Title
Microwave-assisted alkali pretreatment of Haplophragma adenophyllum leaves for bioethanol production
Authors
NASHEEN RUBAB, MISBAH GHAZANFAR, SAMREEN ADNAN, IRFAN AHMAD, HAFIZ ABDULLAH SHAKIR, MUHAMMAD KHAN, MARCELO FRANCO and MUHAMMAD IRFAN

Received February 18, 2023
Published Volume 57 Issue 3-4 March-April
Keywords bioethanol, biomass, cellulose, pretreatment, alkali, assisted

Abstract
The current study is focused on the use of Haplophragma adenophyllum leaves for bioethanol production. The biomass was pretreated with two types of alkalis, i.e. KOH and NaOH. The Box-Behnken Design (BBD), with three levels and three variables, of the response surface methodology (RSM) was employed to determine the effects of alkali concentration, biomass loading and soaking time in the microwave oven on the release of total phenolic compounds, total sugars, reducing sugars and exposure of cellulose. NaOH was found more efficient in the removal of lignin from cellulose. Maximum cellulose (55%) was observed after the treatment with 0.5% NaOH concentration, 10% substrate concentration and 5 s residence time. FTIR spectroscopy of the raw and pretreated samples depicted the chemical changes incurred by the pretreatments. Commercial cellulase (40 FPU) was used for saccharification and maximum hydrolysis (50.1%) was obtained after 28 h. The hydrolysate was fermented using Saccharomyces cerevisiae and the highest ethanol yield (4.11%) was recorded after 96 h of fermentation.