Low-energy-consumption temperature swing system for CO_(2) capture by combining passive radiative cooling and solar heating

Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO_(2) on commercial activated carbons(CACs).During adsorption,the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene)[P(VdF-HFP)HP],which cools the adsorbents to a low temperature under sunlight through radiative cooling.For desorption,CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating.The heating and cooling processes are completely driven by solar energy.Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones.Furthermore,under real sunlight irradiation,the adsorption capacity of the CACs can be well maintained after multiple cycles.The present work may inspire the development of new temperature swing procedures with little energy consumption.

Synthesis of SAPO-34/graphite composites for low temperature heat adsorption pumps

Low temperature heat adsorption pumps represent the innovative cooling systems, where cold is generated through adsorption/desorption cycle of water by a suitable adsorbent with good adsorption and high thermal conductive properties. In this work, the hydrothermal synthesis of zeolite SAPO-34 on thermal conductive grapbitic supports, aiming at the development of highly pertbrming adsorbent materials, is reported. The synthesis was carried out using as-received and oxidized commercial carbon papers, and graphite plate. Composites were characterized by XRD, SEM and also by a thermogravimetric method, using a Cahn microbalance. The water adsorbing capacity showed typical S-shape trend and the maximum water loading was around 25 wt%, a value close to water adsorption capability of pure SAPO-34. These results are very promising for their application in heat adsorption pumps.

Systematic investigation of SO_(2) adsorption and desorption by porous powdered activated coke:Interaction between adsorption temperature and desorption energy consumption

Porous carbon materials have been widely used for the removal of SO_(2) from flue gas.The main objective of this work is to clarify the effects of adsorption temperature on SO_(2) adsorption and desorption energy consumption.Coal-based porous powdered activated coke(PPAC)prepared in the drop-tube reactor was used in this study.The N_(2) adsorption measurements and Fourier transform infrared spectrometer analysis show that PPAC exhibits a developed pore structure and rich functional groups.The experimental results show that with a decrease in adsorption temperature in the range of 50–150℃,the adsorption capacity of SO_(2) increases linearly;meanwhile,the adsorption capacity of H_(2)O increases,resulting in the increase in desorption energy consumption per unit mass of adsorbent.The processes of SO_(2) and H_(2)O desorption were determined by the temperature-programmed desorption test,and the desorption energies for each species were calculated.Considering the energy consumption per unit of desorption and the total amount of adsorbent,the optimal adsorption temperature yielding the minimum total energy consumption of regeneration is calculated.This study systematically demonstrates the effect of adsorption temperature on the adsorption–desorption process,providing a basis for energy saving and emission reduction in desulfurization system design.

K^+ Adsorption Kinetics of Fluvo-Aquic and Cinnamon Soil Under Different Temperature

The K+ adsorption kinetics of fluvo-aquic soil and cinnamon soil under different temperatureswere studied. The results showed: 1) The first order equations were the most suitable forfitting the adsorption under various temperature levels with constant K+ concentration indisplacing fluid. With temperature increasing, the fitness of Elovich equation increased,while those of power equation and parabolic diffusion equation decreased; 2)the apparentadsorption rate constant ka and the product of ka multiplied by the apparent equilibriumadsorption qincreased when temperature increased, while the apparent equilibrium adsorptionqreduced; 3)temperature influenced hardly the reaction order, the order of concentrationand adsorpton site were always 1 under various temperatures, if they were taken intoaccount simultaneously, the adsorption should be a two-order reaction process; 4)theGibbs free energy change △G of potassium adsorption were negative, ranged from -4444.56to -2450.63Jmol-1,and increased with temperature increasing, while enthalpy change △H,entropy change △S, apparent adsorption activation Ea, adsorption activation energy E1and desorption activation energy E2 were temperature-independent; 5)the adsorption wasspontaneous process with heat releasing and entropy dropping, fluvo-aquic soil releasedmore heat than cinnamon soil.

Temperature influence on macro-mechanics parameter of intact coal sample containing original gas from Baijiao Coal Mine in China

Investigation of temperature effect on mechanical parameters of coal is very important for understanding the mechanical response of coal bed at high temperature.It is especially benefcial for mitigating the thermal-induced disasters occurred in those coal mines suffering from heat hazard.In this work,coal samples,obtained from the No.2442 working face of Baijiao Coal Mine,were subjected to uniaxial compression ranging from 20 to 40℃ with an interval of 5℃.The apparatus used was designed to obtain deformation of a stressed sample,as well as the emission of gases desorbing from coal matrix.The adsorbed gas desorption caused by heating is measured during the entire testing.It is evident that the concentrations of releasing gas(containing methane,carbon dioxide and ethane)slightly rise with increasing temperature.Gas movement observed is closely related to the deformation of coal sample.Both uniaxial compressive strength and elastic modulus of coal samples tend to reduce with temperature.It reveals that increasing temperature can not only result in thermal expansion of coal,but also lead to desorption of preexisting gas in coal which can in turns harden coal due to shrinks of the coal matrix.Even though desorption of adsorbed gas can contribute to the hardening effect for the heated coal,by comparison to the results,it could be inferred that the softening of coal resulted from thermal expansion still predominates changes in mechanical characters of coal sample with temperature at the range from20 to 40℃.

A New 4.0-Generation Dendrimer Phosphorescence Labeling Reagent and Its Application to Determination of Trace Alkaline Phosphatase by Affinity Adsorption Solid Substrate-room Temperature Phosphorimetry

A Triton X-100-4.0G-D （4.0G-D refers to a 4.0-generation dendrimer） was brought forward as a new phosphorescence labeling reagent. Two types of specific affinity adsorption （AA） reactions （direct method and sandwich method） were carried out between the labeling product of Triton X-100-4：0G-D-Wheat germ agglutinin （WGA） and alkaline phosphatase （ALP）, the product of AA reaction preserved the good characteristics of room temperature phosphorescence （RTP） of 4.0G-D and △Ip of the product was proportional to the content of ALP. According to the fact stated above, a new method for the determination of trace ALP by affinity adsorption solid substrate-room temperature phosphorimetry （AA-SS-RTP） was established on the basis of WGA labeled with the Triton X-100-4.0G-D. The detection limits were 0.20 ag·spot^-1 （corresponding concentration： 5.0×10^-16 g·mL^-1, namely 5.0×10^-18 mol·L^-1） for a direct method and 0.14 ag·spot^-1 （corresponding concentration： 3.5×10^-16 g·mL^-1, namely 3.5×10^-18 mol·L^-1） for a sandwich method, respectively. For their high sensitivity, good repeatability and high accuracy, the direct method and sandwich method have been successfully appfied to determine the content of ALP in human serum, and the results were coincided with the clinical detection results of the enzyme-linked immunosorbent assay method by the Zhangzhou Hospital of Traditional Chinese Medicine. Meanwhile, the mechanism for the determination of trace ALP by AA-SS-RTP was discussed.

Solid amine sorbents for CO_(2) capture by chemical adsorption: A review

Amines are well-known for their reversible reactions with CO_(2),which make them ideal for CO_(2) capture from several gas streams,including flue gas.In this respect,selective CO_(2) absorption by aqueous alkanolamines is the most mature technology but the process is energy intensive and has also corrosion problems.Both disadvantages can be diminished to a certain extent by chemical adsorption of CO_(2) selectively.The most important element of the chemical adsorption of CO_(2) involves the design and development of a suitable adsorbent which consist of a porous support onto which an amine is attached or immobilized.Such an adsorbent is often called as solid amine sorbent.This review covers solid amine-based studies which are developed and published in recent years.First,the review examines several different types of porous support materials,namely,three mesoporous silica(MCM-41,SBA-15 and KIT-6)and two polymeric supports(PMMA and PS)for CO_(2) adsorption.Emphasis is given to the synthesis,modifications and characterizations-such as BET and PXRD data-of them.Amination of these supports to obtain a solid amine sorbent through impregnation or grafting is reviewed comparatively.Focus is given to the adsorption mechanisms,material characteristics,and synthesis methods which are discussed in detail.Significant amount of original data are also presented which makes this review unique.Finally,relevant CO_(2) adsorption(or equilibrium)capacity data,and cyclic adsorption/desorption performance and stability of important classes of solid amine sorbents are critically reviewed.These include severa PEI or TEPA impregnated adsorbents and APTES-grafted systems.

Thermodynamic analysis on direct air capture for building air condition system:Balance between adsorbent and refrigerant

Direct air capture(DAC)is one of the most potential technologies to mitigate CO_(2) emission.Adsorption technol-ogy is recognized as a promising CO_(2) capture method in view of its desirable characteristics including reusability of adsorbents and low capital investment.To further improve thermal performance,evaporation/condensation heat of vapor compression refrigeration(VCR)cycle in air condition system of buildings is adopted for adsorp-tion/desorption process of DAC.Thermal performance of a 4-step temperature swing adsorption process(TSA)is analyzed at various adsorption/desorption temperatures by using different adsorbents.Analysis on Coefficient of Performance(COP)of VCR cycle is also conducted in search for a balance between adsorbent and refrigerant.Taking both real working capacity and COP into consideration,Mg-MOF-74&R134a is the best choice for more amounts of CO_(2).Real working capacity of Mg-MOF-74 is up to 0.38 mol•kg−1 at 70°C,which is twice as much as that of zeolite 13X.While zeolite 13X&R134a shows the best performance of two cycles in view of exergy efficiency and COP,which could reach 81.9%and 7.21,respectively,at 35°C.These matches will provide some guidelines for the practical application of the combination of DAC with heating,ventilation and air conditioning(HVAC).

Encapsulation of 2-amino-2-methyl-l-propanol with tetraethyl orthosilicate for C02 capture

Carbon capture is widely recognised as an essential strategy to meet global goals for climate protection.Although various C02 capture technologies including absorption,adsorption and membrane exist,they are not yet mature for post-combustion power plants mainly due to high energy penalty.Hence researchers are concentrating on developing non-aqueous solvents like ionic liquids,C 02-binding organic liquids,nanoparticle hybrid materials and microencapsulated sorbents to minimize the energy consumption for carbon capture.This research aims to develop a novel and efficient approach by encapsulating sorbents to capture C02 in a cold environment.The conventional emulsion technique was selected for the microcapsule formulation by using 2-amino-2-methyl-l-propanol(AMP)as the core sorbent and silicon dioxide as the shell.This paper reports the findings on the formulated microcapsules including key formulation parameters,microstructure,size distribution and thermal cycling stability.Furthermore,the effects of microcapsule quality and absorption temperature on the C02 loading capacity of the microcapsules were investigated using a self-developed pressure decay method.The preliminary results have shown that the AMP microcapsules are promising to replace conventional sorbents.

Effect of acoustic field on C02 desorption in a fluidized bed of fine activated carbon

Adsorption using solid sorbents has the potential to complement or replace current absorption technol- ogy, because of its low energy requirements. Among the commercially available adsorbent materials, attention is focused on activated carbons because they are easily regenerable by reason of their low heat of adsorption. These sorbents are generally available in the form of fine powders. Sound-assisted fluidization can process large amounts of fine powders, promoting and enhancing CO2 capture on fine sorbents, because it maximizes gas-solid contact. Temperature swing adsorption （TSA）, consisting of inducing sor- bent regeneration and CO2 recovery by appropriate temperature increase and gas purge, is one of the most promising techniques. This study investigates the CO2 desorption process by TSA in a sound-assisted flu- idized bed of fine activated carbon. Desorption tests were performed under ordinary and sound-assisted fluidization conditions to assess the capability of sound to promote and enhance the desorption efficiency in terms of CO2 recovery, CO2 purity, and desorption time. The results show that the application of sound results in higher desorption rates, CO2 recovery and purity. Regular and stable desorption profiles can be obtained under sound-assisted fluidization conditions. This stability makes it possible to successfully realize a cyclic adsorption/desorption process.

Greenhouses for CO_(2) sequestration from atmosphere

Escalating threat of global warming and the steady growth in world population require the development of transformative greenhouse gas control technologies and food production systems of high energy efficiency,small environmental footprint and low cost.To control the global temperature rise below 2℃ by 2050,global greenhouse gas emissions need to be cut by more than 80%.At the same time,our land needs to be utilized more efficiently and productively in order to produce enough food to feed projected 9 billion people with less available land area for food production in 2050.We propose to develop a modern urban vertical farming system,i.e.greenhouses equipped with a Carbon Enrichment for Plant Stimulation(CEPS)system,to enhance land use efficiency and thus increase food productivity and,at the same time,to sequestrate CO_(2) from ambient air.The deployment of such a CEPS system will have a potential to remove more than 500 million tonnes CO_(2) from air annually,and increase the current food productivity by more than 15 times than the open field operation.The deployment of the CEPS technology will also promote locally produced food,benefiting urban economical development and job creation.