Synthesis and optimization of TiO2-biochar composite for degradation of Basic Blue 41 dye in textile wastewater using response surface methodology

• The discharge of high BB41 dye concentration into the environment causes significant impacts. • TiO 2 -Biochar nanocomposite photocatalysts were successfully prepared. • The BB41 dye removal efficiency of 99.6 % was attained initial dye concentration 40 mg/L. • Over five recycling of the photocatalyst material, only a 3.3 % decrease in photodegradation efficiency. • The removal of BB41 dye via TiO 2 -Biochar is promising for future application at the industrial level. This study aimed to degrade mainly Basic Blue 41 dye from textile wastewater using photocatalytic TiO 2 -biochar (TiO 2 -BC) composite under UV irradiation. The physicochemical characteristics of textile wastewater were examined. The TiO 2 -BC was synthesized by a Sol-gel method and was characterized by Fourier-transform infrared spectroscopy (FT-IR), BET surface area analyzer, X-ray diffraction (XRD), Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS) and Raman spectroscopy. The photocatalytic performance of the TiO 2 -BC composite was optimized using solution photocatalyst dosage 0.5–2.5 g/L, dye concentration 10–50 mg/L, pH 3–11, and Uv-irradiation time 30–150 min under Response Surface Methodology-Central composite design approach. The textile wastewater was characterized using temperature 45 °C, pH 5.61, electrical conductivity 1605 µS/cm, turbidity 48.5 ± 0.4 NTU, TDS 1105 mg/L, BOD 5 350 mg/L, and COD 928 mg/L. The maximum photodegradation efficiency of 99.6 % was found for the removal of BB41 dye at optimal experimental conditions of pH 8.3, initial dye concentration 40 mg/L, photocatalyst dosage 1.85 g/L, and Uv irradiation 117 min. Similarly, this photocatalytic material was also applied from remediation of the textile wastewater which resulted in the removal of BB41 dye 94.8 %, color 96.2 %, turbidity 89.3 %, and COD 66.6 %. This photodegradation process obeys the first-order kinetic model (k = 0.049 min −1 ). Finally, after over five recycling of the photocatalyst material, only a 3.3 % decrease in photodegradation efficiency was found. In conclusion, the TiO 2 -BC composite material is promising and can be applied for industrial wastewater treatment at a large scale.