APPLICATION OF TIO2-BIOCHAR NANOCOMPOSITES FOR INTEGRATED ADSORPTIVE - PHOTOCATALYTIC WASTEWATER TREATMENT: A TECHNO-ECONOMIC ASSESSMENT ON LAB AND LARGE-SCALE

Abstract

This study synthesized mandarin biochar (MP500) and a TiO2-impregnated nanocomposite, TiO2@MP500, through a hydrothermal approach. A comprehensive set of characterization techniques confirmed the successful synthesis of TiO2@MP500 and its structural properties. Incorporating TiO2 nanoparticles onto MP500 increased the surface area from 4.58 m²/g for MP500 to 91.16 m²/g for 3%TiO2@MP500. TGA analysis confirmed the thermal stability of the produced nanocomposite, and TEM data revealed the presence of fine TiO2 nanoparticles with a particle size of 1.79±0.44 nm. The 3%TiO2@MP500 demonstrated an enhanced ability to remove methyl orange (MO) from water, attributed to a synergistic combination of adsorption and photocatalysis. The Box-Behnken design was used to study the effect of five factors on MO adsorption, including pH, adsorbent dose, reaction time, %TiO2 added to the MP500 biochar, and MO concentration. The adsorption behavior of MO dyes on 3%TiO2@MP500 was studied using equilibrium and kinetic models. It showed a qmax of 104.2 mg/g and followed a pseudo-second-order model, indicating a good fit with an R2 of 0.9731. In the photocatalytic degradation of MO, 3%TiO2@MP500 exhibited a 98.87% decolorization efficiency in only 30 min, with a rate constant of 0.0609 min−1, showing that the photocatalytic performance of 3%TiO2@MP500 was about 1.6 times faster than MO decolorization through adsorption alone. The nanocomposite was successfully regenerated and reused for up to six cycles, maintaining a decolorization efficiency of 90.91%.