Microwave-assisted low-temperature hydrothermal treatment of red seaweed (Gracilaria lemaneiformis) for production of levulinic acid and algae hydrochar

Leichang Cao; Iris K M Yu; Dong-Wan Cho; Di Wang; Daniel C W Tsang; Shicheng Zhang; Shiming Ding; Linling Wang; Yong Sik Ok

doi:10.1016/j.biortech.2018.11.013

Microwave-assisted low-temperature hydrothermal treatment of red seaweed (Gracilaria lemaneiformis) for production of levulinic acid and algae hydrochar

Bioresour Technol. 2019 Feb:273:251-258. doi: 10.1016/j.biortech.2018.11.013. Epub 2018 Nov 5.

Authors

Leichang Cao¹, Iris K M Yu², Dong-Wan Cho³, Di Wang⁴, Daniel C W Tsang⁵, Shicheng Zhang⁶, Shiming Ding⁷, Linling Wang⁸, Yong Sik Ok⁹

Affiliations

¹ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
² Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; Green Chemistry Centre of Excellence, Department of Chemistry, University of York, York YO10 5DD, UK.
³ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
⁴ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
⁵ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China. Electronic address: dan.tsang@polyu.edu.hk.
⁶ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
⁷ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
⁸ School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
⁹ O-Jeong Eco-Resilience Institute (OJERI), Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea.

PMID: 30448676
DOI: 10.1016/j.biortech.2018.11.013

Abstract

In this study, red seaweed (Gracilaria lemaneiformis) food waste with high carbohydrate content was valorized into levulinic acid (LA) and algae hydrochar through microwave-assisted low-temperature hydrothermal treatment in dilute acid solution. Various parameters including treatment temperature (160-200 °C), reaction time (1-40 min), acid concentration (0-0.6 M), and biomass-to-liquid ratio (1%-10%, w/v) were examined. The energy efficiency and carbon recovery of the proposed process were investigated. Under the experimental conditions of 5% (w/v) biomass loading, 0.2 M H₂SO_4, 180 °C, and 20 min, the highest levulinic acid yield of 16.3 wt% was produced. The resulting hydrochar showed approximately 45-55% energy yield and higher heating values of 19-25 MJ kg^-1. The energy efficiency of the present study (1.31 × 10^-6 g LA/J) was comparable to those of the conventional hydrothermal treatment of lignocellulosic biomass, while the reaction time (20 min) was much shorter with a high carbon recovery (73.3%).

Keywords: Acid hydrolysis; Carbohydrate-rich biomass; Engineered biochar; Food waste valorization; Macroalgae biorefinery.

MeSH terms

Biomass
Carbon / metabolism
Cold Temperature
Gracilaria / metabolism*
Levulinic Acids / metabolism*
Microwaves*
Seaweed / metabolism*

Substances

Levulinic Acids
Carbon
levulinic acid