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desorption Behavior and Thermogravimetric Analysis of Bio-Hardeners

Journal of Renewable Materials 2022年第8期10卷 2015-2027页

作者： Benoit Ndiwe Antonio Pizzi Hubert Chapuis Noel Konai Lionel Karga Pierre Girods Raidandi Danwe Department of Mechanical Engineering Higher Technical Teacher Training College Douala(ENSET)University of DoualaDoualaCameroon Laboratory of Forest Resources and Wood Valorization(Larefob) ENSET of DoualaDoualaCameroon Department of Engineering Science West UniversityTrollhättanSweden LERMAB-ENSTIB University of LorraineEpinal88051France Laboratoire D’Etudes et de Recherche sur le Matériau Bois LERMAB Facultédes Sciences et TechnologiesUniversitéde LorraineNancyFrance Laboratory of Materials Mechanics Structures and Integrated ManufacturingNational Advanced School of EngineeringYaoundé1 UniversityYaoundéCameroon Department of Mechanical Petroleum and Gas Engineering Faculty of Mines and Petroleum IndustriesUniversity of MarouaKaéléCameroon Laboratory of Mechanic Materials and BuildingSahel Institute of Maroua UniversityMarouaCameroon

In this work,the thermal degradation and drying of bio-hardeners are investigated.Four bio-hardeners based on exudates of Senegalia senegal,Vachellia nilotica,Vachellia seyal,and Acacia siebteriana were analyzed by FTIR and thermogravimetric analysis,and a desorption study was also conducted.The analysis by infrared spectroscopy indicates the existence of oligomers of different types all giving 5-hydroxy-2-hydroxymethylfuran and 2,5-dihydroxymethylfuran which are then the real hardening molecules.The pyrolysis of these extracts reveals three main regions of mass loss,a first region is located between 25℃and 110℃reflecting the loss of water from the adhesive and the formation of some traces of volatile organic compounds such as CO_(2)and CO,a second zone characterized by the release of CO,CO_(2)and CH4 gases with peaks between 110°and 798.8℃.At the end of the analysis,about 22%of the initial mass remains undecomposed,this mass corresponds to the rigid segments of the bio-hardener which are not completely decomposed.

关键词： Exudates pyrolysis FTIR bio-hardener desorption

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desorption of VOC from polymer adsorbent in multistage fluidized bed

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Chinese Journal of Chemical Engineering 2020年第6期28卷 1709-1716页

作者： Jiale Zheng Wenli Song Lin Du Lina Wang Songgeng Li State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The desorption process of volatile organic compounds(VOC)from a polymer adsorbent in counter-current multistage fluidized bed was studied.And a mathematical model considering the mass transfer dynamics was developed,which was validated from experiment data.The gaseous ethyl acetate mass transfer was discussed,and the limiting step is the intraparticle mass transfer of the desorption process.The value of intraparticle mass transfer coefficient is between 1.85×10-6 and 1.38×10-5 m·s-1 under temperature of 100–160°C.Experiments under different operating conditions were carried out.The effects of operating conditions such as gas–solid flow ratio,gas inlet temperature and total stage number of multistage fluidized bed on outlet VOCs concentration and desorption efficiency were discussed.The maximum outlet VOCs concentration and corresponding desorption efficiency of the multistage fluidized bed desorber was calculated under different gas inlet temperatures and total stage numbers.

关键词： VOC desorption Mass transfer Fluidized bed

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desorption isotherms and isosteric heat of anaerobic fermentation residues

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Chinese Journal of Chemical Engineering 2019年第10期27卷 2510-2517页

作者： Tibor Poós Viktor Szabó Department of Building Services and Process Engineering Faculty of Mechanical EngineeringBudapest University of Technology and EconomicsBertalan Lajos u.4-6H-1111 BudapestHungary

This paper presents the equilibrium desorption isotherms and the isosteric heat of sorption of a mixture containing mechanically dewatered fermentation residue(obtained from a blend of chicken,swine and cattle manure)used in biogas plants and corn spoiled silage in a ratio of 2:1.The moisture desorption isotherms of the fermentation residue were determined at 32°C,40°C and 80°C and in the relative humidity range of 0.057/1 using static gravimetric method.Mathematical equations were used to analyze the desorption data of Modified Henderson,Modified Halsey,Modified Oswin,Modified Chung–Pfost and Modified GAB models.The constants of the model equations were calculated by non-linear regression analysis.The Modified Henderson model fitted to the desorption isotherm data well.Using the proposed function,the final moisture content of the material can be determined as long as it can be dried in infinite time with the drying gas in the given conditions.The isosteric heat of desorption was calculated by using the Modified Henderson model in the studied temperature range based on the Clausius–Clapeyron equation.The isosteric heat varied between 46 k J·mol-1 and 67 k J·mol-1 at moisture levels 1.91 b Xe<4.05 kgH2O·kgdP-1 for the material.

关键词： desorption Equilibrium Model Measurement Isosteric heat

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Adsorption and desorption of Cd in reclaimed soil under the influence of humic acid:characteristics and mechanisms

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International Journal of Coal Science & Technology 2022年第1期9卷 225-235页

作者： Yonghong Zheng Zhiguo Zhang Yongchun Chen Shikai An Lei Zhang Fangling Chen Chengnan Ma Weiqing CAi Huainan Mining(Group)Co.LTD Huainan 232001China National Engineering Laboratory for Protection of Colliery Eco-Environment Huainan 232001China School of Earth and Environment Anhui University of Science and TechnologyHuainan 232001China

Exogenous humus can change the content and migration activity of cadmium(Cd)in soil.Humic acid(HA)is an important soluble humus component in soil.In order to explore the relationship between cadmium pollution mechanism and ecological environment of humic acid in reclaimed soil,the characteristics of humic acid adsorbing cadmium in alkaline conditions were studied.This study employed reclaimed soil from the Huainan mining area,China.The adsorption and desorption characteristics as well as influence mechanisms on the heavy metal cadmium(Cd)were explored under the influence of HA.The results show that:(1)When Cd concentration was low(0.2–10 mg/L),HA had little effect on Cd adsorption and desorption in reclaimed soil.When the Cd concentration was high(15–80 mg/L),HA had a great influence on the adsorption and desorption of Cd in reclaimed soil.The addition of HA can inhibit the adsorption of Cd by reclaimed soil and effectively improve the desorption capacity of Cd by reclaimed soil.(2)The kinetic curves of Cd adsorption and desorption of reclaimed soil with added HA show that both processes(adsorption and desorption)include two stages:rapid reaction and slow reaction.The adsorption of Cd by reclaimed soil under the influence of HA was 18.18%lower than that of normal reclaimed soil,and the increase of Cd desorption was 50.29%.(3)The factors affecting the adsorption and desorption of Cd in the soil were analyzed with gray theory,and their importance can be ordered as follows:Cd concentration>HA concentration>pH>temperature.Considering the influence of HA,a multi-factor coupling function model of adsorption and desorption of Cd in soil is established.This model provides theoretical guidance for the scientific prediction and evaluation of Cd environmental pollution risks in soil and will be useful for developing a new solution for engineering remediation of high concentration Cd contaminated soil.

关键词： Reclaimed soil Humic acid Heavy metal Cadmium Adsorption desorption

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Insight into leaching of rare earth and aluminum from ion adsorption type rare earth ore:Adsorption and desorption

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稀土学报:英文版 2023年第9期41卷 1398-1407,I0005页

作者： Qiang He Jinfa Chen Limei Gan Menglan Gao Miaomiao Zan Yanfei Xiao Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China Ganzhou Engineering Technology Research Center of Green Metallurgy and Process Intensification Ganzhou 341000China Key Laboratory of Ionic Rare Earth Resources and Environment Ministry of Natural ResourcesGanzhou 341oooChina Key Laboratory of Testing and Tracing of Rare Earth Products for State Market Regulation Ganzhou 34100oChina

Clay minerals are inferred to be the primary host materials for ion-exchangeable rare earth in ion adsorption type rare earth ore(IAREO).During the rare earth leaching process,the adsorption and desorption reactions of the cations controlling the leaching process continue to occur at the clay minerals-leaching agent solution interface.In order to understand the leaching mechanism and behavior of rare earth and co-leached aluminum,adsorption,competitive adsorption,and desorption experiments were carried out using kaolin as a typical clay mineral.The powerful electrostatic attraction and concentration driving forces facilitate the adsorption of cations.The adsorption ability and competitive adsorption ability of cations depend on their charge,hydration radius,and hydrolysis properties,and decrease in the order of La^(3+),Y^(3+),Al^(3+),Mg^(2+),and NH_(4)^(+).The desorption of rare earth and aluminum is positively affected by the concentration-driving force exerted by high concentrations of Mg^(2+) and NH_(4)^(+),with the order of the desorption ability being opposite to the adsorption ability.However,unspecified interactions between clay mineral particles enhanced by high-concentration desorbents,especially by Mg^(2+) than NH_(4)^(+),will adversely affect desorption reactions,which result in lower desorption efficiencies of rare earth and aluminum obtained with magnesium sulfate compared to those obtained with ammonium sulfate at high concentrations.Solid-phase Al(OH)_(3) generated at a high peak aluminum concentration leads to a considerably delayed aluminum efflux,thereby partially separating the rare earth from aluminum during the actual column leaching process.To advance the mining technology of IAREO by selectively improving the rare earth leaching efficiency with minimal leaching agent consumption,higher charged cations with concentrations limited to suitable levels should be preferred as leaching agents.

关键词： Rare earths Aluminum Kaolin Adsorption desorption

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Coalbed methane desorption characteristics controlled by coalification and its implication on gas co-production from multiple coal seams

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Frontiers of Earth Science 2023年第1期17卷 121-134页

作者： Bin ZHANG Yafei ZHANG Suping ZHAO Wei HE Shu TAO Zhejun PAN Yi CUI School of Energy Resources China University of Geosciences(Beijing)Beijing 100083China Coal Reservoir Laboratory of National Engineering Research Center of CBM Development&Utilization Beijing 100083China China United Coalbed Methane Corporation Ltd. Beijing 100016China PetroChina Research Institute of Petroleum Exploration and Development Beijing 100083China Ningxia Mineral Geological survey Institute Yinchuan 750021China Key Laboratory of Continental Shale Hydrocarbon Accumulation and Efficient Development(Ministry of Education) Northeast Petroleum UniversityDaqing 163318China China Huaneng Group Beijing 100031China

In this work,CH4 isothermal adsorption measurements were carried out on 64 coal samples collected from western Guizhou Province of China,and the coalbed methane(CBM)desorption processes were quantitatively analyzed.The results show that the Langmuir volume and the Langmuir pressure are controlled by coalification,and tend to increase as the vitrinite reflectance changes from 0.98% to 4.3%.Based on a division method of CBM desorption stages,the CBM desorption process were divided into four stages(inefficient,slow,fast and sensitive desorption stages)by three key pressure nodes(the initial,turning and sensitive pressures).The fast and sensitive desorption stages with high desorption efficiency are the key for achieving high gas production.A theoretical chart of the critical desorption pressure(P_(cd))and its relationship with different pressure nodes was established.The higher-rank coals have the higher initial,turning and sensitive pressures,with larger difference between pressure nodes.Most CBM wells only undergo partial desorption stages due to the differences in P_(cd) caused by the present-gas content.Under the same gas content conditions,the higher the coal rank,the less desorption stages that CBM needs to go through.During coalbed methane co-production from multiple coal seams within vertically superposed pressure systems,the reservoir pressure,the P_(cd),the initial working liquid level(WLL)height,and coal depth are key factors for evaluating whether coal seams can produce CBM simultaneously.It must be ensured that each production layer enters at least the fast desorption stage prior to that the WLL was lower than the depth of each layer.Only on this basis can all layers achieve the maximum gas production.

关键词： co-production from multiple coal seams CBM adsorption desorption coal rank

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Removal and desorption of chromium in synthetic effluent by a mixed culture in a bioreactor with a magnetic field

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Journal of Environmental Sciences 2020年第5期32卷 151-159页

作者： Roseli MDias Jessica GSilva Vicelma LCardoso Miriam Mde Resende Faculty of Civil Engineering Federal University of UberlandiaMinas GeraisBrazil Faculty of Chemical Engineering Federal University of UberlandiaMinas GeraisBrazil

Two chromium removal experiments were performed in bioreactors with and without a magnetic field under the same conditions.The release of the chromium present in the biomass was tested in two experiments one with the initial pH of the medium and one with pH 4.0.The objective was to remove Cr(Ⅵ)and total Cr from the effluent,this was carried out by placing biological treatments of synthetic effluent contaminated with 100 mg/L of Cr(Ⅵ)in a bioreactor with neodymium magnets that applied a magnetic field(intensity85.4 mT)to the mixed culture.The removal of Cr(Ⅵ)was approximately 100.0%for the bioreactor with a magnetic field and 93,3%for the bioreactor without a magnetic field for9 hr of recirculation of the synthetic effluent by the bioreactor.The removal of total Cr was61.6%and 48.4%,with and without a magnetic field,respectively;for 24 hr.The desorption of Cr(VI)in the synthetic effluent was 0.05 mg/L,which is below the limit established by Brazilian legislation(0.1 mg/L)for the discharge of effluent containing Cr(Ⅵ)into bodies of water.The results obtained for the removal of chromium in synthetic effluent suggested that there was no significant influence on the viable cell count of the mixed culture.The desorption of Cr(Ⅵ)in synthetic effluent after bioadsorption of chromium by the mixed culture in the process of removal of chromium in bioreactors with and without a magnetic field was not significant in either of the experiments with different initial pHs.

关键词： Chromium removal Mixed culture Magnetic field desorption Effluent treatment

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Adsorption and desorption mechanisms on graphene oxide nanosheets: Kinetics and tuning

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The Innovation 2021年第3期2卷 79-85页

作者： Xiaodan Qu Qiong Hu Zhongqian Song Zhonghui Sun Baohua Zhang Jialing Zhong Xuyou Cao Yuanjin Liu Bolin Zhao Zhenbang Liu Yujie Shen Yu Bao Zhenxin Wang Yuwei Zhang Li Niu Center for Advanced Analytical Science c/o School of Chemistry and Chemical EngineeringGuangzhou UniversityGuangzhou 510006China State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryUniversity of Science and Technology of ChinaChangchun 130022China School of Civil Engineering Guangzhou UniversityGuangzhou 510006China University of Science and Technology of China Hefei 230026China

A knowledge of the adsorption and desorption behavior of sorbates on surface adsorptive site(SAS)is the key to optimizing the chemical reactivity of catalysts.However,direct identification of the chemical reactivity of SASs is still a challenge due to the limitations of characterization techniques.Here,we present a new pathway to determine the kinetics of adsorption/desorption on SASs of graphene oxide(GO)based on total internal reflectance fluorescence microscopy.The switching on and off of the fluorescent signal of SAS lit by carbon dots(CDs)was used to trace the adsorption process and desorption process.We find that sodium pyrophosphate(PPi)could increase the adsorption equilibrium of CDs thermodynamically and promote the substrate-assisted desorption pathway kinetically.At the single turnover level,it was disclosed that the species that can promote desorption may also be an adsorption promoter.Such discovery provides significant guidance for improving the chemical reactivity of the heterogeneous catalyst.

关键词： adsorption desorption fluorescence microscopy graphene oxide carbon dots

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Impact of crystalline and amorphous iron-and aluminum hydroxides on mechanisms of phosphate adsorption and desorption

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Journal of Environmental Sciences 2018年第8期30卷 175-189页

作者： Stella Gypser Florian Hirsch Anja M.Schleicher Dirk Freese Brandenburg University of Technology Cottbus-Senftenberg Faculty of Environment Process Engineering Biotechnology and Chemistry Department of Soil Protection and Recultivation Brandenburg University of Technology Cottbus-Senftenberg Faculty of Environment Process Engineering Biotechnology and Chemistry Department of Geopedology and Landscape Development German Research Centre for Geosciences Section 3.1 Inorganic and Isotope Geochchemistry

Fourier-transform infrared（FT-IR） spectroscopic experiments were carried out during phosphate adsorption on highly crystalline gibbsite, poorly crystalline 2-line-ferrihydrite and amorphous iron–aluminum–hydroxide mixtures in the molar ratio 1：0, 10：1, 5：1, 1：1, 1：5, 1：10 and 0：1. The OH stretching vibrational bands were utilized to analyze changes in structural and surface OH groups during adsorption, because the position of characteristic P／O vibrational bands can shift depending on reaction conditions, pH or adsorbed phosphate content.Adsorption and desorption kinetics were studied at pH6 and different initial phosphate concentrations to achieve varying phosphate coverage on the mineral surfaces. For gibbsite the formation of AlHPO4 and Al2HPO4 can be assumed, while for ferrihydrite, a FeHPO4 or Fe2PO4 complex and the precipitation of FePO4 with longer equilibration time were proposed.Fe2HPO4 or a Fe2PO4 surface complex was deduced for Fe-hydroxides, an AlH2PO4 surface complex was identified for Al-hydroxide, and both displayed either hydrogen bonds to neighboring hydroxyl groups or hydrogen bonds to outer-sphere complexes. Fe：Al-hydroxide mixtures with high Al ratios showed a low phosphate desorption rate, while ferrihydrite and the Fe：Al-hydroxide mixtures with high Fe ratios had almost negligible desorption rates. It was concluded that within the weakly associated amorphous FeO（OH） materials, FePO4 precipitated, which was bound by outer-sphere hydrogen bonds. With high Al ratios, desorption increased, which indicated weaker phosphate binding of both inner-sphere and outer-sphere complexes and hence, either no or minor quantities of precipitate. Ferrihydrite showed a more rigid structure and a lower extent of precipitation compared to amorphous Fe-hydroxide.

关键词： Phosphate Adsorption desorption Surface complexation Precipitation FT-IR

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Adsorption-desorption of phenolic compounds from olive mills wastewater using Tunisian natural clay

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Chinese Journal of Chemical Engineering 2021年第12期34卷 287-292页

作者： Islem Chaari Atef Touil Mounir Medhioub Useful Materials Valorization Laboratory National Center for Research in Materials SciencesSoliman 8027Tunisia Department of Geology Faculty of ScienceSfaxTunisia

Olive mills wastewater(OMW) exhibit substantial contaminated properties due to their content of phenolic constituents and organic substances. The purpose of this work was the investigation of the efficiency of clay materials for the adsorption of phenolic compounds, which are contained in OMW.Furthermore, thermal activation of the clay took place in order to improve phenolic compounds uptake and afterwards, desorption process was studied. The adsorbent was characterized using XRD, XRF and BET surface area analyses. The adsorption efficiency of phenolic compounds by raw and calcined clay at 600 °C was 77.61% and 84.21%, respectively at acidic p H. The values of Gibbs free energy indicated that adsorption process is spontaneous and beneficial at higher temperatures. Alkaline medium was propitious for phenolic compounds desorption. The obtained results showed that natural clay could be used as a low-cost adsorbent for OMW treatment.

关键词： Clayey material Adsorption Phenolic compounds Olive mills wastewaters desorption

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