Showing papers by "Alan L. Chaffee published in 2019"

CO2 Capture from Air Using Pelletized Polyethylenimine Impregnated MCF Silica

Abstract: Two polyethylenimine impregnated mesocellular foam silica sorbents (PEI_80a and PEI_80b) were evaluated for capturing CO2 from 420 ppm of CO2 in N2 under both dry and humid conditions. A fixed bed ...

Desorption Process for Capturing CO2 from Air with Supported Amine Sorbent

Abstract: A polyethylenimine impregnated silica sorbent was evaluated for steam-assisted temperature vacuum swing desorption (TVSD) of CO2, adsorbed from 420 ppm of CO2 in N2. Results indicate that essential...

A Multifunctional, Charge-Neutral, Chiral Octahedral M12L12 Cage

Abstract: A chiral, octahedral M12 L12 cage, which is charge neutral and contains an internal void of about 2000 A3 , is reported. The cage was synthesised as an enantiopure complex by virtue of amino-acid-based dicarboxylate ligands, which assemble around copper paddlewheels at the vertices of the octahedron. The cage persists in solution with retention of the fluorescence properties of the parent acid. The solid-state structure contains large pores both within and between the cages, and displays permanent porosity for the sorption of gases with retention of crystallinity. Initial tests show some enantioselectivity of the cage towards guests in solution.

Technoeconomic Evaluation of a Process Capturing CO2 Directly from Air

Abstract: Capturing CO2 directly from air is one of the options for mitigating the effects global climate change, and therefore determining its cost is of great interest. A process model was proposed and validated using laboratory results for adsorption/desorption of CO2, with a branched polyethyleneimine (PEI) loaded mesocellular foam (MCF) silica sorbent. The model was subjected to a Multi-Objective Optimization (MOO) to evaluate the technoeconomic feasibility of the process and to identify the operating conditions which yielded the lowest cost. The objectives of the MOO were to minimize the cost of CO2 capture based on a discounted cash flow analysis, while simultaneously maximizing the quantity of CO2 captured. This optimization identified the minimum cost of capture as 612 USD tonne−1 for dry air entering the process at 25 °C, and 657 USD tonne−1 for air at 22 °C and 39% relative humidity. The latter represents more realistic conditions which can be expected for subtropical climates. The cost of direct air capture could be reduced by ~42% if waste heat was utilized for the process, and by ~27% if the kinetics of the sorbent could be improved by a factor of two. A combination of both would allow cost reductions of ~54%.

UV-induced colour generation of pulp and paper mill effluents as a proxy of ligno-cellulosic biorefinery wastewater

Abstract: UV-induced colour generation of treated (clear) wastewater effluents from a modern bisulphite pulp and paper mill was investigated as a model for aqueous discharges likely to be encountered with emerging biorefinery concepts. Aqueous solutions of selected model compounds, namely lignosulfonic acid (LSA), humic acid and vanillin were exposed to UV light and the colour generation of these solutions compared to the industrial effluent. The colour generation trend of the wastewater was found to be similar to that of LSA. Analysis by HPLC, FTIR, MS and NMR showed that the colour development of the wastewater mimicked the paper yellowing mechanism, with the formation of quinones as a major route. UV-induced dimerization of vanillin solutions showed a dramatic increase in colour. Thus results suggest the UV induced polymerization of lignin compounds play a major role in colour development of lignocellulosic wastewater effluents unless the phenol precursors are removed or degraded.

Isolation of organic matter by the NaOH-HCl method from two marine oil shales using oven and sealed autoclave techniques

Abstract: Organic matter (OM) was isolated from two marine oil shales, ElLajjun and Julia Creek, using NaOH-HCl and humin and humic acid fractions separated. Two treatments were required to reduce humin ash yield to below 11 wt% db. The humin yield of the autoclave method was 80 wt% of OM (dry mineral-matter-free, dmmf), compared to only 20–60 wt% dmmf for the oven method, possibly due to the increased NaOH solution strength and some oxidation. Oven and autoclave methods both gave humin similar in chemical structure to shale OM, regardless of yield. This similarity has implications as to shale OM structure.

P -Xylylenediamine derived ligands as flexible connectors in the design of porous coordination polymers

Abstract: The use of flexible ligands in coordination polymers provides both opportunities and unpredictability. A new series of flexible ligands derived from p-xylylenediamine, which vary in the positioning of carboxylic acid functional groups, have been found to form a series of coordination polymers and a discrete coordination complex. Use of the tetra-substituted meta-carboxylic acid ligand N,N,N′,N′-tetra(3-carboxybenzyl)-p-xylylenediamine, isolated as its dihydrochloride salt (H6M4pxy)Cl2, resulted in the simultaneous formation of two products from the same synthetic conditions. One of these products was a discrete cage-type coordination complex of the form [Cu4(M4pxy)2(DMF)2(OH2)] (1), while the other product was the two-dimensional coordination polymer poly-[Cu2(M4pxy)(OH2)2] (2). Synthesis utilising the tetra-substituted para-carboxylic acid ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-p-xylylenediamine dihydrochloride (H6P4pxy)Cl2, resulted in the formation of multiple two-dimensional coordination polymers, poly-[Cu2(P4pxy)(DMF)(OH2)]·2DMF·3H2O (3·2DMF·3H2O), poly-[Mn2(P4pxy)(DMA)2] (4), poly-[Co4(P4pxy)2(DMF)2(μ-OH2)2(OH2)2]·6DMF·4H2O (5·6DMF·4H2O) and poly-[Cd2(P4pxy)(OH2)2]·DMA·3H2O (6·DMA·3H2O). The last of these materials, a three-dimensional coordination polymer, was found to adsorb approximately 32 cm3 g−1 STP of CO2 at atmospheric pressure at 273 K.