Hydrolyzed Al(III) clusters: Speciation stability of nano-Al13

Abstract

Pure nano-Al 13 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, 27 Al-NMR, photo correlation spectroscopy (PCS), and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al 13 . The quantity of Al b species analyzed by ferron assay in the initial aging period corresponded well with that of Al 13 , which has been confirmed in a dimension range of 1-2 nm by PCS. Al 13 solutions at high concentrations (0.5-2.11 mol/L) were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al 13 basis on the 27 Al-NMR spectrum, whereas a part of Al 13 would still remain as Al b . At low concentrations, Al 13 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90°C.

Hydrolyzed Al(III)-clusters. II: Speciation transformation and stability of Al13 aggregates

“…As shown in the Table 2, the LLS intensity increases linearly with increase of B value and further aging. The average particle size increases from 2 mm to 10 mm for B values from 2.46 to 2.9, and the particles change gradually from mono-distribution to multiple-distribution [3]. With aging, the particles undergo slow growth.…”

“…The separation and preparation of pure Al 13 was carried out shown in a previous publication [3,10]. Batches of purified Al 13 samples were mixed together and freeze-dried to a white solid powder.…”

“…Compared with the traditional coagulants, IPFs can give markedly improved coagulation effects, and show many advantages such as low dosage, efficient sedimentation, lower sludge volume and flexibility to various water quality conditions [1][2][3]. Among the IPFs, polyaluminum chloride (PACl) is the most efficient, widely applied coagulant and has a mature production technology.…”

“…A previous paper discussed in detail the stability of pure Al 13 [3]. This paper aims to characterize Al 13 aggregates at various concentrations by using 27 Al-NMR, PCS, and Ferron assay in combination.…”

Evaluation of enhanced coagulation coupled with magnetic ion exchange (MIEX) in natural organic matter and sulfamethoxazole removals: The role of Al-based coagulant characteristic

“…Hydrolyzing Al (III) salts are presently a kind of widely used inorganic coagulants through the world [4,5]. It is generally believed that the coagulation performances of Al-based coagulants are greatly dependent on the hydrolyzed Al species, which are commonly divided into the monomeric and dimeric species (Al a ), the species with medium molecular weight (Al 13 /Al b ) and the colloidal or solid-phase species (Al c ) [6,7].…”