Mixed-Phase Ion-Exchangers from Waste Amber Container Glass

Abstract

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.

Calcium Silicate Hydrate Cation-Exchanger from Paper Recycling Ash and Waste Container Glass

“…Irrespective of color, the typical major oxide components of soda-lime-silica container glasses are SiO 2 (70-75 wt%), Na 2 O (12-16 wt%), CaO (5-15 wt%), and Al 2 O 3 (1-5 wt%), which provide a potentially reactive source of amorphous calcium, silicate, and aluminate species in the following molar ranges: 0.13 < [Ca]/[Si+Al] < 0.23 and 0.015 < [Al]/[Si+Al] < 0.078 [17][18][19][20][21]39,64]. Optimal [Ca]/[Si+Al] ratios for tobermorite formation have been obtained by supplementing the WCG reaction mixture with lime [17][18][19]21,39] or cement bypass dust (CBD) [20]. Mixtures of WCG and lime require additional alkalinity, such as sodium hydroxide, to depolymerize and dissolve the silicate network [17][18][19]21,39], whereas CBD possesses sufficient intrinsic alkalinity to activate the glass [20].…”

“…Optimal [Ca]/[Si+Al] ratios for tobermorite formation have been obtained by supplementing the WCG reaction mixture with lime [17][18][19]21,39] or cement bypass dust (CBD) [20]. Mixtures of WCG and lime require additional alkalinity, such as sodium hydroxide, to depolymerize and dissolve the silicate network [17][18][19]21,39], whereas CBD possesses sufficient intrinsic alkalinity to activate the glass [20].…”

“…Many studies have been carried out to upcycle this WCG into value-added products such as sorbents, ion-exchangers, catalysts, ceramics, geopolymers, and construction materials [57,[59][60][61][62][63][64][65]. WCG has also been used as a feedstock for the preparation of tobermorite in alkaline media [17][18][19][20][21]39].…”

Waste Glass-Derived Tobermorite Carriers for Ag+ and Zn2+ Ions

“…Despite the theoretical potential to recycle up to 90% of container glass, approximately 200 Mt of post-consumer soda-lime-silica glass is landfilled per annum [1]. The failure to effectively recycle container glass arises from various technical, geographical, and economic barriers, particularly compositional heterogeneity, wide dispersal coupled with poor collection infrastructure, inadequate separation from other wastes, and lack of regional demand [2][3][4][5].…”

“…Recent research to explore alternative options to upcycle waste container glass (also known as cullet) into value-added products includes the production of zeolites [2][3][4][6][7][8][9][10], silicate minerals [5,[11][12][13][14][15][16], geopolymers [17][18][19], and ceramics [20][21][22] for applications in catalysis, sorption/separation technology, and construction. In this respect, several studies have utilized a facile one-pot hydrothermal method to synthesize the layer-lattice calcium silicate phase, 11Å tobermorite (Ca 5 Si 6 O 16 (OH) 2 •4H 2 O), from a mixture of waste glass cullet and lime or other calcium-bearing wastes [2,5,[11][12][13][14]23]. The waste glass-derived tobermorite products have demonstrated high cation exchange capacities for a range of heavy metal contaminants [5,[11][12][13] and basic catalytic properties for organic condensation reactions [23].…”