The novel method to reduce the silica content in lignin recovered from black liquor originating from rice straw

Nghi H Do,Tan M Le,Phung K Le,Jeroen Lauwaert,Ludo Diels,Nga H N Do,Viet T Tran,Hieu H Pham,An Verberckmoes

doi:10.1038/s41598-020-77867-5

Abstract

Difficulties in the production of lignin from rice straw because of high silica content in the recovered lignin reduce its recovery yield and applications as bio-fuel and aromatic chemicals. Therefore, the objective of this study is to develop a novel method to reduce the silica content in lignin from rice straw more effectively and selectively. The method is established by monitoring the precipitation behavior as well as the chemical structure of precipitate by single-stage acidification at different pH values of black liquor collected from the alkaline treatment of rice straw. The result illustrates the significant influence of pH on the physical and chemical properties of the precipitate and the supernatant. The simple two-step acidification of the black liquor at pilot-scale by sulfuric acid 20w/v% is applied to recover lignin at pH 9 and pH 3 and gives a percentage of silica removal as high as 94.38%. Following the developed process, the high-quality lignin could be produced from abundant rice straw at the industrial-scale.

Highlights

Difficulties in the production of lignin from rice straw because of high silica content in the recovered lignin reduce its recovery yield and applications as bio-fuel and aromatic chemicals
In the case of rice straw, alkaline pretreatment is the outstanding selection for lignin recovery in rice straw since this method is more effective for herbaceous plants than woody plants[17]
The objective of this study is to develop a novel method to reduce the silica content in lignin from rice straw more effectively and selectively

Summary

Introduction

Difficulties in the production of lignin from rice straw because of high silica content in the recovered lignin reduce its recovery yield and applications as bio-fuel and aromatic chemicals. The objective of this study is to develop a novel method to reduce the silica content in lignin from rice straw more effectively and selectively. The method is established by monitoring the precipitation behavior as well as the chemical structure of precipitate by single-stage acidification at different pH values of black liquor collected from the alkaline treatment of rice straw. The simple two-step acidification of the black liquor at pilot-scale by sulfuric acid 20w/v% is applied to recover lignin at pH 9 and pH 3 and gives a percentage of silica removal as high as 94.38%. HCl and nitric acid ( HNO3) had lower efficiency compared to sulfuric acid ( H2SO4)[8]

Objectives

Methods

Results

Conclusion