Purification of Crude Glycerol Recovered From Fish Processing Waste Biodiesel Process

Abstract

Biodiesel and crude glycerol are byproducts of the esterification and transesterification reactions that occur between triglyceride molecules and alcohol in the presence of acid and base catalysts. Purification of crude glycerol is necessary to increase the economic sustainability of the biodiesel industry. This study was carried out for pre-treatment of crude glycerol sourced from fish processing waste during biodiesel manufacturing, treated through an acidification process using phosphoric acid (H3PO4), and then using further purification treatment with Jatropha curcas bio-adsorbent. Based on the measurement, the quantity of 0.1% phosphoric acid (H3PO4) solution was required to treat the crude glycerin. The reaction conditions include heating solution to 60°C and stirring it at 40 rpm for varying treatment periods such as 15, 30, 45, and 60 min. The crude glycerol's pH was adjusted to begin the acidification process, and soap was then converted into fatty acids and salts using phosphoric acid. The maximum purified glycerol yield of 76.6% by weight was obtained with treatment time of 15min using vacuum distillation at 120°C. The crude and purified glycerol’s density was measured as 1.013 g/mL and 1.001 g/mL, respectively. However, after bio-adsorbent treatment at temperature of 50°C and 10% loading weight of the Jatropha curcas bio-adsorbent, the best impurity elimination was accomplished in 15 min. The research findings demonstrated that, following acidification and bio-adsorbent treatments, the FFA% decreased from 2.82% to 2.24%, while its density increased from 1.002 g/mL to 1.032 g/mL, respectively. The purified glycerol properties were found in accordance with BS 2621-1979 standard, showing that the acidification method for purifying of crude glycerol, in conjunction with bio-adsorbent treatment is efficient in enhancing the glycerol purity. It also improves glycerol's application in generating high-value products that enhance revenue streams for the biodiesel production.