ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Oxidation of glycerol to a lactic, glycolic acid mixture using a Li, Ni, Mn, Co oxide catalyst and p-TsOH—SnCl₂ catalyzed polymerization to poly(lactic-co-glycolic acid)

Ananda S. Amarasekara, Hashini N. K. Herath, and Deping Wang

Department of Chemistry, Prairie View A&M University, Prairie View, USA

E-mail: asamarasekara@pvamu.edu

Received: 5 December 2023  Accepted: 2 April 2024

Abstract:

Oxidation of glycerol to lactic and glycolic acids is one of the most sought-after upgrades for this waste product in the biodiesel industry. These renewable glycerol-based hydroxy—carboxylic acid products are valuable monomers for the synthesis of new generation biodegradable polymers. In this work, a practically no-cost catalyst was prepared by using electrode coatings in 18,650 type Li-ion cells found in a spent DELL laptop battery. The combined cathode and anode coatings collected from Li-ion cells were pyrolyzed at 600 °C in air for 30 min. to prepare the catalyst with formula LiNi_0.03Mn_0.02Co_0.11O_0.85/C. Oxidation of glycerol using 25 mg/mmol catalyst in 0.50 M aqueous NaOH, under 3.4 atm. O₂, 230 °C, 4 h. gave the highest yields of lactic and glycolic acids, 54 and 41%, respectively. Next, this hydroxy acid mixture was directly polymerized using p-toluene sulfonic acid—SnCl₂ catalyst in refluxing xylene to give poly(lactic-co-glycolic acid) with M_w = 8017, M_w/M_n = 1.435, T_g = 41 °C, T_m = 182 °C and in 74% yield.

Keywords: Glycerol; Lactic acid; Glycolic acid; Lithium nickel manganese cobalt oxide; Poly(lactic-co-glycolic acid)

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-024-03449-8

Chemical Papers 78 (8) 5019–5029 (2024)