Physicochemical Characterization Study of Prepared Carbon Fibers from Lignin Extracted from Different Biomass Sources

Abstract

Lignocellulosic materials such as agricultural residues have been identified as potential sustainable sources that can replace petroleum-based polymers used in many industrial applications. Clean technologies can also be implemented to replace organic wastes by recycling. From the green chemistry viewpoint, we are attempting to explore regenerative materials for carbon-based products as carbon fibers (CFs). Sustainable raw materials made up of biopolymers or biogenic polymers are an especially fascinating source for handling CFs. Given lignin (L) low price and carbon building chemical structure, it is reputable as a potential for CF precursor. The presenting thesis examines the synthesis of CFs from lignin derived from agricultural residues (bagasse (B), palm frond (PF) and banana bunch (BB)) by means of various processing techniques, as follows: 1- The first step involves the extraction of lignin from aforementioned residues used for the treatment of delignification. Among delignification techniques, alkali and organosolv treatments can produce high yields of free-sulfur lignin with better physicochemical properties including high levels of carbon, low ash and low levels of humidity. Alkali hydrolysis technique optimized alkali solution concentration (NaOH), processing time and temperature for high yield (%) of alkali extracted lignins (alkali bagasse lignin (ABL), alkali palm frond lignin (APFL), and alkali banana bunch lignin (ABBL). We concluded that 10% and 100°C are the optimum NaOH concentration and processing temperature for the three biomasses respectively, but the efficacy of alkaline pretreatment was assessed with 12, 6 and 2h run-time, adequate for B, PF and BB biomass. 2- For organosolv hydrolysis technique, the ratio of formic acid (85%) : acetic acid (85%) was (70 : 30) (v/v), boiling for 2 hours in the presence