• Title/Summary/Keyword: adsorption modeling

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Effect of Soil Organic Matter on Arsenic Adsorption in the Hematite-Water Interface: Chemical Speciation Modeling and Adsorption Mechanism (비소의 적철석 표면 흡착에 토양유기물이 미치는 영향: 화학종 모델링과 흡착 기작)

  • Ko, Il-Won;Kim, Ju-Yong;Kim, Gyeong-Ung;An, Ju-Seong;Davis, A. P.
    • Economic and Environmental Geology
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    • v.38 no.1
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    • pp.23-31
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    • 2005
  • This study was performed to investigate the effect of humic acid on the adsorption of arsenic onto hematite and its binding mechanism through the chemical speciation modeling in the binary system and the adsorption modeling in the ternary system. The complexation modeling of arsenic and humic acid was suitable for the binding model with the basis of the electrostatic repulsion and the effect of bridging metal. In comparison with the experimental adsorption data in the ternary system, the competitive adsorption model from the binary intrinsic equilibrium constants was consistent with the amount of arsenic adsorption. However, the additive rule showed the deviation of model in the opposite way of cationic heavy metals, because the reduced organic complexation of arsenic and the enhanced oxyanionic competition diminished the adsorption of arsenic. In terms of the reaction mechanism, the organic complex of arsenic, neutral As(III) and oxyanionic As(V) species were transported and adsorbed competitively to the hematite surface forming the inner-sphere complex in the presence of humic acid.

Comparative Study of $Cu^{2+}$ Adsorption of Goethite, Hematite and Kaolinite : Mechanistic Modeling Approach

  • 정진호;조영환;한필수
    • Bulletin of the Korean Chemical Society
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    • v.19 no.3
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    • pp.324-327
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    • 1998
  • The mechanisms of Cu2+ adsorption onto goethite, hematite and kaolinite are different. Goethite and hematite showed a similar adsorption behavior (ionic-strength independent), but kaolinite gave somewhat different result (ionic-strength dependent). These experimenal results were successfully simulated using a surface complexation model, TLM, which defines the inner- or outer-sphere complex. The chemical nature of Cu2+ adsorption onto kaolinite was qualitatively identified by EPR spectroscopy.

Equilibrium modeling for adsorption of NO3- from aqueous solution on activated carbon produced from pomegranate peel

  • Rouabeh, I.;Amrani, M.
    • Advances in environmental research
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    • v.1 no.2
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    • pp.143-151
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    • 2012
  • Nitrate removal from aqueous solution was investigated using $ZnCl_2$ and phosphoric acid activated carbon developed from pomegranate peel with particle size 0.4 mm. Potassium nitrate solution was used in batch adsorption experiments for nitrate removal from water. The effects of activated carbon dosage, time of contact, and pH were studied. The equilibrium time was fond to be 45 min. Two theoretical adsorption isotherms namely Langmuir and Freundlich were used to describe the experimental results. The Langmuir fit the isotherm with the theoretical adsorption capacity ($q_t$) was fond 78.125 mg g-1. Adsorption kinetics data were modeled using the pseudo-first, pseudo-second order, and intraparticle diffusion models. The results indicate that the second-order model best describes adsorption kinetic data. Results show activated carbon produced from pomegranate is effective for removal of nitrate from aqueous solution.

Pressure Swing Adsorption Based Hydrogen Purification Vessel 3D Modeling and Feasibility Study (Pressure Swing Adsorption 기반 수소정제용기 3차원 모델링 및 타당성 검증 연구)

  • CHA, YOHAN;CHOI, JAEYOO;JU, HYUNCHUL
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.4
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    • pp.197-204
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    • 2021
  • Pressure swing adsorption is a purification process which can get pure hydrogen. The purification process is composed of four process: compression, adsorption, desorption and discharge. In this study the adsorption process was simulated by using the Fluent and validated with experimental results. A gas used in experiment is composed of H2, CO2, CH4, and CO. Adsorption process conducted under 313 kelvin and 3 bar and bituminous-coal-based (BPL) activated carbon was used as the adsorbent. Langmuir model was applied to explain the gas adsorption. And diffusion of all the gases was controlled by micro-pore resistances. The result shows that, the most adsorbed gas was carbon dioxide, followed by methane and carbon monoxide. And carbon monoxide took the least amount of time to reach the maximum adsorption amount. The molar fraction of the off-gas became the same as the molar fraction of the gas supplied from the inlet after adsorption reached the equilibrium.

Adsorption Characteristics of Sr Ions by Coal Fly Ash-Based-Zeolite X using Response Surface Modeling Approach (반응표면분석법을 이용한 석탄회로 합성한 제올라이트 X에서의 Sr 이온 제거특성)

  • Lee, Chang-Han;Kam, Sang-Kyu;Lee, Min-Gyu
    • Journal of Environmental Science International
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    • v.26 no.6
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    • pp.719-728
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    • 2017
  • In order to investigate the adsorption characteristics for Sr ion using the Na-X zeolite synthesized from coal fly ash, batch tests and response surface analyses were carried out. The adsorption kinetic data for Sr ions, using Na-X zeolite, fitted well with the pseudo-second-order model. The uptake of Sr ions followed the Langmuir isotherm model, with a maximum adsorption capacity of 196.46 mg/g. Thermodynamic studies were conducted at different reaction temperatures, with the results indicating that Sr ion adsorption by Na-X zeolite was an endothermic (${\Delta}H^o$>0) and spontaneous (${\Delta}G^o$<0) process. Using the response surface methodology of the Box-Behnken method, initial Sr ion concentration ($X_1$), initial temperature ($X_2$), and initial pH ($X_3$) were selected as the independent variables, while the adsorption of Sr ions by Na-X zeolite was selected as the dependent variable. The experimental data fitted well with a second-order polynomial equation by multiple regression analysis. The value of the determination coefficient ($R^2=0.9937$) and the adjusted determination coefficient (adjusted $R^2=0.9823$) was close to 1, indicating high significance of the model. Statistical results showed the order of Sr removal based on experimental factors to be initial pH > initial concentration > temperature.

Modeling of the Nitrate Adsorption Kinetics onto $ZnCl_2$ Treated Granular Activated Carbon (염화아연으로 표면개질된 입상활성탄의 질산성질소 흡착속도의 모델링 연구)

  • Ji, Min-Kyu;Jung, Woo-Sik;Bhatnagar, Amit;Jeon, Byong-Hun
    • Journal of Soil and Groundwater Environment
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    • v.13 no.3
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    • pp.21-26
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    • 2008
  • Nitrate adsorption from aqueous solutions onto zinc chloride ($ZnCl_2$) treated coconut Granular Activated Carbon (GAC) was studied in a batch mode at two different initial nitrate concentrations (25 and 50 mg/L). The rate of nitrate uptake on prepared media was fast in the beginning, and 50% of adsorption was occurred within 10 min. The adsorption equilibrium was achieved within one hour. The mechanism of adsorption of nitrate on $ZnCl_2$ treated coconut GAC was investigated using four simplified kinetic models : the rate parameters were calculated for each model. The kinetic analysis indicated that pseudo-second-order kinetic with pore-diffusion-controlled was the best correlation of the experimental kinetic data in the present adsorption study.

The influence of heavy metal on microbial biodegradation of organic contaminants in soil (토양내의 중금속이 유기오염물질 생분해에 미치는 영향 연구)

  • 최재영;박재우
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2000.11a
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    • pp.196-201
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    • 2000
  • The influence of adsorption on cadmium toxicity to soil microorganisms in smectite-rich soils and sediments was quantified as a function of solution and sorbent characteristics. Adsorption and surface complexation experiments were conducted to infer Cd sorption mechanisms to a reference smectite and three fractions of a Veritsol soil, and to elucidate the effects of the surface complexation on Cd bioavailability and toxicity in soils and sediments. Cadmium adsorption isotherms conformed to the Langmuir adsorption model, with adsorptive capacities of the different samples dependent on their characteristics. Equilibrium geochemical modeling (MINTEQA2) was used to predict the speciation of Cd in the soil suspensions using Langmuir and Triple Layer surface complexation models. The influence of adsorption and surface complexation on cadmium toxicity to soil microorganisms was assessed indirectly through the relative change in microbial hydrolysis of fluorescein diacetate (FDA) as a function of total Cd concentration and sorbent characteristics. Adsorption decreased the toxicity of Cd to soil microorganisms. Inner-sphere complexation is more effective than outer-sphere complexation in reducing the bioavailability and toxicity of heavy metals in soils and sediments.

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Triple-layer Surface Complexation Modeling on the Adsorption of cs-137 and Sr-90 onto Kaolinite: Effect of Groundwater Ions and pH (캐올리나이트의 셰슘-137 및 스트론튬-90 흡착에 대한 삼중층 표면복합반응 모델링: 지하수 이온성분 및 pH의 영향)

  • 정찬호;박상원;김수진
    • Journal of the Mineralogical Society of Korea
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    • v.11 no.2
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    • pp.106-116
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    • 1998
  • The adsorption of Cs-137 and Sr-90 onto kaolinite in prescence of major groundwater cations (Ca2+, K+, Na+) with different concentrations was simulated by using triple-layer surface complexation model (TL-SCM). The site density (8.73 sites/nm2) of kaolinite used for TL-SCM was calculated from it's CEC and specific surface area. TL-SCM modeling results indicate that concentrations dependence on 137Cs and 90Sr adsorption onto kaolinite as a function of pH is best modeled as an outer-sphere surface reaction. This suggests that Cs+ and Sr2+ are adsorbed at the $\beta$-layer in kaolinite-water interface where the electrolytes, Nacl, KCl and CaCl2, bind. However, TL-SCM results on Sr adsorption show a discrepancy between batch data and fitting data in alkaline condition. This may be due to precipitation of SrCO3 and complexation such as SrOH+. Intrinsic reaction constants of ions obtained from model fit are as follows: Kintcs=10-2.10, KintSr=10-2.30, KintK=10-2.80, KintCa=10-3.10 and KintNa=10-3.32. The results are in the agreement with competition order among groundwater ions (K+>Ca2+>Na+) and sorption reference of nuclides (Cs-137>Sr-90) at kaolinite-water interface showed in batch test.

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Adsorption Kinetics for Polymeric Additives in Papermaking Aqueous Fibrous Media by UV Spectroscopic Analysis

  • Yoon, Sung-Hoon;Chai, Xin-Sheng
    • Bulletin of the Korean Chemical Society
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    • v.27 no.11
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    • pp.1819-1824
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    • 2006
  • The general objective of the present study was to investigate the potential application of the UV spectroscopic method for determination of the polymeric additives present in papermaking fibrous stock solutions. The study also intended to establish the surface-chemical retention model associated with the adsorption kinetics of additives on fiber surfaces. Polyamide epichlorohydrin (PAE) wet strength resin and imidazolinium quaternary (IZQ) softening agents were selected to evaluate the analytical method. Concentrations of PAE and IZQ in solution were proportional to the UV absorption at 314 and 400 nm, respectively. The time-dependent behavior of polymeric additives obeyed a mono-molecular layer adsorption as characterized in Langmuir-type expression. The kinetic modeling for polymeric adsorption on fiber surfaces was based on a concept that polymeric adsorption on fiber surfaces has two distinguishable stages including initial dynamic adsorption phase and the final near-equilibrium state. The simulation model predicted not only the real-time additive adsorption behavior for polymeric additives at high accuracy once the kinetic parameters were determined, but showed a good agreement with the experimental data. The spectroscopic method examined on the PAE and IZQ adsorption study could potentially be considered as an effective tool for the wet-end retention control as applied to the paper industry.