Arsenic and Copper Stabilisation in a Contaminated Soil by Coal Fly Ash and Green Waste

Arsenic and Copper Stabilisation in a Contaminated Soil by Coal Fly Ash and Green Waste Compost

Daniel C.W. Tsang1,2,*, Alex C.K. Yip3, William E. Olds1,4, Paul A. Weber4

Supplementary Material:

NMR Analytical Method

Table SM-1. Physicochemical Characteristics of Coal Fly Ash and Bentonite

Table SM-2. Elemental Composition of Green Waste Compost and Lignite

Table SM-3. Carbon Distribution of Green Waste Compost and Lignite

Figure SM-1. Solid-state 13C NMR spectra of the carbonaceous stabilisers.

11 Department of Civil and Natural Resources Engineering, University of Canterbury, Christchurch 8140, New Zealand. 22 Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China. 3 Department of Chemical and Process Engineering, University of Canterbury, Christchurch 8140, New Zealand. 4 Solid Energy New Zealand, Private Bag 1303, Christchurch 8140, New Zealand. * Corresponding author (email: [email protected], phone: 852-2766-6072, fax: 852-2334-6389). 1 NMR Analytical Method For NMR analysis, the samples were acid-washed with 1 M HCl at 80 L kg -1 for 48 h and repeated for ten times to minimise iron interference with NMR. The oven-dried samples (0.26-0.29 g) were packed into 7 mm diameter Doty MAS rotors and spun at speeds of 5.0 ±0.3 kHz in a dual resonance magic angle-spinning (MAS) probe from Doty Scientific. During acquisition the sample temperature was maintained at 20oC. The 13C CP-MAS spectra were acquired with a 1H 90o pulse of 5.5 µs, a cross-polarisation contact time of 900 µs, an acquisition time of 20 ms, and a relaxation time of 1 s. Scans were either at 8 or 16 k accumulations, depending on the carbon concentration of the sample to achieve a satisfactory signal-to-noise ratio. All 13C spectra were referenced externally against glycine and processed with MestReNova (version 6.03) NMR processing Software (Mestrelab Research Ltd, Spain). The integrated peak areas between specific spectral bands were calculated to determine the distribution of structural carbons (Olds et al., 2013; Wang and Tsang, 2013). All analyses were run in duplicates to ensure reproducibility.

2 Table SM-1. Physicochemical Characteristics of Coal Fly Ash and Bentonite

Major Oxides (wt%) a Mineralogy (wt%) b Surface Area (m2 g-1) c Coal Fly Ash Ca (13.6%) / Si (9.1%) / Fe (6.2%) / Al (2.2%) Fe (39%), Al (30%), quartz (14%), 211.6 merwinite (12%), calcite (4%), portlandite (2%)

Bentonite Si (24.7%) / Fe (8.9%) / Al (7.9%) / Ca (1.6%) kaolin (44%), illite (29%), quartz (15%), 42.9 calcic plagioclase feldspar (12%) a Measured by borate fusion X-ray fluorescence spectrometry and loss on ignition at 1000°C for 1 h; b Determined by X-ray diffraction and SIROQUANT search/match programme for phase identification and semi-quantification (quartz – SiO 2; calcite –

CaCO3; calcic plagioclase feldspar – Ca(Al2Si2O8)); kaolin – Al2(Si2O5)(OH)4; illite – K0.5(Al,Fe,Mg)3(Si,Al)4O10(OH)2; merwinite – Ca3Mg(SiO4)2; portlandite – Ca(OH)2); c Calculated by using nitrogen gas adsorption isotherm at 77.3 K and BET equation.

3 Table SM-2. Elemental Composition of Green Waste Compost and Lignite

C a H a O a N a S a Green Waste Compost 24.2% 2.82% 24.8% 2.13% <0.3% Lignite 57.7% 5.14% 31.1% 0.73% <0.3% a Weight percent, measured by Elementar Combustion Analyzer.

4 Table SM-3. Carbon Distribution of Green Waste Compost and Lignite

Aliphatic a Carbohydrate Aromatic a Phenolic a Carboxylic a Carbonyl a (0-48 ppm) a (50-100 ppm) (100-140 ppm) (140-165 ppm) (165-190 ppm) (190-220 ppm) Green Waste Compost 25.3% 31.7% 22.3% 10.6% 8.8% 1.3%

Lignite 33.8% 17.0% 30.2% 12.1% 4.9% 2.0% a 13C CP-MAS solid-state NMR spectra were acquired by using Bruker AMX 200Mhz horizontal bore MRI system.

Figure SM-1. Solid-state 13C NMR spectra of the carbonaceous stabilisers: (a) green waste compost; (b) lignite.