LC Separation of Enantiomers on Silica-Bonded Thiostrepton Derivatives

2012

J Chinese Chemical Soc

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A variety of silica-based solid phases, whose surfaces are functionalized with ligands containing sulfur and nitrogen elements, are used as self-supporting adsorbents for environmental remediation evaluation and potential separation application. Each adsorbent is tested for its ability to scavenge five metallic ions: Hg 2+ , Cu 2+ , Cd 2+ , Mn 2+ , Pb 2+ , and two organometallic ions: ethylmercury and phenylmercury, from independent homoionic solutions at both neutral and acidic pH values. The results indicate that the percentage of these ions scavenged by a given adsorbent varies, and is found to be highly related to the structural environment in the vicinity of the sulfur and nitrogen elements on the ligand. It is believed that the scavenging of metallic ions is a result of the complexation formation between the metallic ions and the ligands containing sulfur and nitrogen elements, and is not due to the irreversible association chemistry with the sulfur or nitrogen element itself. In the case of organometallic ions, a p-p interaction is thought to be involved in the adsorption with ligands containing an aromatic moiety in addition to the aforementioned forces. The time needed to reach the maximum percent of adsorption decreases as the amount of adsorbent increases. The longer the adsorption time, the higher percent of ion is removed. Other factors, such as the temperature and the acidity in the liquid phase of the matrix affect the percentage of ions scavenged as well.

Section: Resultsmentioning

confidence: 99%

Heavy Metallic and Organometallic Ions Scavenging Using Silica‐Based Adsorbent Functionalized with Ligands Containing Sulfur and Nitrogen Elements

Yeh

2012

J Chinese Chemical Soc

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“…Lignin, not sulfonated and used directly without further fractional purification, was immobilized chemically onto the surface of silica gel under the conditions previously described. [61][62][63] This lignin-bonded material was prepared to serve as a multipurpose adsorbent for metallic ions, nanoparticles and various agricultural organophosphate pesticides in hexane. Table 1 lists the corresponding elemental analysis results.…”

Section: Resultsmentioning

confidence: 99%

A Multipurpose Lignin‐based Adsorbent for Metallic Ions, Nanoparticles and Various Organophosphate Pesticides in Hexane

2015

J Chinese Chemical Soc

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A lignin-based adsorbent for metallic ions, nanoparticles and various agricultural organophosphate pesticides in hexane is immobilized on silica gel without further fractional purification. For most organophosphate analytes examined in this study under the same conditions, the percentage of adsorption achieved was well above 90% in 15 min, was found to be highly related to the dipole-dipole attractions that occurred among the oxygen-containing functional groups attached to analyte and lignin molecules and was greatly enhanced in hexane. The adsorption is believed to be reversible and surface oriented; furthermore, the interaction leading to the adsorption is not as significantly subject to the steric hindrance effect caused by the bulky group or elements surrounding the phosphorus element. Other types of interactions enhanced in hexane, such as the p-p interaction, and hydrogen bonding in some cases, were also observed and contributed less to the percentage of adsorption. However, the adsorption of ions and nanoparticles under aqueous conditions is thought to be mainly a result of the complexation of the oxygen-bearing hydrophobic cleft of the lignin molecule. In all cases, the nature of the analyte, the amount of adsorbent and the acidic or basic origin of the additive in matrix also affect the percentage of adsorption.

“…The organosilane reagent used as a linker in chemical immobilization reactions and the organomercuric compounds studied in this study were purchased from Sigma (St. Louis, MO, USA) and the Aldrich Chemical Co. (Milwaukee, WI, USA), respectively. Silica gel (5-µm particle diameter, 100 Å porosity with a specific surface area of 400 m 2 /g), used as the supporting matrix of the solid phase and as the adsorbent in the adsorption and capacity evaluations at ambient temperatures after chemical modification with a lignin without further purification, was obtained from Silicycle (Quebec City, QC, Canada) [ 21 , 22 ]. The HPLC-grade solvents, including toluene, acetonitrile, methanol, triethylamine, methylene chloride, hexane, chloroform, and ethyl ether used in this study were purchased from Fisher Scientific (Pittsburgh, PA, USA).…”

Section: Methodsmentioning

confidence: 99%

Study of Lignin-Modified Silica Gel Adsorption after Association with Six Different Organophenylmercuric Compounds in Chloroform

Gao

2018

IJMS

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In this study, the adsorption of lignin-modified silica gel after association with six different organophenylmercuric compounds in chloroform was investigated. Adsorption reached approximately 90% of the maximum value within 15 min. The adsorption capacity, Fourier transform infrared spectroscopy, and interaction simulation results indicated that the adsorption proportion resulted from the strong dipole-dipole interaction between the lignin and analyte molecules, and was considered to be size- and structure-dependent. However, the π-π complexation interaction arising from the acidic aromatic moiety of the analyte, which was significant in an apolar environment, was not the major force responsible for the resulting adsorption. Additives, such as acid or ether, which competed with the analyte for the binding site on the lignin molecule, were not beneficial to the interaction, and thus not beneficial to the adsorption processes.