Silica surface controversies, strong adsorption sites, their blockage and removal. Part II

1991 ◽  
Vol 31 (3-4) ◽  
pp. 193-205 ◽  
Author(s):  
J. Nawrocki
Keyword(s):  
Silica Surface ◽  
Adsorption Sites ◽  
Strong Adsorption

scholarly journals Smart adsorbents for CO2 capture: Making strong adsorption sites respond to visible light

2020 ◽  
Author(s):  
Qiu-Rong Wu ◽  
Peng Tan ◽  
Chen Gu ◽  
Rui Zhou ◽  
Shi-Chao Qi ◽  
...  
Keyword(s):  
Visible Light ◽  
Co2 Capture ◽  
Adsorption Sites ◽  
Strong Adsorption

scholarly journals Effect of aluminum and sodium on the sorption of water and methanol in microporous MFI-type zeolites and mesoporous SBA-15 materials

Adsorption ◽  
2020 ◽  
Author(s):  
Zheng Li ◽  
Carolin Rieg ◽  
Ann-Katrin Beurer ◽  
Michael Benz ◽  
Johannes Bender ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Acid Sites ◽  
Mas Nmr ◽  
Nmr Studies ◽  
Oh Groups ◽  
Adsorption Sites ◽  
Low Field ◽  
Strong Adsorption ◽  
Nmr Signals

Abstract The interaction and nature of surface sites for water and methanol sorption on MFI-type zeolites and mesoporous SBA-15 were investigated by solid-state NMR spectroscopy and correlated with the desorption enthalpies determined via TGA/DSC. For siliceous Silicalite-1, 29Si CPMAS NMR studies support stronger methanol than water interactions with SiOH groups of Q3-type. On siliceous SBA-15, SiOH groups of Q2-type are accompanied by an enhanced hydrophilicity. In aluminum-containing Na-ZSM-5, Na+ cations are strong adsorption sites for water and methanol as evidenced by 23Na MAS NMR in agreement with high desorption enthalpies of ΔH = 66–74 kJ/mol. Solid-state NMR of aluminum-containing Na-[Al]SBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of ΔH = 44–60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Brønsted acidic OH groups are strong adsorption sites as indicated by partial protonation of water and methanol causing low-field shifts of their 1H MAS NMR signals and enhanced desorption enthalpies. Due to the small number of Brønsted acid sites in aluminum-containing H-[Al]SBA-15, water and methanol adsorption on this material is suggested to mainly occur at SiOH groups with distant framework aluminum species, as in the case of Na-[Al]SBA-15.

Adsorption characteristics of seston in irrigation water: implications for the use of aquatic herbicides

1982 ◽  
Vol 33 (3) ◽  
pp. 443 ◽  
Author(s):  
KH Bowmer
Keyword(s):  
High Capacity ◽  
Adsorption Sites ◽  
South Wales ◽  
Suspended Particulate ◽  
Strong Adsorption ◽  
Aquatic Herbicides ◽  
Order Of Magnitude ◽  
Transport Behaviour ◽  
The Difference ◽  
Irrigation Drainage

Adsorption of three important aquatic herbicides by seston (suspended particulate matter) in water from the Murrumbidgee Irrigation Areas of New South Wales was investigated. Seston was extremely reactive: the adsorption of terbutryn and glyphosate was generally at least an order of magnitude higher than reported in the literature for soils. although adsorption is expected to have little effect in reducing concentrations of terbutryn in practice. Adsorption of glyphosate was decreased by addition of phosphate, which may contribute to the difference in adsorbing power observed for seston from different sources. Since phosphate and glyphosate compete for adsorption sites, a high adsorption maximum for glyphosate may reflect the high capacity of seston to adsorb and transport phosphates. Although several other factors may also be involved, adsorption by seston alone was sufficient to completely inactivate diquat in irrigation drainage waters, at concentrations up to 0.5 mg 1-1. However, once the strong adsorption capacity of seston (about 8 mg g-1) was saturated. an increasing proportion of the initial concentration remained in solution, so this herbicide could be effective if sufficient were used. The general implications of adsorption on the transport, behaviour and persistence of organic compounds and pollutants in the aquatic system are also discussed.

scholarly journals The Effect of Mg, Fe(II), and Al Doping on CH4: Adsorption and Diffusion on the Surface of Na-Kaolinite (001) by Molecular Simulations

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 1001 ◽  
Author(s):  
Kai Wang ◽  
Bin Zhang ◽  
Tianhe Kang
Keyword(s):  
Molecular Simulations ◽  
Distribution Functions ◽  
Key Factors ◽  
Al Doping ◽  
Adsorption Sites ◽  
Strong Adsorption ◽  
Ion Doping ◽  
Ch4 Adsorption ◽  
And Diffusion ◽  
Peak Value

Because kaolinite includes a large range of defect elements, the effects of Mg, Fe(II), and Al doping on the CH4 adsorption and diffusion on the surface of Na-kaolinite (001) were investigated by molecular simulations. The simulation results illustrate that ion doping can significantly reduce the amount of CH4 adsorbed by kaolinite, but the type of doped ions has little effect on the amount of adsorption. The specific surface area of kaolinite and the interaction energy between CH4 and the kaolinite’s surface are two key factors that can determine CH4 adsorption capacity. The first peak value of the radial distribution functions (RDFs) between CH4 and the pure kaolinite is larger than that between Mg-, Fe(II)-, and Al-doped kaolinite, which indicates that ion doping can reduce the strength of the interactions between CH4 and the kaolinite’s surface. Besides hydrogen and oxygen atoms, interlayer sodium ions are also strong adsorption sites for CH4 and lead to a weakened interaction between CH4 and the kaolinite’s surface, as well as a decrease in CH4 adsorption. Contrary to the adsorption results, ion doping facilitates the diffusion of CH4, which is beneficial for actual shale gas extraction.

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