Photocatalytic hydrogenation of organic compounds in membrane reactors

Molinari, Raffaele; Argurio, Pietro; Lavorato, Cristina

doi:10.1016/b978-1-78242-223-5.00020-0

Cited by 5 publications

(2 citation statements)

References 129 publications

(120 reference statements)

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“…as the reduction reaction. At the same time, the valence band that has more positive potential than the redox potential energy of reduced species agent will oxidize electron to reduced species agent (Red 2 to OX 2 ) as the reduction reaction [21].…”

Section: Photocatalystsmentioning

confidence: 99%

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Mechanism and reaction pathways of CO2 AND HCO3-photoreduction to hydrocarbons

Sattayamuk

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CO2/HCO3-�photocatalytic reductions in water, using P25 Titanium dioxide, produce�gas products�at the order of the following rate: �CO>H2>CH4, using bicarbonate as a substrate, reduction rates are ca. �5 times faster than using CO2�due to the adsorption constant of CO2�on the TiO2�surface is smaller than the bicarbonate. Langmuir-Hinshelwood kinetic model was used to describe the mechanism; therefore, adsorption constant (K) and the�rate of maximum substrate coverage (k) at different charges of P25-surface were readily obtained. The K constant of TiO2-adduct formation favors�no charge surface but k constant favors positive charge surface. Most of the products formed come from partitioning of the radical anion (TiO2-CO2.-) in the rate-limiting step. However, the bicarbonate�absorption at OV�promotes alternative pathways. This�provides more CO and H2�production. Solvent isotope effect (H2O Vs. D2O) is ca. 1.5. This means that during the radical anion formation in the transition state, there is H being transferred from water in the radical anion intermediate step.�In addition, the collapse of anatase and rutile phases from sonication increases CH4�production rate and selectivity due to improved charge separation�that reduces�alternative pathways.

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Section: Photocatalystsmentioning

confidence: 99%

“…The Heavy atom isotope effects have KIEs around 1. The small isotope effect occurs by slightly different from the mass number between the substrate such as 14 N/ 15 N, 20 Ne/ 21 Ne and 35 Cl/ 37 Cl etc.…”

Section: Heavy Atom Isotope Effectsmentioning

confidence: 99%

Mechanism and reaction pathways of CO2 AND HCO3-photoreduction to hydrocarbons

Sattayamuk

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Removal of Heavy Metals from Industrial Wastewaters: A Review

et al. 2017

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Heavy metals like arsenic, copper, cadmium, chromium, nickel, zinc, lead, and mercury are major pollutants of fresh water reservoirs because of their toxic, non‐biodegradable, and persistent nature. The industrial growth is the major source of heavy metals introducing such pollutants into different segments of the environment including air, water, soil, and biosphere. Heavy metals are easily absorbed by fishes and vegetables due to their high solubility in the aquatic environments. Hence, they may accumulate in the human body by means of the food chain. Various methods have been developed and used for water and wastewater treatment to decrease heavy metal concentrations. These technologies include membrane filtration, ion‐exchange, adsorption, chemical precipitation, nanotechnology treatments, electrochemical and advanced oxidation processes. In this review, the methods as well as their mechanisms and efficiency are discussed.

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Emerging trends in photodegradation of petrochemical wastes: a review

Singh

Ojha

Borthakur

et al. 2016

Environ Sci Pollut Res

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Various human activities like mining and extraction of mineral oils have been used for the modernization of society and well-beings. However, the by-products such as petrochemical wastes generated from such industries are carcinogenic and toxic, which had increased environmental pollution and risks to human health several folds. Various methods such as physical, chemical and biological methods have been used to degrade these pollutants from wastewater. Advance oxidation processes (AOPs) are evolving techniques for efficient sequestration of chemically stable and less biodegradable organic pollutants. In the present review, photocatalytic degradation of petrochemical wastes containing monoaromatic and poly-aromatic hydrocarbons has been studied using various heterogeneous photocatalysts (such as TiO, ZnO and CdS. The present article seeks to offer a scientific and technical overview of the current trend in the use of the photocatalyst for remediation and degradation of petrochemical waste depending upon the recent advances in photodegradation of petrochemical research using bibliometric analysis. We further outlined the effect of various heterogeneous catalysts and their ecotoxicity, various degradation pathways of petrochemical wastes, the key regulatory parameters and the reactors used. A critical analysis of the available literature revealed that TiO is widely reported in the degradation processes along with other semiconductors/nanomaterials in visible and UV light irradiation. Further, various degradation studies have been carried out at laboratory scale in the presence of UV light. However, further elaborative research is needed for successful application of the laboratory scale techniques to pilot-scale operation and to develop environmental friendly catalysts which support the sustainable treatment technology with the "zero concept" of industrial wastewater. Nevertheless, there is a need to develop more effective methods which consume less energy and are more efficient in pilot scale for the demineralization of pollutant.

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Photocatalytic hydrogenation of organic compounds in membrane reactors

Cited by 5 publications

References 129 publications

Mechanism and reaction pathways of CO2 AND HCO3-photoreduction to hydrocarbons

Mechanism and reaction pathways of CO2 AND HCO3-photoreduction to hydrocarbons

Removal of Heavy Metals from Industrial Wastewaters: A Review

Emerging trends in photodegradation of petrochemical wastes: a review

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