Quaternary ammonium groups were grafted onto ligno-cellulosic material (cotton, wood sawdust, and maize-cob flour) to obtain a support able to adsorb oxyanions containing chromium atoms (chromate and dichromate). For both anions in aqueous solutions, adsorption proceeded very quickly and reached a limit value dependent on the rate of ammonium grafting; at saturation, the Cr/N ϩ ratio was always close to 1/1 for chromate anions, but two ammonium sites were needed to link a dichromate anion in a stable structure, resulting in the same 1/1 Cr/N ϩ ratio. Tentatives for modeling the adsorption process were performed with the Langmuir, Freundlich, and Jossen equations. A nearly total desorption occurred only when these saturated supports were treated with solutions of high ionic strength (4M potassium chloride).

For use as an ion exchanger, a cationized nylon (EPTMAC-nylon) was prepared by reacting nylon-6,6 with epoxy propyl trimethyl ammonium chloride (EPT-MAC), using anhydrous tin chloride (SnCl 2 ) as catalyst in a nonaqueous medium. Evidence of grafting was provided by atomic force microscopy and the exchange capacity of EPT-MAC-nylon was evaluated by potentiometric titration. The adsorption of four dyes (Acid Blue 25, Acid Yellow 99, Reactive Yellow 23, and Acid Blue 74) from aqueous solutions using a batch process was studied according to the adsorption capacity of the cationized support. The effect of experimental parameters such as dye concentration and adsorption temperature were analyzed. The adsorption isotherms were determined at different temperatures and modeled using Langmuir, Freundlich, and Jossens equations.

Oleic acid and its salts are present among the toxic pollutants in olive oil mill wastewaters. Four lignocellulosic materials modified by grafting quaternary ammonium groups have been tested for the adsorption of the oleate anion from aqueous solutions, viz. cotton fibres, viscose fabric, wood sawdust and maize cob powder. As a result of their strong ionic interactions, the carboxylate moities were entrapped at a rate equivalent to the ammonium content of the support. Furthermore, when this charged support was left in contact with the polluted solution without agitation, an additional quantity of pollutant was adsorbed due to associations by the hydrophobic tails of the oleate moities. Partial desorption was achieved in 1 M HCl solution.

Cationized lignocellulosic materials (cotton fibers, wood sawdust, and maize-cob flour) are prepared by grafting quaternary ammonium groups for use as scavengers for anionic surfactants. Generally, rapid adsorption occurs and at saturation leads to a stoichiometric ratio of cationic sites and anionic surfactants such as sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, and sodium oleate. Modeling of these adsorptions is tested using Langmuir, Freundlich, or Jossens equations, the latter giving the best fit with experimental data. The results are compared with the adsorption of chromate and dichromate anions on the same sorbents.

As reported in Part I of this study, anionic surfactants are rapidly adsorbed and strongly retained on cationized lignocellulosic materials as a result of ionic interactions. Consequently, the initially hydrophilic surface of the sorbent is strongly modified by the adsorbed surfactant molecules. Hydrophobic interactions with this modified surface allow a second layer of surfactant molecules to be adsorbed via their alkyl chains. Many combinations are possible with different kinds of surfactants, with the highest adsorption capacity being obtained when zwitterionic surfactants are involved in the second step.