Coating of Pinus elliottii-derived biochar with titanium thin film via magnetron sputtering to enhance paracetamol adsorption

Abstract

The study evaluated the use of titanium thin films coated onto biochar derived from Pinus elliottii using magnetron sputtering to enhance paracetamol adsorption. Paracetamol produces toxic and potentially carcinogenic byproducts during degradation, posing environmental and health risks. Adsorption is an effective method for removing these contaminants from water. First, raw biochar was prepared from Pinus elliottii. Then, titanium thin films were deposited onto the biochar using the magnetron sputtering technique, which modified its properties. These modified biochars were extensively characterized. The sputtering conditions were set at 100 W for 10 min, 150 W for 20, 30, and 40 min, and 200 W for 30 min, and the resulting adsorbents were labeled as R1, R2, R3, R4, and R5, respectively. The results showed that the Sips model provided the best fit for the equilibrium tests, with adsorption capacity increasing as the amount of Ti coating increased. The adsorption capacities were 6.98, 14.2, 11.29, 11.93, 13.77, and 21.3 µmol g⁻¹ for Raw, R1, R2, R3, R4, and R5, respectively. This represents a threefold increase in adsorption capacity when comparing raw biochar to R5. Thermodynamic analysis indicated a spontaneous adsorption process, with ΔG⁰ values ranging from − 3.47 to − 5.96 kJ mol⁻¹. Kinetic studies revealed that the pseudo-first-order model best fit the data for Raw and R5, while the pseudo-second-order model was more suitable for R1 to R4. Equilibrium was reached at 200 min for all samples. Regeneration and reuse tests revealed that the adsorbent maintained its original adsorption capacity after 5 cycles. Finally, titanium-coated biochar significantly improved paracetamol adsorption. This enhancement is attributed to the synergistic effects of the surface chemistry introduced by the Ti thin films.