Surfactant-Template/Ultrasound-Assisted Method for the Preparation of Porous Nanoparticle Lithium Zirconate

Post-combustion CO2 capture via a variety of temperature ranges and material adsorption process: A review

Carbon dioxide (CO₂) emissions from fossil fuel combustion have been linked to increased average global temperatures, a global challenge for many decades. Mitigating CO₂ concentration in the atmosphere is a priority for the protection of the environment. This is a comparison of the three main technological categories available for CO₂ capture and storage. They include: oxy-fuel combustion, pre-combustion, and post-combustion. Each capture technology has inherent benefits and disadvantages in cost, implementation, and flexibility, but post-combustion CO₂ capture has demonstrated the most promising results in typical power plant configurations. This paper presents a review of different post-combustion CO₂ capture materials; solvents, membranes, and adsorbents, focusing on economical and environmentally safe low to high temperature solid adsorbents. Furthermore, the authors summarize the advantages and limitations of the materials investigated to provide insight into the challenges and opportunities currently facing the development of post-combustion CO₂ capture technologies. The solid sorbents currently available for CO₂ capture are also reviewed in detail, including physical and chemical properties, reactions, and current research efforts on improvement.

Hydrogen Production with In Situ CO2 Capture at High and Medium Temperatures Using Solid Sorbents

Hydrogen is a versatile vector for heat and power, mobility, and stationary applications. Steam methane reforming and coal gasification have been, until now, the main technologies for H2 production, and in the shorter term may remain due to the current costs of green H2. To minimize the carbon footprint of these technologies, the capture of CO2 emitted is a priority. The in situ capture of CO2 during the reforming and gasification processes, or even during the syngas upgrade by water–gas shift (WGS) reaction, is especially profitable since it contributes to an additional production of H2. This includes biomass gasification processes, where CO2 capture can also contribute to negative emissions. In the sorption-enhanced processes, the WGS reaction and the CO2 capture occur simultaneously, the selection of suitable CO2 sorbents, i.e., with high activity and stability, being a crucial aspect for their success. This review identifies and describes the solid sorbents with more potential for in situ CO2 capture at high and medium temperatures, i.e., Ca- or alkali-based sorbents, and Mg-based sorbents, respectively. The effects of temperature, steam and pressure on sorbents’ performance and H2 production during the sorption-enhanced processes are discussed, as well as the influence of catalyst–sorbent arrangement, i.e., hybrid/mixed or sequential configuration.

Core-shell nanoparticles used in drug delivery-microfluidics: a review

Developments in the fields of lab-on-a-chip and microfluidic technology have benefited nanomaterial production processes due to fluid miniaturization. The ability to acquire, manage, create, and modify structures on a nanoscale is of great interest in scientific and technological fields. Recently, more attention has been paid to the production of core-shell nanomaterials because of their use in various fields, such as drug delivery. Heterostructured nanomaterials have more reliable performance than the individual core or shell materials. Nanoparticle synthesis is a complex process; therefore, various techniques exist for the production of different types of nanoparticles. Among these techniques, microfluidic methods are unique and reliable routes, which can be used to produce nanoparticles for drug delivery applications.

Ultrafast Carbon Dioxide Sorption Kinetics Using Morphology-Controllable Lithium Zirconate

It was reported that the main obstacle of Li₂ZrO₃ as high-temperature CO₂ absorbents is the very slow CO₂ sorption kinetics, which are ascribed to the gradual formation of compact zirconia and carbonate shells along with inner unreacted lithium zirconate cores; accordingly, the "sticky" Li⁺ and O^2- ions have to travel a long distance through the solid shells by diffusion. We report here that three-dimensional interconnected nanoporous Li₂ZrO₃ exhibiting ultrafast kinetics is promising for CO₂ sorption. Specifically, nanoporous Li₂ZrO₃ (LZ-NP) exhibited a rapid sorption rate of 10.28 wt %/min with an uptake of 27 wt % of CO₂. Typically, the k₁ values of LZ-NP (kinetic parameters extracted from sorption kinetics) were nearly 1 order of magnitude higher than the previously reported conventional Li₂ZrO₃ reaction systems. Its sorption capacity of 25 wt % within ∼4 min is 2 orders of magnitude faster than those obtained using spherical Li₂ZrO₃ powders. Furthermore, nanoporous Li₂ZrO₃ exhibited good stability over 60 absorption-desorption cycles, showing its potential for practical CO₂ capture applications. CO₂ adsorption isotherms for Li₂ZrO₃ absorbents were successfully modeled using a double-exponential equation at various CO₂ partial pressures.

Ultrasound-assisted synthesis of Zinc(II)-based metal organic framework nanoparticles in the presence of modulator for adsorption enhancement of 2,4-dichlorophenol and amoxicillin

In this study, under a sonochemical method, a 3D, porous Zn(II)-based metal-organic framework [Zn(TDC)(4-BPMH)]_n·n(H₂O) is produced, which is called compound 1. To this end, the dicarboxylate linker of TDC, (2,5-thiophene dicarboxylic acid) and the pillar spacer of 4-BPMH, (N,N-bis-pyridin-4-ylmethylene-hydrazine) were employed. Moreover, variations in the morphology and growth of the micro/nanoparticles of compound 1 were investigated in terms of the effect of temperature, ultrasound irradiation power, sonication time, initial reagent concentrations, and pyridine concentration as a modulator. DFT model was used to examine the sonication effect on the distribution of the pore sizes. Moreover, the preparation method effect on the porosity and removal of two sample pollutants (i.e., 2,4-dichlorophenol (24-DCP) and amoxicillin (AMX)) from wastewater was studied.

Alkali Metal CO2 Sorbents and the Resulting Metal Carbonates: Potential for Process Intensification of Sorption-Enhanced Steam Reforming

Sorption-enhanced steam reforming (SESR) is an energy and cost efficient approach to produce hydrogen with high purity. SESR makes it economically feasible to use a wide range of feedstocks for hydrogen production such as methane, ethanol, and biomass. Selection of catalysts and sorbents plays a vital role in SESR. This article reviews the recent research aimed at process intensification by the integration of catalysis and chemisorption functions into a single material. Alkali metal ceramic powders, including Li₂ZrO₃, Li₄SiO₄ and Na₂ZrO₃ display characteristics suitable for capturing CO₂ at low concentrations (<15% CO₂) and high temperatures (>500 °C), and thus are applicable to precombustion technologies such as SESR, as well as postcombustion capture of CO₂ from flue gases. This paper reviews the progress made in improving the operational performance of alkali metal ceramics under conditions that simulate power plant and SESR operation, by adopting new methods of sorbent synthesis and doping with additional elements. The paper also discusses the role of carbonates formed after in situ CO₂ chemisorption during a steam reforming process in respect of catalysts for tar cracking.

CO2 chemisorption in Li2CuO2 microstructurally modified by ball milling: study performed with different physicochemical CO2 capture conditions

Lithium cuprate (Li₂CuO₂) was obtained by a solid state reaction and a subsequent ball milling process. Then, the samples were characterized (structurally and microstructurally) and evaluated as CO₂ captors.

Operando Raman spectroscopic studies of lithium zirconates during CO2 capture at high temperature

Operando Raman spectroscopy allowed following up the phase evolution for K-doped lithium zirconates during the CO₂ capture process.

Ultrasound-assisted/biosurfactant-templated size-tunable synthesis of nano-calcium sulfate with controllable crystal morphology

Nano-sized crystals of alpha calcium sulfate hemihydrate (α-HH) with considerable morphology-dependent properties find promising applications in the clinical fields as a cementitious material. Towards this end, ultrasound-assisted rhamnolipid and surfactin biosurfactant-template route is explored to control the morphology and aspect ratio of nano-CaSO4 by adjusting the mass ratio of rhamnolipid/H2O, surfactin/H2O and rhamnolipid/surfactin. The change in the molar ratio of [SO4(2-)]:[Ca(2+)] results in modification in variable morphology and size of nano-CaSO4 including long, short rods and nanoplates. With increase in the rhamnolipid/H2O ratio from 1.3 to 4.5, the crystal length decreases from 3 μm to 600 nm with the corresponding aspect ratio reduced sharply from 10 to 3. Similarly, the crystal morphology gradually changes from submicrometer-sized long rod to hexagonal plate, and then plate-like appearance with increase in surfactin concentration. The preferential adsorption of rhamnolipid on the side facets and surfactin on the top facets contributes to the morphology control. The process using 50% amplitude with a power input of 45.5 W was found to be the most ideal as observed from the high yields and lower average l/w aspect ratio, leading to more than 94% energy savings as compared to that utilized by the conventional process. As a morphology and crystal habit modifier, effects of Mg(2+) and K(+) ions on α-HH growth were investigated to find an optimal composition of solution for α-HH preparation. Mg(2+) ions apparently show an accelerating effect on the α-HH growth; however, the nucleation of α-HH is probably retarded by K(+) ions. Thus, the present work is a simple, versatile, highly efficient approach to controlling the morphology of α-HH and thereby, offers more opportunities for α-HH multiple applications.