Removal of doxorubicin hydrochloride and crystal violet from aqueous solutions using spray-dried niobium oxide coated with chitosan-activated carbon: Experimental and DFT calculations

Abstract

Spray-dried niobium oxide coated with chitosan-activated carbon (NIC) was synthesized and used to remove doxorubicin hydrochloride and crystal violet from aqueous solutions under different parameters such as solution pH (2, 4, 6, and 8), contact time (1 to 9 h), initial concentration (20 to 200 mg L^-1), and competing ions (0.1 M of CaCl₂ and NaCl). The addition of 5 % chitosan-activated carbon to the matrix of niobium oxide slightly increased the specific surface area from 26 to 30 m² g^-1, with the introduction of a carboxylic functional group. This led to an increase in the amount of adsorbed doxorubicin hydrochloride (DOH) from 30 to 44 mg g^-1 and that of crystal violet (CV) from 15 to 32 mg g^-1 from the initial respective 100 mg L^-1 at pH 8. The data from the concentration study fitted into Liu isotherm having adsorption capacity of 128 and 57 mg g^-1 for DOH and CV respectively, while pseudo first and second order are more suitable for adsorption kinetics. The additional functional groups on the IR spectrum of NIC after the adsorption of DOH and CV confirmed the interaction between NIC and the adsorbates' molecules. The mechanism of adsorption was supported by DFT calculations.

Keywords: Adsorption; Chitosan-activated carbon; Mechanism; Niobium oxide.