Metal-modified silica adsorbents for removal of humic substances in water

Adsorbability and photocatalytic degradability of humic substances in water on Ti-modified silica

“…Charcoal (activated, powder) and titanium tetraisopropoxide (Ti(OPr-i) 4 ) were purchased from Wako Pure Chemical Industrial Co. (Osaka, Japan) and used without purification. In humic substances, Wako humic acid (Wako-HA) was purchased from Wako Pure Chemical Industrial Co. and used after purification by a reprecipitation method [2]. Nordic aquatic humic acid (Nordic-HA), Nordic aquatic fulvic acid (Nordic-FA), and Suwannee river fulvic acid (Suwannee-FA) were purchased from the International Humic Substances Society (IHSS) and used without purification.…”

“…As removal agents for humic substances in aqueous media, we have reported on silica adsorbents modified with Fe, Mg, and Ca [2]. Particularly, Fe-modified silica SiO 2 -Fe exhibited the highest adsorption capacity.…”

ADSORBABILITY AND PHOTO-FENTON REACTIVITY OF AQUATIC HUMIC SUBSTANCES WITH Fe(III)-TREATED HYDROXYAPATITES IN WATER

“…7) exhibited the highest rate in adsorption of SFA among the all adsorbents but lower rate in adsorption of NHA among them except for the case of HAP-400. Charcoal bears many fine pores, of which diameter is 3-4 nm, 13,28 on the surface to introduce various molecules into its pores by physical adsorption. 12 The order of adsorption rates in charcoal was SFA > NFA > NHA (TABLE 2), which is closely related with the molecular sizes, or predictive Mw (TABLE 1): The smaller molecule is easier to be adsorbed.…”

Humic acid sorption properties of calcium-rich derivatives of Neapolitan Yellow Tuff

“…Moreover, the treatment of HS-containing water with chlorine may produce toxic by-products such as CHCl 3 , a known human carcinogen. Many methods have been developed to remove humic substances from water in drinking water treatment plants: coagulation/flocculation separation, ion exchange, adsorption by activated carbon and membrane filtration are among the most common [1,2]. In recent years, other adsorbing materials have been proposed as HS-removing agents, including metal-modified silica gel, metal oxides (prevalently goethite) and aluminosilicate materials such as clay minerals and zeolites [3,4].…”

“…In recent years, other adsorbing materials have been proposed as HS-removing agents, including metal-modified silica gel, metal oxides (prevalently goethite) and aluminosilicate materials such as clay minerals and zeolites [3,4]. It has been shown that thermal treatment of a mixture containing magnesium, calcium or iron (III) salts and silica gel gives a silica gel derivative, containing metal atoms strongly linked to the silica surface, which are able to bind HS [2]. Goethite (α-FeOOH), a crystalline monohydrate form of ferric oxide, can interact with the carboxylic and phenolic groups of HS by means of the surface metal ions, giving almost irreversible adducts [5].…”