Author
David F. Ollis
Other affiliations: Princeton University, Stanford University, University of California, Davis
Bio: David F. Ollis is an academic researcher from North Carolina State University. The author has contributed to research in topics: Photocatalysis & Catalysis. The author has an hindex of 57, co-authored 175 publications receiving 16711 citations. Previous affiliations of David F. Ollis include Princeton University & Stanford University.
Papers published on a yearly basis
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01 Jan 1986
TL;DR: Biochemical Engineering Fundamentals, 2/e as mentioned in this paper combines contemporary engineering science with relevant biological concepts in a comprehensive introduction to biochemical engineering, which enables students to comprehend the major problems in biochemical engineering and formulate effective solutions.
Abstract: Biochemical Engineering Fundamentals, 2/e, combines contemporary engineering science with relevant biological concepts in a comprehensive introduction to biochemical engineering. The biological background provided enables students to comprehend the major problems in biochemical engineering and formulate effective solutions.
3,155 citations
TL;DR: In this article, it is proposed that the hydroxyl radical, OH·, is the primary oxidant in the photocatalytic system and four possible mechanisms are suggested, all based on OH· attack of the organic reactant.
1,929 citations
TL;DR: Heterogeneous photocatalysis is a process in which the illumination of an oxide semiconductor, usually the anatase form of titanium dioxide, produces photoexcited electrons (e{sup {minus}}) and holes (h{sup +}). These can migrate to the oxide surface and participate in halfcell reactions that are part of a closed, catalytic cycle as mentioned in this paper.
Abstract: Heterogeneous photocatalysis is a process in which the illumination of an oxide semiconductor, usually the anatase form of titanium dioxide, produces photoexcited electrons (e{sup {minus}}) and holes (h{sup +}). These can migrate to the oxide surface and participate in half-cell reactions that are part of a closed, catalytic cycle. In the aqueous phase, the illuminated surface is widely regarded as a producer of hydroxyl radicals (e.g., h{sup +} + OH{sup {minus}} {yields} {center dot}OH), and these and other highly oxidizing initial products of this indirect photochemistry go on to attack oxidizable contaminants. This article highlights recent developments in photocatalysis that are applicable to water treatment. Topics discussed include the generality of photocatalysis for complete contaminant destruction (mineralization); some specific contaminant classes of interest (chlorinated aromatics, surfactants, herbicides, and pesticides); the use of solar versus artificial illumination; the influence of additional oxidants such as H{sub 2}O{sub 2}; catalyst forms (suspended vs. immobilized); and related potential applications of photocatalysis (metal recovery and total organic carbon (TOC) analyses).
1,115 citations
TL;DR: The literature of studies which used a combination of chemical and biological degradation (usually oxidative) of organic contaminants in water is reviewed in this paper, where four wastewater contaminant types are identified which can benefit from combined processes: recalcitrant compounds, biodegradable wastes, inhibitory compounds and intermediate dead-end products.
Abstract: The literature of studies which used a combination of chemical and biological degradation (usually oxidative) of organic contaminants in water is reviewed. Beneficial effects of such two-step treatments are commonly reported; these results, primarily from laboratory studies, suggest potential advantages for water treatment via process integration rather than single technology processing.
Four wastewater contaminant types are identified which can benefit from combined processes: 1.) recalcitrant compounds 2.) biodegradable wastes with small amounts of recalcitrant compounds 3.) inhibitory compounds and 4.) intermediate dead-end products. The design key for such two-step systems lies in choosing processes that complement each other and lead to a synergistic effect. Predicting this performance outcome requires knowledge of the physical, chemical and biological properties of the major reaction intermediates and their susceptibility to degradation by each process.
Economic, physical and technological limitations of the individual processes should be recognized for design of more effective and economical integrated processes. The ultimate treatment goal, whether specific pollutant removal or reduction of a global parameter such as TOC, must be known so that appropriate and complementary processes can be utilized. More work is needed concerning the degradation kinetics within the combined process, from initial attack of the primary compound through dynamics of intermediates and on to total mineralization.
560 citations
TL;DR: In this article, photocatalyzed degradations of trace levels of various oxygenates and an aromatic in air were carried out using near-UV-illuminated titanium dioxide (anatase) powder.
498 citations
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TL;DR: A review of the current progress in the area of TiO 2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy is discussed in this paper.
Abstract: Scientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO 2 ), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this review, current progress in the area of TiO 2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy are discussed together with some fundamental aspects. A novel photoinduced superhydrophilic phenomenon involving TiO 2 and its applications are presented.
6,802 citations
01 Jan 2008
TL;DR: A review of the current progress in the area of TiO 2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy is discussed in this article.
Abstract: Abstract Scientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO 2 ), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this review, current progress in the area of TiO 2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy are discussed together with some fundamental aspects. A novel photoinduced superhydrophilic phenomenon involving TiO 2 and its applications are presented.
6,294 citations
TL;DR: The field of photocatalysis can be traced back more than 80 years to early observations of the chalking of titania-based paints and to studies of the darkening of metal oxides in contact with organic compounds in sunlight as discussed by the authors.
5,729 citations
TL;DR: A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.
Abstract: Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for "consolidated bioprocessing" (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.
4,769 citations
TL;DR: In this paper, photo-induced superhydrophilicity was used on the surface of a wide-band gap semiconductor like titanium dioxide (TiO 2 ) for photocatalytic activity towards environmentally hazardous compounds.
4,241 citations