Regeneration of Honeycomb Zeolite by Nonthermal Plasma Desorption of Toluene

In order to develop an economical volatile organic compound (VOC) removal process, a concentration technique using nonthermal plasma combined with an adsorption process is investigated. Toluene-one of the most commonly used VOCs-is used, and the optimization of plasma desorption is investigated. The effects of toluene concentration and adsorbent regeneration are investigated by varying the plasma desorption methods: closing method, in which a carrier gas is stopped flowing during a portion of plasma desorption time, and nonclosing method. As a result, the closing method is favored with regard to parameters such as concentration, desorption efficiency, regeneration efficiency, and by-product formation. Then, the plasma desorption using closing method is investigated as a function of discharge power, closing time, a carrier gas flow rate for plasma desorption, and plasma desorption time. When a 2-L/min and 30-ppm toluene gas is employed as a target gas, a toluene concentration exceeding 30 times the original concentration is achieved with a reduction in the gas volume by 1/60. The repeatability of adsorption and plasma desorption is successfully demonstrated; these processes yield an extremely effective and practical VOC removal process.