Selecting chemicals for separation of ABS and HIPS in WEEE by froth flotation

Abstract

SbstractThe feasibility of using common chemicals to separate plastics from waste electrical and electronic equipment (WEEE) by froth flotation is investigated. Plastic waste is one of the WEEE polluters and a separation is necessary to recycle it. The most common plastics in electronic industries are acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS). These plastics are difficult to separate due to the similar specific weights and to both being repellent to water. Froth flotation allows for separating particles by the differences in their surface characteristics by selective wetting agents. The common chemicals are ethanol and acetic acid to depress the plastics. The process with 20% weight of ethanol was able to produce a recovery concentrate of HIPS with 98% and ABS with 96%. The process with 40% weight of acetic acid produces a recovery concentrate of HIPS with 96% and ABS with 83%.

Study the effects of flotation agents on ABS – PS flotation

“…The wetting agent is a chemical substance that improves a liquid's spreading and penetrating properties by lowering its surface tension, thus diminishing the substrate's hy drophobic characteristics. There have been numerous reports of wetting agents that are effective for plastic flotation, such as tannic acid (TA) [12][13][14][15], acetic acid [16], lignosulfonate (LS) [17,18], polyvinyl alcohol (PVA) [19,20], and methyl cellulose (MC) [21,22]. For the application of wetting agents in ABS separation, many types of wetting agents have been applied to facilitate the ABS selective separation.…”

Separation of waste plastic resulting from electrical products by forced aeration flotation

“…Water is used as a flotation agent and the wetting agents suitable for flotation are tannic acid, methylcellulose, lignosulfonates which increase the plastics surface hydrophilic capacity [11,12]. Ethyl alcohol and calcium chloride aqueous solutions were used by Pongstabodee et al [13] for plastics separation into subgroups based on their density, while Utimura et al [14] separated plastics from waste electrical and electronic equipment by flotation using ethanol and acetic acid. According to Burat et al [15], the separation of plastics with similar densities by flotation can be performed through modification of plastics surfaces.…”

Reciclagem de ABS proveniente de resíduos de eletroeletrônicos modificados com TiO>sub<2>/sub<-OPM

“…Quando todo o processo de identificação e separação do polímero é realizada e o processo de reciclagem é possível, isso representa que o plástico tenha seu ciclo de vida completo, com ganhos em diversos aspectos, como diminuição do impacto ambiental (com redução da poluição causada por esses equipamentos descartados, da diminuição do uso de produtos oriundos de fontes não-renováveis e nas emissões de gases) (Utimura et al, 2019). Estima-se que a economia energética para a reciclagem do ABS é cerca de 90%; a emissão de CO2 é diminuída em 87%…”