Conversion characteristics and production evaluation of styrene/o-xylene mixtures removed by DBD pretreatment.

Liying Jiang,Jianmeng Chen,Runye Zhu,Liang Zhang,Yubo Mao

doi:10.3390/ijerph120201334

Abstract

The combination of chemical oxidation methods with biotechnology to removal recalcitrant VOCs is a promising technology. In this paper, the aim was to identify the role of key process parameters and biodegradability of the degradation products using a dielectric barrier discharge (DBD) reactor, which provided the fundamental data to evaluate the possibilities of the combined system. Effects of various technologic parameters like initial concentration of mixtures, residence time and relative humidity on the decomposition and the degradation products were examined and discussed. It was found that the removal efficiency of mixed VOCs decreased with increasing initial concentration. The removal efficiency reached the maximum value as relative humidity was approximately 40%–60%. Increasing the residence time resulted in increasing the removal efficiency and the order of destruction efficiency of VOCs followed the order styrene > o-xylene. Compared with the single compounds, the removal efficiency of styrene and o-xylene in the mixtures of VOCs decreased significantly and o-xylene decreased more rapidly. The degradation products were analyzed by gas chromatography and gas chromatography-mass spectrometry, and the main compounds detected were O3, COx and benzene ring derivatives. The biodegradability of mixed VOCs was improved and the products had positive effect on biomass during plasma application, and furthermore typical results indicated that the biodegradability and biotoxicity of gaseous pollutant were quite depending on the specific input energy (SIE).

Highlights

A large number of volatile organic compounds (VOCs) are emitted from various industrial processes and with their toxicity that threatens human health, they contribute to severe environmental problems [1,2], they are tightly controlled in many countries
The input energy should correspondingly be raised to counterbalance the increased initial concentration. The diagram shows another conclusion: despite the fact the removal efficiency decreased by degrees, the amounts of VOCs removed were rising until a balance was achieved
The experiment results of various technical parameters for mixed VOCs decomposition indicated that the removal efficiency was enhanced significantly with the rising reaction time, but overly high residence time is not favorable because of the low energy efficiency

Summary

Introduction

A large number of volatile organic compounds (VOCs) are emitted from various industrial processes and with their toxicity that threatens human health, they contribute to severe environmental problems [1,2], they are tightly controlled in many countries. VOCs, widely coexist in a wide range of industrial production processes, such as pesticide, surface coating and paint manufacturing processes, especially in the coatings industry [3,4]. China is regarded as the second largest country for the manufacture of coatings, large amounts of styrene/o-xylene mixture have been frequently released into the atmosphere accompanying the production and usage of coatings. Indiscriminate exposure to styrene/o-xylene mixtures may cause dizziness, neurasthenia and an increased risk of cancer [3,4]. They could be precursors for the formation of secondary aerosols and photochemical smog. Styrene/o-xylene mixture emissions need to be strictly controlled by developing suitable abatement methods

Methods

Results

Conclusion