*Article* **Initial Conditioning of Used Cigarette Filters for Their Recycling as Acoustical Absorber Materials**

**Valentín Gómez Escobar 1,\*, Celia Moreno González 1, María José Arévalo Caballero <sup>2</sup> and Ana Ma Gata Jaramillo <sup>2</sup>**


**Abstract:** Used cigarette butts represent a major and problematic form of waste, due to their abundance, toxicity, and durability. Moreover, the few proposals for their recycling are clearly insufficient, and new ones are welcome. For a new proposal regarding the reuse of used cigarette butts as acoustical absorbers in building construction, previous conditioning of the used butts is performed. This conditioning includes the elimination of moisture and toxic products accumulated in the filter of the cigarettes. Thus, in this work, the moisture content effect in acoustical absorption was analyzed, and a proposal for elimination is made. Moreover, a chemical cleaning procedure is proposed, and its influence on the acoustical behavior of the samples was also analyzed.

**Keywords:** sound absorber; cigarette butts; sustainable material; recycling; chemical cleaning

**Citation:** Gómez Escobar, V.; Moreno González, C.; Arévalo Caballero, M.J.; Gata Jaramillo, A.M. Initial Conditioning of Used Cigarette Filters for Their Recycling as Acoustical Absorber Materials. *Materials* **2021**, *14*, 4161. https://doi.org/10.3390/ ma14154161

Academic Editor: Neven Ukrainczyk

Received: 1 July 2021 Accepted: 25 July 2021 Published: 27 July 2021

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