**1. Introduction**

Recently, the Chinese public has become increasingly concerned about the levels of chemical air pollution present in the form of haze. A main contributing factor to this pollution is the release of volatile organic compounds (VOCs) from the industry. VOCs are organic compounds with boiling points in the range of 50–260 ◦C at atmospheric pressure or with a Reid vapor pressure of over 10.3 Pa at room temperature (293.15 K) and atmosphere pressure (101.325 kPa) [1,2]. The pharmaceutical industry is a major source of these VOCs [3,4], which can have serious ramifications, such as toxicity, carcinogenesis, mutagenesis, photochemical pollution, haze, and fog [5–9]. The pharmaceutical industry has developed greatly in China, as the production of bulk drug intermediates and Chinese patent drugs increased from 205,070 to 340,830 kilotons, and 112,890 to 374,600 kilotons in the past 10 years (2007–2016), respectively [10]. Meanwhile, the amounts of released VOCs increased from about 174.8 to 393.2 kt in the pharmaceutical industry [11,12]. The guiding emission standards of VOCs went into effect on 1 January, 2018 in China, which led to new imputes to upgrade VOCs elimination equipment and technologies in factories across China [13].
