Sonochemical fabrication of efficient binary Cu/Bi2S3 heterojunction composites towards visible-light active photocatalytic degradation of CV, FL, and SO dyes for wastewater treatment

Abstract

In this study, we have developed a new catalyst (Cu/Bi2S3) via a sonochemical method and applies for the photodegradation of several dyes including crystal violet (CV), fluorescein (FL), and safranin O (SO) dyes under visible light. The optimized Cu/Bi2S3 material is the motivating catalyst due to the excellent ability of copper (0.58 %) to increase the adsorption capacity and electron-hole separation of Bi2S3 for enhancing the degradation of CV, FL, and SO dyes. The efficiency of CV, FL, and SO dyes photodegradation using Cu/Bi2S3 is higher than pure Bi2S3. Cu on Bi2S3, which is devised on adsorption (12.58 %) and photodegradation (54.21 %, 61.03 %, and 63.14 %), has the best degradation efficiency (93.18 %, 99.20 %, and 100 %), respectively for CV, FL, and SO dyes. From the kinetic plots, the calculated apparent rate constants are 0.151 × 10−3 min−1, 0.173 × 10−3 min−1, and 0.186 × 10−3 min−1, respectively for the degradation of CV, FL, and SO dyes using Cu/Bi2S3 composite. The trapping experiment explain that the hydroxyl radical is the most active species in this photocatalytic process due to the total degradation efficiency decreasing from 93.18 %, 99.20 %, and 100 % to 48.25 %, 51.02 %, and 45.36 % by the scavenger using isopropyl alcohol (IPA). The hole (h+) shows its importance in the photodegradation of CV, FL, and SO dyes by detecting that •OH is the intermediate species. The new material (Cu/Bi2S3) also shows excellent photostability in the reusability test. Finally, the result confirms that Cu is a suitable doping metal for Bi2S3 and is interesting for waste water treatment application under visible light.