Metal ion adsorption from industrial wastewater has received increasing attention for the elimination of heavy metals and selective recovery of precious metals. Among the precious metals found in E-waste, gold has attracted considerable attention because of its wide range of practical applications and high economic value. However, the adsorbents used at present for the recovery of precious metals have very low adsorption capacity and poor metal selectivity for commercial uses. Herein, we introduce a new photochemical route for the selective and efficient adsorption of gold ions using bio-inspired metal-philic coatings. Internal surfaces of the mesoporous polymer microspheres were coated with polydopamine via the oxidative polymerization of catecholamines. The polydopamine layer served as a selective photo-active reductant for gold ions. Under 1-sun simulated illumination, the polydopamine layer selectively reduced gold ions to generate metallic gold nuclei. Moreover, once the metallic gold nanostructures were formed, localized surface plasmon further enhanced the reduction of gold ions. The combined effects increased the maximum amount of gold ions adsorbed per unit mass of the adsorbent up to 26 times compared to that in the dark. The adsorbed metallic gold was re-dissolvable in a thiourea solution for the complete recovery of gold ions. The selectivity toward gold ions among various metal ions was demonstrated using a solution mixture containing eight different metal ions that are commonly found in industrial wastewater. Density functional theory calculations revealed that reduction of gold on the polydopamine layer was energetically favorable, while the reduction of other metal ions was not. The dramatic increase in the maximum adsorption capacity and selectivity owing to the combined effect of the photochemical activation and polyphenol chemistry renders this process a promising approach toward urban mining of novel metal ions from electronic wastes.
Covalent amine tethering on ketone modified porous organic polymers for enhanced CO2 capture
P. Jorayev, I. Tashov, V. Rozyyev, T. S. Nguyen, N. A. Dogan, C. T. Yavuz
Effective removal of excess greenhouse gas CO2 necessitates new adsorbents that can overcome the shortcomings of the current capture methods. To achieve that, porous materials are often modified post-synthetically with reactive amine functionalities but suffer from significant surface area losses. Herein, we report a successful amine post-functionalization of a highly porous covalent organic polymer, COP-130, without losing much porosity. By varying the amine substituents, we recorded a remarkable increase in CO2 uptake and selectivity. Ketone functionality, a rarely accessible functional group for porous polymers, was inserted prior to amination and led to covalent tethering of amines. Interestingly, aminated polymers demonstrated relatively low heats of adsorption, which is useful for the rapid recyclability of materials, due to the formation of suspected intramolecular hydrogen bonding.
Precious metal recovery from electronic waste by a porous porphyrin polymer
Hong, D. Thirion, S. Subramanian, M. Yoo, H. Choi, H. Y. Kim, J. F. Stoddart, C. T. Yavuz
Urban mining of precious metals from electronic waste, such as printed circuit boards (PCB), is not yet feasible because of the lengthy isolation process, health risks, and environmental impact. Although porous polymers are particularly effective toward the capture of metal contaminants, those with porphyrin linkers have not yet been considered for precious metal recovery, despite their potential. Here, we report a porous porphyrin polymer that captures precious metals quantitatively from PCB leachate even in the presence of 63 elements from the Periodic Table. The nanoporous polymer is synthesized in two steps from widely available monomers without the need for costly catalysts and can be scaled up without loss of activity. Through a reductive capture mechanism, gold is recovered with 10 times the theoretical limit, reaching a record 1.62 g/g. With 99% uptake taking place in the first 30 min, the metal adsorbed to the porous polymer can be desorbed rapidly and reused for repetitive batches. Density functional theory (DFT) calculations indicate that energetically favorable multinuclear-Au binding enhances adsorption as clusters, leading to rapid capture, while Pt capture remains predominantly at single porphyrin sites.
Gold recovery from e-waste by porous porphyrin-phenazine network polymers
Gold recovery from electronic waste could prevent excessive mining with toxic extractants and provide a sustainable path for recycling precious metals. Unfortunately, no viable recycling is practiced, except burning electronic circuit boards in underdeveloped countries, mainly because of the lack of chemical scavengers as adsorbents. Here, we report the synthesis of a family of porphyrin–phenazine-based polymers and their gold-capturing properties as well as application in gold recovery from actual e-waste. The polymers show high selectivity toward gold as well as other precious metals. The Au(III) adsorption isotherms were well-fitted to the Langmuir adsorption model and proportionality between porosity and uptake capacity was observed. Solution pH values and illumination conditions were shown to have influences on the performance of the adsorbents with the highest capacity of 1.354 g/g obtained in acidic pH and under continuous UV irradiation. Such a remarkable capacity of 7 times the theoretical estimate was achieved through photochemical adsorption–reduction mechanism supported by the observed suppressing effect of oxidant on gold-capturing ability. The adsorbents are robust and recyclable, a significant advantage over other emerging materials.
Direct Z-scheme Tannin-TiO2 Heterostructure for Photocatalytic Gold Ion Recovery from Electronic Waste
Precious-metal recovery from industrial wastewater has received considerable attention because of rapidly increasing amounts of electronic waste. Existing technologies have yet to be widely applied due to their high cost and low selectivity toward precious-metal ions. Herein, we report a direct Z-scheme tannin–TiO2 heterostructure for selective gold adsorption from electronic waste under solar irradiation. The tannin-coated TiO2 nanoparticles were prepared by a simple dipping method, and under light illumination, both tannin and TiO2 can serve as photosensitive components for the reduction of metal ions, with metal-to-ligand charge transfer from TiO2 to tannin extending the lifetime of the excited electrons. Moreover, no additional electron donors are required because the tannin layer scavenges the reactive oxygen species generated by the holes from the light-activated TiO2 surface. The heterostructure allows for the highly efficient photocatalytic recovery of gold ions, with 11 times higher adsorption capacity in the light compared to the dark. High selectivity toward gold ions was also demonstrated using a metal ion mixture including nine different metal ions that are commonly found in electronic waste. Our findings suggest that the Z-scheme heterostructure of polyphenol and semiconductor provides a promising photochemical pathway for efficient and selective metal ion recovery from electronic waste.
The redox and non-redox CO2 utilization: Dry reforming of methane and catalytic cyclic carbonate formation
CO₂ emissions are too large to tackle with a single process, but a combination of avoidance with chemical utilization may be able to slow global warming. In this Focus Review, we identify two large-scale CO₂ conversion processes based on their viability and opposite energy requirements. In the high-energy, stationary path, CO₂ reforming of methane could provide gigatons of CO₂ utilization through synthesis gas. The main problem is the lack of a durable, effective, low-cost dry reforming catalyst. The exothermic cyclic carbonate formation from CO₂ and organic epoxides offers a low-energy, mobile, nonredox route. The catalysts, however, must be metal-free and robust, have a high surface area, and be low-cost while being easily scalable. These two processes could potentially address at least a quarter of all current CO₂ emissions.
Covalent Bond Organic Polymer of Melamine and Paraformaldehyde and Adsorbent of Carbon-Dioxide Using Thereof
KR 10-1683775，Dec 1, 2016
C. T. Yavuz, H. A. Patel
The present invention relates to a covalently bound organic polymer of melamine with para-formaldehyde, and an adsorbent of carbon dioxide comprising the same. More particularly, the present invention relates to a covalently bound organic polymer prepared by polymerizing melamine with para-formaldehyde, an aminated organic polymer obtained by impregnating polyethylene imine with the organic polymer, and an adsorbent of carbon dioxide comprising the same. The covalently bound organic polymer of melamine with para-formaldehyde according to the present invention provides a covalently bound organic polymer by using inexpensive monomers, has high adsorbability and selectivity to carbon dioxide, highly resistant against water and heat to allow easy regeneration, and thus is useful for preparing a high-efficiency adsorbent of carbon dioxide with low cost.
Method for Adsorbing and Recovering Uranium by Amidoxime-Polymers of Intrinsic Microporosity(PIMs)
KR 10-1718052, Mar 14, 2017.
C. T. Yavuz, J. Byun, W. Lee, Y. Sihn
The present invention relates to a method for adsorbing and recovering uranium using a uranium adsorbent, and more particularly, to a uranium adsorbent containing an amidocyclic microporous polymer excellent in uranium adsorbing ability, uranium adsorbent containing uranium adsorbent, And a method for adsorbing and recovering uranium using an adsorbent.
According to the present invention, since the aminocillicotropic polymer has excellent uranium adsorbing ability, the adsorbable uranium can be adsorbed at a high efficiency of 95% or more with respect to uranium of a very small amount (several ppb) in the seawater. It is possible to maintain high efficiency of 90% even when reusing polymer, and it is possible to adsorb uranium and it is easy to apply to membrane process.
Ionic Porous Organic Polymers for Reversible Water Recovery from Atmosphere
KR 10-1738955, May 17, 2017.
C. T. Yavuz, J. Byun, H. A. Patel
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ionic porous polymer capable of reversibly absorbing moisture in the atmosphere and a method for producing the same, and more particularly, to an ionic porous polymer which is obtained by polymerizing a tertiary amine and a monomer having a halogen end, And a method for producing the ionic porous polymer.
The ionic porous polymer that reversibly absorbs moisture in the air according to the present invention can be reversibly adsorbed and desorbed in the air present in a small amount and can be used for a hygroscopic agent or a humidity control agent because of its excellent structural stability.
Nanoporous Fluorinated Covalent Organic Polymers for Selective Adsorption of Organic Molecules and Method of Preparing Same
KR 10-1777838, Sep 6, 2017.
C. T. Yavuz, J. Byun, H. A. Patel
The present invention relates to a fluorine-based porous polymer capable of selectively adsorbing organic molecules and a method for producing the same, and more particularly, to a fluorine-based porous organic polymer polymerized using a fluorine-containing monomer and a method for producing the same. The fluorine-based porous polymer according to the present invention contains micropores and is stable to heat and moisture. In addition, since the polymer has a property of selectively absorbing only water-soluble organic molecules having a size smaller than the pore size among the organic molecules present in the water-soluble phase, it is possible to rapidly and selectively remove the water- And absorbents for water purification.
Cadmium absorbent having disulfide polymer-alginate bead
KR 10-2000389, July 9, 2019.
C. T. Yavuz, D. Ko, Y. Hwang, H. Kim, H. R. Andersen
The present invention is to provide a granular cadmium adsorbent in which a disulfide polymer in a powder type is bonded to the surface of alginate beads. The granular adsorbent, in which a disulfide polymer in a powder type and alginate beads are bonded, has excellent adsorption performance compared to conventional cadmium adsorbents, can be used in a column type treatment process and can be recycled through washing after adsorption.
Metal Oxide Supported Catalyst for Dry Reforming and Method of Preparing Syngas Using the Same
App# 10-2016-0100271 and 10-2017-0099675, 2016.
C. T. Yavuz, Y. Song, E. Ozdemir
he present invention relates to: a dry reforming catalyst in which an active material is impregnated on the surface of a metal oxide support, wherein the active material is surrounded by a surfactant; a method for preparing the same; and a method for preparing a synthetic gas by using the catalyst. Since the surfactant on the surface of the active material prevents sintering of the active material and a phenomenon of covering the active surface with carbon, the dry reforming catalyst exhibits high activity for a long time at a high temperature without using a noble metal, thereby being useful in the preparation of a synthesis gas.
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