Preparation, characterization, and application of synthesized thiourea formaldehyde-calcium alginate in removal of Reactive Black 5

Abstract

Thiourea formaldehyde calcium alginate (TFCA) composite was successfully synthesized and used for removal of Reactive Black 5 (RB5) dye. The synthesized composite was applied and characterized by Fourier transform infrared spectrometer (FTIR) spectra, scanning electron microscope (SEM)/EDS, energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). SEM and EDX analyses confirm the homogeneity of the sorbent in term of composition. Batch adsorption experiments were performed to evaluate the adsorption conditions such as pH value, dye concentration, contact time, temperature, and sorbent dose, as well as the ionic strength effect. Experimental data have been modeled by using Langmuir, Freundlich, Dubinin Radushkevich (D–R), and Temkin isotherms. Kinetic adsorption data modeled using PFORE, PSORE, Morris Weber, and Elovich in order to determine thermodynamic parameters (ΔG, ΔH, and ΔS) for the dye adsorbent systems. These data indicated an exothermic spontaneous adsorption process that kinetically followed the pseudo second-order adsorption process and removal of RB5 dye from aqueous solution. The results showed that the maximum adsorption capacity was 0.2 mmol g−1, observed at pH 1 and temperature 25 °C. Equilibrium adsorption was achieved within 60 min.