pressure rise above the critical point ( P c = 22.1 MPa, T c = 374.1 °C), the properties of water change dramatically, such as the density of hydrogen bonding and the dielectric constant in water prominently decrease, and the supercritical water (SCW) becomes a nonpolar medium. These changes contribute to the reaction of organics and oxidant in a homogeneous phase which eliminates the mass transfer resistance and therefore guarantees the high reaction rate, but gives rise to the low solubility of inorganic salts. , Not only that, the supercritical water can participate in the decomposition process of pollutants in the form of reactants or products, providing active free radicals required for the reaction and further promoting the treatment of wastes. , However, from the point of view of a practical application of SCWO, there still exist the three inevitable problems of corrosion, salt deposition, and high cost that significantly hinder the development of this technology on the industrial scale. ,, At present, in a commercial SCWO system those above issues are solved primarily by two ways: special reactor design and process control method, wherein the addition of auxiliary fuel into main streams was one of the effective solutions for the latter. The oxidation of cofuel compounds not only could provide the required energy for heating reaction streams, it also could facilitate the destruction of refractory components by the co-oxidation effect.…”

Section: Introductionmentioning

confidence: 99%

Effect Mechanism of Auxiliary Fuel in Supercritical Water: A Review

Zhang

Wang

Ren

et al. 2019

Ind. Eng. Chem. Res.

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Supercritical water oxidation is a promising alternative for treatment of wastewater and sludge. The addition of auxiliary fuel can achieve the optimization of the system. Owing to the discrepancy in the fuel parameter and reaction condition, the auxiliary fuel presents two different behavior mechanisms in supercritical water, co-oxidation and hydrothermal combustion. The process mechanism, kinetics analysis, and effect behavior for these two processes were systematically reviewed in this work. The co-oxidation between auxiliary fuel compounds, such as methanol, ethanol, isopropyl alcohol, etc. and ammonia, polychlorinated biphenyls was analyzed, and the mixing kinetics models and mechanism investigation approaches were summerized. Besides, the process analysis, kinetics model, and interaction during the supercritical hydrothermal combustion with higher concentration of auxiliary fuel were discussed. Finally, a supercritical water oxidation system with optimized auxiliary fuel was proposed and evaluated by the mechanism-based kinetics simulation, and further research needs were put forward.

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“…The migration of free radicals leads to the breakdown of the molecule and subsequent ring opening. After enol rearrangement (⑦), the resulting ketones can undergo further free radical fragmentation forming organic acids, which are further oxidized to form CO 2 and H 2 O (⑧) (Dong et al, 2015;Guan et al, 2011;Li et al, 2005). In general, the degradation of BERs in the SCWO3 system results from the oxidation reaction between HO Å and HO 2 Å and the NaOH cation-anion.…”

Section: Bers Degradation Mechanismmentioning

confidence: 99%

Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes

Liu

Zhang

2016

Waste Management

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a b s t r a c tThis work investigated various supercritical water oxidation (SCWO) systems, i.e. SCWO1 (only water), SCWO2 (water + H 2 O 2 ) and SCWO3 (water + H 2 O 2 /NaOH), for waste printed circuit boards (PCBs) detoxification and recycling. Response surface methodology (RSM) was applied to optimize the operating conditions of the optimal SCWO3 systems. The optimal reaction conditions for debromination were found to be the NaOH of 0.21 g, the H 2 O 2 volume of 9.04 mL, the time of 39.7 min, maximum debromination efficiency of 95.14%. Variance analysis indicated that the factors influencing debromination efficiency was in the sequence of NaOH > H 2 O 2 > time. Mechanism studies indicated that the dissociated ions from NaOH in supercritical water promoted the debromination of brominated epoxy resins (BERs) through an elimination reaction and nucleophilic substitution. HO 2 Å , produced by H 2 O 2 could induce the oxidation of phenol ring to open (intermediates of BERs), which were thoroughly degraded to form hydrocarbons, CO 2 , H 2 O and NaBr. In addition, the alkali-silica reaction between OH À and SiO 2 induced the phase transformation of glass fibers, which were simultaneously converted into anorthite and albite. Waste PCBs in H 2 O 2 /NaOH improved SCWO system were fully degraded into useful products and simultaneously transformed into functional materials. These findings are helpful for efficient recycling of waste PCBs.

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Study on catalytic and non-catalytic supercritical water oxidation of p-nitrophenol wastewater

Cited by 64 publications

References 32 publications

Functional Materials for Waste-to-Energy Processes in Supercritical Water

Functional Materials for Waste-to-Energy Processes in Supercritical Water

Effect Mechanism of Auxiliary Fuel in Supercritical Water: A Review

Advanced degradation of brominated epoxy resin and simultaneous transformation of glass fiber from waste printed circuit boards by improved supercritical water oxidation processes

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