*Article* **Optimization of Ultrasonic-Assisted Extraction of Chlorogenic Acid from Tobacco Waste**

**Guoming Zeng 1,†, Yujie Ran 1,†, Xin Huang 1, Yan Li 2, Maolan Zhang 1,\*, Hui Ding 1, Yonggang Ma 2, Hongshuo Ma 1, Libo Jin <sup>3</sup> and Da Sun 3,\***


**Abstract:** Using tobacco waste as raw material, the ultrasonic-assisted extraction of chlorogenic acid was optimized by response surface methodology (RSM). After repeated freezing and thawing of tobacco waste twice, the effect of pH value, ethanol volume fraction, temperature and extraction time on the extraction rate of chlorogenic acid was investigated by a single factor experiment. On the basis of this, the factors affecting the yield of chlorogenic acid were further optimized by using RSM. The optimum extraction conditions for chlorogenic acid were set at pH = 4.1, ethanol volume fraction was 49.57% and extraction time was 2.06 h. Under the above conditions, the extraction rate of chlorogenic acid could reach 0.502%, which was higher than traditional extraction and unpretreated ultrasonic extraction. All these results can be used as a reference for the extraction of effective ingredients in tobacco waste.

**Keywords:** waste treatment; chlorogenic acid; optimal design; preprocessing; ultrasonic-assisted extraction
