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Leonardo Clavijo

Bio: Leonardo Clavijo is an academic researcher from University of the Republic. The author has contributed to research in topics: Biorefinery & Lignin. The author has an hindex of 7, co-authored 11 publications receiving 133 citations.
Topics: Biorefinery, Lignin, Biofuel, Hemicellulose, Pulp mill

Papers
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Journal ArticleDOI
24 Jul 2018
TL;DR: A complete bibliometric analysis of the Scopus database was performed to identify the research trends related to lignin valorization from 2000 to 2016 as discussed by the authors, which revealed an exponentially increasing number of publications and a high relevance of interdisciplinary collaboration.
Abstract: A complete bibliometric analysis of the Scopus database was performed to identify the research trends related to lignin valorization from 2000 to 2016. The results from this analysis revealed an exponentially increasing number of publications and a high relevance of interdisciplinary collaboration. The simultaneous valorization of the three main components of lignocellulosic biomass (cellulose, hemicellulose, and lignin) has been revealed as a key aspect and optimal pretreatment is required for the subsequent lignin valorization. Research covers the determination of the lignin structure, isolation, and characterization; depolymerization by thermal and thermochemical methods; chemical, biochemical and biological conversion of depolymerized lignin; and lignin applications. Most methods for lignin depolymerization are focused on the selective cleavage of the β-O-4 linkage. Although many depolymerization methods have been developed, depolymerization with sodium hydroxide is the dominant process at industrial scale. Oxidative conversion of lignin is the most used method for the chemical lignin upgrading. Lignin uses can be classified according to its structure into lignin-derived aromatic compounds, lignin-derived carbon materials and lignin-derived polymeric materials. There are many advances in all approaches, but lignin-derived polymeric materials appear as a promising option.

48 citations

Journal ArticleDOI
TL;DR: In this paper, technical-grade lignin was obtained experimentally in a pilot plant by acid precipitation (H2SO4), sedimentation, filtration and washing of the slurry and assessed as fuel: it presented a high caloric value (26 MJ/kg), low carbohydrate content, and low K and Na contents.
Abstract: Pulp mills located in Uruguay process Eucalyptus spp. wood from plantations. Black liquor is burnt in the recovery boiler, generating an excess of energy that is converted to electricity and sold to the grid. Lignin, the main component of black liquor, is a natural polymer, abundant, and readily obtained by acid precipitation. A recovery process of lignin from black liquor in a pulp mill produces a biofuel to be used within at the plant or to be marketed locally, diversifying the energy offer of Uruguay, a country with no fossil fuels. In the present contribution, technical-grade lignin (average of 94% total lignin) was obtained experimentally in a pilot plant by acid precipitation (H2SO4), sedimentation, filtration, and washing of the slurry and assessed as fuel: it presented a high caloric value (26 MJ/kg), low carbohydrate content, and low K and Na contents. The results of the economic analysis showed that a production of 3400 tons of lignin per year could be produced at a cost of 692 US$/ton. At a sma...

29 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used organosolv and autohydrolysis pretreatments for integrated valorization of eucalyptus sawdust residue within a biorefinery approach.

28 citations

Journal ArticleDOI
TL;DR: In this article, a technological and economic alternative for mushroom and parsley dehydration combining convective and vacuum drying is presented. But the main objective of this paper is to obtain a technological alternative for reducing the overall drying time and avoiding product damage.

26 citations

Journal ArticleDOI
TL;DR: In this paper, a lignin-based slow-release fertilizer with low environmental impact has been developed, where a granulated simple superphosphate fertilizer consisting of calcium phosphate monobasic and gypsum (CaSO4·2H2O) was coated with modified kraft lignins and the diffusion of phosphorus was observed as a function of time.
Abstract: Abstract A novel lignin-based slow release fertilizer with low environmental impact has been developed. More precisely, a granulated simple superphosphate fertilizer, consisting of calcium phosphate monobasic [Ca(H2PO4)2·H2O] and gypsum (CaSO4·2H2O) was coated with modified kraft lignins and the diffusion of phosphorus was observed as a function of time. The lignin was hydroxymethylated with formaldehyde and subsequently cross-linked with phenol-formaldehyde resin resulting in HML-PF as coating. Moreover, coating films were prepared from a mixture of acetylated lignin (Lac) and acetylated cellulose (Cellac). Both coatings show similar permeability to calcium phosphate and controlled effectively the P-release, particularly at the initial stages of the experiment. The P-release was linear in the decay phase but there is no lag time in the process. A significant P amount was not released from the particles coated with HML-PF, i.e. 80–50% remained irreversible bound, depending on the coating formulation. The maximum fractional P-release varied among the different coatings tested. Phosphorus is partly retained inside the slightly soluble calcium sulfate matrix.

21 citations


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Journal ArticleDOI
01 Jun 2019
TL;DR: In this paper, the authors reviewed different sources of biomass available, along with their chemical composition and properties, and discussed different conversion technologies (i.e., thermo-chemical, biochemical, and physico-chemical conversions) and their corresponding products.
Abstract: Biomass is currently the most widespread form of renewable energy and its exploitation is further increasing due to the concerns over the devastative impacts of fossil fuel consumption, i.e., climate change, global warming and their negative impacts on human health. In line with that, the present articles reviews the different sources of biomass available, along with their chemical composition and properties. Subsequently, different conversion technologies (i.e., thermo-chemical, biochemical, and physico-chemical conversions) and their corresponding products are reviewed and discussed. In the continuation, the global status of biomass vs. the other renewable energies is scrutinized. Moreover, biomass-derived energy production was analyzed from economic and environmental perspectives. Finally, the challenges faced to further expand the share of biomass-derived energy carriers in the global energy market are presented.

461 citations

01 Jan 2015
TL;DR: In this article, the chemical structure of lignocellulosic biomass and factors likely affect the digestibility of LCLs are discussed, and then an overview about the most important pretreatment processes available are provided.
Abstract: Lignocellulosic materials are among the most promising alternative energy resources that can be utilized to produce cellulosic ethanol. However, the physical and chemical structure of lignocellulosic materials forms strong native recalcitrance and results in relatively low yield of ethanol from raw lignocellulosic materials. An appropriate pretreatment method is required to overcome this recalcitrance. For decades various pretreatment processes have been developed to improve the digestibility of lignocellulosic biomass. Each pretreatment process has a different specificity on altering the physical and chemical structure of lignocellulosic materials. In this paper, the chemical structure of lignocellulosic biomass and factors likely affect the digestibility of lignocellulosic materials are discussed, and then an overview about the most important pretreatment processes available are provided. In particular, the combined pretreatment strategies are reviewed for improving the enzymatic hydrolysis of lignocellulose and realizing the comprehensive utilization of lignocellulosic materials.

448 citations

Journal ArticleDOI
TL;DR: In this paper, the authors focused on integrating bioethanol and biodiesel production and valorizing lignin into various useful products, and discussed the prospects of a Lignin biorefinery coupled with economic policies to be deployed along with the practical implications.
Abstract: Lignin is the second most abundant polymer, which comprises15-30% (dry weight) of total lignocellulosic biomass. Recent studies focused on the effective utilization of lignin biopolymer into a myriad of products such as lignin micro and nanocapsules, biosensors, platform chemicals, pharmaceutical compounds, biopolymers, electrodes in electrochemistry, re-useable adsorbent, resins and biodiesel production through oleaginous microbes. The development of eco-friendly and cost-effective techniques is need-of-the-hour, which can be addressed through the circular economy approach. In this review, the emphasis is laid on integrating bioethanol and biodiesel production and valorizing lignin into various useful products. Besides, prospects of lignin biorefinery coupled with economic policies to be deployed along with the practical implications, have been discussed. Adopting these new pragmatic technologies and policies enables not only the development of inexpensive technologies but also boosts the economic growth of lignocellulosic biorefinery.

125 citations

Journal ArticleDOI
TL;DR: There is an urgent need to improve the preparation process of lignin-based slow/controlled release fertilizer, and apply lignIn- based slow/ controlled release fertilizer to production practice as soon as possible.
Abstract: As a skeleton component of plants, lignin is an organic macromolecule polymer that can be regenerated and naturally degraded. Annually, plant growth produces about 150 billion tons of lignin. In industrial processes such as paper and biomass-refining industry, large amounts of lignin are formed as by-products. Most of technical lignins are directly combusted to obtain heat, which not only is a waste of organic matter but also leads to environmental pollution and other issues. Interestingly, lignin can be used as slow-release carriers and coating materials for fertilizers due to its excellent slow release properties as well as chelating and other functionalities. Preparation of lignin-based slow/controlled release fertilizers can be achieved by sustainable chemical (ammoxidation, Mannich reaction, and other chemical modifications), coating (without or with chemical modification), and chelation modifications. This Review systematically summarizes the methods, mechanisms, and application of the above methods for preparing lignin-based slow/controlled release fertilizers. Although the evaluation standards and methods of lignin-based slow/controlled release fertilizers are not perfect, it is believed that more and more scholars will pay more attention to them to accelerate the development and application of lignin-based slow/controlled release fertilizers, so as to improve their relevant standards. In short, there is an urgent need to improve the preparation process of lignin-based slow/controlled release fertilizers and application as lignin-based slow/controlled release fertilizers to production practice as soon as possible.

116 citations

Journal ArticleDOI
TL;DR: In this paper, the most recent advances and opportunities in biomass conversion technologies and biorefineries for the development of a bio-based economy are highlighted and discussed, including the hemicellulose integration and use of sugars for different products, lignin valorization, development of efficient and low-cost pretreatment technologies and development of highly efficient fermentation processes.
Abstract: The desire to have a more sustainable future, with lower emissions of carbon and sulfur to the atmosphere, a more appropriate reuse and valorization of wastes, and less dependency on oil has motivated the society to develop processes where renewable biomass is used as a feedstock for the production of fuels, chemicals, energy and materials. In addition, a bio-based economy has also potential to generate new jobs and new opportunities for entrepreneurship, with further benefits to the society. In view of this, great efforts have been done in order to develop efficient, sustainable and cost competitive bio-based processes able to be implemented in industrial scale. Although important advances were achieved and some processes are already available in a large scale, improvements are still needed to have a final product at a more competitive market price. In this sense, the strategy of integrating biorefineries to produce a variety of products from biomass has been considered as an important alternative to improve the financial performance. This paper highlights the most recent advances and opportunities in biomass conversion technologies and biorefineries for the development of a bio-based economy. Technological aspects including the hemicellulose integration and use of sugars for different products, lignin valorization, development of efficient and low-cost pretreatment technologies and development of highly efficient fermentation processes are also presented and discussed.

102 citations