betadex and terics

A study of adsorption/recovery of nonylphenol 9 mole ethoxylate (NP9EO) on a crosslinked beta-cyclodextrin-carboxymethylcellulose (beta-CD-CMC) polymer was carried out by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies. The adsorption was performed in mixtures containing 500 mg of the beta-CD-CMC polymer and aqueous NP9EO solutions at concentrations 12-82 mg/L, whereas the recovery of NP9EO was effectuated by shaking the beta-CD-CMC polymer loaded with methanol. The assays were made at 25 degrees C and atmospheric pressure under agitation. The results have shown that the adsorption is a rapid process and the beta-CD-CMC polymer exhibits a high NP9EO adsorption capacity of 83-92 w% (1.1-6.8 mg NP9EO/g beta-CD-CMC polymer) dependent of the initial NP9EO concentration in liquid phase. This adsorption may involve the formation of an inclusion complex beta-CD-NP9EO and a physical adsorption in the polymer network. The adsorption equilibrium measurements, which were analyzed using the Langmuir isotherm, have indicated a monolayer coverage and the homogeneous distribution of active sites at the surface of the beta-CD-CMC polymer. Moreover, the negative value obtained for the free energy change (-13.2 kJ/mol) has indicated that the adsorption process is spontaneous. In parallel, the beta-CD-CMC polymer exhibited a high NP9EO recovery efficiency of 97 w% that may occur through a decrease of binding strength between beta-CD-CMC polymer and NP9EO. Together, these results suggest that the beta-CD-CMC polymer could constitute a good adsorbent for removing nonylphenol ethoxylates from wastewater due to its high adsorption capacity and non-toxic character of beta-CD and CMC to environment.

Topics: Adsorption; beta-Cyclodextrins; Carboxymethylcellulose Sodium; Ethylene Glycols; Molecular Structure; Polymers; Waste Disposal, Fluid; Water; Water Pollutants, Chemical; Water Purification

A study of inclusion complexation of liquid non-ionic surfactants, nonylphenol (NP) and nonylphenol 9 mole ethoxylate (NP9EO), with beta-cyclodextrin (beta-CD), was carried out by mass spectrometry, surface tension, and ultraviolet-visible (UV-VIS) and Fourier transform infrared (FTIR) spectroscopies. The inclusion complexation was effectuated by heating at 80 degrees C and filtration of aqueous NP+beta-CD and NP9EO+beta-CD suspensions. The mass spectrometry and surface tension measurements revealed that NP and NP9EO form inclusion complexes with beta-CD and beta-CD possesses a higher affinity for NP. These results are supported by the data from UV-VIS spectroscopic analyses that have indicated that a three times greater amount of NP is entrapped into beta-CD than NP9EO. This phenomenon has been associated with the smaller size and a higher degree of hydrophobicity of NP that favours its entrapment into beta-CD as compared to that of NP9EO. At the structural level, the data from FTIR spectroscopic study have indicated that alkyl chains of NP and NP9EO can form van der Waals interactions with the cavity of beta-CD. Moreover, NP and NP9EO seem to cause a reorganization of the intramolecular hydrogen bonds and change of the hydration of beta-CD, but did not appear to strongly interact with C-C, C-O-C, and OH groups of beta-CD. Together these results suggest that the formation of inclusion complexes by NP and NP9EO with beta-CD molecules could constitute an effective and advantageous technique to remove liquid non-ionic surfactants from wastewater due to the non-toxic character of beta-CD to humans and the environment.

Topics: beta-Cyclodextrins; Ethylene Glycols; Mass Spectrometry; Phenols; Solutions; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Surface Tension