Adsorption analysis of Zn(II) removal from aqueous solution onto Argemone maxicana biochar

In this study, stems of Argemone maxicana (AM) were used to produce biochar for Zn(II) ion adsorption from aqueous solution in a batch experiment mode. The AM biochar was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy-Energy-dispersive X-ray (SEM-EDX), and X-ray diffraction (XRD) in order to use as an adsorbent. The effect of parameters such as adsorbent dosage, contact time, pH of the solution, initial concentration of Zn(II) ion in aqueous solution, and temperature on the removal efficiency of Zn(II) ion was investigated. The results of batch experiments showed that the percentage removal of Zn(II) ion increases as pH increases from 2.10 to 6.12. The results of contact time experiments revealed that removal efficiency increases and reached equilibrium at 110 min after which no more adsorption takes place. Percentage removal increases with adsorbent dosage. Initially the concentration of Zn(II) ion was varied from 10 to 50 mg/L, and the highest percentage removal was obtained at 10 mg/L. Langmuir and Freundlich isotherms have been used to examine the experimental results. Kinetic analysis was carried using pseudo-first-order and pseudo-second-order kinetic models. The thermodynamic study indicated that the process is spontaneous and exothermic.