Adsorption properties of aqueous methylene blue on mesocellular foam silica: Equilibrium, kinetic, isotherm, and thermodynamic characterization

2019 ◽  
Vol 47 (5) ◽  
pp. 467-484
Author(s):  
Qing-Zhou Zhai ◽  
Yuan Dong
2016 ◽  
Vol 75 (2) ◽  
pp. 350-357
Author(s):  
Graham Dawson ◽  
Wei Chen ◽  
Luhua Lu ◽  
Kai Dai

The adsorption properties of two nanomorphologies of trititanate, nanotubes (TiNT) and plates (TiNP), prepared by the hydrothermal reaction of concentrated NaOH with different phases of TiO2, were examined. It was found that the capacity for both morphologies towards methylene blue (MB), an ideal pollutant, was extremely high, with the TiNP having a capacity of 130 mg/g, higher than the TiNT, whose capacity was 120 mg/g at 10 mg/L MB concentration. At capacity, the well-dispersed powders deposit on the floor of the reaction vessel. The two morphologies had very different structural and adsorption properties. TiNT with high surface area and pore volume exhibited exothermic monolayer adsorption of MB. TiNP with low surface area and pore volume yielded a higher adsorption capacity through endothermic multilayer adsorption governed by pore diffusion. TiNP exhibited a higher negative surface charge of −23 mV, compared to −12 mV for TiNT. The adsorption process appears to be an electrostatic interaction, with the cationic dye attracted more strongly to the nanoplates, resulting in a higher adsorption capacity and different adsorption modes. We believe this simple, low cost production of high capacity nanostructured adsorbent material has potential uses in wastewater treatment.


Author(s):  
Nguyen The Manh ◽  
Duong Hong Quan ◽  
Vu Thi Ngoc Minh ◽  
Vuong Pham Hung

Micro/nano urchin-like VO2 particles were synthesized successfully by hydrothermal method. Vanadium pentoxide (V2O5), oxalic acid (C2H2O4) and sodium dodecyl sulfate (SDS) surfactant were used as reagents for the synthesis of VO2. In this article, we have reported the synthesis procedure of VO2 nanorods and micro/nano urchin-like VO2 structure and evaluating the methylene blue (MB) adsorption properties. Morphology and particle size of VO2 were observed by FE-SEM. The phase formation of VO2 was studied by XRD. Raman spectroscopy was also used for characterization of VO2. Micro/nano urchin-like VO2 structure was showed good MB adsorption properties that have potential applications in dye-contaminated water treatments.


2012 ◽  
Vol 454 ◽  
pp. 305-309 ◽  
Author(s):  
Ping Chen ◽  
Xian Jun Lu ◽  
Jun Qiu

Using Octadecyltrimethylammonium cations with long carbon chain to modify calcium montmorillonite samples, the adsorption properties of different dyes on montmorillonite before and after modification were investigated. Results showed that the basic dye of methylene blue was easily adsorbed by natual calcium montmorillonite, while the adsorption ability for acid blue and neutral blue was greatly improved when it was organically modified, and the adsorption amount increased with the increasing of modifier dosage. The adsorption ratio was influnced by reaction time, the temperature and the solution’s pH value. It suggested that the adsorption balance time was about 60min; higher temperature was good for acid blue adsorbed on organic montmorillonite, but neutral blue’s adsorption amount was greater at the room temperature; the optimum pH was 9 for methylene blue adsorption, while low pH was better for acid blue and neutral blue adsorption.


2015 ◽  
Vol 1120-1121 ◽  
pp. 343-346
Author(s):  
Cai Ning Zhang ◽  
Xu Man Wang

By means of solution polymerization, a series of cross-linked starch-g-polyacrylamide/ montmorillonite (St-g-PAM/MMT) nanocomposites were prepared and used to adsorb methylene blue (MB). The effects of different preparation conditions on the adsorption capacity of the nanocomposites were investigated. The experimental results demonstrated that the prepared St-g-PAM/MMT nanocomposites were effective adsorbents for removal of MB from aqueous solution. Furthermore, adsorption capacity increased with the MMT contents up to 14% and decreased as the MMT contents further increased. Adsorption capacity increased with the increasing of the ratio of starch to acrylamide, whereas adsorption capacity decreased with the increasing of crosslinking agent contents.


2020 ◽  
Vol 4 (3) ◽  
pp. 95
Author(s):  
Dexu Kong ◽  
Lee D. Wilson

To address the need to develop improved hybrid biopolymer composites, we report on the preparation of composites that contain chitosan and pectin biopolymers with tunable adsorption properties. Binary biopolymer composites were prepared at variable pectin–chitosan composition in a solvent directed synthesis, dimethyl sulfoxide (DMSO) versus water. The materials were characterized using complementary methods (infrared spectroscopy, thermal gravimetric analysis, pH at the point-of-zero charge, and dye-based adsorption isotherms). Pectin and chitosan composites prepared in DMSO yielded a covalent biopolymer framework (CBF), whereas a polyelectrolyte complex (PEC) was formed in water. The materials characterization provided support that cross-linking occurs between amine groups of chitosan and the –COOH groups of pectin. CBF-based composites had a greater uptake of methylene blue (MB) dye over the PEC-based composites. Composites prepared in DMSO were inferred to have secondary adsorption sites for enhanced MB uptake, as evidenced by a monolayer uptake capacity that exceeded the pectin–chitosan PECs by 1.5-fold. This work provides insight on the role of solvent-dependent cross-linking of pectin and chitosan biopolymers. Sonication-assisted reactions in DMSO favor CBFs, while cross-linking in water yields PECs. Herein, composites with tunable structures and variable physicochemical properties are demonstrated by their unique dye adsorption properties in aqueous media.


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