Conventional solvent-recovery plant

Rich solvent, containing aromatics and sulfur compounds, is routed to the solvent recovery column (SRC) where the hydrocarbons and sulfur species are separated, and lean solvent is recovered in column bottoms. The SRC overhead is hydrotreated by conventional means and either used as desulfurized gasoline or directed to an aromatics plant. Lean solvent from the SRC bottoms is recycled back to the EDC. 

Dimethylsulphoxide is a particular problem. Distillation can be hazardous. Although non-toxic, disposal via a conventional bacteriological effluent treatment plant is not recommended any anaerobic bacteria will convert the dimethylsulphoxide to dimethylsulphide, which is highly malodorous. A recent excellent textbook is available covering the subject of solvent recovery [50]. 

Oil and oil fractions, phenols, tocopherols and peptides are all of interest to the canola/oilseed rape processing industry for their potential use in functional food products and nutraceuticals. The successful use of ultrasound-assisted extraction of these components in various plant or tissue systems demonstrates that ultrasound-assisted extraction is a viable alternative for the canola/oilseed rape industry for the recovery of value-added products from whole seeds, hulls and press cakes. However, due to limited research on pilot-scale application, it is difficult to model cost advantages of ultrasound-assisted extraction versus conventional solvent extraction when applied to commodity oilseed processing. 

Like Soxhlet, sonication is also recognized as an established conventional method, although it is not as widely used. Limited research has focused on sonication per se or its comparison with Soxhlet. Qu et al. [13] developed a method using sonication with methanol for the extraction of linear alkylbenzene sulfonate (LAS) in plant tissues (rice stems and leaves). Both efficiency and accuracy were found to be high. The mean recovery was 89% (84 to 93% for LAS concentration of 1 to 100 mg/kg), and the relative standard deviation (RSD) was 3% for six replicate analyses. Its advantages over Soxhlet extraction were speed (1 hour), less solvent consumption, and smaller sample requirement (2 to 3 g). 

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