Synthesis and Characterization of MC/TiO₂ NPs Nanocomposite for Removal of Pb²⁺ and Reuse of Spent Adsorbent for Blood Fingerprint Detection

The removal of toxic heavy metals from wastewater throughthe useof novel adsorbents is expensive. The challenge arises after the heavymetal is removed by the adsorbent, and the fate of the adsorbent isnot taken care of. This may create secondary pollution. The studyaimed to prepare mesoporous carbon (MC) from macadamia nutshells coatedwith titanium dioxide nanoparticles (TiO2 NPs) using ahydrothermal method to remove Pb2+ and to test the effectivenessof reusing the lead-loaded spent adsorbent (Pb2+-MC/TiO2 NP nanocomposite) in blood fingerprint detection. The sampleswere characterized using SEM, which confirmed spherical and flower-likestructures of the nanomaterials, whereas TEM confirmed a particlesize of 5 nm. The presence of functional groups such as C and Ti anda crystalline size of 4 nm were confirmed by FTIR and XRD, respectively.The surface area of 1283.822 m(2)/g for the MC/TiO2 NP nanocomposite was examined by BET. The removal of Pb2+ at pH 4 and the dosage of 1.6 g/L with the highest percentage removalof 98% were analyzed by ICP-OES. The Langmuir isotherm model bestfit the experimental data, and the maximum adsorption capacity ofthe MC/TiO2 NP nanocomposite was 168.919 mg/g. The adsorptionfollowed the pseudo-second-order kinetic model. The & UDelta;H & DEG; (-54.783) represented the exothermic nature,and & UDelta;G & DEG; (-0.133 to -4.743)indicated that the adsorption process is spontaneous. In the bloodfingerprint detection, the fingerprint details were more visible afterapplying the Pb2+-MC/TiO2 NP nanocomposite thanbefore the application. The reuse application experiments showed thatthe Pb2+-MC/TiO2 NP nanocomposite might be auseful alternative material for blood fingerprint enhancement whenapplied on nonporous surfaces, eliminating secondary pollution.