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Production of Biomass-Based Butanol
Published in Jitendra Kumar Saini, Surender Singh, Lata Nain, Sustainable Microbial Technologies for Valorization of Agro-Industrial Wastes, 2023
Cai et al. (2016) reported the dilute alkaline NaOH treatment of cob, leaf, and stem hydrolysate, flower, and husk of corn produced 9.4 g/L, 7.6 g/L, 7.5 g/L, and 7 g/L butanol respectively by C. acetobutylicum ABE 1301. Valles et al. (2021) optimized butanol production from rice straw by NaOH pretreatment (0.75% w/v) at 134°C for twenty minutes by Clostridium beijerinckii. Butanol production by C. acetobutylicum NRRL B-591 was also improved with organosolv pretreatment of rice straw by aqueous ethanol 75% (v/v) added with 1% w/w sulfuric acid at 180oC for thirty minutes (Amiri et al. 2014). The combination of dilute acid and oxidative ammonolysis increased enzymatic hydrolysis in sugarcane bagasse by C. acetobutylicum CH02. Butanol production was improved to 7.9 g/L from acid hydrolysates of barley straw by C. acetobutylicum DSM 1731 with polyethylene glycol PEG 4000 surfactant-assisted xylanase and cellulase treatment (Yang et al. 2017). Higher butanol was produced by Clostridium beijerinckii DSM 6422 from hydrolysates of wheat straw by steam explosion and ozone treatment (Plaza et al. 2017). Clostridium saccharobutylicum DSM 13864 produced butanol efficiently from pretreatment of corn stover with ten times recycled ionic liquid [Bmim][Cl] (Ding et al. 2015). Butanol production by microwave-assisted alkali pretreatment and enzymatic hydrolysis was studied by Valles et al. (2020).
Greener Synthesis of Potential Drugs
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Renata Studzińska, Renata Kołodziejska, Daria Kupczyk
Hydrolases, more particularly lipases, present different advantages over other biocatalysts, as they require no cofactors for their catalytic behavior, and many of them are commercially available and easy to handle biocatalysts. Due to the availability, stability, and acceptability of a wide range of substrates, lipases are often used in bioorganic syntheses. They can catalyze numerous solvolytic reactions of a carboxyl group such as hydrolysis, transesterification (alcoholysis), esterification, acidolysis, and amino- or ammonolysis (amide synthesis). Moreover, lipases are characterized by high regio- and stereoselectivity. They are capable of carrying out reactions with one specific functional group on a substrate, kinetic resolution of racemic mixtures, and asymmetric biotransformation of prochiral compounds and meso-synthons [9, 106].
First-generation biofuel and second-generation biofuel feedstocks
Published in Ruben Michael Ceballos, Bioethanol and Natural Resources, 2017
The conventional AFEX pretreatment consists of treating lignocellulosic biomass with liquid anhydrous ammonia (0.3–2 g NH3/g dry biomass) at elevated temperature (40°C–180°C) and pressure (250–300 psi) for 5–60 min, then rapidly reducing the pressure to facilitate expansion of the ammonia gas (Balan et al., 2009). This induces swelling in lignocellulosic matrix, disruption in the lignin–carbohydrate linkage, hemicellulose and lignin hydrolysis, ammonolysis of glucuronic cross-linked bonds, and cellulose decrystallization (Laureano-Perez et al., 2005; Chundawat et al., 2007). Although lignin is not robustly affected during the process, it has been reported that close to 100% of the cellulose obtained after AFEX pretreatment can be converted to fermentable sugars via enzymatic action (Teymouri et al., 2005; Balan et al., 2008). Moreover, ~100% of the ammonia can be recovered or removed, and AFEX does not result in the formation of downstream inhibitors to subsequent biological processes (e.g., fermentation) (Dale and Moreira, 1983; Srebotnik et al., 1988). However, the more outstanding results from AFEX may be limited to feedstock that is derived from agricultural residues and herbaceous crops. Efficacy is limited on materials with high lignin (McMillan, 1994). Both AFEX and ARP have only been reported in lab-scale use. AFEX used in conjunction with other methods may also be considered an advanced pretreatment technology (Section 2.3.2).
Production and characterization of recycled polyester (r-PET) blend vortex and ring spun yarns
Published in The Journal of The Textile Institute, 2020
Esin Sarioğlu, Serkan Nohut, Deniz Vuruşkan, Osman Yayla
PET is the mostly used material for packaging products since they provide good mechanical strength, transparency, lightweight and thermal stability. Since PET fibers are used in blends in most of the textile products, recycling of PET is done from PET bottle wastes. In average, it takes 35–45 years and even more for PET bottles to degrade in soil. Instead of storing or burning, these PET bottles can be recycled to raw materials which can also be used in textile industry. There are three main recycling method that can be applied to PET bottles, namely; mechanical, chemical and thermal recycling. Thermal recycling is mainly production of electricity from heat which is gained by burning the PET bottles (Komly, Azzaro-Pantel, Hubert, Pibouleau, & Archambault, 2012). Chemical recycling is suitable to the production of raw materials and can be done according to hydrolysis, methanolysis, glycolysis, ammonolysis and aminolysis processes (Khoonkari, Haghighi, Sefidbakht, Shekoohi, & Ghaderian, 2015) however it is nowadays not preferred due to its high processing cost (less energy efficient) (Aizenshtein, 2016; Dutt & Soni, 2013). Mechanical recycling is a method which is common when the production of secondary material is of principal interest of recycling and is composed of contamination, sorting, washing, drying and melt-processing steps (Doğan, 2008). Luijsterburg reported that the mechanically recycled PET may have good mechanical properties which are close to virgin PET and therefore can be applied in more diverse applications (Luijsterburg, 2015).
Ultrasound-Assisted Alkaline Hydrolysis of Waste Poly(Ethylene Terephthalate) in Aqueous and Non-aqueous Media at Low Temperature
Published in Indian Chemical Engineer, 2018
Chandrakant Sharad Bhogle, Aniruddha Bhalchandra Pandit
Plastics can be recycled in various ways: (i) by mixing the scrap plastic with virgin plastics (primary recycling), (ii) mechanical recycling involving melting of waste plastic and regranulating the same (secondary recycling), (iii) chemical recycling, pyrolysis or gasification to get its original feedstocks or fuels (tertiary recycling) and (iv) energy recovery by incineration (quaternary recycling). Among all the recycling techniques used for PET, chemical recycling techniques are attractive because original raw materials can be recovered using these methods. And these recovered raw materials can be subsequently utilized for polymerization to get virgin polymer [2]. The most recycled polymer is the polyester, in which ester bonds can be cleaved by depolymerizing agents such as water (hydrolysis), methanol (methanolysis), ammonia (ammonolysis), amines (aminolysis) and glycol (glycolysis) [3]. Among these processes, hydrolysis is very interesting because the original feedstocks of PET can be recovered in hydrolysis when compared to other processes, wherein low-molecular-weight oligomers and derivatives can only be obtained.
End-of-waste life: Inventory of alternative end-of-use recirculation routes of bio-based plastics in the European Union context
Published in Critical Reviews in Environmental Science and Technology, 2019
Demetres Briassoulis, Anastasia Pikasi, Miltiadis Hiskakis
Chemical depolymerization (solvolysis or chemolysis), refers to the processes in which the polymer is broken down into the starting monomers or other chemicals (derivatives) that can be further used as raw materials (IPTS, 2013). The most common processes of chemical depolymerization are glycolysis, methanolysis, hydrolysis and ammonolysis depending on the chemical agent used to break down the polymer (Molero, Lucas, Romero, & Rodríguez, 2009; Alavi Nikje & Nikrah, 2007; Schneiderman et al., 2016). Typical depolymerization reactions such as alcoholysis, glycolysis and hydrolysis yield high conversion to their raw monomers (Cornell, 1995). Chemical depolymerization is mainly applicable to condensation polymers such as polyesters, polyamides etc. (IPTS, 2013).