Supplementary material for

Enhanced stability and dissolution of CuO nanoparticles by extracellular polymeric substances in aqueous environment

Lingzhan Miao1,2, Chao Wang1,2, Jun Hou*1,2, Peifang Wang 1,2, Yanhui Ao1,2, Yi Li1,2, Bowen Lv1,2, Yangyang Yang1,2, Guoxiang You1,2, Yi Xu1,2

1. Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, People’s Republic of China, 210098

2. College of Environment, Hohai University, Nanjing, People’s Republic of China, 210098

*Corresponding author. Address: College of Environment, Hohai University

Contents

3 pages, 2 tables.

EPS production and extraction technique

The sequencing batch reactor(SBR) used in this study had an internal diameter of 10 cm and an effective height of 20 cm, with a working volume of 1.5 L. A peristaltic pump was used to feed the influent into the reactor. The SBR was operated daily in 6 h cycles consisting of 0.1 h of influent addition, 5.4 h of the aerobic stage, 0.4 h of settling, and 0.1 h of effluent withdrawal and the volume exchange ratio was 50%. Fine air bubbles were supplied at a flow rate of 1.8-2.0 L/min through a dispenser set at the bottom of the reactor. The temperature was maintained at about 20-22 °C and the pH was controlled at 7.0-7.5. The synthetic wastewater used in the SBR contained 1060 mg/L of glucose, 90 mg/L of NH4Cl, 400 mg/L of K2HPO4•3H2O, 360 mg/L of KH2PO4•2H2O, 12 mg/L of CaCl2•2H2O, 50 mg/L of MgSO4, MgSO4 50 mg/L of MgSO4, 8 mg/L of MnSO4•H2O, 2 mg/L of ZnSO4•7H2O, 1 mg/L of CuSO4•5H2O, and 1 mg/L of (NH4)6MoO24•4H2O.

Extracellular polymeric substances were extracted according to the method reported by Xu et al. (2013).Briefly, sludge samples were collectedfrom the SBR and centrifuged at 2500g for 10 min. The residues were recovered and re-suspended in Milli-Q water and then heated at 60°C for 30 min. After that, the suspensions were centrifuged at 12000g for 20 min. The supernatants after filtration through 0.22μm acetate cellulose membraneswere freeze-dried and used as EPS in subsequent experiments.

Table S1

Summary of CuO nanoparticle properties.

Parameter / Value
Density (g/cm3) / 6.372
Vendor reported size (nm) / 60-100
TEM particle size-measured (nm) / 89±12
DLS HDD-measured in Milli-Q water (nm) / 270±34
BET specific surface area-measured (m2/g) / 29 ± 3
Isoelectric point (IEP) / 6.5
Zeta potential (mV) in Milli-Q water(pH = 7) / -14.8
Purity by ICP-MS (wt%) / 98.21

Table S2.

Main functional groups of alginate, BSA, and EPS observed in the FT-IR spectra.

Representative NOM / Wavenumber/cm-1 / Vibration
Alginate / 3451 / vibration of –OH in water
1618 / asymmetric vibration of COO-
1413 / C-H bending and C-N stretching
1087 / C-O-C stretching
BSA / 3442 / –OH and –NH2 stretching
1655 / C=O and C-N stretching(amide I)
1544 / N-H bending and C-N stretching(amide II)
1399 / C-H bending and C-N stretching
1085 / C-O-C stretching
EPS / 3407 / –OH and –NH2 stretching
2962 / C-H stretching
1638 / C=O and C-N stretching(amide I)
1458 / C-H bending and C-N stretching
1405 / C-H bending and C-N stretching
1260 / C-O deformation
1081 / C-O-C stretching