Recycling waste tantalum capacitors to synthesize high value-added Ta2O5 and polyaniline-decorated Ta2O5 photocatalyst by an integrated chlorination-sintering-chemisorption process

Waste tantalum capacitors, containing about 30-40 wt% rare metal tantalum (Ta), are one of the main Ta secondary resources. Not just to achieve the Ta resource recovery but to realize the value-added utilization, we recycled waste tantalum capacitors to prepare Ta2O5 photocatalyst by a chlorination-sintering process. To enhance the photocatalytic performance, Ta2O5 was further decorated by polyaniline (PANI) through a chemisorption approach. The as-prepared Ta2O5 and TTa2O5/PANI photocatalysts exhibited irregular nanoparticles with the particle size of 50-80 nm. After the PANI decoration, the photocatalytic performance of Ta2O5 was significantly enhanced. The optimal simulated sunlight H-2 evolution rate and RhB degradation rate constant of TTa2O5/PANI (3 wt%) could reach 200.8 mu molg(-1)h(-1) and 0.1342 min(-1), which were about 3.3 and 5.6 times higher than those of Ta2O5. The superior photocatalytic performance of Ta2O5/PANI was ascribed to the intense interfacial interaction, increased visible light absorption and efficient charge carrier separation. In short, this study demonstrates a sustainable approach to convert e-waste to high-value-added and high-efficient photocatalyst, which is significant for waste utilization and environmental protection. (C) 2019 Published by Elsevier Ltd.