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Eco-Friendly Synthesis of Waterborne Polyurethanes
Published in Ram K. Gupta, Ajay Kumar Mishra, Eco-Friendly Waterborne Polyurethanes, 2022
Pavan M. Paraskar, Vinod M. Hatkar, Ravindra D. Kulkarni
Ferulic acid, vanillic acid, guaiacol, syringic acid, eugenol, and syringol are the major chemical constituents available in lignin that attracted polymer scientists’ attention to use lignin as a starting ingredient for the preparation of difunctional monomers suitable in the synthesis of step-growth polymers. Bis(4-isocyanato2,6-dimethoxyphenoxy)alkane, aromatic diisocyanates, and bis(4-isocyanato-2-methoxyphenoxy)alkane were produced using syringic acid and vanillic acid and polycondensed with bio-based diols 1,12-dodecanediol and 1,10-decanediol to produce poly(ether urethane)s [27]. Chauhan et al. synthesized lignin-based diisocyanates by functionalizing lignin using 4,4′-diphenyl methane diisocyanate (MDI) at 90°C for 60 min and evaluated their usage in PU formulation by determining phase miscibility, wettability, rheology, and mechanical properties [30].
Pesticides in Fog
Published in James N. Seiber, Thomas M. Cahill, Pesticides, Organic Contaminants, and Pathogens in Air, 2022
James N. Seiber, Thomas M. Cahill
Fogwater entrainment and concentration of chemicals are not unique to pesticides. Sagebiel and Seiber (1993) analyzed wintertime fog and interstitial air from a community in the Central Valley during a time when residential wood burning occurred. Guaiacol, 4-methyl guaiacol, and syringol were the most commonly found among the 16 methoxylated phenolic lignin combustion products confirmed by GC/MS in fog samples. The distribution of methoxylated phenols generally followed Henry’s law, that is, did not show the dramatic enrichments observed for less polar pesticides. This suggested that enrichment is a function of analyte hydrophobicity rather than any special structural features. Concentrations of methoxylated phenols in fogwater ranged to 1,408 µg/L for syringol, and generally were in the 1–100 µg/L range when detected.
Less Hazardous Chemical Synthesis from Palm Oil Biomass
Published in Aidé Sáenz-Galindo, Adali Oliva Castañeda-Facio, Raúl Rodríguez-Herrera, Green Chemistry and Applications, 2020
Raja Safazliana Raja Sulong, Seri Elyanie Zulkifli, Fatimatul Zaharah Abas, Muhammad Fakhrul Syukri Abd Aziz, Zainul Akmar Zakaria
Pyroligneous Acid (PA) known as pyrolysis liquid or wood vinegar can be obtained by condensing the smoke produced during pyrolysis heating process of plant biomass in the absence of oxygen. It generally consists of 80–90% of water and 10–20% organic compounds with a distinctive smoky odor, reddish brown appearance, and acidic pH. PA comprises of complex mixtures of compounds such as phenolics compound (guaiacol, phenol, catechol, syringol), organic acids, aldehyde, ketone, furan, pyran and nitrogen compounds (Wanderley et al., 2012). Various biomass feedstocks from agricultural waste have been reported for the production of PA which includes Oil Palm Fiber (OPF) (Abas et al., 2018), Palm Kernel Shell (PKS) (Ariffin et al., 2017), Citrus Plant (CP) (Bacanli et al., 2015), Coconut Shell (CS) (Wititsiri, 2011), Walnut Shell (WS) (Zhai et al., 2015), Bamboo (B) (Harada et al., 2013), Pineapple Waste (PW) (Mathew et al., 2015), Cotton Stalk (CS) (Wu et al., 2015) just to mention a few.
Elucidating the pyrolysis properties of water hyacinth (Eichhornia crassipes) biomass and characterisation of its pyrolysis products
Published in International Journal of Sustainable Energy, 2023
Dionisio Malagón Romero, Jhony Stiphen Gómez Junca, Lizeth Katherine Tinoco Navarro, Juan Pablo Arrubla Vélez
According to previous studies, the thermal degradation characteristics of wood materials or plants are strongly influenced by their chemical composition (cellulose, hemicellulose, and lignin). For instance, from materials rich in cellulose, levoglucosan is obtained as the main reaction product from pyrolysis between 289°C and 314°C, for which a kinetic model has been developed (Bradbury, Sakai, and Shafizadeh 1979). The biomass that undergoes pyrolytic reactions at high temperatures forms different compounds such as saccharides, including cellulose, hemicellulose, and pectin, which degrade thermally to ketones, alcohols, furan, and pyran derivatives. However, lignin is converted into phenol, guaiacol, syringol, pyrocatechol, and their derivatives, which dissolve in the bio-oil layer (Ma et al. 2014).
Chemicals from lignocellulosic biomass: A critical comparison between biochemical, microwave and thermochemical conversion methods
Published in Critical Reviews in Environmental Science and Technology, 2021
Iris K. M. Yu, Huihui Chen, Felix Abeln, Hadiza Auta, Jiajun Fan, Vitaly L. Budarin, James H. Clark, Sophie Parsons, Christopher J. Chuck, Shicheng Zhang, Gang Luo, Daniel C.W Tsang
Lignin is usually isolated from hemicellulose and cellulose prior to phenol production. A recent study suggested that microwaves efficiently isolated lignin of high purity from softwood, with the performance superior to that of the traditional Klason method (Zhou, Budarin, et al., 2017). Palm empty fruit bunch lignin was subjected to oxidative depolymerization in the presence of Cu(OH)2 and Fe2O3 catalysts, NaOH, and H2O2 under microwave heating (Panyadee et al., 2018). The process generated 92% phenolic compounds, including syringol, vanillin, acetovanillone, syringaldehyde, and acetosyringone. Rapid decomposition of lignin (7 min) was reported over CuSO4 and H2O2 under microwave heating at 110 °C (Dai et al., 2018). The corresponding yield of low-molecular-weight molecules was 2.6 times higher than that in autoclaving, given the same temperature and reaction time. It was suggested that microwaves promoted the CuSO4-catalyzed hydroxyl radical formation from H2O2, which attacked the lignin leading to its degradation. Alternatively, polyphenols can be easily extracted from phenolics-rich algae under simple microwave hydrothermal conditions without the need for a catalyst (Yuan et al., 2018).