A dual-function TCCN-LaFeO3 Z-scheme heterojunction for the photocatalytic degradation of tetracycline and the colorimetric detection of gallic acid

A dual-functional TCCN-LaFeO₃ Z-scheme heterojunction is constructed for synchronous tetracycline degradation and gallic acid detection. • The composite achieves 95.27% tetracycline removal within 120 min and excellent reusability via Z-scheme charge transfer. • Sensitive and selective colorimetric detection of gallic acid is realized with a low detection limit of 0.32 μM. • The bifunctional material shows satisfactory practical performance in real water and pharmaceutical samples. TCCN-LaFeO 3 (TCCN refers to graphite carbon nitride modified by tetracyanoethylene) composite materials were successfully prepared using a simple hydrothermal method. The photocatalytic degradation performance of the composite was investigated using tetracycline (TC) as the target pollutant. The results indicate that under conditions of a catalyst loading of 40 mg, an initial TC concentration of 20 mg/L, a solution pH of 7, under visible-light irradiation from a 250 W xenon lamp with a 400 nm cut-off filter (400–800 nm), the tetracycline degradation rate reached 95.27% after 120 min of reaction. The degradation process followed a first-order kinetic model with a rate constant of 0.0243 min −1 . Furthermore, the TC degradation rate remained above 85% after five reuse cycles, demonstrating excellent stability. Additionally, when this composite was used for the colorimetric detection of gallic acid (GA), a good linear relationship (R 2  = 0.993) was observed between the GA concentration and the absorbance of the reaction system at 652 nm over the concentration range of 0–110 μM, with a detection limit as low as 0.32 μM. Interference and spiked recovery experiments using actual samples demonstrated that this method exhibits good selectivity and accuracy, with recovery rates ranging from 98.3% to 101.4%. The TCCN-LaFeO 3 composite prepared in this study holds significant application value in the fields of tetracycline degradation in water and the rapid detection of gallic acid. Download: Download high-res image (167KB) Download: Download full-size image