Successive Extraction of As(V), Cu(II) and P(V) Ions from Water. Using Surface Modified Ghee Residue Protein

Transcription

1 Successive Extraction of As(V), Cu(II) and P(V) Ions from Water Using Surface Modified Ghee Residue Protein Linlin Hao a,b, Masoom Kartik Desai b, Peng Wang a, Suresh Valiyaveettil b* a State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, P. R. China 159 b Department of chemistry, National University of Singapore, 3 Science Drive 3, Singapore *Corresponding author, address: chmsv@nus.edu.sg (S. Valiyaveettil) Langmuir and Freundlich models The Langmuir equation assumes that adsorbates form continuous monolayer on energetically equivalent sites on the adsorbent. The expression was given as 1 : (1) where Q e (mg/g) is the equilibrium adsorption capacity, Q max (mg/g) is the maximum adsorption capacity, C e (mg/l) is the equilibrium arsenic concentration, KL is a constant related to the binding energy. The separation factor R L, as a characteristic parameter of this isotherm, is expressed as: (2) S1

2 The Freundlich model is usually seen as an empirical equation, which is based on the assumption that multilayer adsorption on an energetically heterogeneous surface 2. (3) where Q e (mg/g) is the amount of adsorbed arsenic per unit mass of the adsorbent at equilibrium, Ce (mg/l) is the equilibrium arsenic concentration, Kf, n are parameters related to the adsorption capacity and the intensity of adsorption. Kinetics Models The pseudo-first-order kinetic model is expressed as follows 3 : (4) where qt is the quantity of arsenic adsorbed at a time t (mg/g), qe the quantity of arsenic adsorbed at equilibrium (mg/g), k 2 (g mg -1 min-1 ) is the rate constant. The pseudo-second-order kinetic model was expressed as follows 3 : (5) (6) where q t is the quantity of arsenic adsorbed at time t (mg/g), q e the quantity of arsenic adsorbed at equilibrium (mg/g), k 2 (g mg -1 min -1 ) is the rate constant and v(mg g -1 min-1 )is the initial adsorption rate. Thomas model The model is described as the following equation 4 : S2

3 (7) where, C and C t are the influent and effluent concentrations (mg/l), q is the adsorption capacity (mg/g), kt is the Thomas model constant (ml/mg min), and t stands for total flow time (min). Q is the volumetric flow rate (ml/min). Values of k T and q are determined from the linear plot of ln[(c /C t)-1] against t. Table S1 Thomas model constants for As(V), Cu(II) and P(V) adsorption on Prot-PEI-Fe Elements Z (cm) v (ml/min) C (mg/l) k T (ml/mg min) q (mg/g) q exp (mg/g) R 2 As(V) Cu(II) P(V) S3

4 Figure S1- SEM images of Prot-PEI After PEI modification, the surface of pretreated protein became rough. The tiny pores and protuberance can be observed. The rough surface can significantly increase the surface area of Prot-PEI, thus enhancing the adsorption capacities for adsorbates. S4

5 Adsorption Capacity (mg/g) ph = 2 ph = 5 ph = 7 As(V) Cu(II) P(V) Fig. S2 The ph effect on successive adsorption of As(V)/Cu(II)/P(V) on Prot-PEI-Fe q e (mg/g) t 1/2 (min 1/2 ) Figure S3 - Weber and Morris Intra-particle diffusion plot of As(V), Cu(II) and P(V) adsorption on Prot-PEI-Fe. For As(V) and P(V), the plots are divided into the first phase and the second phase. ( ) As(V), ( ) Cu(II), ( ) P(V) ions. S5

6 ln (C /C t - 1) Time (min) Figure S4 - Linear Thomas model fit of breakthrough data for (A) As(V), (B) Cu(II)and (C) P(V) ions adsorption on Prot-PEI-Fe. ( ) As(V), ( ) Cu(II), ( ) P(V) ions. (----) indicates the Thomas model fitting curve. S6

7 2. (A) ln(q) y =.821x R² = ln(q) ln (t) y =.945x R² =.997 (B) ln (t) 2. (C) ln(q) y =.777x R² = ln (t) Figure S5 -Linear regression analysis for the adsorption of (A) As(V), (B) Cu(II) and (C) P(V) ions adsorption on Prot-PEI-Fe adsorbent.( ) As(V), ( ) Cu(II), S7

8 ( ) P(V) ions. Adsorption capacity (mg/g) Adsorption capacity (mg/g) First regeneration Second regeneration (A) 25 5 Initial conc. (mg/l) First regeneration Second regeneration (B) 25 5 Initial conc. (mg/l) Adsorption capacity (mg/g) First regeneration (C) Second regeneration 25 5 Initial conc. (mg/l) Figure S6 - Regeneration of (A) As(V), (B) Cu(II)and (C) P(V) ions adsorption on S8

9 Prot-PEI-Fe surface. REFERENCES 1. Fu, J.; Chen, Z.; Wang, M.; Liu, S.; Zhang, J.; Zhang, J.; Han, R.; Xu, Q., Adsorption of methylene blue by a high-efficiency adsorbent (polydopamine microspheres): kinetics, isotherm, thermodynamics and mechanism analysis. Chem. Eng. J. 215, 259, Umpleby, R. J.; Baxter, S. C.; Bode, M.; Berch, J. K.; Shah, R. N.; Shimizu, K. D., Application of the Freundlich adsorption isotherm in the characterization of molecularly imprinted polymers. Anal. Chim. Acta 21, 435, Ho, Y.-S.; McKay, G., Pseudo-second order model for sorption processes. Process Biochem. 1999, 34, Han, R.; Wang, Y.; Zou, W.; Wang, Y.; Shi, J., Comparison of linear and nonlinear analysis in estimating the Thomas model parameters for methylene blue adsorption onto natural zeolite in fixed-bed column. J. Hazard. Mater. 27, 145, S9