Characterization of the effluents condensated by volatile organic compounds during heat-treated rubberwood process

Tongtong Li,Jianing Li,Xiaowen Li,Guanjun Li,Min Li,Quanji Lu

doi:10.1186/s10086-020-01897-w

Abstract

Heat treatment was an eco-friendly modification technology for rubberwood, without the addition of chemical reagents into the wood and wood performance has been improved remarkably. Many effluents are generated from heat-treated rubberwood process, which were rarely researched. The effluents contain relatively high content of volatile organic compounds, which may seriously threaten the environment and human health. In this study, effluents condensated during different heat-treated stages (125 ℃, 145 ℃, 175 ℃, 185 ℃, 215 ℃) and frequently used industrial heat treatment production technology (185 ℃/3 h, 215 ℃/3 h) were characterized by gas chromatography–mass spectrometry (GC–MS). The effluents were classified as aldehydes, phenols, esters, ketones, acids, alcohols, alkanes, anhydride, aromatics and compounds released the most during all heat-treated stages were aldehydes. With the temperature increased, the relative amounts of aldehydes decreased, while the ketones, esters and aromatics increased under acidic constituents (pH ranged from 4.17 to 2.47) and high moisture condition. The vanillin and coniferyl aldehyde accounted for much higher proportion in the aldehydes. The mass loss of rubberwood was larger under 215 ℃/3 h (16.61%), correspondingly the effluents had more kinds of compounds at 215 ℃. These results would provide guidance for research of effluent disposal and transform biomass residues into valuable things.

Highlights

In China, the rubber (Hevea brasiliensis) plantations are mainly located in Hainan, Yunnan, and Guangdong provinces
The aim of our work is the characterization of these emissions by gas chromatography–mass spectrometry (GC–MS), and focus on the condensable effluents emitted by rubberwood heat-treatment processing
The rubber trees were planted for the production of latex, and the rubberwood was rich in starch, soluble sugars and other carbohydrates

Summary

Introduction

In China, the rubber (Hevea brasiliensis) plantations are mainly located in Hainan, Yunnan, and Guangdong provinces. The rubber trees, which provide raw materials for the rubber industry and abundant wood resources, are the main plantation tree species of the tropics [1]. In 2009, the total planted area of rubber trees was 13.314 million hectares in the world’s rubber producing countries. 12.2251 million hectares were in Asia, accounting for about 90% of the global rubber tree planting area. The rubber tree planted area of China ranked the third, with a total area of 1.161 million hectares [2], and the rubber logs were updated more. Heat treatment was an eco-friendly modification technology, without chemical reagents were added into the wood. Heat treatment improved various wood properties, including the dimensional stability, color, and decay resistance [5]. After the rubberwood was heat treated, the dimensional stability and decay resistance of rubberwood were elevated [6]. Due to the extracts and structural materials in rubberwood, it

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