Simultaneous sorption of dyes and toxic metals from waters using synthesized titania-incorporated polyamide

Interfacial polymerization of trimesoyl chloride (TMC) and 1,3- phenylene diamine (MPD) was simultaneously combined with the in-situ formation of TiO₂ from TiCl₄ using urea. The titania-polyamide nanocomposite (TPN) was characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, N₂-physisorption analysis and a scanning electron microscope equipped with energy-dispersive X-ray spectroscopy. The TPN was evaluated as an adsorbent for the removal of dyes. It showed high efficiency for the removal of several dyes in the order: methylene blue > bromo phenol > methyl orange > congo red > rhodamine B. The dosage, contact time, and temperature which are the main factors that affect adsorption efficiency, were optimized. Among isotherm models, the experimental adsorption results fitted well with the Langmuir model with a maximum adsorption capacity of 43 mg/g. Kinetic experiments were conducted to describe the equilibrium rate. The model of the pseudo-second-order adequately fitted the experimental data with a correlation coefficient R² of 0.998. Thermodynamic studies were performed to evaluate the performance of TPN at various temperatures. Thus, parameters including free energy (ΔG°), enthalpy (ΔH°) and the entropy (ΔS°) were calculated. The influence of the interference on adsorption was investigated in the presence of metals including Ni, Hg, As, Cu, and Cr. Interestingly, with ≈100% removal of the dye, TPN showed a rapid simultaneous uptake of the toxic metals as well.