scholarly journals Defluoridation performance comparison of aluminum hydroxides with different crystalline phases

2022 ◽  
Author(s):  
Wei-Zhuo Gai ◽  
Shi-Hu Zhang ◽  
Yang Yang ◽  
Kexi Sun ◽  
Hong Jia ◽  
...  
Keyword(s):  
Aluminum Hydroxide ◽  
Performance Comparison ◽  
Hydroxyl Group ◽  
Fluoride Removal ◽  
Hydroxyl Groups ◽  
Order Kinetic ◽  
Crystalline Phases ◽  
Surface Hydroxyl ◽  
Ph Values ◽  
Aluminum Hydroxides

Abstract Aluminum hydroxide is an eye catching and extensively researched adsorbent for fluoride removal and its defluoridation performance is closely related to the preparation method and crystalline phase. In this research, the defluoridation performances of aluminum hydroxides with different crystalline phases are compared and evaluated in terms of fluoride removal capacity, sensitivity to pH values and residual Al contents after defluoridation. It is found that the defluoridation performance of different aluminum hydroxides follows the order of boehmite > bayerite > gibbsite. The fluoride adsorption on aluminum hydroxides follows pseudo-second-order kinetic model and Langmuir isotherm model, and the maximum defluoridation capacities of boehmite, bayerite and gibbsite are 42.08, 2.97 and 2.74 mg m−2, respectively. The pH values and FTIR analyses reveal that the ligand exchange between fluoride and surface hydroxyl groups is the fluoride removal mechanism. Different aluminum hydroxides have different surface hydroxyl group densities, which results in the different defluoridation capacities. This work provides a new idea to prepare aluminum hydroxide with outstanding defluoridation performance.

Biocompatibility and Functional Performance of a Polyethylene Glycol Acid-Grafted Cellulosic Membrane for Hemodialysis

2000 ◽  
Vol 23 (6) ◽  
pp. 356-364 ◽  
Author(s):  
V. Sirolli ◽  
S. Di Stante ◽  
S. Stuard ◽  
L. Di Liberato ◽  
L. Amoroso ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Functional Performance ◽  
Sialyl Lewis X ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Dialysis Session ◽  
Cellulose Diacetate ◽  
Activation Markers ◽  
Surface Hydroxyl ◽  
Cellular Expression

In order to improve the biochemical reactivity of the cellulose polymer, which is mainly attributed to the presence of surface hydroxyl groups, derivatized cellulosic membranes have been engineered replacing or masking some or all of the hydroxyl groups in the manufacturing process of the membrane. The present study was set up to analyze both biocompatibility and functional performance of two different derivatized cellulosic membranes (cellulose diacetate; polyethylene glycol, PEG, acid-grafted cellulose) as compared to a synthetic membrane (polymethylmethacrylate, PMMA). Cellulose diacetate is prepared by substituting hydroxyl groups with acetyl groups; PEG cellulose is obtained by grafting PEG chains onto the cellulosic polymer with a smaller amount of substitution than cellulose diacetate. While the three dialyzers provided similar urea and creatinine removal, the dialyzer containing cellulose diacetate showed a reduced ability to remove β2-microglobulin compared to that containing PEG cellulose or PMMA. A transient reduction in leukocyte count was observed for both derivatized cellulosic membranes. The neutrophil and monocyte counts throughout the entire dialysis session showed a closer parallelism with the cellular expression of the adhesive receptor CD15s (sialyl-Lewis x molecole) than with CD11b/CD18 expression. Platelet activation, as indicated by the percentage of cells expressing the activation markers CD62P (P-selectin) and CD63 (gp53), occurred with all membranes at 15 min of dialysis and also with PMMA at 30 min. An increased formation of platelet-neutrophil and platelet-monocyte coaggregates was found at 15 and 30 min during dialysis with cellulose diacetate and PMMA but not with PEG cellulose. Generally in concomitance with the increase in platelet-neutrophil coaggregates, an increased hydrogen peroxide production by neutrophils occurred. Our results indicate that derivatizing cellulose may represent a useful approach to improve the biocompatibility of the cellulose polymer, though some homeostatic reactions remain activated. Our results also indicate that there may be a great variability in the biocompatibility profile of derivatized cellulosic membranes which most likely stem from the different type of structural modification rather than from the degree of hydroxyl group replacement.

The structure of an intercalated ordered kaolinite — a Raman microscopy study

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 587-596 ◽  
Author(s):  
R. L. Frost ◽  
T. H. Tran ◽  
J. Kristof
Keyword(s):  
Raman Band ◽  
Low Frequency ◽  
Potassium Acetate ◽  
Microscopy Study ◽  
Raman Microscopy ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Inner Surface ◽  
Order Of Magnitude

AbstractChanges in the molecular structure of a highly ordered kaolinite, intercalated with urea and potassium acetate, have been studied using Raman microscopy. A new Raman band, attributed to the inner surface hydroxyl groups strongly hydrogen bound to the acetate, is observed at 3605 cm-1 for the potassium acetate intercalate with the consequential loss of intensity in the bands at 3652, 3670, 3684 and 3693 cm-1. Remarkable changes in intensity of the Raman spectral bands of the low-frequency region of the kaolinite occurred upon intercalation. In particular, the 144 and 935 cm-1 bands increased by an order of magnitude and were found to be polarized. These spectroscopic changes provide evidence for the inner surface hydroxyl group-acetate bond being at an angle approaching 90° to the 001 face. Decreases in intensity of the bands at 243, 271 and 336 cm-1 were observed. The urea intercalate shows additional Raman bands at 3387, 3408 and 3500 cm-1 which are attributed to N-H vibrations after formation of the urea-kaolinite complex. Changes in the spectra of the inserting molecules were also observed.

AN INFRARED STUDY OF THE ADSORPTION OF AMMONIA ON POROUS VYCOR GLASS

1964 ◽  
Vol 42 (4) ◽  
pp. 802-809 ◽  
Author(s):  
N. W. Cant ◽  
L. H. Little
Keyword(s):  
Hydrogen Exchange ◽  
Lone Pair ◽  
Acid Sites ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Infrared Study ◽  
Vycor Glass ◽  
Oh Groups ◽  
Surface Hydroxyl ◽  
Adsorption Sites

The infrared spectrum of ammonia adsorbed on porous glass at 20 °C and 150 °C has been studied in the region 1450–4000 cm−1. No absorption band due to the asymmetric bending mode of ammonia was observed but in the NH stretching region, bands occurred at 3280 cm−1, 3320 cm−1, 3365 cm−1, and 3400 cm−1. The bands at 3320 cm−1 and 3400 cm−1 were easily removed by evacuation and are due to ammonia molecules hydrogen bonded through the nitrogen atom to surface hydroxyl groups. The bands at 3280 cm−1 and 3365 cm−1 were not removed by evacuation even at 150 °C and are due to ammonia molecules held to surface Lewis acid sites by the nitrogen lone-pair electrons. The site for this adsorption is not a surface hydroxyl group. These results are further evidence for the existence of the two adsorption sites proposed by Folman and Yates. Deuteration of the surface OH groups was easily accomplished with D2O vapor at 300 °C and the rate of hydrogen exchange between adsorbed ammonia molecules and surface OD groups was found to be rapid.

Preparation of New Nano-MnO2 and Its Molybdenum Adsorption in Manganese Sulfate Solution

2020 ◽  
Vol 12 (9) ◽  
pp. 1070-1078
Author(s):  
Wang Haifeng ◽  
Chen Xiaoliang ◽  
Zhao Pingyuan ◽  
Gao Zhaowei ◽  
You Xiaoyu ◽  
...  
Keyword(s):  
Manganese Dioxide ◽  
Adsorption Process ◽  
Removal Rate ◽  
Sulfate Solution ◽  
Crystal Form ◽  
Quality Standard ◽  
Hydroxyl Groups ◽  
Manganese Sulfate ◽  
Order Kinetic ◽  
Surface Hydroxyl

Manganese sulfate solution was in this study oxidized, using H2O2 as oxidant, to obtain new Nano-MnO2 in situ. The characterization of new MnO2 was carried out by XRD, SEM, FT-IR and BET. The effect of new manganese dioxide adsorpting molybdenum ion in manganese sulfate solution was also studied. Results showed that the main crystal form of the new MnO2 was γ type, and there was agglomeration of nanospheres with 200∼300 nm diameter from the microscopic morphology, which had abundant surface hydroxyl groups, and its specific surface area was as high as 146 m2/g. MnO2 addition was 1.0 g under optimal adsorption conditions when the pH was 2, and the reaction time was 30 min, with removal rate of 99.2% molybdenum and 0.26 ppm residual amount of molybdenum in manganese sulfate solution, which met the quality standard for high purity manganese sulfate (HG/T4823-2015) with ≤5 ppm molybdenum content. Moreover, the thermodynamics and kinetics of molybdenum adsorption by new manganese dioxide were also studied. The experiments showed that the adsorption process was in accordance with the Freundlich adsorption equation. The adsorption process of molybdenum on manganese dioxide could be described with pseudo second order kinetic model, and the internal diffusion was a controlling link of adsorption rate.

Formation of borate complexes of inosamines (aminodeoxyinositols) and their separation by paper electrophoresis

1974 ◽  
Vol 27 (4) ◽  
pp. 853 ◽  
Author(s):  
JL Frahn ◽  
JA Mills
Keyword(s):  
Carbon Dioxide ◽  
Paper Electrophoresis ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Amino Group ◽  
Ph Values ◽  
Borate Complex ◽  
Wide Range ◽  
Borate Complexes ◽  
Probable Site

The electrophoretic mobility of an inosamine in borate buffer is very dependent on configuration, and a set of 10 inosamines showed a wide range of mobilities. The order of mobilities within the set changed as the pH of the buffer was changed in the range 7.7-9.5. Paper electrophoresis in borate buffers can effectively separate mixtures of inosamines. The probable site of reaction between an inosamine and borate ions has been identified for some isomers. In aminodeoxy-scyllo-inositol and 3-amino-3-deoxy-epi-inositol the amino group is involved in the formation of a tridentate borate complex of adamantane-type structure, which is electrically neutral over the above range of pH values. Aminodeoxy-scyllo-inositol simultaneously combines with a second molecule of borate, forming a bis-tridentate complex with one anionic centre. There is evidence that in other isomers protonation of the amino group and formation of anionic borate complexes at hydroxyl groups are not independent reactions. Paper electrophoresis in non-complexing buffers provides evidence for the relative basicities of inosamines. DL-2-Amino-2-deoxy-epi-inositol, which has an interaction between axial amino and hydroxyl group in the preferred conformation, was the strongest base in the set, whereas the bases with an axial amino group free of such an interaction were the weakest. Inosamines form N-carboxyl derivatives in the normal way on exposure to carbon dioxide in the presence of strong alkali.

Chemical Stability of 2D-Nanostructured WO3 in Hydrogen Sensing Under Varied Operation Temperature

NANO ◽  
2016 ◽  
Vol 11 (08) ◽  
pp. 1650092 ◽  
Author(s):  
Taisheng Yang ◽  
Hui Tian ◽  
Yue Zhang ◽  
Chen Li
Keyword(s):  
Water Molecule ◽  
Chemical Stability ◽  
Density Functional ◽  
Stable State ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Hydrogen Sensing ◽  
Operation Temperature ◽  
Surface Hydroxyl Groups

Nanostructured metal oxide-based resistive-type gas sensors are of high research interest. Chemical stability is the most critical issue due to the surface electron species and density. In the present paper, 2D-nanostructured WO3 was prepared and characterized, and a WO3-based sensor was fabricated and analyzed. The results showed that the synthesized WO3 material exhibited nanosheet structure, and during hydrogen sensing testing, the current baseline shifted with various tendencies, even completely opposite directions under different operation temperatures. The chemistry analysis results indicated that water molecule and hydroxyl group were formed under low operation temperature but further oxidation occurred at higher temperatures. The adsorption of H2 on oxygen terminated WO3(0 0 1) surfaces by density functional theory (DFT) method indicated that a water molecule formed by adsorption of a hydrogen molecule at the O site with the most thermodynamically stable state, and two surface hydroxyl groups formed by dissociative adsorption with a thermodynamically less stable state. The water molecule and surface hydroxyl groups increased the conductivity of the WO3 film while that was decreased as the oxidation occurred.

scholarly journals Evaluation of a Novel Water Treatment Residual Nanoparticles as a Sorbent for Arsenic Removal

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Elsayed Elkhatib ◽  
Ahmed Mahdy ◽  
Fatma Sherif ◽  
Hala Hamadeen
Keyword(s):  
Water Treatment ◽  
Arsenic Removal ◽  
Batch Adsorption ◽  
Hydroxyl Groups ◽  
Surface Complexes ◽  
Surface Hydroxyl ◽  
Ph Values ◽  
First Order Kinetics ◽  
The Stability ◽  
Water Treatment Residual

A novel sorbent, water treatment residual nanoparticles (nWTR), was synthesized and used to remove As(V) from water solutions. The kinetics and equilibrium of As(V) adsorption by nWTR were evaluated. The kinetic data for nWTR at 3 different pH values indicate that As(V) sorption is biphasic, is favored at low pH values, and followed the power function and first-order kinetics models fit. The results of the batch adsorption study showed that nWTR was effective in As(V) removal and its removal capability was 16 times higher than that of bulk WTR. Fourier transmission infrared (FTIR), SEM-EDX spectra, and As fractionation results indicate the crucial role of surface hydroxyl groups in As retention onto nWTR and the high capability of nWTR to immobilize As(V). The stability of As-nWTR surface complexes is suggested as less than 2% of adsorbed As(V) was released from nWTR after 4 consecutive desorption cycles.

scholarly journals Synthesis and Characterization of Modified Kaolin-Bentonite Composites for Enhanced Fluoride Removal from Drinking Water

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ebenezer Annan ◽  
Emmanuel Nyankson ◽  
Benjamin Agyei-Tuffour ◽  
Stephen Kofi Armah ◽  
George Nkrumah-Buandoh ◽  
...  
Keyword(s):  
Drinking Water ◽  
Magnetite Nanoparticles ◽  
Second Order ◽  
Fluoride Removal ◽  
Average Weight ◽  
Hydroxyl Groups ◽  
Order Kinetic ◽  
Sem Images ◽  
Pseudo Second Order ◽  
The Impact

Fluoride-contaminated drinking waters are known to cause severe health hazards such as fluorosis and arthritis. This paper presents the encapsulation of iron oxide nanoparticles in kaolin-bentonite composites adsorbents (KBNPs) for the removal of fluoride from drinking water by adsorption compared with kaolin-bentonite composite (KB). Adsorbents with an average weight of ∼200 mg and ∼7 mm diameter (granules) were prepared in the ratio of 10 : 10 : 0.1 for kaolinite, bentonite, and magnetite nanoparticles, respectively. The granules were air-dried and calcined at 750°C and contacted with 2 mg/L sodium fluoride solution at varying time periods. The adsorbents were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) formulation, and Brunauer–Emmett–Teller (BET), whereas the adsorption mechanism and the kinetics were explained using the Langmuir isotherm, Freundlich models, and pseudo-first-order and pseudo-second-order models. The results showed that the BET surface areas for the granules were 10 m2/g and 3 m2/g for KBNPs and KB, respectively. The SEM images for the adsorbents before and after adsorption confirm the plate-like morphology of kaolin and bentonite. The FTIR analyses of bentonite (3550 cm−1–4000 cm−1) and kaolin (400–1200 cm−1) correspond to the structural hydroxyl groups and water molecules in the interlayer space of bentonites and the vibrational modes of SiO4 tetrahedron of kaolin, respectively. The KBNPs composites also recorded a fluoride removal efficiency of ∼91% after 120 minutes compared with 64% for KB composites without Fe3O4 nanoparticles. The adsorptions of fluoride by the KBNPs and KB granules were found to agree with the Freundlich isotherm and a pseudo-second-order kinetic model, respectively. The results clearly show that the impregnation of clays with magnetite nanoparticles has significant effect in the removal of fluoride, and the implication of the results has been discussed to show the impact of clay-magnetite nanoparticles composites in the removal of fluoride from contaminated water.

scholarly journals Tailoring the component of protein corona via simple chemistry

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xiang Lu ◽  
Peipei Xu ◽  
Hong-Ming Ding ◽  
You-Sheng Yu ◽  
Da Huo ◽  
...  
Keyword(s):  
Surface Properties ◽  
Blood Circulation ◽  
Molecular Simulations ◽  
Protein Corona ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
In Vitro Measurements

Abstract Control over the protein corona of nanomaterials allows them to function better. Here, by taking graphene/gold as examples, we comprehensively assessed the association of surface properties with the protein corona. As revealed by in vitro measurements and computations, the interaction between graphene/gold and HSA/IgE was inversely correlated with the hydroxyl group availability, whereas the interaction between that and ApoE was comparatively less relevant. Molecular simulations revealed that the number and the distribution of surface hydroxyl groups could regulate the manner in which nanomaterials interact with proteins. Moreover, we validated that ApoE pre-adsorption before injection enhances the blood circulation of nanomaterials relative to their pristine and IgE-coated counterparts. This benefit can be attributed to the invulnerability of the complementary system provided by ApoE, whose encasement does not increase cytotoxicity. Overall, this study offers a robust yet simple way to create protein corona enriched in dysopsonins to realize better delivery efficacy.

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