RESUMEN

The increasingly urgent issue of climate change is driving the development of carbon dioxide (CO2) capture and separation technologies in flue gas after combustion. The monolithic adsorbent stands out in practical adsorption applications for its simplified powder compaction process while maintaining the inherent balance between energy consumption for regeneration and selectivity for adsorption. However, optimizing the adsorption capacity and selectivity of CO2 separation materials remains a significant challenge. Herein, we synthesized monolithic polymer networks (N-CMPs) with triphenylamine adsorption sites, acid-base environment tolerance, and precise narrow microchannel pore systems for the selective sieving of CO2 and particulate matter (PM) in flue gas. The inherent continuous covalent bonding of N-CMPs, along with their highly delocalized π-π conjugated porous framework, ensures the stability of the monolithic polymer network's adsorption and separation capabilities under wet and acid-base conditions. Specifically, under the conditions of 1 bar at 273 K, the CO2 adsorption capacity of N-CMP-1 is 3.35 mmol/g. Attributed to the highly polar environment generated by triphenylamine and the inherent high micropore/mesopore ratio, N-CMPs exhibit an excellent ideal adsorbed solution theory (IAST) selectivity for CO2/N2 under simulated flue gas conditions (CO2/N2 = 15:85). Dynamic breakthrough experiments further visualize the high separation efficiency of N-CMPs in practical adsorption applications. Moreover, under acid-base conditions, N-CMPs achieve a capture efficiency exceeding 99.76 % for PM0.3, enabling the selective separation of CO2 and PM in flue gas. In fact, the combined capture of hazardous PM and CO2 from the exhaust gases produced by the combustion of fossil fuels will play a pivotal role in mitigating climate change and environmental issues until low-carbon and alternative energy technologies are widely adopted.

RESUMEN

Adsorbed natural gas (ANG) is a promising solution for improving the safety and storage capacity of low-pressure gas storage systems. The structural-energetic and adsorption properties of active carbon ACPK, synthesized from cheap peat raw materials, are presented. Calculations of the methane-ethane mixture adsorption on ACPK were performed using the experimental adsorption isotherms of pure components. It is shown that the accumulation of ethane can significantly increase the energy capacity of the ANG storage. Numerical molecular modeling of the methane-ethane mixture adsorption in slit-like model micropores has been carried out. The molecular effects associated with the displacement of ethane by methane molecules and the formation of a molecule layered structure are shown. The integral molecular adsorption isotherm of the mixture according to the molecular modeling adequately corresponds to the ideal adsorbed solution theory (IAST). The cyclic processes of gas charging and discharging from the ANG storage based on the ACPK are simulated in three modes: adiabatic, isothermal, and thermocontrolled. The adiabatic mode leads to a loss of 27-33% of energy capacity at 3.5 MPa compared to the isothermal mode, which has a 9.4-19.5% lower energy capacity compared to the thermocontrolled mode, with more efficient desorption of both methane and ethane.

RESUMEN

This work presents a mathematical method to describe adsorptive removal of organic micropollutants (OMPs) and dissolved organic carbon (DOC) from wastewater treatment plant effluent using powdered activated carbon (PAC). The developed model is based on the tracer model (TRM) as a modification of the ideal adsorbed solution theory (IAST) and uses the fictive component approach for organic matter fractionation. It enables the simulation of multisolute adsorption of OMPs considering competitive adsorption behavior of organic background compounds (OBC). Adsorption equilibrium data for DOC and seven different OMPs as well as kinetic data for DOC were derived from batch experiments performed with secondary clarifier effluent of two municipal wastewater treatment plants (WWTP 1 and WWTP 2). Two conventional PAC products were investigated as well as one biogenic PAC (BioPAC). Verification and validation of the fitting results based on operational data of WWTP 1 showed promising prediction of DOC and OMP removal efficiency. However, when applied to a static simulation of a full-scale PAC adsorption stage, the model overpredicts the removal efficiency of sulfamethoxazole and candesartan. For benzotriazole, carbamazepine or hydrochlorothiazide, predicted removal falls below operational removal. The model can be used to predict removals of good adsorbable OMPs but fails to accurately predict the removals of OMPs with variable or low PAC affinity. The model was further used for a dynamic simulation of DOC and diclofenac effluent concentrations of a full-scale PAC adsorption stage with varying operating conditions and influent concentrations. Results show that the hydraulic retention time (HRT) in the contact reactor is a decisive operational parameter for OMP removal efficiency besides the PAC dose.

Asunto(s)

Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Carbón Orgánico , Compuestos Orgánicos , Polvos , Eliminación de Residuos Líquidos/métodos , Aguas Residuales , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos

RESUMEN

Tuning the selective sorption features of microporous organic networks is of great importance for subsequent applications in gas uptake and hiding, while it is more attractive in terms of being both time and cost effective to realize these optimizations without using functional groups in the core and linker. "Knitting" is one of the easiest and most used method to obtain a broad scope of hyper-crosslinked polymers on a large scale from aromatic structures that do not contain functional groups for polymerization. By the use of Knitting method, a hypercrosslinked covalent ultramicroporous organic polymer was obtained via stepwise process from using triazatruxene (TAT) as core -a planar indole trimer- through anhydrous FeCl3 catalyzed Friedel-Crafts alkylation using dimethoxybenzene as a linker. The resulting microporous polymer, namely TATHCCP was completely identified by analytical and spectral techniques after examined for gas properties (CO2, CH4, O2, CO, and H2) and selectivity (CO2/N2, CO2/O2, for CO2/CO and CO2/CH4) up to 1 bar and increased temperatures (273 K, 296 K and 320 K). Although it has a relatively low (Brunauer-Emmett-Teller) BET specific surface area around 557 m2/g, it was seen to have a high CO2 capture capacity approaching 10% wt. at 273 K. In accordance with (ideal adsorbed solution theory) IAST computations, it was revealed that interesting selectivity features hitting up to 60 for CO2/N2, 45 for CO2/O2, 35 for CO2/CO, 13 for CO2/CH4 at lower temperatures revealed that the material has much better selectivity values than many HCP (hyper-crosslinked polymer) derivatives in the literature even from its most similar analog dimethoxymethane derivative TATHCP, which has a surface area of 950 m2/g.

RESUMEN

The three-parameter (K, b, and n) Song isotherm model was slightly modified to make it possible to obtain analytical integration of the spreading pressure integral. The modified Song model (MSM) allows more efficient and accurate calculation of the ideal adsorbed solution theory (IAST). The MSM also satisfies the Henry's law and the Freundlich model at low and high concentrations, respectively, and reverts to the Langmuir and the linear models when n equals zero and one, respectively. Approximate values of each parameter could be estimated from a plot of log (q/c) versus log c; the partition coefficient in the Henry's law region (K) and the Freundlich index (n) can be estimated from the ordinate value of the low-concentration asymptote and the slope of the high-concentration asymptote, respectively, and the parameter (b) can be estimated from the solution-phase concentration of the intersection point of the two asymptotes. The MSM was fitted to the single-solute sorption of 2-chloro-, 3-cyano-, and 4-nitrophenol onto montmorillonites modified with either HDTMA cation or TMA/HDTMA dual cations. The ideal adsorbed solution theory (IAST) combined with either dual-mode model, Khan model or MSM as a single-solute isotherm model was used to predict three bisolute and one trisolute sorption to organoclays. The Sheindorf-Rebhun-Sheintuch (SRS) and Murali-Aylmore (M-A) were also used to predict bisolute sorption to organoclays. The IAST predictions were generally in good agreement with the multisolute sorption data. The advantages of MSM over other three-parameter models were fully discussed.

Asunto(s)

Bentonita , Fenoles , Adsorción , Cationes , Soluciones

RESUMEN

The formulation of a thermodynamic framework for mixtures based on absolute, excess or net adsorption is discussed and the qualitative dependence with pressure and fugacity is used to highlight a practical issue that arises when extending the formulations to mixtures and to the Ideal Adsorbed Solution Theory (IAST). Two important conclusions are derived: the correct fundamental thermodynamic variable is the absolute adsorbed amount; there is only one possible definition of the ideal adsorbed solution and whichever starting point is used the same final IAST equations are obtained, contrary to what has been reported in the literature.

RESUMEN

The first example of an inorganic-organic composite framework with an interpenetrated diamondoid inorganic building block, featuring unique {InNa}n helices and {In12 Na16 } nano-rings, has been constructed and structurally characterized. This framework also represents a unique example of encapsulation of an interpenetrated diamondoid inorganic building block in a metal-organic framework.