Bùi Minh Quý và Đtg Tạp chí KHOA HỌC & CÔNG NGHỆ 178(02): 15 - 18
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COMPARISON BETWEEN SINGLE AND BINARY ADSORPTIONS
OF LEAD (II) AND CADMIUM (II) IONS
ONTO POLYANILINE – PEANUT SHELL COMPOSITE
Bui Minh Quy*, Vu Quang Tung, Pham Thi Thu Ha University of Science - TNU
ABSTRACT
The adsorption using polyaniline (PANi) - peanut shell (PS) composite for removal of Pb (II) and Cd (II) from aqueous solution was studied. The experimental adsorption data fitted into Langmuir adsorption isotherm models for both single and binary adsorption systems. The adsorption of Pb (II) onto PANi/PS was better than Cd (II) for both the single and binary systems. In single systems, the maximum capacity of lead (II) ion and cadmium (II) ion were 26.53 mg/g, 23.75 mg/g. In binary systems, the maximum capacity of them were lower than that in single systems. They were calculated follow Langmuir competitive adsorption isotherm models of 13.11 mg/g for Pb (II), of 1.31 mg/g for Cd (II).
Keywords: Polyaniline – peanut shell composite, Cd (II) adsorption, Pb (II) adsorption, Langmuir adsorption isotherm, Langmuir competitive; binary adsorption
INTRODUCTION *
Lead or cadmium is one of the most toxic heavy metals for not only human but also animals [4]. These belong into industrial waste. There are many methods for removing them from wastewater, one of them is adsorption method. These studies usually remove mono ion from wastewater, such as:
adsorption lead (II), adsorption cadmium (II) by polyaniline and rice raw composite [1], adsorption cadmium (II) onto peanut – polyaniline nanocomposite [9]. However in practice, industrial waste water usually contains more than one metal ion. Thus, the study of adsorptions of heavy metal ions from single and binary system is important.
The main objective of this work is to study the mono adsorption isotherms for lead (II), cadmium (II) ions and study the binary adsorption of these ions onto PANi-peanut shell (PANi/PS) composite.
EXPERIMENTAL Single adsorption studies
The PANi/PS composite was synthesized like references [1] and [2]. The adsorbent was belong to type of fiber. It has size in nano range [1,2]. The experiments for removing
*Tel: 0915 836448, Email: bminhquy09@gmail.com
lead (II) and cadmium (II) ions from waste water were studied under the determine conditions. In each case, the volume of solution was 50 ml, pH of 6, shaking rate of 150 rpm, PANi/PS composite mass of 20 mg, contact time of 40 minutes. The initial metal ion concentrations were varied from 10 to 100 mg/l.
Binary adsorption studies
For the effect of ions Pb (II) and Cd (II) ions each other during their adsorption onto PANi/PS composite, solution of Pb – Cd combination were prepared in the concentration ratios of 0:5, 1:4; 2:3; 1:1; 3:2; 4:1; 5:0. The volume of solution was 50 ml, pH of 6, shaking rate of 150 rpm, PANi/PS composite mass of 20 mg, contact time of 40 minutes.
Pb (II) and Cd (II) concentrations in solution before and after adsorption onto that composite were analysed by Atomic Absorption Spectroscopy (AAS) from which the adsorption amount could be calculated.
The adsorption capacity (qt, mg/g) and the removal efficiency (H, %) were obtained owing to the following equations:
( 0 t)
t
C C V
q m
(1)
0 0
( )
.100%
C C
tH C
(2)
Bùi Minh Quý và Đtg Tạp chí KHOA HỌC & CÔNG NGHỆ 178(02): 15 - 18
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where C0 and Ce are the concentration of Pb(II) (mg/l) initially and at equilibrium; V is the initial volume of the solution (ml), m is the mass of adsorbent (g).
The Langmuir adsorption isotherms were used to analyse the equilibrium data. The generalized and linearized isotherm equations are shown in table 1.
Table 1. Adsorption isotherm equations [6,7,8]
Isotherm Generalized form Linearized form
Langmuir e
1
ee m L m
C C
q q K q
Langmuir competitive
where, KL is Langmuir isotherm constant (l/mg), qe, qm are the adsorption capacity at equilibrium and maximum adsorption capacity (mg/g), KLi, KLj are Langmuir isotherm constant of ion i, j (l/mg), qei, qmi are the adsorption capacity at equilibrium and maximum adsorption capacity of ion i onto PANi/PS (mg/g).
RESULTS AND DISCUSSION Single adsorption systems
Figure 1. Langmuir plots for the adsorption of Pb (II) and Cd (II) onto PANi/PS
Figure 1 showed the linearized Langmuir plots for Pb (II) and Cd (II) ions adsorption onto PANi/PS. Table 2 showed the mono adsorption parameters. The correlation coefficients (R2 = 0.99) showed that the adsorption of Pb (II) and Cd (II) ions onto PANi/PS fitted to Langmuir adsorption isotherm. The maximum adsorption of Pb (II) (qm = 26.53 mg/g) is larger than Cd (II) (qm =
23.75 mg/g) showed that PANi/PS adsorbed Pb (II) better than Cd (II).
Table 2. Mono adsorption parameters of Langmuir isotherm
Metal ion qm (mg/g) KL (l/mg) R2
Pb (II) 26.53 3.97 0.99
Cd (II) 23.75 0.07 0.99
Binary adsorption system
Effect of the removal efficiency of Cd (II) and Pb (II) ions in binary adsorption solution was given in figure 2. The results showed that the adsorption of lead ion higher than that of cadmium ion in the solution containing both of them.
The results given in figure 3, figure 4 and table 3 showed that the R2 values of linear lines were very high (R2 > 0.95). Therefore, the binary adsorption system of lead and cadmium ions onto PANi/PS was well followed the Langmuir competitive isotherm model.
Figure 2. The removal efficiency of Cd (II) and Pb (II) ions in binary adsorption solution
Bùi Minh Quý và Đtg Tạp chí KHOA HỌC & CÔNG NGHỆ 178(02): 15 - 18
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onto PANi/PS
Figure 4. Binary adsorption of Cd (II) in Pb (II) onto PANi/PS
Table 3. Langmuir competitive model parameters onto PANi/PS
Metal ion q*m (mg/g) *b/b R2 qm* /qm
Pb/Cd 13.11 0.23 0.99 0.49
Cd/Pb 1.31 6.43 0.96 0.06
(*b/b specifies the ratio of the b parameter of the interfering metal ion to that being adsorbed b [6]) The result in table 3 showed the adsorption
capacity of Pb (II) (qm
* = 13.11 mg/g) was larger than Cd (II) (qm
* = 1.31 mg/g). These adsorption capacities were less than its in single system. Cause the ratio qm*/qm < 1 for both Pb (II) and Cd (II), system was antagonism, That means the effect of mixture is less than that of each individual adsorbate in the mixture [3,6,7,8].
The ratio *b/b value of Pb/Cd (0.23) was lower than Cd/Pb (6.43), that means the effect of Cd (II) to adsorbed Pb (II) was smaller than that of Pb (II) to adsorbed Cd (II) in mixture [3, 5, 8]. This indicated that the adsorption of Pb (II) was more favourable than the adsorption of Cd (II) onto PANi/PS in the binary adsorption system.
CONCLUSION
The adsorption using polyaniline - peanut shell composite for removal of Pb (II) and Cd (II) from aqueous solution was fitted to Langmuir adsorption isotherm models for both the single and binary systems. The competitive adsorption of Pb (II) was stronger than Cd (II) in binary system. The adsorption of Pb (II) onto PANi/PS was better than Cd (II) for both the single and binary systems.
REFERENCES
1. Phan Thi Binh, Pham Thi Tot, Mai Thi Thanh Thuy, Mai Thi Xuan, Bui Minh Quy, Nguyen The Duyen, (2013), “Nanostructured composite based on polyaniline and rice raw for removal of lead (II) and cadmium(II) from solution”, Asian Jounal of Chemistry, 25(14), pp. 8163-8168.
2. Bùi Minh Quý, Vũ Thị Thái Hà, Vũ Quang Tùng, Nguyễn Như Lâm, Đào Việt Hùng, (2012),
“Nghiên cứu khả năng hấp phụ Cd(II) của compozit polyanilin – vỏ lạc”, Tạp chí Khoa học và Công nghệ - ĐHTN , 96(08), pp. 85 – 89.
3. A.G.El-Said, N. A. Badawy, S.E. Garamon, (2012), “Adsorption of Cadmium (II) and Mercury (II) onto Natural Adsorbent Rice Husk Ash (RHA) from Aqueous Solutions: Study in Single and Binary system”, International Journal of Chemistry, 1, pp. 58-68.
4. M. P. Ireland, H. K. Dillon, M. H. Ho, (1991), Biology Monitoring of Heavy Metals, Wiley, New York.
5. C. Mahamadi, T. Nharingo, (2010), “An adsorption isotherm analysis of the sorption dynamics during the removal of Pb(II), Cd(II) and Zn(II) by Eichhornia Crassipes”, Environmental Chemistry, 31(11), pp. 1221-1228.
6. F. Bouhamed, Z. Elouear, J. Bouzid, B. Ouddane, (2016), “Multi-component adsorption of copper, nickel and zinc from aqueous solutions onto activated carbon prepared from date stones”, Environmental Science and Pollution Research, 23(16), pp. 15801–15806.
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and binary adsorption of heavy metal ions from aqueous solutions using sugarcane cellulose- based adsorbent”, Bioresource Technology, 241, pp. 482-490.
8. T. Nharigo, J. T. Ngwenya, (2013), “Single and Binary sorption of lead (II) and Zinc (II) ions onto Eichhornia Crassipes (water hyacinth) ash”,
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TÓM TẮT
SO SÁNH GIỮA HẤP PHỤ ĐƠN VÀ HẤP PHỤ HỖN HỢP CỦA ION CHÌ (II) VÀ CADMI (II) TRÊN VẬT LIỆU COMPOZIT PANi/ VỎ LẠC
Bùi Minh Quý*, Vũ Quang Tùng, Phạm Thị Thu Hà Trường Đại học Khoa học – ĐH Thái Nguyên Bài báo nghiên cứu quá trình hấp phụ ion chì (II) và cadmi (II) ra khỏi môi trường nước trên vật liệu compozit PANi/ vỏ lạc theo 2 cách hấp phụ đơn và hấp phụ hỗn hợp. Kết quả thực nghiệm cho thấy, cả hai quá trình hấp phụ đều tuân theo mô hình hấp phụ đẳng nhiệt Langmuir. Trong đó, PANi/ vỏ lạc hấp phụ ion chì (II) tốt hơn hấp phụ Cd (II) với cả hai trường hợp. Trong hấp phụ đơn, dung lượng hấp phụ cực đại của ion chì (II) và cadmi (II) trên PANi/ vỏ lạc lần lượt là 26,53 mg/g và 23,75 mg/g. Trong hấp phụ hỗn hợp, dung lượng hấp phụ cực đại của chì (II) và cadmi (II) đều nhỏ hơn dung lượng hấp phụ cực đại của chúng trong hệ hấp phụ đơn. Các giá trị dung lượng hấp phụ cực đại xác định theo mô hình hấp phụ Langmuir cạnh tranh là 13,11 mg/g với Pb (II) và 1,31 mg/g với Cd (II).
Từ khóa: Compozit PANi/vỏ lạc; hấp phụ Cd (II); hấp phụ Pb (II); hấp phụ đẳng nhiệt Langmuir;
hấp phụ cạnh tranh, hấp phụ 2 cấu tử.
Ngày nhận bài: 13/11/2017; Ngày phản biện: 23/11/2017; Ngày duyệt đăng: 05/3/2018
*Tel: 0915 836448, Email: bminhquy09@gmail.com
