Adsorption kinetics and isotherm of anionic dyes onto organo-bentonite from single and multisolute systems

2009 ◽  
Vol 172 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Dazhong Shen ◽  
Jianxin Fan ◽  
Weizhi Zhou ◽  
Baoyu Gao ◽  
Qinyan Yue ◽  
...  
2021 ◽  
Author(s):  
Brahim Guezzen ◽  
Mehdi Adjdir ◽  
Abdelkader Elaziouti ◽  
Mohamed Amine Didi

Abstract The present work focused on the preparation of hybrid-bentonite adsorbents by treating sodium bentonite (Na-B) with different amounts of hexadecyltrimethylammonium bromide (HDTMA+ Br-), corresponding to 50, 100 and 200% the value of the cation exchange capacity (CEC). The samples prepared, namely 50HDTMA-B, 100HDTMA and 200HDTMA-B, were characterized by different techniques including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA ). The removal efficiency of two anionic dyes, namely. Congo Red (CR) and Indigo Carmine (IC), from aqueous solutions, was studied as a function of the amount of HDTMA, contact time, hybrid adsorbent and initial dye concentration. In addition, a kinetic study was conducted to fit the experimental data in order to compare the adsorption rate constants and the equilibrium sorption capacities of anionic dyes on the prepared materials. The results obtained indicated that the adsorption kinetics of clay samples could be best described by the pseudo-second-order model, and the adsorption capacity of the hybrid-Bentonite is affected by the amount of modifier used. Based on Weber-Morris intra-particle diffusion equation, it was found that the CR and IC dyes diffused faster as the cationic surfactant loading increased from 0 to 100% of the CEC value. The Langmuir isotherm exhibited the best fit, with an adsorption capacity equal to 292 and 289 mg g-1, for CR and IC dyes, respectively.


Separations ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 32 ◽  
Author(s):  
Changgil Son ◽  
Wonyeol An ◽  
Geonhee Lee ◽  
Inho Jeong ◽  
Yong-Gu Lee ◽  
...  

This study has evaluated the removal efficiencies of phosphate ions (PO43−) using pristine (TB) and chemical-activated tangerine peel biochars. The adsorption kinetics and isotherm presented that the enhanced physicochemical properties of TB surface through the chemical activation with CaCl2 (CTB) and FeCl3 (FTB) were helpful in the adsorption capacities of PO43− (equilibrium adsorption capacity: FTB (1.655 mg g−1) > CTB (0.354 mg g−1) > TB (0.104 mg g−1)). The adsorption kinetics results revealed that PO43− removal by TB, CTB, and FTB was well fitted with the pseudo-second-order model (R2 = 0.999) than the pseudo-first-order model (R2 ≥ 0.929). The adsorption isotherm models showed that the Freundlich equation was suitable for PO43− removal by TB (R2 = 0.975) and CTB (R2 = 0.955). In contrast, the Langmuir equation was proper for PO43− removal by FTB (R2 = 0.987). The PO43− removal efficiency of CTB and FTB decreased with the ionic strength increased due to the compression of the electrical double layer on the CTB and FTB surfaces. Besides, the PO43− adsorptions by TB, CTB, and FTB were spontaneous endothermic reactions. These findings demonstrated FTB was the most promising method for removing PO43− in waters.


Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3128 ◽  
Author(s):  
Jie Li ◽  
Chen Si ◽  
Haiyan Zhao ◽  
Qingxi Meng ◽  
Bowen Chang ◽  
...  

The magnetic adsorbent, Fe3O4@[Ni(HL)2]2H2[P2Mo5O23]·2H2O (Fe3O4@1), is synthesized by employing the nanoparticles Fe3O4 and polyoxometalate hybrid 1. Zero-field-cooled (ZFC) and field-cooled (FC) curves show that the blocking temperature of Fe3O4@1 was at 120 K. Studies of Fe3O4@1 removing cationic and anionic dyes from water have been explored. The characterization of Fe3O4@1, effects of critical factors such as dosage, the concentration of methylene blue (MB), pH, adsorption kinetics, isotherm, the removal selectivity of substrate and the reusability of Fe3O4@1 were assessed. The magnetic adsorbent displayed an outstanding removal activity for the cationic dye at a broad range of pH. The adsorption kinetics and isotherm models revealed that the adsorption process of Fe3O4@1 was mainly governed via chemisorption. The maximum capacity of Fe3O4@1 adsorbing substance was 41.91 mg g−1. Furthermore, Fe3O4@1 showed its high stability by remaining for seven runs of the adsorption-desorption process with an effective MB removal rate, and could also be developed as a valuable adsorbent for dyes elimination from aqueous system.


2017 ◽  
Vol 75 (10) ◽  
pp. 2316-2321 ◽  
Author(s):  
Hao Peng ◽  
Zuohua Liu ◽  
Changyuan Tao

Melamine, possessing three free amino groups and three aromatic nitrogen atoms in its molecule, has great potential as an adsorbent for metal ions. We investigated three impact factors of the adsorption process: the initial pH of the vanadium solution, contact time and reaction temperature. The adsorption kinetics could be accurately described by the pseudo-second-order kinetic model. Langmuir and Freundlich models fitted well with the experimental equilibrium data, and the maximal adsorption capacity was found to be 1,428.57 mg vanadium/g melamine, and the Freundlich model showed the adsorption is privilege type.


NANO ◽  
2015 ◽  
Vol 10 (05) ◽  
pp. 1550065 ◽  
Author(s):  
Hui Huang ◽  
Jingang Yu ◽  
Wei Liu ◽  
Xinyu Jiang

In this study, amino-functionalized multi-walled carbon nanotubes ( MWCNTs - NH 2) were successfully synthesized via an improved method and used for removal of organic dyes in aqueous solution. The synthesized MWCNTs - NH 2 were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscope (SEM), etc. The adsorption capacity and selectivity of MWCNTs - NH 2 for organic dyes was evaluated using rhodamine B ( RhB ), malachite green (MG), methyl orange (MO) and congo red (CR) as models. The selective adsorption toward anionic dyes was found for the MWCNTs - NH 2, and MO was selected as a typical anionic dye to deeply investigate the adsorption kinetics, equilibrium isotherms and thermodynamic parameters of the adsorption process. The adsorption kinetics and equilibrium isotherms data fitted well with the pseudo-second-order kinetic equation and Langmuir isotherm model. The thermodynamics study revealed that the adsorption of MO onto MWCNTs - NH 2 was spontaneous, exothermic and physisorptive in nature. The results indicated that MWCNTs - NH 2 are promising nanomaterials for removal of anionic dyes from industrial wastewater.


Sign in / Sign up

Export Citation Format

Share Document