Synthesis and properties of phosphate cation-exchangers based on silica

Journal of Hazardous Materials

Fajardo

et al. 2006

174

Section: Chemical Stabilitymentioning

confidence: 97%

2-Mercaptothiazoline modified mesoporous silica for mercury removal from aqueous media

Journal of Hazardous Materials

Fajardo

et al. 2006

174

“…It has been shown that the rupture of Si -C bond by beta-elimination of the Si cation did not occur in the mineral acid medium because of a no longer enough chain [33,36]. Also the length from methyl to propyl increases the hydrophobic character of the sur- face [56,57]. On the other hand, functionalized HMS was found to be unstable in 1, 3 and 6 M NaOH solutions due to breaking of the Si -O -Si bonds by hydroxide ions.…”

Section: Adsorbent Characterization and Stabilitymentioning

confidence: 97%

Functionalized HMS mesoporous silica as solid phase extractant for Pb(II) prior to its determination by flame atomic absorption spectrometry

Sánchez

J of Separation Science

et al. 2007

In this work, a mesoporous silica has been chemically modified with 5-mercapto-1-methyl-1-H-tetrazol using the homogeneous route (MTTZ-HMS). This synthetic route involved the reaction of 5-mercapto-1-methyl-1-H-tetrazol with 3-chloropropyltriethoxysilane, prior to immobilization on the support. The resulting material has been characterized and employed as solid phase extractant for Pb(II). The effect of several variables (stirring time, pH, temperature, metal concentration, presence of other metals) has been studied using batch and column techniques. In batch experiments, 15 min stirring time, 55 degrees C and pH 8 were the optimal conditions for Pb(II) adsorption. In column experiments, sorption was quantitative for 1000 mL of 2.41 x 10(-4 )mM of Pb(II) solution and adsorbed ions were eluted out by 5 mL of 1 M HCl (preconcentration factor of 200). Spiked tap water was used for the preconcentration and determination of Pb(II) by flame atomic absorption spectrometry, and a 100% recovery was obtained. The LOD and LOQ values of the proposed method were found to be 3.52 x 10(-3) and 4.20 x 10(-3 )mM, respectively. The RSD for three preconcentration experiments was found to be

show abstract

“…It has been shown that when the length of the hydrocarbon bridge is more than two methylene groups, the rupture of Si-C bond do not occur in mineral acid medium, since longer chains no longer have a functional handle that can undergo beta-elimination of the Si cation [36,37]. In addition, the increase in the chain length increases the hydrophobic character of the surface [38,39]. On the other hand, functionalized MCM-41 was found to be unstable in 1, 3, and 6 M NaOH solutions due to breaking of the Si-O-Si bonds by hydroxide ions.…”

Section: Adsorbent Characterization and Stabilitymentioning

confidence: 97%

Preparation, characterization, and Zn2+ adsorption behavior of chemically modified MCM-41 with 5-mercapto-1-methyltetrazole

Sánchez

Journal of Colloid and Interface Science

et al. 2007

100