Publications by authors named "Melissa Agustin"

A new valorization pathway based on solvent fractionation was applied to kraft lignin, a major by-stream of the pulping industry, to extract a soluble lignin intermediate featuring an improved structural homogeneity, a low molecular weight, and a high content of phenolic hydroxyl and carboxylic acid groups to serve as a substitute of the nonrenewable polyacids in the formulation of alkyd resins, a dominant material used in the production of anticorrosion surface coatings. Herein, softwood kraft lignin was mixed in a low-cost green solvent, aqueous ethanol, prepared at different ratios, at room temperature to generate a soluble fraction of a low of ≤2200 g mol and an insoluble fraction of a high of ≥3950 g mol of lignin. The best combination of yields and molecular weights of soluble lignin (16-36% yield, 1740-1890 g mol) was attained using 50-80 vol % ethanol in fractionation.

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Pharmaceuticals, designed for treating diseases, ironically endanger humans and aquatic ecosystems as pollutants. Adsorption-based wastewater treatment could address this problem, however, creating efficient adsorbents remains a challenge. Recent efforts have shifted towards sustainable bio-based adsorbents.

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Unlabelled: Nanocellulose is very hydrophilic, preventing interactions with the oil phase in Pickering emulsions. This limitation is herein addressed by incorporating lignin nanoparticles (LNPs) as co-stabilizers of nanocellulose-based Pickering emulsions. LNP addition decreases the oil droplet size and slows creaming at pH 5 and 8 and with increasing LNP content.

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Adsorption is a relatively simple wastewater treatment method that has the potential to mitigate the impacts of pharmaceutical pollution. This requires the development of reusable adsorbents that can simultaneously remove pharmaceuticals of varying chemical structure and properties. Here, the adsorption potential of nanostructured wood-based adsorbents towards different pharmaceuticals in a multi-component system was investigated.

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Lignin is an abundant natural feedstock that offers great potential as a renewable substitute for fossil-based resources. Its polyaromatic structure and unique properties have attracted significant research efforts. The advantages of an enzymatic over chemical or thermal approach to construct or deconstruct lignins are that it operates in mild conditions, requires less energy, and usually uses non-toxic chemicals.

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The production of lignin nanoparticles (LNPs) has emerged as a way to overcome the highly variable and complex molecular structure of lignin. It can offer morphological control of the lignin polymer, allowing the formation of stable LNP dispersions in aqueous media, while increasing the potential of lignin for high-value applications. However, the polydispersity and morphology of LNPs varies depending on the lignin grade and preparation method, and a systematic comparison using different technical lignins is lacking.

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Improvement in the thermal stability of wood-based cellulose; the needle-leaf, bleached, krafp pulp (NBKP) and the wood cellulose nanofibers (WCNF) obtained from the NBKP, was achieved by esterification. Initially, four different types of NBKP esters (acetyl, C2; myristoyl, C14; benzoyl, BNZ; and pivaloyl, PIV) with different degree of substitution (DS) values were prepared to evaluate the effect of esterifying the hemicellulose. The findings revealed that an optimum DS, which possibly completely esterifies the hemicellulose and amorphous cellulose, is needed to achieve significant improvement in thermal stability.

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Article Synopsis
  • The study found that modifying nanocellulose with benzoyl (BNZ) and pivaloyl (PIV) esters enhances its resistance to thermal breakdown.
  • Analysis revealed that these modifications resulted in higher degrees of polymerization (DP) and narrower molecular weight distributions (MWD) compared to pure bacterial cellulose.
  • Additionally, improved resistance to depolymerization led to reduced thermal discoloration, indicating that these esterification techniques significantly enhance the thermal stability of nanocellulose.
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Electrocoagulation (EC) is an electrochemical technique which has been employed in the treatment of various kinds of wastewater. In this work the potential use of EC for the treatment of palm oil mill effluent (POME) was investigated. In a laboratory scale, POME from a factory site in Chumporn Province (Thailand) was subjected to EC using aluminum as electrodes and sodium chloride as supporting electrolyte.

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