Fast preparation of carbon spheres from enzymatic hydrolysis lignin: Effects of hydrothermal carbonization conditions

Haiyan Mao,Pin Lan,Xianwen Chen,Xiaoyan Zhou,Runzhou Huang,Feng Zhang,Rui Yang,Minzhi Chen,Yu Yang,Meijun Zhou

doi:10.1038/s41598-018-27777-4

Haiyan Mao, Pin Lan + Show 8 more

Open Access

https://doi.org/10.1038/s41598-018-27777-4

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Abstract

This study explores the effect of carbon sphere preparation conditions on the morphology of the carbon spheres and the micropore development by fast potassium hydroxide activation via microwave heating. Enzymatic hydrolysis lignin is used as the precursor for carbon sphere preparation via environmentally friendly hydrothermal carbonization. The effects of various carbonization temperatures, carbonization times and reaction concentrations on the physical morphology of the carbon sphere surfaces are investigated. The Brunauer-Emmett-Teller surface area, yield and scanning electron microscopic images are used to characterize the carbon spheres. High carbonization temperatures and times result in large particle sizes, high sphericity, uniform size, and high dispersity of the carbon spheres. The best carbon spheres are obtained at 270 °C for 7 hours with a reaction concentration of 0.06 g ml−1 and a particle size of 3–6 μm. After activation, the Brunauer-Emmett-Teller surface area of the activated carbon spheres increases from 248 m2 g−1 to 1278 m2 g−1. Carbon spheres activated by treatment with fast potassium hydroxide and microwave heating can develop micropores that enhance the adsorptive capacity for small molecules, such as gases. Enzymatic hydrolysis lignin-derived carbon spheres formed via hydrothermal carbonization should be potentially sustainable materials applicable in energy and environmental fields.

Highlights

Carbon spheres (CSs) have garnered significant interest among researchers because of their potential applications, e.g., in gas separation and as molecular sieves[1,2], photonic band gap crystals[3,4], catalyst supports[5,6] and electrode materials for lithium ion batteries[7,8]
scanning electron microscopy (SEM) images of enzymatic hydrolysis lignin (EHL)-derived carbon spheres synthesized by hydrothermal carbonization (HTC) at different reaction temperatures
CSs synthesized at different reaction temperatures showed variations in morphology, particle size and dispersion

Summary

Introduction

Carbon spheres (CSs) have garnered significant interest among researchers because of their potential applications, e.g., in gas separation and as molecular sieves[1,2], photonic band gap crystals[3,4], catalyst supports[5,6] and electrode materials for lithium ion batteries[7,8]. In 2009, Sevilla and Fuertes used glucose, sucrose and starch as raw materials to study the effect of hydrothermal carbonization on the structure and properties of carbon microspheres[27]. Stable and uniform carbon spheres, this study used the EHL as the raw material and the HTC method to synthesize carbon spheres. The research involved the following: (1) use of the HTC method to investigate the effects of the EHL concentration, reaction temperatures and reaction times on the characterization of the microstructure and surface functional groups of the spheres via scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) and (2) systematic examination of the effects of KOH and microwave heating on the porous structure and surface chemistry of carbon spheres. Enzymatic hydrolysis lignin-derived carbon spheres activated by microwave heating and KOH should be potentially sustainable materials for application in environmental gas adsorption

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Conclusion