Characterization of Anticholinesterase-Active 3-Alkylpyridinium Polymers from the Marine SpongeReniera saraiin Aqueous Solutions

1997 ◽  
Vol 60 (10) ◽  
pp. 991-996 ◽  
Author(s):  
Kristina Sepčić ◽  
Graziano Guella ◽  
Ines Mancini ◽  
Francesco Pietra ◽  
Mauro Dalla Serra ◽  
...  
Keyword(s):  
Aqueous Solutions

scholarly journals Preparation and Characterization of the Sulfur-Impregnated Natural Zeolite Clinoptilolite for Hg(II) Removal from Aqueous Solutions

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 217
Author(s):  
Marin Ugrina ◽  
Martin Gaberšek ◽  
Aleksandra Daković ◽  
Ivona Nuić
Keyword(s):  
Chemical Modification ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Natural Zeolite ◽  
Contact Time ◽  
Liquid Ratio ◽  
X Ray ◽  
Solid Liquid

Sulfur-impregnated zeolite has been obtained from the natural zeolite clinoptilolite by chemical modification with Na2S at 150 °C. The purpose of zeolite impregnation was to enhance the sorption of Hg(II) from aqueous solutions. Chemical analysis, acid and basic properties determined by Bohem’s method, chemical behavior at different pHo values, zeta potential, cation-exchange capacity (CEC), specific surface area, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetry with derivative thermogravimetry (TG-DTG) were used for detailed comparative mineralogical and physico-chemical characterization of natural and sulfur-impregnated zeolites. Results revealed that the surface of the natural zeolite was successfully impregnated with sulfur species in the form of FeS and CaS. Chemical modification caused an increase in basicity and the net negative surface charge due to an increase in oxygen-containing functional groups as well as a decrease in specific surface area and crystallinity due to the formation of sulfur-containing clusters at the zeolite surface. The sorption of Hg(II) species onto the sulfur-impregnated zeolite was affected by the pH, solid/liquid ratio, initial Hg(II) concentration, and contact time. The optimal sorption conditions were determined as pH 2, a solid/liquid ratio of 10 g/L, and a contact time of 800 min. The maximum obtained sorption capacity of the sulfur-impregnated zeolite toward Hg(II) was 1.02 mmol/g. The sorption mechanism of Hg(II) onto the sulfur-impregnated zeolite involves electrostatic attraction, ion exchange, and surface complexation, accompanied by co-precipitation of Hg(II) in the form of HgS. It was found that sulfur-impregnation enhanced the sorption of Hg(II) by 3.6 times compared to the natural zeolite. The leaching test indicated the retention of Hg(II) in the zeolite structure over a wide pH range, making this sulfur-impregnated sorbent a promising material for the remediation of a mercury-polluted environment.

Synthesis and Characterization of Chitosan/Fluorapatite Composites for the Removal of Cr (VI) from Aqueous Solutions and Optimized Parameters

2020 ◽  
Vol 231 (4) ◽  
Author(s):  
Rachid El Kaim Billah ◽  
Youness Abdellaoui ◽  
Zakaria Anfar ◽  
Germán Giácoman-Vallejos ◽  
Mahfoud Agunaou ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Synthesis And Characterization

Characterization of Structural Changes of Poly(vinyl methyl ether) γ-Irradiated in Diluted Aqueous Solutions

Langmuir ◽  
2004 ◽  
Vol 20 (7) ◽  
pp. 2883-2889 ◽  
Author(s):  
Claudia Querner ◽  
Thomas Schmidt ◽  
Karl-Friedrich Arndt
Keyword(s):  
Aqueous Solutions ◽  
Methyl Ether ◽  
Structural Changes ◽  
Vinyl Methyl ◽  
Vinyl Methyl Ether

scholarly journals Über Isopolywolframatfeststoffe und deren Beziehung zu Isopolywolframationen in wäßriger Lösun / Concerning Solid Isopolytungstates and their Relation to Isopolytungstate Ions in Aqueous Solutio

1975 ◽  
Vol 30 (11-12) ◽  
pp. 834-841 ◽  
Author(s):  
Vasile Cordis ◽  
Karl-Heinz Tytko ◽  
Oskar Glemser
Keyword(s):  
Aqueous Solutions ◽  
Reaction Scheme

A classification and characterization of the solid isopolytungstates obtainable from acidified aqueous solutions is given and the relation of the solid isopolytungstates to the isopolytungstate ions in the corresponding solutions is studied. As distinguished from the molybdate system all the polytungstate ions forming a solid exist in solution as well. The reasons for the non-occurrence of insoluble solids of species absent from solution are discussed. For setting up a reaction scheme on the polytungstates only very few of the large number of papers on this subject give evidentiary informations.

Characterization of saline aqueous solutions upwelling under Ceres' surface: a focus on chemical equilibria in the H2O-CO2-NaCl supply ascent system

2019 ◽  
Author(s):  
Maria PEDONE ◽  
Eleonora Ammannito ◽  
Christina Plainaki ◽  
Maria Cristina De Sanctis ◽  
Andrea Raponi ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Chemical Equilibria

Characterization of PVA and Chitosan/PVA Blends Prepared from Aqueous Solutions of Various Na2SO4 Concentrations

2006 ◽  
Vol 242 (1) ◽  
pp. 146-156 ◽  
Author(s):  
Petronela Drambei ◽  
Yumiko Nakano ◽  
Yuezhen Bin ◽  
Tsumuko Okuno ◽  
Masaru Matsuo
Keyword(s):  
Aqueous Solutions
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