低温等离子体技术去除船舶尾气脱硫洗涤水中多环芳烃的研究

Study of Degradation of Polycyclic Aromatic Hydrocarbons from Ship Emission Desulfurization Wash Water by Non-thermal Plasma

船舶尾气排放硫氧化物和氮氧化物是大气污染主要来源之一,采用湿法脱硫技术是减少硫氧化物排放的有效途径。但湿法脱硫后产生的洗涤水含有多种有害物质,其中多环芳烃为主要污染物之一,国际海事组织规定其含量不得超过2 250μg/L。文章以萘为多环芳烃代表物,采用低温等离子体技术处理船舶尾气脱硫洗涤水,分别考察低温等离子体工艺参数(放电功率、氧气进气量)和处理过程特征参数(温度、pH、水中阴离子)对萘去除率的影响。结果表明:最佳氧气进气量和放电功率分别为3 L/min和132 W时,萘去除率随温度升高先增大后降低;pH升高有利于萘的降解;水中SO_4^(2-)、SO_3^(2-)、NO_3^-、NO_2^-、HCO_3^-对萘的降解有不同程度的影响,其中HCO_3^-的影响最为显著。

SOx and NOx of ship emission are the main air pollutants.Wet desulfurization technology is an effective approach to reduce SOx emission.However,desulfurization wash water produced from desulfurization process contains many harmful materials,in which polycyclic aromatic hydrocarbons (PAHs)are one of the major pollutants.IMO requires that the concentrations of PAHs in washing water shouM not more than 2 250 μg/L.In the paper,degradation of naphthalene as a key PAHs using non-thermal plasma technology to treat ship emission desulfurization wash.water,the influence of non-thermal plasma technical parameters (discharge power,O2 flow rate)and treatment procedure (temperature,pH and anions in water)on naphthalene degradation is investigated.The results indicate that when the optimal O2flow rate and discharge power are 3 L/min and 132 W respectively,the degradation rate of naphthalene increases and then decreases with increasing temperature.Increasing of pH enhances the naphthalene degradation.Then anions such as S042^-,SO32^-,NO3^-,NO2^- and HC03^- in water cause different degrees of influence on naphthalene degradation,in which HC03^- has the most significant effect on naphthalene degradation.