Cobalt Incorporated Porous Aromatic Framework for CO2/CH4 Separation

Porous carbon supported calcium oxide for CO2 adsorption and separation of CO2/CH4

Calcium oxide incorporated porous carbon materials were synthesized by the impregnation method to study CO₂ adsorption and separation of CO₂/CH₄. The X-ray diffraction, Raman analysis, N₂ isotherms at 77 K, and SEM with EDX analysis were used to characterize synthesized materials. XRD and N₂ isotherm results have confirmed that synthesized carbon has porosity, and EDX analysis has reported that the presence of CaO on porous carbon. 10CaO/porous carbon has shown 31 cm³ g^-1 of CO₂ adsorption which was higher than bare porous carbon CO₂ adsorption 17.5 cm³ g^-1 at 298 K, 1 bar. It was attributed to electrostatic interaction between CaO and CO₂. However, CH₄ adsorption was decreased by a decrease in surface area. The selectivity of CO₂/CH₄ was higher for 10CaO/porous carbon and the heat of CO₂ adsorption was 36 KJ/mol at high adsorption of CO₂. Moreover, CO₂ adsorption was the same in each adsorption cycle.

Efficient Gold Recovery from E-Waste via a Chelate-Containing Porous Aromatic Framework

Extracting gold from wastes of electronic equipment (e-waste) is a sustainable strategy for the recovery of the precious metal, reducing environmental pollution, and addressing the growing demands for gold resources. In this work, we synthesized a thiourea-modified porous aromatic framework (PAF-1-thiourea) with exceptional gold-extraction ability. The optimum adsorption capacity for PAF-1-thiourea to gold reaches up to 2629.87 mg g^-1. The adsorption process can be well fitted according to the pseudo-second-order kinetic model and Langmuir model, featuring strong affinity caused by strong soft-soft interactions between Au(III) and the S and N donor atoms of the modified PAF and the electrostatic interactions between protonated amino groups and AuCl₄^-. PAF-1-thiourea was especially capable of extracting gold rapidly and efficiently (capturing 98.73% of gold within 5 min) from a central processing unit (CPU) in extremely acidic conditions. It is found that PAF-1-thiourea captures gold ions and simultaneously converts it to a Au(0) solid, obtaining gold with purity up to 23.5 karat. PAF-1-thiourea with its high acid resistance and anti-interference against cheap metals in the recovery process presents a practical means to extract gold from e-waste.

Porous Aromatic Frameworks (PAFs)

Porous aromatic frameworks (PAFs) represent an important category of porous solids. PAFs possess rigid frameworks and exceptionally high surface areas, and, uniquely, they are constructed from carbon-carbon-bond-linked aromatic-based building units. Various functionalities can either originate from the intrinsic chemistry of their building units or are achieved by postmodification of the aromatic motifs using established reactions. Specially, the strong carbon-carbon bonding renders PAFs stable under harsh chemical treatments. Therefore, PAFs exhibit specificity in their chemistry and functionalities compared with conventional porous materials such as zeolites and metal organic frameworks. The unique features of PAFs render them being tolerant of severe environments and readily functionalized by harsh chemical treatments. The research field of PAFs has experienced rapid expansion over the past decade, and it is necessary to provide a comprehensive guide to the essential development of the field at this stage. Regarding research into PAFs, the synthesis, functionalization, and applications are the three most important topics. In this thematic review, the three topics are comprehensively explained and aptly exemplified to shed light on developments in the field. Current questions and a perspective outlook will be summarized.