Study On Adsorption And Thermodynamics Behavior Of Organic Acid Onto Crosslinked Chitosan Resin By Static Adsorptive Method

The adsorption behavior of formyl , acetic , propionic acid , chloroethanoic acid, dichloroethanoic acid, trichloroethanoic acid and oxalic acid adsorption with crosslinked chitosan resin in binary system was studied by the static adsorption method. The result showed than under the investigative conditions the equilibrium data for the adsorption except that of propionic acid were correlated with a Langmiur isotherm equation, and the equilibrium data for the adsorption with propionic acid was correlated with a Freudlich isotherm equation. When the temperature was increased, the adsorptive capacity for formyl,acetic,propionic acid, chloroethanoic acid and oxalic acid decreased, but that of trichloroethanoic acid increased. The changing of temperature had little effect on adsorption with dichloroethanoic acid onto crosslinked chitosan.The thermodynamics action showed the adsorption for formyl, acetic, chloroethanoic acid, dichloroethanoic acid and oxalic onto crosslinked chitosan absorbed heat,but the adsorption for trichloroethanoic acid released heat.By taking advantage of salt effect, the adsprption behavior and thermodynamics behavoir of chloroethanoin acid and trichloroethanoic acid adsorption onto crosslinked chitosan resin was studied in ternary system when salt or glucose was added as the medium. The experiment results showed the adsorptive capacity for chloroethanoic acid and trichloroethanoic acid was increased when salt was added;whereas it was decreased when glucose was added. With the increase of concentration ofsalt, the adsorptive capacity also was increased. When the medium was one of sodium chloride, sodium nitrate and sodium sulfate, salting-out effect was gradually transferred into salting-in effect ,so under the same temperature the adsorptive capacity was Q(Na₂SO₄)>Q (NaNO₃) >Q(NaCl).The adsorptive capacity of divalent salt( GaCl₂) was larger than that of monovalent salt (NaCl). The thermodynamics data showed there was the same thermodynamic behavior in ternary system compared with it in binary system.The study of mixed acid adsorption onto crosslinked chitosan resin showed when the concentration of acetic was fixed, the adsorptive capacity was increased with the increse of concentration of another acid. The reseach results about adsorption of benzoic acid and hydrobenzoic acid onto crosslinked chiotsan resin showed when the concentration of benzoic acid was fixed, the adsorptive capacity was declined with the increase of sobent. Compared the adsoptive capacity of benzoic acid,M-hydrobenzoic acid and O-hydrobenzoic acid, it was found that because of substitutional group effect, the adsorptive capacity was as follows: Q (benzoic)