Organo-clays (hexadecil trimethyl ammoniun and gelatin-Montmorillonite) as Humic Acid adsorbents

M. FERNANDEZ; J. ZHU; R. M. TORRES SÁNCHEZ

Rio de Janeiro

Conferencia; XV International Clay Conference; 2013

The use of organoclays, from quaternary ammonium molecules (as hexadecyltrimethylammonium, HDTMA) and montmorillonite (MMT) or hectorites clays, have shown significant improvements in polymers properties such as mechanical, thermal and gas barrier [Paul et al., 2005; Lepoittevin et al. 2002; Gorrasi et al., 2003). Also, organoclays had also been used in remediation where nonpolar organic molecules as pesticides generated the water pollution (Celis et al., 2007). The organoclays, from gelatin montmorillonite, could be also associated to treat pesticides groundwater contamination, being these organoclays ore environmentally friendly than those obtained from quaternary ammonium molecules. Remotion of organic matter (or humic acid) by clays from water was largely studied. In addition, the hydrophobic character of a surface with long alkyl chains result from a complex interplay between the structure of carbon chains and the interactions of polar areas humic acid. From this behavior organoclays, (from gelatinMMT and gelatinHDTMAMMT) are proposed for the adsorption of organic matter, using as a model molecule the humic acid (HA). To attain this, 2 and 10% gelatin was added to MMT suspensions to obtain G2MMT and G10MMT samples and HDTMA bromide concentration corresponding to 1 CEC of the MMT originated the HDTMAMMT sample. A fraction of the HDTMAMMT was also exchanged with 2% gelatin (G2HDTMAMMT). All products were characterized by XRD, apparent diameter and Zeta potential curves. The d (001) spacing of G2MMT and G2HDTMAMMT samples respect to that of MMT, showed an increase of 1.58 and 1.87 nm, respectively, indicating the insertion of the respective organic molecules. The subsequent adsorption of HA, showed no significant interlayer change. The presence of gelatin in G2, G10MMT+ HA and G2HDTMAMMT+ HA samples showed asorption decrease of around 20% respect to that achieved in MMT+AH sample, while for G10HDTMAMMT+ HA, adsorption was close to that for MMT+HA sample. Dapp values, indicative of tactoid?s agglomeration, for G2MMT+ HA samples maintain the same relative increase and approximate values to than found for G2MMT. While in G2 and G10MMTHDTMA+ HA samples, the gelatin increase generated a strong agglomeration, reducing the Dapp values of G10MMTHDTMA+ HA sample twice over that found for G2HDTMAMMT+ HA and more than 58 times compared to G10HDTMAMMT, assigned to electrostatic attractions of the organic compounds on the surface of the initial MMT. The favorable agglomeration of these new adsorbents could to advantage the coagulation process and streamline the process of separation. The zeta potential values of G2 and G10MMT+ HA samples were similar to the respective samples without HA, while the HA sorption. In the samples G2MMTHDTMA+ HA and G10HDTMAMMT+ HA produced an increase of negative charge and a sign change, respect to the corresponding samples without HA.