Removal of Pb(ii) by nano-titanium oxide investigated by batch, XPS and model techniques

RSC Advances ◽  
2015 ◽  
Vol 5 (107) ◽  
pp. 88520-88528 ◽  
Author(s):  
Zhongxiu Jin ◽  
Huiyi Gao ◽  
Linhua Hu
Keyword(s):  
Ion Exchange ◽  
Titanium Oxide ◽  
Surface Complexation ◽  
Sphere Surface ◽  
Adsorption Mechanisms ◽  
Inner Sphere

The ion exchange and inner-sphere surface complexation were inferred as the adsorption mechanisms of Pb(ii) on nano-TiO2.

Retracted Article: Enhanced adsorption of Eu(iii) on mesoporous Al2O3/expanded graphite composites investigated by macroscopic and microscopic techniques

2012 ◽  
Vol 41 (43) ◽  
pp. 13388-13394 ◽  
Author(s):  
Yubing Sun ◽  
Changlun Chen ◽  
Xiaoli Tan ◽  
Dadong Shao ◽  
Jiaxing Li ◽  
...  
Keyword(s):  
Adsorption Mechanism ◽  
Surface Complexation ◽  
Expanded Graphite ◽  
Outer Sphere ◽  
Sphere Surface ◽  
Inner Sphere ◽  
Retracted Article ◽  
Enhanced Adsorption ◽  
Graphite Composites ◽  
Microscopic Techniques

The adsorption mechanism between Eu(iii) and mesoporous Al2O3/EG composites shifts from outer-sphere to inner-sphere surface complexation with increasing pH.

Surface complexation modelling of uranyl adsorption onto kaolinite based clay minerals using FITEQL 3.2

2006 ◽  
Vol 94 (12) ◽  
Author(s):  
Deniz Arda ◽  
Julide Hizal ◽  
Resat Apak
Keyword(s):  
Clay Minerals ◽  
Surface Complexation ◽  
Outer Sphere ◽  
Uranyl Ion ◽  
Sphere Surface ◽  
Hexavalent Uranium ◽  
Inner Sphere

The aim of this study is to explain how the kaolinite-based clay minerals adsorb hexavalent uranium (uranyl ion), and to model uranyl adsorption based on inner-sphere surface complexation with the kaolinite edge hydroxyl sites and outer-sphere complexation with the permanent charge sites. The adsorption of UO

scholarly journals Sorption and mechanism studies of Cu2+, Sr2+ and Pb2+ ions on mesoporous aluminosilicates/zeolite composite sorbents

2020 ◽  
Vol 82 (5) ◽  
pp. 984-997
Author(s):  
Tatyana Kouznetsova ◽  
Andrei Ivanets ◽  
Vladimir Prozorovich ◽  
Ahmad Hosseini-Bandegharaei ◽  
Hai Nguyen Tran ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Metal Ions ◽  
Adsorption Capacity ◽  
Surface Complexation ◽  
Bet Surface Area ◽  
Precipitation Method ◽  
Maximum Adsorption Capacity ◽  
Zeolite Nay ◽  
Inner Surface ◽  
Zeolite Composite

Abstract The research aimed to develop a novel mesoporous aluminosilicate/zeolite composite by the template co-precipitation method. The effect of aluminosilicate (AlSi) and zeolite (NaY) on the basic properties and adsorption capacity of the resultant composite was conducted at different mass ratios of AlSi/NaY (i.e., 5/90, 10/80, 15/85, 20/80, and 50/50). The adsorption characteristics of such composite and its feedstock materials (i.e., aluminosilicates and zeolite) towards radioactive Sr2+ ions and toxic metals (Cu2+ and Pb2+ ions) in aqueous solutions were investigated. Results indicated that BET surface area (SBET), total pore volume (VTotal), and mesopore volume (VMeso) of prepared materials followed the decreasing order: aluminosilicate (890 m2/g, 0.680 cm3/g, and 0.644 cm3/g) > zeolite (623 m2/g, 0.352 cm3/g, and 0.111 cm3/g) > AlSi/NaY (20/80) composite (370 m2/g, 0.254 cm3/g, and 0.154 cm3/g, respectively). The Langmuir maximum adsorption capacity (Qm) of metal ions (Sr2+, Cu2+, and Pb2+) in single-component solution was 260 mg/g, 220 mg/g, and 161 mg/g (for zeolite), 153 mg/g, 37.9 mg/g, and 66.5 mg/g (for aluminosilicate), and 186 mg/g, 140 mg/g, and 77.8 mg/g for (AlSi/NaY (20/80) composite), respectively. Ion exchange was regarded as a domain adsorption mechanism of metal ions in solution by zeolite; meanwhile, inner-surface complexation was domain one for aluminosilicate. Ion exchange and inner-surface complexation might be mainly responsible for adsorbing metal ions onto the AlSi/NaY composite. Pore-filling mechanism was a less important contributor during the adsorption process. The results of competitive adsorption under binary-components (Cu2+ and Sr2+) and ternary-components (Cu2+, Pb2+, and Sr2) demonstrated that the removal efficacy of target metals by the aluminosilicate, zeolite, and their composite remarkably decreased. The synthesized AlSi/NaY composite might serve as a promising adsorbent for real water treatment.

Thermodynamic Modeling and Sensitivity Analysis of Kd Values for Radionuclide Migration in Sedimentary Host Rocks

2003 ◽  
Vol 807 ◽  
Author(s):  
Caterina Talerico ◽  
Michael Ochs ◽  
Shinzo Ueta ◽  
Noriyuki Sasaki
Keyword(s):  
Sensitivity Analysis ◽  
Ion Exchange ◽  
Mineral Assemblage ◽  
Surface Complexation ◽  
Critical Component ◽  
Radionuclide Migration ◽  
Sorption Model ◽  
Geochemical Parameters ◽  
Kd Values ◽  
Host Rocks

ABSTRACTThe effects of key geochemical parameters on Kd values for radionuclides in the host rock (pumice, sandstone) of a LLW repository were elucidated through a sensitivity analysis, using a thermodynamic speciation/sorption model for the elements Sr and Ni. The complex mineral assemblage of the rock was approximated by a component-additivity approach. Using published ion exchange and surface complexation parameters, Kd for both Sr and Ni could be well explained by the same model mineralogy and surface chemistry. Model results suggest that pCO2 can have a significant effect on Kd, and that a correct approximation of groundwater chemistry is a critical component of sorption modeling.

scholarly journals Adsorption Behavior and Relative Distribution of Cd2+ Adsorption Mechanisms by the Magnetic and Nonmagnetic Biochars Derived from Chicken Manure

2020 ◽  
Vol 17 (5) ◽  
pp. 1602 ◽  
Author(s):  
Fei Huang ◽  
Lu Zhang ◽  
Ren-Ren Wu ◽  
Si-Ming Zhang ◽  
Rong-Bo Xiao
Keyword(s):  
Ion Exchange ◽  
Magnetic Separation ◽  
Adsorption Process ◽  
Freundlich Isotherm ◽  
Chicken Manure ◽  
Relative Distribution ◽  
Order Kinetic ◽  
Practical Applications ◽  
Adsorption Mechanisms ◽  
Before And After

The present study investigated the adsorption of Cd2+ by nonmagnetic and magnetic biochars (CMB and M-CMB) derived from chicken manure, respectively. The adsorption characteristics were investigated as a function of initial pH, contact time, initial Cd2+ concentration and magnetic separation. Adsorption process of both biochars were better described by Pseudo-second-order kinetic equation and Freundlich isotherm model, which were spontaneous and endothermic in nature. It was found that maximum capacities were 60.69 and 41.07 mg/g obtained at the initial Cd2+ concentration of 180 mg/L for CMB and M-CMB, and the turbidity of adsorption-treated solution was reduced from 244.3 to 11.3 NTU after magnetic separation of 0.5 min. These indicated that M-CMB had lower adsorption capacity of Cd2+ than CMB, though it was successfully separated from the treated solutions. Furthermore, both biochars before and after adsorption were analyzed by SEM-EDS, XRD and FTIR. Adsorption mechanisms mainly included precipitation, ion-exchange, complexation and Cπ-coordination, in which precipitation and ion-exchange dominated the adsorption process by CMB, while in M-CMB, precipitation was always predominant mechanism, followed by ion-exchange. The two other mechanisms of complexation and Cπ-coordination were trivial in both biochars, jointly contributing 7.21% for CMB and 5.05% for M-CMB to total adsorption. The findings deepen our understanding of the mechanisms governing the adsorption process, which are also important for future practical applications in the removal of heavy metals from wastewater by the biochars.

scholarly journals The Tournemire industrial analogue: reactive-transport modelling of a cement–clay interface

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 167-184 ◽  
Author(s):  
C. Watson ◽  
D. Savage ◽  
J. Wilson ◽  
S. Benbow ◽  
C. Walker ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Reactive Transport ◽  
Transport Model ◽  
Surface Complexation ◽  
General Purpose ◽  
Transport Modelling ◽  
Mineralogical Characterization ◽  
Modelling Techniques ◽  
Materials Used ◽  
Set Up

AbstractIn the post-closure period of a geological disposal facility for radioactive waste, leaching of cement components is likely to give rise to an alkaline plume which will be in chemical disequilibrium with the host rock (which is clay in some concepts) and other engineered barrier system materials used in the facility, such as bentonite. An industrial analogue for cement-clay interaction can be found at Tournemire, southern France, where boreholes filled with concrete and cement remained in contact with the natural mudstone for 15–20 years. The boreholes have been overcored, extracted and mineralogical characterization has been performed. In this study, a reactive-transport model of the Tournemire system has been set up using the general-purpose modelling tool QPAC. Previous modelling work has been built upon by using the most up-to-date data and modelling techniques, and by adding both ion exchange and surface complexation processes in the mudstone. The main features observed at Tournemire were replicated by the model, including porosity variations and precipitation of carbonates, K-feldspar, ettringite and calcite. It was found that ion exchange needed to be included in order for C-S-H minerals to precipitate in the mudstone, providing a better match with the mineralogical characterization. The additional inclusion of surface complexation, however, led to limited calcite growth at the concrete-mudstone interface unlike samples taken from the Tournemire site that have a visible line of crusty carbonates along the interface.

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