Evaluation of ultrasound assisted potassium permanganate pre-treatment of spent coffee waste

•A novel one-step pretreatment for spent coffee waste has been presented in this study.•Extensive delignification in coffee was achieved using ultrasound-assisted potassium permanganate pretreatment.•The polysaccharide fraction of spent coffee waste was left unaffected.•Pretreatment leads to high re...

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Bibliographic Details
Published in:Bioresource technology 2017-01, Vol.224, p.680-687
Main Authors: Ravindran, Rajeev, Jaiswal, Swarna, Abu-Ghannam, Nissreen, Jaiswal, Amit K.
Format: Article
Language:English
Subjects:
Alkalies - chemistry
Alkaline potassium permanganate
Biomass
Biomass pretreatment
Carbohydrates - chemistry
Cellulose - chemistry
Coffee - chemistry
Hydrolysis
Lignin - chemistry
Lignocellulose
Potassium Permanganate - chemistry
Reducing sugar
Sonication
Spent coffee waste
Temperature
Ultrasonication
Ultrasonics - methods
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Summary:•A novel one-step pretreatment for spent coffee waste has been presented in this study.•Extensive delignification in coffee was achieved using ultrasound-assisted potassium permanganate pretreatment.•The polysaccharide fraction of spent coffee waste was left unaffected.•Pretreatment leads to high reducing sugar yield upon enzymatic hydrolysis of spent coffee waste. In the present study, novel pre-treatment for spent coffee waste (SCW) has been proposed which utilises the superior oxidising capacity of alkaline KMnO4 assisted by ultra-sonication. The pre-treatment was conducted for different exposure times (10, 20, 30 and 40min) using different concentrations of KMnO4 (1, 2, 3, 4, 5%w/v) at room temperature with solid/liquid ratio of 1:10. Pretreating SCW with 4% KMnO4 and exposing it to ultrasound for 20min resulted in 98% cellulose recovery and a maximum lignin removal of 46%. 1.7 fold increase in reducing sugar yield was obtained after enzymatic hydrolysis of KMnO4 pretreated SCW as compared to raw. SEM, XRD and FTIR analysis of the pretreated SCW revealed the various effects of pretreatment. Thermal behaviour of the pretreated substrate against the native biomass was also studied using DSC. Ultrasound-assisted potassium permanganate oxidation was found to be an effective pretreatment for SCW, and can be a used as a potential feedstock pretreatment strategy for bioethanol production.
ISSN:0960-8524
1873-2976
DOI:10.1016/j.biortech.2016.11.034