TiO2-polymeric composites, i.e. chitosan supported TiO2 (CS-TiO2) and polyvinyl alcohol/chitosan blend supported TiO2 (PVA-CS-TiO2), were synthesized via precipitation in an alkali/solvent medium and applied for photocatalytic removal of metronidazole (MNZ) in a batch reactor. The composites have produced 100% MNZ removal (10 mg L-1) within 120 min at a catalyst loading of 0.3 g L-1. However, a maximum TOC removal of 76.1% and 63.7% was observed in PVA-CS-TiO2 and CS-TiO2 systems, respectively. In comparison, complete MNZ removal in suspended TiO2 system was observed at 8.3 times higher dosage under similar conditions. The stability of the composites in water and adsorption mechanism was modelled through density functional theory (DFT). The energy of formation for CS-TiO2, PVA-TiO2 and PVA-CS in water were found to be -0.144, -0.153 and -0.220 eV, respectively. It was inferred that the presence of CS significantly enhanced MNZ adsorption and moreover, the removal was due to synergetic removal by adsorption (pseudo-second-order) and photocatalysis (pseudo-first-order) as evidenced via kinetic models. The hierarchy of adsorption capability of different adsorbents towards MNZ is as follows: PVA-CS-TiO2 > CS-TiO2 > CS > TiO2 > PVA. The prepared composites showed consistent MNZ removal rates and structural integrity over 15 photocatalytic treatment cycles. Moreover, a kinetic model was developed to identify a best combination of retention time and TiO2 content in PVA-CS-TiO2 to predict 100% MNZ. Overall, MNZ removal along with enthalpy values indicated that the prepared composites could be applied for pharmaceutical removal on a long-term basis.