Bismuth sulfide photocatalysis water treatment under visible irradiation

Many contaminants in water are not completely removed by conventional water purification techniques. So, the need of fast and efficient technique for water purification is required for efficient removal. Photocatalysis using low bandgap semiconductors is capable of detoxifying contaminated water. Herein, bismuth sulfide (Bi 2 S 3 ) nanorods were synthesized using a solid-state reaction method and their photocatalytic performance was tested for the removal of Congo red dye from water. X-ray diffraction (XRD) results confirmed the formation of Bi 2 S 3 with a crystallite size of 5.0 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirmed the formation of Bi 2 S 3 nanorods with a diameter of 20–30 nm, length of 100 nm -150 nm and an aspect ratio of 5. Photoluminescence (PL) spectrum revealed the bandgap value of 2.47 eV. The specific surface area calculated using Brunauer–Emmett–Teller (BET) of Bi 2 S 3 nanorods was 94.44 m 2 /g and pore volume was 0.158 cm 3 /g. The photodegradation of toxic Congo red was performed using Bi 2 S 3 nanorods under UV irradiation. Photodegradation efficiencies up to 87% for Congo red dye were observed within 90 min. The pseudo-first-order (PFO) kinetic model was best fitted to understand the kinetics of photocatalysis. For Bi 2 S 3 nanorods photocatalysts, the apparent rate constant value was 0.01573/min with a 0.997 correlation coefficient value.