Determination of point of zero charge of PILCS with single and mixed oxide pillars prepared from Tunisian-smectite

Abstract

Different pillared interlayer clays (PILCs) with single oxide pillars of Cr and Al and mixed oxide pillars of these metals have been prepared from a Tunisian purified smectite (Hp): Several Al/metal, OH/metal and metal/clay ratios were used in order to investigate the effect on the chemical and physical properties, specifically the point of zero charge of the synthesized pillared clays. These chromium pillared clays compounds at n meq (Nitrate) and at n meq (Chlorite) are noted pillared clay and pillared clays \(Hp(20,40,60)_{NO_3 } \) and Hp(20,40,60)Cl. The structure of the pillared materials are studied by XRD and cationic exchange capacity, the textural property are investigated by the specific surface area SBET. The acid-base chemistry “surface acidity” of these products was analysed by using acid-base potentiometric in order to determine the PZC of each sample. The resulting materials exhibited basal spacings in the range of 13.96–21.13 A, with high surface areas (10.58–198 m2 g−1). Pillared clays prepared from Tunisian purified smectite showed an increase of basal spacings and surface areas. A relatively strong interaction between metal and aluminium in the pillars was observed. The samples are studied by acid-base potentiometric. This experimental method is used to determine the point of zero charge (PZC). The PZC values of the edge sites are 8.2 for Tunisian purified smectite and 6.8; 5.9; 5.19; 6.84; 5.86; 5.73; 6.78; 7.56 for the differents samples respectively: \(Hp(20,40,60meq)_{NO_3 } \) Hp(20,40,60meq)Cl; Hp-Cr/Al; Hp-Al.