scholarly journals The Adsorption of Chloromethanes on KCl. The Role of the Surface Ions as Adsorption Sites

1983 ◽  
Vol 56 (7) ◽  
pp. 2086-2089 ◽  
Author(s):  
Masatoshi Chikazawa ◽  
Masatoshi Amada ◽  
Takafumi Kanazawa
Keyword(s):  
Adsorption Sites ◽  
As Adsorption

Modification Effects in Argon Plasma Treated S1O2 Spin-On Glass

1995 ◽  
Vol 381 ◽  
Author(s):  
Min Park ◽  
Joong Whan Lee ◽  
Jin Gun Koo ◽  
Kyung Soo Kim ◽  
Hyung Joun Yoo ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Treatment Time ◽  
Argon Plasma ◽  
Treatment Temperature ◽  
Adsorption Sites ◽  
Long Time ◽  
As Adsorption ◽  
Wet Etch

AbstractWe demonstrated that the quality of siloxane spin-on glass (SOG) films, widely used as interlevel planarization dielectrics, is improved significantly by curing in argon plasma. The wet etch rate of SOG film decreases with increasing plasma treatment temperature or treatment time, and is much lower than that cured in a furnace. Long-time plasma treatment reduces the density of silanols (Si-OH) and methyl (−CH3) group, which act as adsorption sites of water. The results were compared with those obtained from the N2O (or H2 ) plasma treated SOG films. The modification of the SOG film by Ar plasma is related to the radiation damage and the reconstruction of the atomic structure during the plasma exposure. The role of metastable Ar (Ar*) appears to be very important to improve the SOG film; SOG film is more relaxed by the energy released from the conversion of Ar* to Ar.

The role of sodium ions as adsorption sites in silicalite-1

1990 ◽  
Vol 86 (3) ◽  
pp. 561 ◽  
Author(s):  
Yasuyuki Matsumura ◽  
Keiji Hashimoto ◽  
Hisayoshi Kobayashi ◽  
Satohiro Yoshida
Keyword(s):  
Sodium Ions ◽  
Adsorption Sites ◽  
As Adsorption

scholarly journals Uptake of Methylene Blue from Aqueous Solution by Pectin–Chitosan Binary Composites

2020 ◽  
Vol 4 (3) ◽  
pp. 95
Author(s):  
Dexu Kong ◽  
Lee D. Wilson
Keyword(s):  
Methylene Blue ◽  
Aqueous Media ◽  
Dye Adsorption ◽  
Adsorption Properties ◽  
Point Of Zero Charge ◽  
Cross Linking ◽  
Gravimetric Analysis ◽  
Adsorption Sites ◽  
Biopolymer Composites

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.

scholarly journals Flax Biomass Conversion via Controlled Oxidation: Facile Tuning of Physicochemical Properties

2020 ◽  
Vol 7 (2) ◽  
pp. 38
Author(s):  
Leila Dehabadi ◽  
Abdalla H. Karoyo ◽  
Majid Soleimani ◽  
Wahab O. Alabi ◽  
Carey J. Simonson ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Pore Structure ◽  
Surface Charge ◽  
Chemical Treatment ◽  
Textural Properties ◽  
Adsorption Properties ◽  
Biomass Composition ◽  
Adsorption Sites ◽  
Modified Forms

The role of chemical modification of pristine linen fiber (LF) on its physicochemical and adsorption properties is reported in this contribution. The surface and textural properties of the pristine LF and its peroxyacetic acid- (PAF) and chlorite-treated (CF) fiber forms were characterized by several complementary methods: spectroscopy (SEM, TEM, FT-IR, and XPS), thermal analysis (DSC and TGA), gas/water adsorption isotherms, and zeta potential (ξ). The results obtained reveal that the surface charge and textural properties (surface area and pore structure) of the LF material was modified upon chemical treatment, as indicated by changes in the biomass composition, morphology, ξ-values, and water/dye uptake properties of the fiber samples. Particularly, the pristine LF sample displays preferential removal efficiency (ER) of methylene blue (MB) dye with ER ~3-fold greater (ER~62%) as compared to the modified materials (CF or PAF; ER~21%), due to the role of surface charge of pectins and lignins present in pristine LF. At higher MB concentration, the relative ER values for LF (~19%) relative to CF or PAF (~16%) reveal the greater role of micropore adsorption sites due to the contributing effect of the textural porosity observed for the modified flax biomass at these conditions. Similar trends occur for the adsorption of water in the liquid vs. vapour phases. The chemical treatment of LF alters the polarity/charge of the surface functional groups, and pore structure properties of the chemically treated fibers, according to the variable hydration properties. The surface and textural properties of LF are altered upon chemical modification, according to the variable adsorption properties with liquid water (l) vs. water vapor (g) due to the role of surface- vs. pore-sites. This study contributes to an understanding of the structure-adsorption properties for pristine and oxidized flax fiber biomass. The chemical conversion of such biomass yields biomaterials with tunable surface and textural properties, as evidenced by the unique adsorption properties observed for pristine LF and its modified forms (CF and PAF). This study addresses knowledge gaps in the field by contributing insight on the relationship between structure and adsorption properties of such LF biomass in its pristine and chemically modified forms.

The role of sorbate in the determination of preferential adsorption sites in zeolite HY: A theoretical study

2007 ◽  
Vol 103 (1-3) ◽  
pp. 280-283 ◽  
Author(s):  
Siricharn S. Jirapongphan ◽  
Juliusz Warzywoda ◽  
David E. Budil ◽  
Albert Sacco
Keyword(s):  
Theoretical Study ◽  
Adsorption Sites ◽  
Preferential Adsorption

Chemisorption of Ammonia on Silica

1973 ◽  
Vol 51 (11) ◽  
pp. 1771-1781 ◽  
Author(s):  
G. A. Blomfield ◽  
L. H. Little
Keyword(s):  
Adsorption Process ◽  
Ammonia Adsorption ◽  
Adsorption Sites ◽  
Added Water ◽  
Adsorption Of Water ◽  
Amine Groups

The interaction of ammonia with silicas prepared by a variety of methods was studied to resolve conflicting reports of the mode of ammonia adsorption and to determine the role of chlorine impurities (present in the silica) in the adsorption process. Results for the adsorption of water on silica assisted in making band assignments and competition between ammonia and water for silica adsorption sites was observed. It was concluded that dehydroxylated silicas contain sites which dissociate ammonia to form Si—NH2 groups having infrared bands at 3540, 3450, and 1550 cm−1 (the surface amine groups are not displaced by added water). The presence of chlorine in the silica is not a prerequisite for chemisorption of ammonia.

The role of surface boron as adsorption center for the sorption of water by porous glass

1967 ◽  
Vol 71 (9) ◽  
pp. 3077-3081 ◽  
Author(s):  
Manfred J. D. Low ◽  
Natesan Ramasubramanian
Keyword(s):  
Porous Glass ◽  
Adsorption Center ◽  
As Adsorption

scholarly journals Phosphate has a differential influence on arsenate adsorption by soils with different properties

2012 ◽  
Vol 58 (No. 9) ◽  
pp. 405-411 ◽  
Author(s):  
X. Zeng ◽  
P. Wu ◽  
S. Su ◽  
L. Bai ◽  
Q. Feng
Keyword(s):  
Adsorption Capacity ◽  
Agricultural Soils ◽  
Molar Ratio ◽  
Adsorption Sites ◽  
Adsorption Capacities ◽  
Minimum Capacity ◽  
P Application ◽  
As Adsorption ◽  
Langmuir And Freundlich Equations ◽  
Different Soils

The adverse effect of the application of phosphorus (P) on arsenic (As) adsorption by soils can result in increasing mobility and availability of As. However, in different soils, P might influence As adsorption differently. In this study, the arsenate [As<sup>(V)</sup>] adsorption capacities of six soils with different properties and the effects of P application were studied. The results indicated that the adsorbed As<sup>(V)</sup> contents all increased as a function of the As<sup>(V)</sup> content in equilibrium. When analysed using the Langmuir and Freundlich equations, the maximum As<sup>(V)</sup> adsorption capacity of 0.72 mg/g was found for an Alumi-Plinthic Acrisol, while the minimum capacity of 0.09 mg/g was observed for an Epigleyic Cambisol. The adverse effects of P application on As<sup>(V)</sup> adsorption by the six soils were observed to be variable. When the P/As molar ratio in a culture experiment was increased from 0 to 10, the maximal and minimal decreases in the As<sup>(V)</sup> adsorption capacity of 0.086 and 0.014 mg/g were found in the Alumi-Plinthic Acrisol and Epigleyic Cambisol, respectively. P was relatively more effective in competing for adsorption sites with As<sup>(V)</sup> in the Alumi-Plinthic Acrisol and Luvi-Endogleyic Phaeozem due to their higher A/P values (decrease in adsorbed<br />As/added P) of 1.143 and 1.135, respectively. These results will help decrease the environmental risk of some As-contaminated agricultural soils through the controlled application of P.

scholarly journals Arsenic in Soils Affected by Mining: Microscopic Studies vs. Sequential Chemical Extraction

2020 ◽  
Vol 17 (22) ◽  
pp. 8426
Author(s):  
Jessica Álvarez-Quintana ◽  
Rodrigo Álvarez ◽  
Almudena Ordóñez
Keyword(s):  
Electron Microscopy ◽  
Residual Fraction ◽  
Chemical Extraction ◽  
Sequential Chemical Extraction ◽  
Transmission Electron ◽  
Microscopic Studies ◽  
Sequential Extraction Method ◽  
As Adsorption ◽  
Microscopic Techniques

Soil samples from three inactive mines, corresponding to different Arsenic-bearing mineralization types, were collected and studied. The aim was to determine the influence of mine wastes mineralogy/geochemistry and texture in As mobility and to compare results from sequential chemical extraction and microscopic techniques (optical and electron) at a grain scale. Arsenic in soils is found mainly associated to the residual fraction, indicating that mechanical As dispersion is mainly responsible for As soil pollution. The use of objective microscopic techniques (i.e., Scanning Electron Microscopy-Energy Dispersive Spectroscopy -SEM-EDS-, High Resolution Transmission Electron Microscopy -HR-TEM) has pointed out that the selected sequential extraction method overestimates the role of Mn amorphous oxy-hydroxides and organic matter in As retention while underestimating the mechanism of As adsorption onto clay particle surfaces.

STRUCTURAL PROPERTIES OF ALKALI-METAL ATOMS ADSORBED ON Ru(0001)

1995 ◽  
Vol 02 (03) ◽  
pp. 409-422 ◽  
Author(s):  
H. OVER ◽  
H. BLUDAU ◽  
M. GIERER ◽  
G. ERTL
Keyword(s):  
Alkali Metal ◽  
Structural Properties ◽  
Energy Cost ◽  
Hard Sphere ◽  
Energy Difference ◽  
Singular Behavior ◽  
Adsorption Sites ◽  
Metal Atoms ◽  
Substrate Surfaces

The structural properties of the ordered overlayers of Li, Na, K, Rb , and Cs on Ru (0001) are summarized. The major result is that the adsorption site depends on the coverage while the hard-sphere radii of the alkali-metal atoms do not change (if corrected for different numbers of coordination). This comparison also emphasizes the singular behavior of Cs for which adsorption takes place over single Ru atoms at a Cs coverage of 0.25. While on other close-packed substrate surfaces potassium and rubidium occupy ontop positions at low temperatures, this has not been found with Ru (0001). This finding points towards the important role of the substrate. For the ontop adsorption to be favored, an inward displacement of the substrate atoms directly underneath the alkali-metal atoms by a substantial amount is necessary which results in the formation of a quasisevenfold-coordinated bond geometry in connection with a reduction of the dipole-dipole repulsion. The stiffness of the substrate determines the energy cost for this local reconstruction, and consequently ontop adsorption on the hard Ru (0001) substrate has only been observed for the biggest alkali metal Cs where the energy difference between various adsorption sites [on the unrelaxed Ru (0001) surface] is assumed to be small. In order to force potassium to reside in the ontop position, the Ru (0001) surface has to be “softened” which task was accomplished by adding CO molecules to the K-(2×2) overlayer.

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