Rubber/BiOCl: Yb,Er composite for the enhanced degradation of methylene blue and Rhodamine B dyes under solar irradiation

BiOCl:Yb,Er (BiOCl) photocatalyst was synthesized by combustion method using urea or thiourea as fuel. The analysis by scanning-electron microscopy revealed that BiOCl photocatalysts made with urea and thiourea had irregular-like and rod-like shapes, respectively. The BiOCl photocatalyst synthesized with urea and thiourea degraded Methylene Blue (MB) by 90 % and 100 %, respectively, after 90 min under UV–VIS light. Interestingly, BiOCl photocatalyst made with thiourea degraded completely MB after only 60 min under solar light. Later, the BiOCl photocatalyst was supported on recycled rubber (taken from bicycle tires) and this rubber/BiOCl (R/BiOCl) composite produced 100 % degradation for MB after 90 min of photocatalytic reaction. BiOCl powder synthesized with thiourea also degraded totally Rhodamine B (RhB) dye (after 90 min using UV–VIS light and after 10 min using sunlight). The R/BiOCl composite degraded 100 % of RhB after 120 min. Thus, the R/BiOCl composite produced slower dye degradation, but it was easily removed (manually) from the clean water. BiOCl synthesized with thiourea produced the highest photocatalytic performance because: i) it had the highest absorbance in the UV–VIS range and ii) it had the highest content of defects, which promoted the photocatalytic activity. In fact, BiOCl made with thiourea induced the highest mineralization of carbon (86 %) according to the TOC analysis. Additionally, the incorporation of Er and Yb ions into the BiOCl lattice facilitated the Up-conversion process under solar irradiation, enhancing the generation of electron-hole pairs, which in turn, incremented the photocatalytic degradation of MB and RhB dyes. The main oxidizing species responsible for the degradation of MB/RhB dyes were • O 2 − radicals according to scavenger tests. The findings of this research demonstrated the potential of rubber/BiOCl based photocatalytic floaters for the degradation of dyes. Thus, the recycled rubber can be used as support for photocatalytic powders, which also reduces the contamination of water by microplastics. • MB and RhB were completely degraded using BiOCl under solar light by 60–90 min. • The presence of Er and Yb dopants enhanced in BiOCl enhanced the photocatalytic degradation of MB and RhB. • BiOCl/rubber composite totally degraded MB and RhB at lower times (6–60 min). • • O 2 − was the main oxidizing agent produced by BiOCl during the photocatalytic activity under solar light. • The highest degradation percentages for MB and RhB were reached using BiOCl synthesized with thiourea.