Highly Developed Surface Area Thiosemicarbazide Biochar Derived from Aloe Vera for Efficient Adsorption of Uranium

Uranium(VI) was removed from the aqueous environment using Aloe vera shell ash modified with thiosemicarbazide. The adsorbent was characterized by several methods, including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), BET isotherm, and elemental analysis. The absorption of uranium (VI) onto this adsorbent was studied in relation to pH (2-7), adsorbent dose (0.01-0.5 g), U(VI) concentration (50, 100, 200, 300, 500, 700, and 1000 mg L-1), and exposure time (5-100 min). The highest efficiency of U(VI) removal was achieved under optimum conditions (30 min, pH 4). The optimum adsorbent dose was 0.8 g (in 20 mL of 250 mg L-1 U(VI) solution); it ensured 98.3% removal efficiency. The maximum monolayer adsorption capacity based on the Langmuir isotherm was 336.05 mg g(-1). The negative sign of Delta G degrees and positive signs of Delta H degrees and Delta S degrees show that the adsorption is spontaneous and endothermic and is accompanied by an increase in the randomness. The experimental data were fitted well with the Langmuir isotherm model. The synthesized adsorbent has the desired surface area and adsorption capacity for uranium(VI) adsorption from aqueous solutions.