scholarly journals Waste Brick Dust as Potential Sorbent of Lead and Cesium from Contaminated Water

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1647 ◽  
Author(s):  
Barbora Doušová ◽  
David Koloušek ◽  
Miloslav Lhotka ◽  
Martin Keppert ◽  
Martina Urbanová ◽  
...  
Keyword(s):  
Amorphous Material ◽  
Surface Complexation ◽  
Total Pore Volume ◽  
Zero Point ◽  
Outer Sphere ◽  
Aqueous System ◽  
Sphere Surface ◽  
Adsorption Condition ◽  
Weak Adsorption ◽  
Brick Dust

Adsorption properties of waste brick dust (WBD) were studied by the removing of PbII and CsI from an aqueous system. For adsorption experiments, 0.1 M and 0.5 M aqueous solutions of Cs+ and Pb2+ and two WBD (Libochovice—LB, and Tyn nad Vltavou—TN) in the fraction below 125 µm were used. The structural and surface properties of WBD were characterized by X-ray diffraction (XRD) in combination with solid-state nuclear magnetic resonance (NMR), supplemented by scanning electron microscopy (SEM), specific surface area (SBET), total pore volume and zero point of charge (pHZPC). LB was a more amorphous material showing a better adsorption condition than that of TN. The adsorption process indicated better results for Pb2+, due to the inner-sphere surface complexation in all Pb2+ systems, supported by the formation of insoluble Pb(OH)2 precipitation on the sorbent surface. A weak adsorption of Cs+ on WBD corresponded to the non-Langmuir adsorption run followed by the outer-sphere surface complexation. The leachability of Pb2+ from saturated WBDs varied from 0.001% to 0.3%, while in the case of Cs+, 4% to 12% of the initial amount was leached. Both LB and TN met the standards for PbII adsorption, yet completely failed for any CsI removal from water systems.

Retracted Article: Enhanced adsorption of Eu(iii) on mesoporous Al2O3/expanded graphite composites investigated by macroscopic and microscopic techniques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Retracted Article ◽  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

The Role of Outer-Sphere Surface Acidity in Alkene Epoxidation Catalyzed by Calixarene−Ti(IV) Complexes

2007 ◽  
Vol 129 (50) ◽  
pp. 15585-15595 ◽  
Author(s):  
Justin M. Notestein ◽  
Leandro R. Andrini ◽  
Felix G. Requejo ◽  
Alexander Katz ◽  
Enrique Iglesia
Keyword(s):  
Surface Acidity ◽  
Outer Sphere ◽  
Sphere Surface

scholarly journals THERMODINAMIC PARAMETERS ON THE SORPTION OF PHOSPHATE IONS BY MONTMORILLONITE

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Ikhsan Jaslin ◽  
Wijayanti Endang ◽  
Sunarto Sunarto
Keyword(s):  
Active Sites ◽  
Surface Complexation ◽  
Outer Sphere ◽  
Hydroxyl Groups ◽  
Process Data ◽  
Surface Complexes ◽  
Surface Complexation Model ◽  
Surface Hydroxyl ◽  
Phosphate Ions ◽  
Sorbate Concentration

The sorption of phosphate by montmorillonite at 10, 30, and 50 oC were investigated aiming to mainly determine thermodynamic parameters for the formation of surface complexes in the adsorption of phosphate ions by montmorillonite. Data were collected by adsorption edge experiments investigating the effect of pH, adsorption isotherms enabling the effect of sorbate concentration, and acid-base titration calculating protons released or taken up by adsorption process. Data analysis was carried out using surface complexation model to fit the data collected in this study using the parameters obtained from previous study, as well as to calculate the values of ΔH and ΔS. Previous study reported that phosphate ions formed two outer-sphere surface complexes with active sites of montmorillonite through hydrogen bonding. In the first complex,  [(XH)0– H2L─]─, the phosphate was held to permanent-charge X─ sites on the tetrahedral siloxane faces, and the second complex, [[(SO─)(SOH)]– – [H2L]─] 2─ was formed through the interaction between the phosphate and variable charge surface hydroxyl groups at the edges of montmorillonite crystals and on the octahedral alumina faces. The values of ΔH for the first and second reactions are 39.756 and 3.765x10-7 kJ mol‒1 respectively. Since both reactions have positive enthalpy values, it can be concluded that the reactions are endothermic. Large energy for the first reaction is needed by X─  sites (permanent negatively charge sites of montmorillonite) to be partially desolvated, on which K+ or other surface cations are replaced by H+ ions in the surface protonated process, and are then ready to interact phosphate ions in the solution. Small values of ΔH for the second reactions indicates that hydrogen bonds formed by phosphate and SOH sites in the second reaction are easily broken out, and the phosphate can easily desorbed from the surface. The values of ΔS for the first and second reactions are 122.523 and 2.393 x10-2  J K‒1 mol‒1, which are greater than -10 kJ mol‒1 and indicates that the surface reactions occurs through dissociative mechanisms.Keywords:   montmorillonite, adsorption edge, extended constant capacitance, surface complexation model, enthalpy, reaction mechanisms

Adsorption characteristics of Pb(II) from aqueous solutions onto a natural biosorbent, fallen arborvitae leaves

2016 ◽  
Vol 73 (10) ◽  
pp. 2422-2429 ◽  
Author(s):  
Jie Shi ◽  
Zhiwei Zhao ◽  
Zhijie Liang ◽  
Tianyi Sun
Keyword(s):  
Aqueous Solutions ◽  
Photoelectron Spectroscopy ◽  
Pore Diameter ◽  
Surface Complexation ◽  
Zero Point ◽  
X Ray ◽  
High Potentials ◽  
Initial Ph ◽  
Natural Organic Matters ◽  
Adsorbent Dose

In this study, the potential of the oriental arborvitae leaves for the adsorption of Pb(II) from aqueous solutions was evaluated. Brunauer–Emmett–Teller analysis showed that the surface area of arborvitae leaves was 29.52 m2/g with pore diameter ranging from 2 to 50 nm. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy showed C—;C or C—;H, C—;O, and O—;C=O were the main groups on the arborvitae leaves, which were the main sites for surface complexation. Finally, effects of adsorbent dose, initial pH, contact time, and coexisting natural organic matters (humic acid (HA)) on the adsorption of Pb(II) were investigated. The results indicated that the pHZPC (adsorbents with zero point charge at this pH) was 5.3 and the adsorption reached equilibrium in 120 min. Isotherm simulations revealed that the natural arborvitae leaves exhibit effective adsorption for Pb(II) in aqueous solution, giving adsorptive affinity and capacity in an order of ‘no HA’ > 5 mg/L HA > 10 mg/L HA, and according to the Langmuir models, the maximum adsorptions of Pb(II) were 43.67 mg/g, 38.61 mg/g and 35.97 mg/g, respectively. The results demonstrated that the oriental arborvitae leaves showed high potentials for the adsorption of Pb(II) from aqueous solutions.

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.

scholarly journals Enhanced Selenate Removal in Aqueous Phase by Copper-Coated Activated Carbon

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 468
Author(s):  
Xinhai Zhao ◽  
Aiqing Zhang ◽  
Jianhong Zhang ◽  
Qipeng Wang ◽  
Xuquan Huang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Zeta Potential ◽  
Copper Ion ◽  
Total Pore Volume ◽  
Freundlich Isotherm ◽  
Outer Sphere ◽  
Low Salinity ◽  
Adsorption Data ◽  
Salinity Water ◽  
Zeta Potential Analysis

In this study, we prepared a novel sorbent derived from precipitating copper ion onto the surfaces of activated carbon (Cu-AC). The sorbents were comprehensively characterized by Brunauer–Emmett–Teller (BET), zeta potential analysis, SEM, XRD, and FTIR. Batch experiments were conducted to evaluate selenate removal by Cu-AC under different conditions. The results showed that Cu was uniformly coated on the AC surface. Copper pretreatment markedly decreased the specific surface area and total pore volume of AC, and changed its surface zeta potential from highly negative to low negative and even positive. The Cu-AC substantially improved selenate adsorption capacity from the 1.36 mg Se/g AC of raw AC to 3.32, 3.56, 4.23, and 4.48 mg Se/g AC after loading of 0.1, 0.5, 1.0, and 5 mmol Cu/g AC, respectively. The results of toxicity leaching test showed AC coated with ≤1.0 mmol Cu/g was acceptable for potential application. Selenate adsorption was significantly inhibited by high ionic strength (>50 mM NaCl) and pH (>10). The electrostatic attraction between positive surface charge of Cu-AC and selenate ions and hydrogen bonding between CuO and HSeO4− might contribute to selenate sorption. Evidence showed that the selenate adsorption might involve outer-sphere surface complexation. The adsorption data appeared to be better described by Langmuir than Freundlich isotherm. The spent adsorbent could be effectively regenerated by hydroxide for reuse. Only a little decrease of removal efficiency was observed in the second and third run. This study implies that Cu-coated AC is a potential adsorbent for sustainable removal selenate from relative low salinity water/wastewater.

scholarly journals Antimony (V) Adsorption at the Hematite–Water Interface: A Macroscopic and In Situ ATR-FTIR Study

Soil Systems ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 20
Author(s):  
Jerzy Mierzwa ◽  
Rose Mumbi ◽  
Avedananda Ray ◽  
Sudipta Rakshit ◽  
Michael E. Essington ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Adsorption Mechanism ◽  
Surface Complexation ◽  
Outer Sphere ◽  
Surface Complexation Modeling ◽  
Surface Complexes ◽  
Ph Values ◽  
Oxide Minerals ◽  
Complexation Mechanism

The environmental mobility of antimony (Sb) is largely unexplored in geochemical environments. Iron oxide minerals are considered major sinks for Sb. Among the different oxidation states of Sb, (+) V is found more commonly in a wide redox range. Despite many adsorption studies of Sb (V) with various iron oxide minerals, detailed research on the adsorption mechanism of Sb (V) on hematite using macroscopic, spectroscopic, and surface complexation modeling is rare. Thus, the main objective of our study is to evaluate the surface complexation mechanism of Sb (V) on hematite under a range of solution properties using macroscopic, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic, and surface complexation modeling. The results indicate that the Sb (V) adsorption on hematite was highest at pH 4–6. After pH 6, the adsorption decreased sharply and became negligible above pH 9. The effect of ionic strength was negligible from pH 4 to 6. The spectroscopic results confirmed the presence of inner- and outer-sphere surface complexes at lower pH values, and only outer-sphere-type surface complex at pH 8. Surface complexation models successfully predicted the Sb (V) adsorption envelope. Our research will improve the understanding of Sb (V) mobility in iron-oxide-rich environments.

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