Application of chewed gum for treating oil sands tailings and adsorbing organic dyes and heavy metal ions

Abstract

Here, we investigated the use of waste chewing gum as an environmentally problematic waste product for use as a sorbent for treating tailings pond water (TPW) from the Alberta oil sands. TPW has been found to contain toxic substances, including heavy metals, certain naphthenic acids, and polycyclic aromatic hydrocarbons. These pollutants are known to pose significant risks to the environment and living organisms. In this study, we demonstrated that the gum sorbent exhibited good sorption affinity for model compounds, e.g., crystal violet (CV), rhodamine B (RB), and methylene blue (MB). Furthermore, a slight decrease in adsorption efficiency was observed over four reuse cycles. Good removal efficiency of heavy metal ions (Pb²⁺, Fe³⁺, Cu²⁺, Zn²⁺, Hg²⁺, Ag⁺, and Cd²⁺) was also observed, especially for lead (100%), iron (99%), and copper (98%), and even in heavy metal ion mixtures. The greatest reduction in TPW cytotoxicity was shown by filtration columns prepared with gum and silica, based on cell viability measured using HeLa cells, even when compared to columns containing charcoal and silica. Interestingly, higher levels of untreated organic carbon were found in the filtrate from these gum-based columns, suggesting that the gum might have reacted with the harmful compounds rather than simply trapping them. These results point to chewing gum as a recyclable waste material that is promising for the development of effective waste-based systems for cleaning industrial wastewater.