A highly Semi Critical Assisted-Solvent method for continuous to fractional extraction of biofuel from macro-/micro-algae and poly-aromatic hydrocarbons from coal, and soil materials

T. Chavez-Gil
Coppin State University,
United States

Keywords: semi critical, assisted-solvent, extraction, algae, biodiesel, hydrocarbon, coal, soil


Fuels (gas, liquid), polymers, fertilizers, resins, additives, lubricants and medicines are derivatives from linear/branched/aromatic hydrocarbon feedstock’s after refining/cracking processes on petroleum/coal. Fatty acid methyl esters (FAME) extracted from algae (macro, micro) and cereal grains have increased also its industrial demand as similar manufacturing materials among their environmental benefits for power plants, and all kinds of transportation. Coal and petroleum feedstock extraction’s had been established since long time ago, but to date, biodiesel extraction remains a challenging task for engineering and chemical technologies. Contaminants extraction (ash, heavy metals, poly-aromatic hydrocarbons, PAH’s) from these resources is another challenge in regards of adding economical value directly related with an enhancement of energy content. Thus, supercritical carbon dioxide, SCE (high pressure/temperature, dependent) and modified Soxhlet, Sx (solvent density, dependent) methods had dominated the biodiesel and PAH’s extraction process. However, parallel methods for the same purposes shows similar results as those obtained with these two technologies, so new methods to address the short stage for biodiesel, FAME, and contaminants extraction are highly in needs. Herein, we report on an improved thermochemical method termed semi critical assisted-solvent extraction (SmCA-Sol) that applies for a broad scope of technological, scientific, and academic fields in regards of extract/separate biodiesel, ash, PAH’s from different kind of sources. Briefly, the innovation designed to carried out SmCA-Sol experiments is hypothesized that works to generate a laminar flow, with the fluid phase being composed by almost two different physical states (liquid/vapor) but coexisting in isothermal equilibrium. Under this stage of equilibrium the binary fluid possesses the force required to maintain a stationary velocity difference between two parallel planes (liquid/vapor), which is directly proportional to the phase area and is inversely proportional to the planes distance.1 The novel aspect of the innovation is related with its facile operation, less time and solvent consume, in situ thermodynamic property (temperature, polarity, pressure, pH) measurements - impossible to be determinate by using Soxhlet, Gregar or Soxtec extractors. The innovation can be setup to works in continuous, fractionation or step-by-step processes under mild or high temperatures (500°C) as well for moderate vacuum to above 1.0 atmosphere of pressure. Under SmCA-Sol the sample is thoroughly soaked (percolate) in two opposite pathways leading to high yields of extract (bio-crude or PAH’s). For wild green macro algae, crude oil plus residual biomass gave combined calorific values of 49.05 MJ/kg in agreement with high-detected hydrocarbons (C, 72.56%; H, 10.59%) consistent with high quality liquid fuels. In addition, the yield of oil was improved from 13.2% (Sx) to 34.8 %.2 Heavy metals and PAH’s from raw a material (bituminous, low-rank coal) and contaminated soil were extracted for characterization in large amount/short time, but avoiding expensive/complicate extractor assemblies as well as personnel with high qualifications for a safety operation. 1 - Chavez-Gil, T., 2016. Compact extractor/separator apparatus for solid/liquid/gel sample. United States Patent, US-Patent # 9,259,666-B1. 2 - Chavez-Gil. T. et al. American Journal of Biochemistry and Biotechnology, 2018, 14 (2): 124-136. DOI: 10.3844/ajbbsp.2018.124.136