Use of exhausted biosorbent ash as eco‐friendly filler in natural rubber

Biosorption is a promising cost-effective clean-up technology for treating wastewater laden with heavy metals. However, the commercial application of biosorption technologies has been limited because a large amount of toxic waste is left behind in this process. The post-sorbents need to be handled in a way that does not negatively affect the environment. In this research, one possibility to solve this problem was proposed and developed: incineration of used adsorbent, followed by the use of the obtained ash as a filler in rubber production. The results showed that the addition of biosorbent ash does not significantly affect the rubber mechanical and elastic properties. The ash addition affected only the beginning of the vulcanization by increasing the activation energy of the curing chemical reaction. This property can be used to prevent the premature start of vulcanization. Furthermore, it was determined whether and to what extent the ash-filled rubber releases metal ions in contact with water. Results showed that the amount of copper leached from rubber samples was negligible compared to the copper that remained permanently built in the rubber. Therefore, this novel approach to utilizing saturated biosorbents as rubber fillers is acceptable from the environmental safety perspective. (c) 2022 Society of Industrial Chemistry.