Mixed-Phase Ion-Exchangers from Waste Amber Container Glass

This study investigated the one-pot hydrothermal synthesis of mixed-phase ion-exchangers from waste amber container glass and three different aluminium sources (Si/Al = 2) in 4.5 M NaOH_(aq) at 100 °C. Reaction products were characterised by X-ray diffraction analysis, Fourier transform infrared spectroscopy, ²⁷Al and ²⁹Si magic angle spinning nuclear magnetic resonance spectroscopy and scanning electron microscopy at 24, 48 and 150 h. Nitrated forms of cancrinite and sodalite were the predominant products obtained with reagent grade aluminium nitrate (Al(NO₃)₃∙9H₂O). Waste aluminium foil gave rise to sodalite, tobermorite and zeolite Na-P1 as major phases; and the principal products arising from amorphous aluminium hydroxide waste were sodalite, tobermorite and zeolite A. Minor proportions of the hydrogarnet, katoite, and calcite were also present in each sample. In each case, crystallisation was incomplete and products of 52, 65 and 49% crystallinity were obtained at 150 h for the samples prepared with aluminium nitrate (AN-150), aluminium foil (AF-150) and amorphous aluminium hydroxide waste (AH-150), respectively. Batch Pb²⁺-uptake (~100 mg g^-1) was similar for all 150-h samples irrespective of the nature of the aluminium reagent and composition of the product. Batch Cd²⁺-uptakes of AF-150 (54 mg g^-1) and AH-150 (48 mg g^-1) were greater than that of AN-150 (36 mg g^-1) indicating that the sodalite- and tobermorite-rich products exhibited a superior affinity for Cd²⁺ ions. The observed Pb²⁺- and Cd²⁺-uptake capacities of the mixed-product ion-exchangers compared favourably with those of other inorganic waste-derived sorbents reported in the literature.