A surface science perspective on TiO2 photocatalysis

Recent developments of zinc oxide based photocatalyst in water treatment technology: A review

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

/pdf/chemicals-from-lignin-an-interplay-of-lignocellulose-1th1dk0l26.pdf

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

https://cyberleninka.org/article/n/638974.pdf

Characteristics and adsorption capacities of low-cost sorbents for wastewater treatment: A review

In the present study, seven diverse biomasses of Indian origin were characterized and pyrolyzed at 450 °C to produce biochars. The biochars were thoroughly characterized using a variety of techniques to assure their potential energy and environmental and agricultural applications. Biochars derived from crop wastes with low lignin content, viz., rice husk biochar (RHB), rice straw biochar (RSB), maize stover biochar (MSB), and sugarcane biochar (SCB), possessed high ash content, high pH, and low fixed carbon making them suitable for soil amelioration. RSB, RHB, and MSB recorded high cation exchange capacity, making their potential utilization as liming material and removal of heavy metal contaminants. Elemental O/C ratios for all biochars, except maize stover biochar, were in the range of 0.27–0.32, which showed better stability and half-life period. Thermogravimetric analysis (TGA) was carried out to evaluate the thermal stability of biochars up to 900 °C, and the overall mass loss varied in the range of 16–27 wt%. Biochars from eucalyptus (EB), lantana (LB), and pine needle (PNB) were found to have high higher heating values (HHVs) (23–28 MJ/kg), higher fixed carbon, and lower ash content. Correlations were constructed between HHV of biochars and their volatile matter, ash, and fixed carbon content with high but negative correlation with ash content. Rice straw, rice husk, maize stover, and sugarcane trash were poor substrates, as the resultant biochars contained ≤ 60 wt% fixed carbon, high ash, and a relatively low HHV. It is shown that RHB, RSB, MSB, and SCB can be potential materials for soil amendment and plant nutrient, while PNB, LB, and EB are suitable for renewable solid fuel purpose.

Characterization, bioenergy value, and thermal stability of biochars derived from diverse agriculture and forestry lignocellulosic wastes

Kinetics of sono-photooxidative degradation of poly(alkyl methacrylate)s

Effects of aqueous phase recirculation on product yields and quality from hydrothermal liquefaction of rice straw.

Biolubricants generated from biomass and other wastes can reduce the carbon footprint of manufacturing processes and power generation. In this paper, the properties and uses of biolubricants have been compared thoroughly with conventional mineral-based lubricants. The biolubricants, which are currently based on vegetable oils, are discussed in terms of their physicochemical and thermophysical properties, stability, and biodegradability. This mini-review points out the main features of the existing biolubricants, and puts forward the case of using sustainable biolubricants, which can be generated from agro-residues via thermochemical processes. The properties, applications, and limitations of non-edible oils and waste-derived oils, such as bio-oil from pyrolysis and bio-crude from hydrothermal liquefaction, are discussed in the context of biolubricants. While the existing studies on biolubricants have mostly focused on the use of vegetable oils and some non-edible oils, there is a need to shift to waste-derived oils, which is highlighted in this paper. This perspective compares the key properties of conventional oils with different oils derived from renewable resources and wastes. In the authors’ opinion, the use of waste-derived oils is a potential future option to address the problem of the waste management and supply of biolubricant for various applications including machining, milling applications, biological applications, engine oils, and compressor oils. In order to achieve this, significant research needs to be conducted to evaluate salient properties such as viscosity, flash point, biodegradability, thermo-oxidative and storage stability of the oils, technoeconomics, and sustainability, which are highlighted in this review.

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Current Status and Future Prospects of Biolubricants: Properties and Applications

Pyrolysis is a promising thermochemical conversion technique to recover valuable building blocks and chemicals from waste polymers. After outlining the need for recycling and comparing the various strategies for recycling polymer wastes, this article evaluates noncatalytic and catalytic pyrolysis of a number of common polymers by giving due emphasis to pyrolysis products and product formation pathways. Free radical, concerted, and acid-catalyzed mechanisms involved in noncatalytic and catalytic pyrolysis of vinyl polymers are discussed. The different types of analytic pyrolyzers and their applications are outlined. Polymer pyrolysis via microwave-assisted heating is evaluated for tuning of product yields and selectivities.

Ravikrishnan Vinu

Papers

Characterization, bioenergy value, and thermal stability of biochars derived from diverse agriculture and forestry lignocellulosic wastes

Kinetics of sono-photooxidative degradation of poly(alkyl methacrylate)s

Effects of aqueous phase recirculation on product yields and quality from hydrothermal liquefaction of rice straw.

Current Status and Future Prospects of Biolubricants: Properties and Applications

Polymer Pyrolysis for Resource Recovery