Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

Of Theory and Practice

and Fuels Changzhi Li,† Xiaochen Zhao,† Aiqin Wang,† George W. Huber,†,‡ and Tao Zhang*,† †State Key Laborotary of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China ‡Department of Chemical and Biological Engineering, University of WisconsinMadison, Madison, Wisconsin 53706, United States

Catalytic Transformation of Lignin for the Production of Chemicals and Fuels

Lignocellulosic biomass pyrolysis mechanism: A state-of-the-art review

Advanced oxidation processes (AOPs) constitute important, promising, efficient, and environmental-friendly methods developed to principally remove persistent organic pollutants (POPs) from waters and wastewaters. Generally, AOPs are based on the in situ generation of a powerful oxidizing agent, such as hydroxyl radicals (•OH), obtained at a sufficient concentration to effectively decontaminate waters. This critical review presents a precise and overall description of the recent literature (period 1990–2012) concerning the main types of AOPs, based on chemical, photochemical, sonochemical, and electrochemical reactions. The principles, performances, advantages, drawbacks, and applications of these AOPs to the degradation and destruction of POPs in aquatic media and to the treatment of waters and waste waters have been reported and compared.

Advanced Oxidation Processes in Water/Wastewater Treatment: Principles and Applications. A Review

In pursuit of more sustainable and competitive biorefineries, the effective valorisation of lignin is key. An alluring opportunity is the exploitation of lignin as a resource for chemicals. Three technological biorefinery aspects will determine the realisation of a successful lignin-to-chemicals valorisation chain, namely (i) lignocellulose fractionation, (ii) lignin depolymerisation, and (iii) upgrading towards targeted chemicals. This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations. To navigate the reader through the overwhelming collection of literature on each topic, distinct strategies/topics were delineated and summarised in comprehensive overview figures. Upon closer inspection, conceptual principles arise that rationalise the success of certain methodologies, and more importantly, can guide future research to further expand the portfolio of promising technologies. When targeting chemicals, a key objective during the fractionation and depolymerisation stage is to minimise lignin condensation (i.e. formation of resistive carbon–carbon linkages). During fractionation, this can be achieved by either (i) preserving the (native) lignin structure or (ii) by tolerating depolymerisation of the lignin polymer but preventing condensation through chemical quenching or physical removal of reactive intermediates. The latter strategy is also commonly applied in the lignin depolymerisation stage, while an alternative approach is to augment the relative rate of depolymerisation vs. condensation by enhancing the reactivity of the lignin structure towards depolymerisation. Finally, because depolymerised lignins often consist of a complex mixture of various compounds, upgrading of the raw product mixture through convergent transformations embodies a promising approach to decrease the complexity. This particular upgrading approach is termed funneling, and includes both chemocatalytic and biological strategies.

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Chemicals from lignin: an interplay of lignocellulose fractionation, depolymerisation, and upgrading

Preparation of ultrafine magnetic biochar and activated carbon for pharmaceutical adsorption and subsequent degradation by ball milling.

This study investigated the effects of desilication of ZSM-5 zeolite on its catalytic properties in catalytic fast pyrolysis (CFP) of lignocellulosic biomass. A series of mesoporous ZSM-5 zeolites were prepared by desilication of a conventional microporous ZSM-5 zeolite with NaOH solutions of varying concentrations (0.1–0.5 M). The creation of mesopores improved the diffusion property of the desilicated ZSM-5 zeolites and their catalytic activity for cracking bulky oxygenates (e.g., syringols derived from the lignin component of biomass). Consequently, the desilicated zeolites produced more aromatic hydrocarbons (carbon yields of 26.2–30.2%) and less coke (39.9–41.2%) in CFP of beech wood than the parent microporous ZSM-5 (23.2% aromatics and 44.4% coke). The highest aromatic yield (30.2%) and lowest coke yield (39.9%) were obtained in CFP of beech wood with mildly desilicated zeolite treated with 0.3 M NaOH solution. However, desilication with a greater concentration, 0.5 M NaOH, decreased the aromatic yield to 26.2% due to a considerable loss of microporosity in the severely desilicated zeolite. The results indicate that carefully controlled desilication of zeolite can improve the conversion of lignocellulose to valuable aromatic hydrocarbons and decrease the formation of undesired coke, thus improving the product distribution in CFP of lignocellulose.

Catalytic fast pyrolysis of biomass with mesoporous ZSM-5 zeolites prepared by desilication with NaOH solutions

Catalytic fast pyrolysis (CFP) of lignin with four different zeolite catalysts was investigated to determine the role of shape selectivity of zeolites in CFP. These zeolites included ZSM-5, mordenite, beta, and Y zeolites, which have various crystallographically determined static pore sizes between 5.6 and 7.6 A. The molecular dimensions of pyrolysis products, including lignin-derived oxygenates and aromatics, were calculated using quantum chemical computations. The effective pore sizes of the four zeolites at 650 °C were then determined by analyzing the molecular size and conversion behavior of the pyrolysis products in CFP. Results suggest that thermal distortion of the zeolite pore structure under high-temperature conditions of CFP effectively enlarge the crystallographically determined pore sizes of the zeolites by 2.5–3.4 A. Therefore, many lignin-derived oxygenates with a molecular size considerably larger than the static pore size were able to enter the pores of the zeolites and become effectively converted in our CFP tests. Bulkier monolignols derived from syringyl lignin, however, could not be effectively converted by ZSM-5 and mordenite zeolites due to size exclusion or pore blockage. Among the four zeolites, ZSM-5 produced the highest aromatic yield, followed in order by beta, mordenite, and Y zeolites. Beta and Y zeolites were the most effective catalysts for deoxygenating lignin-derived oxygenates. This analysis indicates that for CFP of softwood, ZSM-5 is the optimal catalyst because it can achieve satisfactory deoxygenation and aromatic production simultaneously, whereas for hardwood feedstock, beta zeolite may be used to convert bulky oxygenates derived from syringyl lignin.

The role of shape selectivity in catalytic fast pyrolysis of lignin with zeolite catalysts

This study describes a promising sunlight-driven photocatalyst for the treatment of ofloxacin and other fluoroquinolone antibiotics in water and wastewater. Perylene diimide (PDI) supramolecular nanofibers, which absorb a broad spectrum of sunlight, were prepared via a facile acidification polymerization protocol. Under natural sunlight, the PDI photocatalysts achieved rapid treatment of fluoroquinolone antibiotics, including ciprofloxacin, enrofloxacin, norfloxacin, and ofloxacin. The fastest degradation was observed for ofloxacin, which had a half-life of 2.08 min for the investigated conditions. Various light sources emitting in the UV-vis spectrum were tested, and blue light was found to exhibit the fastest ofloxacin transformation kinetics due to the strong absorption by the PDI catalyst. Reactive species, namely, h+, 1O2, and O2•-, comprised the primary photocatalytic mechanisms for ofloxacin degradation. Frontier electron density calculations and mass spectrometry were used to verify the major degradation pathways of ofloxacin by the PDI-sunlight photocatalytic system and identify the transformation products of ofloxacin, respectively. Degradation mainly occurred through demethylation at the piperazine ring, ketone formation at the morpholine moiety, and aldehyde reaction at the piperazinyl group. An overall mechanism was proposed for ofloxacin degradation in the PDI-sunlight photocatalytic system, and the effects of water quality constituents were examined to determine performance in real water/wastewater systems. Ultimately, the aggregate results from this study highlight the suitability of the PDI-sunlight photocatalytic system to treat antibiotics in real water and wastewater systems.

Yujue Wang

Papers

Preparation of ultrafine magnetic biochar and activated carbon for pharmaceutical adsorption and subsequent degradation by ball milling.

Catalytic fast pyrolysis of biomass with mesoporous ZSM-5 zeolites prepared by desilication with NaOH solutions

The role of shape selectivity in catalytic fast pyrolysis of lignin with zeolite catalysts

Degradation of Ofloxacin by Perylene Diimide Supramolecular Nanofiber Sunlight-Driven Photocatalysis.

Electro-peroxone treatment of Orange II dye wastewater.