Reliable estimation of adsorption isotherm parameters using adequate pore size distribution

Danial Husseinzadeh,Akbar Shahsavand 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.5

The equilibrium adsorption isotherm has a crucial effect on various characteristics of the solid adsorbent (e.g., pore volume, bulk density, surface area, pore geometry). A historical paradox exists in conventional estimation of adsorption isotherm parameters. Traditionally, the total amount of adsorb material (total adsorption isotherm) has been considered equivalent to the local adsorption isotherm. This assumption is only valid when the corresponding pore size or energy distribution (PSD or ED) of the porous adsorbent can be successfully represented with the Dirac delta function. In practice, the actual PSD (or ED) is far from such assumption, and the traditional method for prediction of local adsorption isotherm parameters leads to serious errors. Up to now, the powerful combination of inverse theory and linear regularization technique has drastically failed when used for extraction of PSD from real adsorption data. For this reason, all previous researches used synthetic data because they were not able to extract proper PSD from the measured total adsorption isotherm with unrealistic parameters of local adsorption isotherm. We propose a novel approach that can successfully provide the correct values of local adsorption isotherm parameters without any a priori and unrealistic assumptions. Two distinct methods are suggested and several illustrative (synthetic and real experimental) examples are presented to clearly demonstrate the effectiveness of the newly proposed methods on computing the correct values of local adsorption isotherm parameters. The so-called Iterative and Optima methods’ impressive performances on extraction of correct PSD are validated using several experimental data sets.

활성탄에 의한 작용기가 다른 염료의 흡착: 파라미터 및 경쟁 흡착

이종집,Lee, Jong Jib 한국공업화학회 2022 공업화학 Vol.33 No.2

In this paper, parameter characteristics such as pH effect, isotherm, kinetic and thermodynamic parameters and competitive adsorption of dyes including malachite green (MG), direct red 81 (DR 81) and thioflavin S (TS), which have different functional groups, being adsorbed onto activated carbon were investigated. Langmuir, Freundlich and Temkin isotherm models were employed to find the adsorption mechanism. Effectiveness of adsorption treatment of three dyes by activated carbon were confirmed by the Langmuir dimensionless separation factor. The mechanism was found to be a physical adsorption which can be verified through the adsorption heat calculated by Temkin equation. The adsorption kinetics followed the pseudo second order and the rate limiting step was intra-particle diffusion. The positive enthalpy and entropy changes showed an endothermic reaction and increased disorder via adsorption at the S-L interface, respectively. For each dye molecule, negative Gibbs free energy increased with the temperature, which means that the process is spontaneous. In the binary component system, it was found that the same functional groups of the dye could interfere with the mutual adsorption, and different functional groups did not significantly affect the adsorption. In the ternary component system, the adsorption for MG lowered a bit, likely to be disturbed by the other dyes meanwhile DR 81 and TS were to be positively affected by the presence of MG, thus resulting in much higher adsorption.

Isotherm, kinetic and thermodynamic studies on the adsorption of 13-dehydroxybaccatin III from <i>Taxus chinensis</i> onto Sylopute

Lim, Yeon-Su,Kim, Jin-Hyun Elsevier 2017 The Journal of chemical thermodynamics Vol.115 No.-

<P><B>Abstract</B></P> <P>Batch experimental studies were carried out on the adsorption of 13-dehydroxybaccatin III (13-DHB III) using Sylopute while varying parameters such as initial 13-DHB III concentrations, contact times and adsorption temperatures. Out of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models, adsorption data with the highest accuracy were best described by the Langmuir isotherm. It was found that the adsorption capacity decreased with an increasing temperature and the adsorption of 13-DHB III onto Sylopute was favourable. The adsorption kinetics were well described by the pseudo-second-order kinetic model, while intraparticle diffusion and boundary layer diffusion did not play a dominant role in 13-DHB III adsorption according to the intraparticle diffusion model. Thermodynamic parameters revealed the exothermic, irreversible and non-spontaneous nature of adsorption. The isosteric heat of adsorption was constant even with variations in surface loading, indicating a heterogeneous surface.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Langmuir isotherm accounted for adsorption data of 13-dehydroxybaccatin III on Sylopute. </LI> <LI> The adsorption process was physical in nature. </LI> <LI> The kinetics data agreed well with the pseudo-second-order model. </LI> <LI> The adsorption process was exothermic, irreversible and nonspontaneous. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Isotherm, kinetic and thermodynamic studies on the adsorption of paclitaxel onto Sylopute

Kim, Ye-Sol,Kim, Jin-Hyun Elsevier 2019 The Journal of chemical thermodynamics Vol.130 No.-

<P><B>Abstract</B></P> <P>Batch experimental studies were carried out on the adsorption of paclitaxel onto Sylopute, with the data then being fit to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. A comparison of the results revealed that, among the four isotherm models considered, the Freundlich isotherm model could account for the adsorption isotherm data with the highest accuracy. From the analysis of adsorption isotherms, it was found that the adsorption capacity increased with an increasing temperature and the adsorption of paclitaxel onto Sylopute was favourable. The obtained kinetics data for paclitaxel adsorption with Sylopute agreed well with the pseudo-second-order model. In addition, according to the intraparticle diffusion model, intraparticle diffusion played a dominant role in paclitaxel adsorption. Thermodynamic parameters revealed the endothermic, irreversible, and nonspontaneous nature of the adsorption.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Freundlich isotherm accounted for adsorption data of paclitaxel on Sylopute. </LI> <LI> The adsorption process was physical in nature. </LI> <LI> The kinetics data agreed well with the pseudo-second-order model. </LI> <LI> The adsorption process was endothermic, irreversible and nonspontaneous. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Adsorption of Cd, Cu and Zn from aqueous solutions onto ferronickel slag under different potentially toxic metal combination

Park, Jong-Hwan,Kim, Seong-Heon,Kang, Se-Won,Kang, Byung-Hwa,Cho, Ju-Sik,Heo, Jong-Soo,Delaune, Ronald D.,Ok, Yong Sik,Seo, Dong-Cheol IWA Publishing 2016 Water Science & Technology Vol.73 No.5

<P>Adsorption characteristics of potentially toxic metals in single-and multi-metal forms onto ferronickel slag were evaluated. Competitive sorption of metals by ferronickel slag has never been reported previously. The maximum adsorption capacities of toxic metals on ferronickel were in the order of Cd (10.2 mg g(-1)) > Cu (8.4 mg g(-1)) > Zn (4.4 mg g(-1)) in the single-metal adsorption isotherm and Cu (6.1 mg g(-1)) >> Cd (2.3 mg g(-1)) > Zn (0.3 mg g(-1)) in the multi-metal adsorption isotherm. In comparison with single-metal adsorption isotherm, the reduction rates of maximum toxic metal adsorption capacity in the multi-metal adsorption isotherm were in the following order of Zn (93%) > Cd (78%) >> Cu (27%). The Freundlich isotherm provides a slightly better fit than the Langmuir isotherm equation using ferronickel slag for potentially toxic metal adsorption. Multi-metal adsorption behaviors differed from single-metal adsorption due to competition, based on data obtained from Freundlich and Langmuir adsorption models and three-dimensional simulation. Especially, Cd and Zn were easily exchanged and substituted by Cu during multi-metal adsorption. Further competitive adsorption studies are necessary in order to accurately estimate adsorption capacity of ferronickel slag for potentially toxic metals in natural environments.</P>

흡착입자간 상호작용에 따른 흡착등온선 패턴

김철호,Kim, Cheol Ho 한국재료학회 2013 한국재료학회지 Vol.23 No.8

We study and describe-from the point of view of the interactions of the adsorbed particles-three types of the adsorption isotherms, namely, Langmuir type adsorption isotherms, phase transition type adsorption isotherms, and adsorption limited type adsorption isotherms, which are observed by experiments. By introducing and using a one dimensional statistical occupancy model, we derived analytical adsorption isotherms for the no force, the attractive force, and the repulsive force exerted on the other adsorbed particles. Our derived adsorption isotherms qualitatively pretty well agree with the experimental results of the adsorption isotherms. To specify each adsorption type, Langmuir type adsorption is a phenomenon that occurs with no forces between the adsorbed particles, phase transition type adsorption is a phenomenon that occurs with the strong attractive forces between the adsorbed particles, and adsorption limited type adsorption is a phenomenon that occurs with the repulsive forces between the adsorbed particles. The theoretical analysis-only using fundamental thermodynamics and occupancy statistics though-qualitatively quite well explains the experimental results.

Adsorption of Methylene Blue Using Green Pea Peels (Pisum sativum): A Cost-effective Option for Dye-based Wastewater Treatment

Ramesh Dod,Goutam Banerjee,S. Saini 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.4

Methylene blue (MB), a common toxic dye, is largely discharged from dyeing processes for acrylic,nylon, silk, and woolen fabrics in textile industries. While application of conventional removal processes like chemical precipitation, ion exchange, commercial activated carbon adsorption, etc often become cost-prohibitive, the adsorption of MB by abundantly available green pea peel (GPP: Pisum sativum) derived and acid-treated carbon (GPP-AC) has proved to be a cost-attractive option in the present study. The physicochemical and morphological characteristics of GPP-AC were examined with the help of XRD, BET surface area, SEM, and Fourier transform infrared spectrophotometry ((FT-IR) analysis. The influences of such adsorption parameters as initial dye concentration, pH, contact time,adsorbent dosage, agitation speed, particle size, and temperature were evaluated and optimized. The equilibrium contact time for maximum adsorption of MB on to GPPAC was found to be 7 h. The equilibrium data of the adsorption process were modeled by using the Langmuir,Freundlich, Temkin, and Dubinin-Raduskevich (D-R)isotherms. However, the adsorption equilibrium data were best described by the Langmuir Isotherm model, with a maximum adsorption capacity of 163.94 mg MB/g GPPAC at 30℃. Methylene blue (MB), a common toxic dye, is largely discharged from dyeing processes for acrylic,nylon, silk, and woolen fabrics in textile industries. While application of conventional removal processes like chemical precipitation, ion exchange, commercial activated carbon adsorption, etc often become cost-prohibitive, the adsorption of MB by abundantly available green pea peel (GPP: Pisum sativum) derived and acid-treated carbon (GPP-AC) has proved to be a cost-attractive option in the present study. The physicochemical and morphological characteristics of GPP-AC were examined with the help of XRD, BET surface area, SEM, and Fourier transform infrared spectrophotometry ((FT-IR) analysis. The influences of such adsorption parameters as initial dye concentration, pH, contact time,adsorbent dosage, agitation speed, particle size, and temperature were evaluated and optimized. The equilibrium contact time for maximum adsorption of MB on to GPPAC was found to be 7 h. The equilibrium data of the adsorption process were modeled by using the Langmuir,Freundlich, Temkin, and Dubinin-Raduskevich (D-R)isotherms. However, the adsorption equilibrium data were best described by the Langmuir Isotherm model, with a maximum adsorption capacity of 163.94 mg MB/g GPPAC at 30℃.

입상 활성탄에 대한 New Fuchsin 염료흡착의 등온선, 동력학 및 열역학 파라미터에 관한 연구

이종집 ( Jong Jib Lee ) 한국공업화학회 2014 공업화학 Vol.25 No.6

Batch adsorption studies including equilibrium, kinetics and thermodynamic parameters for the adsorption of new fuchsin dye using granular activated carbon were investigated with varying the operating variables such as initial concentration, contact time and temperature. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms. Adsorption equilibrium was mostly well described by Langmuir Isotherm. From the estimated separation factor of Langmuir (RL = 0.023), and Freundlich (1/n = 0.198), this process could be employed as an effective treatment for the adsorption of new fuchsin dye. Also based on the adsorption energy (E = 0.002 kJ/mol) from Dubinin-Radushkevich isotherm and the adsorption heat constant (B = 1.920 J/mol) from Temkin isotherm, this adsorption is physical adsorption. From kinetic experiments, the adsorption reaction processes were confirmed following the pseudo second order model with good correlation. The intraparticle diffusion was a rate controlling step. Thermodynamic parameters including changes of free energy, enthalpy, and entropy were also calculated to predict the nature of adsorption. The change of enthalpy (92.49 kJ/mol) and activation energy (11.79 kJ/mol) indicated the endothermic nature of adsorption processes. The change of entropy (313.7 J/mol K) showed an increasing disorder in the adsorption process. The change of free energy found that the spontaneity of process increased with increasing the adsorption temperature.

등온 및 동적 흡착 실험을 통한 제강 슬래그의 비소 흡착 특성

오참뜻,이성수,Toshifumi, Igarashi,권호진,이원택,박준범 한국지반공학회 2010 한국지반공학회논문집 Vol.26 No.9

Sorption characteristics of arsenic on furnace slag were investigated to remove arsenic from groundwater using furnace slag, which is industrial waste generated from steel company. Adsorption isotherm experiments and kinetic sorption experiments were performed and the chemical characteristics of supernatants from these experiments were analyzed. Results showed that all supernatants were alkaline (above pH 9) and the highest ion concentration in the solution was found with calcium (30~50 mg/L). Results of adsorption isotherms were more adequately described by the Freundlich model than Langmuir model. From adsorption isotherms experiments, it was noted that the adsorption amount of As(V) was 87% higher than that of As(III). Results of kinetic sorption experiments were more properly fitted by pseudo second order (PSO) model than pseudo first order model. Equilibrium adsorption amount (qe) and relaxation time (tr) calculated from PSO model increased with initial concentration of arsenic. Equilibrium adsorption amount of As(V) was higher than that of As(III) and relaxation time of As(V) was shorter than that of As(III). Adsorption isotherm results could be predicted by kinetic adsorption results, since equilibrium adsorption amount calculated through PSO model generally agreed with equilibrium adsorption amount measured from adsorption isotherm.

활성탄에 의한 Brilliant Green과 Quinoline Yellow 염료의 흡착에 대한 등온선, 동력학, 열역학 및 경쟁흡착

이종집 ( Jong Jib Lee ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.4

활성탄에 의한 Brilliant Green(BG), Quinoline Yellow(QY) 염료의 흡착에 대한 등온선, 동력학, 열역학적 특성치와 경쟁흡착을 흡착제의 양, pH, 초기농도, 접촉시간 및 온도를 변수로 하여 수행하였다. BG와 QY는 가지고 있는 atomic nitrogen 이온(N⁺)의 영향으로 pH 11에서 92.4%의 최고 흡착율을 나타내었고, QY는 sulfite 이온(SO₃^-)의 영향으로 pH3에서 90.9%의 최고 흡착률을 나타냈다. 등온흡착 데이터로부터, BG의 경우는 Freundlich 등온식에 잘 맞아서 다분자층 흡착이었고, QY는 Langmuir 등온식이 가장 높은 일치도를 나타내어 주로 단분자층흡착이었다. Freundlich 식과 Langmuir 식의 분리계수는 활성탄에 의해 이들 염료를 효과적으로 처리할 수 있는 공정임을 나타냈다. Temkin 등온식에 의해 평가된 흡착 에너지는 활성탄에 의한 BG와 QY의 흡착이 물리 흡착임을 확인시켰다. 동력학적 실험결과는 유사 이차 반응속도식이 유사일차 반응속도식보다 일치도가 높았고 평형흡착량에 대한 오차도 더 작았다. 입자내 확산식을 이용하여 도시한 그래프는 2단계의 직선으로 나타났는데 기울기가 낮은 입자내 확산이 율속단계임을 확인하였다. 흡착공정의 활성화 에너지와 엔탈피 변화는 흡착과정이 비교적 수월하게 일어나며 흡열반응임을 나타냈다. 엔트로피 변화는 활성탄에 대한 BG와 QY 염료의 흡착이 진행됨에 따라 흡착시스템의 무질서도가 증가함을 나타냈고, Gibbs자유 에너지 변화로 부터 흡착반응이 온도가 높아질수록 자발성이 더 커진다는 것을 알았다. 혼합용액의 경쟁흡착 결과는 상대적으로 흡착률이 높은 QY가 BG에 의해 큰 방해를 받아 흡착률이 크게 감소하는 것으로 나타났다. Isotherms, kinetics and thermodynamic properties for adsorption of Brilliant Green(BG), Quinoline Yellow(QY) dyes by activated carbon were carried out using variables such as dose of adsorbent, pH, initial concentration, contact time, temperature and competitive. BG showed the highest adsorption rate of 92.4% at pH 11, and QY was adsorbed at 90.9% at pH 3. BG was in good agreement with the Freundlich isothermal model, and QY was well matched with Langmuir model. The separation coefficients of isotherm model indicated that these dyes could be effectively treated by activated carbon. Estimated adsorption energy by Temkin isotherm model indicated that the adsorption of BG and QY by activated carbon is a physical adsorption. The kinetic experimental results showed that the pseudo second order model had a better fit than the pseudo first order model with a smaller in the equilibrium adsorption amount. It was confirmed that surface diffusion was a rate controlling step by the intraparticle diffusion model. The activation energy and enthalpy change of the adsorption process indicated that the adsorption process was a relatively easy endothermic reaction. The entropy change indicated that the disorder of the adsorption system increased as the adsorption of BG and QY dyes to activated carbon proceeded. Gibbs free energy was found that the adsorption reaction became more spontaneous with increasing temperature. As a result of competitive adsorption of the mixed solution, it was found that QY was disturbed by BG and the adsorption reduced.