China
Africa
Explore chapters and articles related to this topic
Concepts and Recent Trends in Life Cycle Analyses in Waste Valorization
Published in Jitendra Kumar Saini, Surender Singh, Lata Nain, Sustainable Microbial Technologies for Valorization of Agro-Industrial Wastes, 2023
Valeria Caltzontzin-Rabell, Sergio Iván Martínez-Guido, Claudia Gutiérrez-Antonio, Juan Fernando García-Trejo, Ana Angélica Feregrino-Pérez
Soxhlet extraction, or extraction with solvents, consists of the interaction of the sample embedded in a filter paper or cellulose cartridge with the extraction solvent, which is heated through an equipment called Soxhlet extractor; this extractor carries out the heating process of the solvent, followed by its evaporation and condensation. Soxhlet extraction allows the volatile compounds of the solvent to interact with the compounds to be extracted and to be carried by the solvent in the condensation step (Soxhlet, 1879; Azwanida, 2015). The advantage of this process is the speed of obtaining the compounds with respect to the maceration. The disadvantages of Soxhlet extraction include the generation of large amount of volatile compounds that are toxic to the environment as well as human health; in addition, this process uses dangerous and flammable materials, and it is necessary to use dry residual biomass with a small particle size.
Flame Retardants: Analytical Aspect of Brominated Flame Retardants
Published in Narendra Kumar, Vertika Shukla, Persistent Organic Pollutants in the Environment, 2021
Devendra Kumar Patel, Sandeep Kumar, Neha Gupta
Soxhlet extraction, a traditional solid–liquid technique, it is the oldest and slowest of all the extraction techniques. Extraction time varies from 6 to 48 hours, depending on the extraction procedure and type of sample or sample intake. Soxhlet extraction requires a large amount of solvent (150–400 mL), although the specific amount required usually depends on the size of the Soxhlet apparatus. The commonly used solvent for Soxhlet extraction is a system of n-hexane, dichloromethane (DCM), acetone, and toluene in different ratios. But a combination of polar and nonpolar solvents, called a binary solvent, can be used to improve extraction efficiency (de Boer, 1988; de Boer, 2001). This technique is widely used as a standard extraction method due to its low cost, simplicity, high efficiency, and robustness. There are two types of Soxhlet extraction: hot and regular. In hot Soxhlet extraction, to enhance the efficiency of the process, the temperature of the extraction chamber should remain below the boiling point of the solvent; this significantly increases the contact time of the sample with the solvent. The temperature of the hot solvent directly affects the duration of the extraction process, because the heat from the solvent speeds up the desorption of the target analyte from the sample, ultimately increasing the speed of the process and reducing its duration (Covaci et al., 2002). In soil samples of 20 g, 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) and 2,3,4,5,6-pentabromoethylbenzene were determined using hexane/acetone (1:1) over 24 h (Wang et al., 2009). From soil, sediment, and sewage sludge, BATE, DPTE, ATE, TBECH, TBCO, OBIND, 2,3,4,5,6-pentabromoethylbenzene, hexabromobenzene, BDBPE, TBB, HCDBCO, decabromodiphenyl ethane (DBDPE), and tribromophenol were determined by keeping samples on the Soxhlet apparatus overnight in toluene (Kolic et al., 2009). TBBPA, DBPE, BTBPE, and DBDPE were extracted from freeze-dried soil and sewage sludge using n-hexane/acetone (1:1) on the Soxhlet apparatus for 48 h (Shi et al., 2009). Hexabromobenzene and TBECH were extracted from a soil sample using n-hexane/acetone (2:5) (Nyholm et al., 2010). Mixtures of acetone and cyclohexane have been used in the past to extract decaBDE, pentaBDE, and octaBDE (Wäger et al., 2012).
Investigation of rejuvenation mechanisms of reclaimed asphalt rubber pavement through mortar tests
Published in International Journal of Pavement Engineering, 2023
Danning Li, Zhen Leng, Zhifei Tan, Bin Yang, Zhaojie Chen, Haopeng Wang, Guoyang Lu
As aforementioned, the swelling rubber content decreases during aging due to the dissolution of CRM particles. The dissolution of CRM particles refers to their size reduction attributed to the degradation of rubber polymers, physical split and component loss during mixing and aging. In many studies considering AR binder as a binary system, the undissolved CRM particles are defined as the CRM particles that cannot pass the 200-mesh sieve net (CRM particle size > 0.075 mm). Li et al. found that the Soxhlet extraction method using dichloromethane (DCM) solvent can extract and measure the undissolved CRM contents in AR binders at different aging conditions (Li et al. 2022a). Soxhlet extraction is a conventional laboratory method used for separating soluble components from insoluble solids by a small amount of specific solvent based on solvent reflux and siphonage (Jensen 2007). However, the direct measurement of undissolved CRM content in AR mixture is difficult because Soxhlet extraction can only separate the bitumen phase that is dissolved in the solvent while the insoluble CRM remains with aggregates. Although CRM can be further separated from aggregates based on their density difference, a complete separation is challenging because some extremely fine aggregates and fillers may be embedded in the CRM particles. Therefore, this study proposes a chemistry-based method to indirectly estimate the dissolution extent of CRM in AR and RARP mortar.
Emerging contaminants in the atmosphere: Analysis, occurrence and future challenges
Published in Critical Reviews in Environmental Science and Technology, 2019
Pedro José Barroso, Juan Luis Santos, Julia Martín, Irene Aparicio, Esteban Alonso
When passive samplers are used, Soxhlet is the most commonly chosen extraction technique (Gioia, Steinnes, Thomas, Mejier, & Jones, 2006; Gioia, Sweetman, & Jones, 2007; Gouin, Harner, Blanchard, & Mackay, 2005; Jaward et al., 2005; Kim, Shoeib, Kim, & Park, 2012; Li et al., 2011; Liu et al., 2015; Müller et al., 2012; Pozo et al., 2004; Pozo et al., 2006; Shen et al., 2006; Shoeib, Harner, Wilford, Jones, & Zhu, 2005; Wilford, Harner, Zhu, Shoeib, & Jones, 2004; Zhang et al., 2008). As advantage, during Soxhlet extraction, there is continuous interaction between the solvent and the sample, which makes it a very efficient extraction process. The main drawback is the higher consumption of solvents and the extraction time (up to 24 hours and 400 mL) (Hoh, Zhu, & Hites, 2005; Ma et al., 2012), compared to USE, which usually requires three extraction steps and smaller volumes (5 to 10 mL) (Balducci et al., 2016; Das et al., 2014). Considering the extraction solvents, dichloromethane and acetone, and their mixtures, are the most widely used in the determination of OP (Solbu et al., 2007), BPA (Sabatini, Barbieri, & Violante, 2005), PBDEs (Gioia et al., 2006; Gouin et al., 2002; Wang et al., 2005), AP (Xie et al., 2006a) and phthalates (Xie, Ebinghaus, Temme, Caba, & Ruck, 2005), among others. Other solvents used for the extraction of EC are: methanol, applied in the extraction of PFAS (Barber et al., 2007; Jahnke, Berger, Ebinghaus, & Temme, 2007b; Müller et al., 2012; Stock et al.) and illicit drugs (Postigo et al., 2009; Salapasidou et al., 2011; Viana et al., 2010), hexane, used for the determination of phthalates (Wang, Wang, & Fan, 2008), AP and BPA (Berkner et al., 2004), SMF (Peck & Hornbuckle, 2004; Peck & Hornbuckle, 2006) PBDE (Cetin & Odabasi, 2007; Ter Schure, Larsson, Agrell, & Boon, 2004) and PFAS (Stock, Furdui, Muir, & Mabury, 2007), and petroleum ether, mainly in the case of PBDEs (Gouin et al., 2005; Pozo et al., 2004; Pozo et al., 2006; Wilford et al., 2004) and AP (Dachs, Van Ry, & Eisenreich, 1999; Van Ry et al., 2000).