Recovery of organic acids from pre-treated Kraft black liquor using ultrafiltration and liquid-liquid extraction

Organic solvents are known as carbon-based solvents and their general property is primarily based on their volatility, boiling point, the molecular weight and color. Having enormous hazards associated with the organic solvents, they are used for millions of purposes which alert us to think more on its toxicity points. Almost all of the solvents are hazardous to health, if swallowed or inhaled more than the limit quantity and on contact to the skin most of them cause irritation. Some of the common solvents are acetone, ethyl acetate, hexane, heptane, dichloromethane, methanol, ethanol, tetrahydrofuran, acetonitrile, dimethylformamide, toluene, dimethylsulfoxide etc. Researchers, scientists, workers in the chemical industry and research institutes use these solvents on regular basis leading them to be affected in major aspects. But also, the nearby persons are affected by the contamination to the soil, water, air etc. If constantly exposed with solvents, it will badly affect the function of CNS and other body parts. The level of impact, sign and symptoms will depend on concentration, time, duration, frequency and nature of solvents, leading to common effects like headache, dizziness, tiredness, blurred vision, behavioral changes, unconsciousness, and even(Zimmermann, Mayer et al. 1985) death. To overcome it, the green chemistry concept is growing rapidly, and the solvent selection guide is in practice in many big company and research institute. A researcher or chemical worker is the primary person who works with solvents and they need to consider throughout these things while performing their activities for their own good health and for the sake of the world. The purpose of this review is to provide needed basic knowledge about common organic solvents and their potential toxicities which will alert researchers to think twice and always think for their health as well as for the environment via safe and green practice.

Background Lignin is often overlooked in the valorization of lignocellulosic biomass, but lignin-based materials and chemicals represent potential value-added products for biorefineries that could significantly improve the economics of a biorefinery. Fluctuating crude oil prices and changing fuel specifications are some of the driving factors to develop new technologies that could be used to convert polymeric lignin into low molecular weight lignin and or monomeric aromatic feedstocks to assist in the displacement of the current products associated with the conversion of a whole barrel of oil. We present an approach to produce these chemicals based on the selective breakdown of lignin during ionic liquid pretreatment. Results The lignin breakdown products generated are found to be dependent on the starting biomass, and significant levels were generated on dissolution at 160°C for 6 hrs. Guaiacol was produced on dissolution of biomass and technical lignins. Vanillin was produced on dissolution of kraft lignin and eucalytpus. Syringol and allyl guaiacol were the major products observed on dissolution of switchgrass and pine, respectively, whereas syringol and allyl syringol were obtained by dissolution of eucalyptus. Furthermore, it was observed that different lignin-derived products could be generated by tuning the process conditions. Conclusions We have developed an ionic liquid based process that depolymerizes lignin and converts the low molecular weight lignin fractions into a variety of renewable chemicals from biomass. The generated chemicals (phenols, guaiacols, syringols, eugenol, catechols), their oxidized products (vanillin, vanillic acid, syringaldehyde) and their easily derivatized hydrocarbons (benzene, toluene, xylene, styrene, biphenyls and cyclohexane) already have relatively high market value as commodity and specialty chemicals, green building materials, nylons, and resins.