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

Yvonne Boitumelo Nthwane; Bienvenu Gael Fouda-Mbanga; Melusi Thwala; Kriveshini Pillay

doi:10.1021/acsomega.2c05765

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

ACS Omega. 2023 Jul 17;8(30):26725-26738. doi: 10.1021/acsomega.2c05765. eCollection 2023 Aug 1.

Authors

Yvonne Boitumelo Nthwane¹, Bienvenu Gael Fouda-Mbanga², Melusi Thwala^{3

4}, Kriveshini Pillay¹

Affiliations

¹ Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, Johannesburg 2028, South Africa.
² Department of Chemistry, Center for Rubber Science and Technology, Nelson Mandela University, Gqeberha 6031, South Africa.
³ Science Advisory and Strategic Partnerships, Academy of Science of South Africa, Pretoria 0040, South Africa.
⁴ Department of Environmental Health, Nelson Mandela University, Port Elizabeth 6031, South Africa.

Abstract

The removal of toxic heavy metals from wastewater through the use of novel adsorbents is expensive. The challenge arises after the heavy metal is removed by the adsorbent, and the fate of the adsorbent is not taken care of. This may create secondary pollution. The study aimed to prepare mesoporous carbon (MC) from macadamia nutshells coated with titanium dioxide nanoparticles (TiO₂ NPs) using a hydrothermal method to remove Pb²⁺ and to test the effectiveness of reusing the lead-loaded spent adsorbent (Pb²⁺-MC/TiO₂ NP nanocomposite) in blood fingerprint detection. The samples were characterized using SEM, which confirmed spherical and flower-like structures of the nanomaterials, whereas TEM confirmed a particle size of 5 nm. The presence of functional groups such as C and Ti and a crystalline size of 4 nm were confirmed by FTIR and XRD, respectively. The surface area of 1283.822 m²/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 removal of 98% were analyzed by ICP-OES. The Langmuir isotherm model best fit the experimental data, and the maximum adsorption capacity of the MC/TiO₂ NP nanocomposite was 168.919 mg/g. The adsorption followed the pseudo-second-order kinetic model. The ΔH° (-54.783) represented the exothermic nature, and ΔG° (-0.133 to -4.743) indicated that the adsorption process is spontaneous. In the blood fingerprint detection, the fingerprint details were more visible after applying the Pb²⁺-MC/TiO₂ NP nanocomposite than before the application. The reuse application experiments showed that the Pb²⁺-MC/TiO₂ NP nanocomposite might be a useful alternative material for blood fingerprint enhancement when applied on nonporous surfaces, eliminating secondary pollution.