Browsing by Author "Zhao, Y."
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Item Development of melamine-impregnated alginate capsule for selective recovery of Pd(II) from a binary metal solution(Journal of Cleaner Production, 2021) Wei, W.; Qiu, Y.; Zhao, Y.; Zhang, K.; Ji, Y.; Gao, H.; Bediako, J.K.; Yun, Yeoung-Sang.An “ionic barrier” concept is proposed to introduce selectivity function to adsorbents towards precious metals (PMs) in the present study. As a model system, melamine-impregnated alginate capsule (MIAC) was prepared and used as a Pd(II) selective adsorbent from a binary metal solution containing Pt (IV) and Pd(II). The MIAC exhibited excellent Pd(II) selectivity for a pH around 4.3, where the selectivity coefficient reached a high value of 2190.66. In comparison to the very low Pt (IV) uptake, a high maximum uptake of Pd(II) was estimated of 316.92 ± 9.50 mg/g by the Langmuir isotherm model. Sorptiondesorption studies showed that the MIAC had a good reutilization property. The selective process for Pd(II) recovery was proposed as follows: the electroneutral Pd(OH)2 but not anionic PtCl5 first penetrate the outer ionic barrier; then, the penetrated Pd(OH)2 was bound by the inner melamine through chelation. The ionic barrier-based sorbent thus can be considered as an alternative one for separation and recovery of Pd(II).Item Recovery of gold via adsorption-incineration techniques using banana peel and its derivatives: Selectivity and mechanisms(Waste Management, 2020-06-11) Bediako, J.K.; Choi, J-W.; Song, M-H.; Zhao, Y.; Lin, S.; Sarka, A.K.; Cho, C-W.; Yun, Y-S.In this study, banana peel (BP) and its derivatives after sequential extraction of biochemical components were evaluated for selective recovery of gold. In-depth instrumental characterizations including XPS, FTIR, XRD and HR-TEM were performed to understand the adsorption mechanisms. The biomass after lipid extraction, BP-L, demonstrated very good affinity and selectivity towards gold. In multi-metal systems containing 100 mg/L of Pt(IV), Au(III), Pd(II), Zn(II), Co(II), Ni(II) and Li(I), the selectivity coefficient increased from 978.45 in BP to 2034.70 in BP-L. Moreover, the equilibrium gold uptake was improved and reached 475.48 ± 3.08 mg/g owing to reduction-coupled adsorption mechanisms. The BP-L also showed improved gold nanoparticle formation properties that were pH-dependent. In a strategic adsorptioncombined incineration process, metallic gold reaching 99.96% in purity was obtained. The BP and its derivative, BP-L have thus shown potentials for multiple applications in the areas of precious metal recovery and nanoscience.