Smectite, organoclay

D. Siptak. Smectite organoclay chemistry organically modified bentonite reacted with organic cations. Chemistry and Manufacture of Cosmetics (3rd edn) (2002), 3(Bk 2), 845-855. 

Fig. 2. Diagram showing the intercalation of compact quaternary ammonium cations, such as trimethylphenylammonium (TMPA) into different smectites, giving rise to type I organoclays with a basal spacing of about 1.5 nm. SWa is a high-charge nontronite (iron-rich smectite) and SAz is a high-charge montmorillonite, while SAC is a low-charge montmorillonite. After Jaynes and Boyd (1991b).

Another feature of the process is that the sorption capacity of type II organoclays is inversely related to the aqueous solubility of the NOCs (Chiou 1989). For example, the affinity of HDTMA-smectite for various phenols increases in the order phenol < chlorophenol < dichlorophenol < trichlorophenol since phenol is the most water-soluble while trichlorophe-nol is the most hydrophobic (Mortland et al. 1986, Lo et al. 1998). The relationship between the distribution (partition) coefficient in a type II organoclay and water-solubility is illustrated in Fig. 5 for a range of nonionic organic pollutants. 

Carrizosa MJ, Hermosin MC, Koskinen WC, Cornejo J (2004) Interactions of two sulfonylurea herbicides with organoclays. Clays Clay Miner 52 643-649 Celis R, Hermosin MC, Cornejo J (2000) Heavy metal adsorption by functionalized clays. Environ Sci Technol 34 4593-4599 Chappell MA, Laird DA, Thompson ML, Li H, Teppen BJ, Johnston CT, Boyd SA (2005) Influence of smectite hydration and swelling on atrazine sorption behavior. Environ. Sci Technol 39 3150-3156 Chiou CT (1989) Theoretical considerations of the partition uptake of nonionic organic compounds by soil organic matter. In Sawhney BL, Brown K (eds) Reactions and movement of organic chemicals in soils. Soil Science Society of America, Madison, WI, pp 1-29... 

Glucose oxidase Polyphenol oxidase from mushroom Organoclay natural Cameroonian smectites grafted with either aminopropyl or trimethylpropylammonium groups. Modified electrodes [40]... 

Most commercial organoclays are made from mont-morillonite or hectorite. Clays are also referred to as bentonites. This is actually the name given to the ore from which the smectites are extracted. 

The preparation of organoclays is fairly standard. A slurry of purified smectites in water is made up and stirred to maintain good agitation. A quaternary ammonium salt is then added to this stirring slurry. After the exchange, the organoclay is filtered and dried. A number of process adjustments and improvements have been patented, mostly concerned with improving the efficiency or consistency of the finished product. 

In another study were investigated the effects of phenol in adsorptive organoclay with different characteristics. The adsorption experiments were performed in batch with 0.2 g of modified clay with 22 mL of phenol solution at pH 7 for 4 h. The equilibrium time, in preliminary studies pointed 2 h. The results showed the influence of modified clays in adsorptive power. According to the author, a change in the smectite interlayers increased the effectiveness of interactions between the phenol and the organoclay. Therefore, this clay is an effective adsorbent material for removal of nonionic organic compounds (Shen, 2005). 

Fig. 7.5 Multisweep cyclic voltaramograms recorded at 0.05 Vs in 0.1 M NaCl solution containing 1.5 mM [Fe(CN)6] or 1.5 mM [RuCNHsle] Signal recorded on (a, c) native smectite clay and (b, d) the relevant organoclay. The dotted line on (a) and (d) represents the signal of [Fe(CN)6] and [RuCNHsle] respectively, on the bare glassy carbon electrode (Reproduced from Ref. [15] with the permission of Elsevier)...

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