Isolation and characterisation of L-quebrachitol from rubber factory wastewater

In the production process of natural rubber (NR), large quantities of wastewater containing substantial amounts of L-quebrachitol are discharged. To date, published methods of extracting L-quebrachitol from wastewater are still at the laboratory stage. In this study, membrane separation technology was applied to the extraction of L-quebrachitol from wastewater and the experimental parameters were studied in order to determine optimal experimental conditions. Results show that the optimum source material for L-quebrachitol extraction was the serum collected by squeezing the latex coagulum. When this serum was passed through a microfiltration (MF) membrane and two ultrafiltration (UF) membranes, majority of the organic impurities were removed. The resulting ultrafiltrate was concentrated by a nanofiltration (NF) membrane and washed twice. Finally, a new and convenient approach for large scale extraction of L-quebrachitol is proposed combining membrane separation and crystallisation. The output achieved with this approach would be 10 kg per year under laboratory conditions with 99.20% purity. The structure of L-quebrachitol was confirmed by elementary analysis, infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy (MS) and single-crystal X-ray diffraction.