Abstract
An increasing amount of water pollution is being caused by an increase in industrial activity. Recently, a wide range of methods, including as extraction, chemical coagulation, membrane separation, chemical precipitation, adsorption, and ion exchange, have been used to remove heavy metals from aqueous solutions. The adsorption technique is believed to be the most highly effective method for eliminating heavy metals from wastewater among all of them. However, it generates secondary waste that can pose risk to the environment. Agricultural waste was collected and converted into carbon nanomaterial, then coated with metal oxides for the removal of Pb2+, Cd2+, and Ni2+ ions and explored the reuse of heavy metal spent adsorbent in blood fingerprint detection (BFP).
Mesoporous carbon coated with titanium dioxide (MC/TiO2 nanocomposite), nitrogen-carbon nanosheet coated zinc oxide (N-CNS/ZnO nanocomposite), and carbon hollow nanosheet coated gamma-alumimium oxide (γ-Al2O3/CHN nanocomposite) was utilized to remove Pb2+, Cd2+, and Ni2+ ions, respectively. The collected spent adsorbent was reused in blood fingerprint enhancement. The surface chemistry of the materials was examined via Fourier Transformed Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy-Energy Dispersive X-ray (SEM–EDS), point of zero charges (pHpzc), and Brunauer emmett teller (BET).
In the first chapter, mesoporous carbon (MC) from macadamia nutshells coated with titanium dioxide nanoparticles (TiO2 NPs) were prepared to remove Pb2+ and to test the effectiveness of reusing the lead-loaded spent adsorbent (Pb2+-MC/TiO2 NPs nanocomposite) in blood fingerprint detection. The uptake of Pb2+ ions by MC/TiO2 NPs was reached in 30 min then decrease with the increase in concentrations. The Langmuir isotherm model best fitted the experimental data, and the adsorption followed the pseudo-second-order kinetic model. In the blood fingerprint detection, the fingerprint details were more visible after applying Pb2+-MC/TiO2 NPs nanocomposite than before the application. The reuse application experiments showed that Pb2+-MC/TiO2 NPs nanocomposite might be a useful alternative material for blood fingerprint enhancement when applied on non-porous surfaces, eliminating the secondary pollution. In the second experimental chapter, an N-CNS/ZnO nanocomposite was used as an adsorbent to adsorb the Cd2+ ion from an aqueous solution, and the spent Cd2+-loaded N-CNS/ZnO nanocomposite collected was tested in BFP. N-carbon nanosheets (N-CNS) were produced from potato peels and then coated with ZnO nanoparticles. Additionally, the adsorption pseudo-second-order and Langmuir isotherm models were best fitted for Cd2+ ion removal. Therefore, N-CNS/ZnO nanocomposite showed a rapid removal of Cd2+ ions in wastewater and its potential for re-use in blood fingerprint detection on different surfaces. In the last experimental chapter, carbon hollow nanosphere was prepared from orange peels by a reflux method. The carbon hollow nanosphere was coated with γ-Al2O3 NPs via the hydrothermal method. Batch adsorption experiments revealed that the uptake of Ni2+ best fit the Langmuir model adsorption isotherm, and the pseudo-second-order kinetics model. The adsorbent was then used to identify latent blood fingerprints, and it was discovered that Ni2+-γ-Al2O3/carbon hollow nanosphere generated clear images of blood fingerprints (BFP) on different substrates. Overall, the finding of the current study confirmed that the MC/TiO2 NPs, N-CNS/ZnO nanocomposite and γ-Al2O3/carbon hollow nanosphere nanocomposite can remove pollutants in wastewater, respectively. Furthermore, the collected heavy metal loaded spent adsorbent showed good results in enhancing the fingerprint in blood. The study is the first to report the reuse of heavy metals loaded spent adsorbent in blood fingerprint detection.