Pauh, Penang, Malaysia. Keywords: Binary metal, immobilized, Saccharomyces cerevisiae, response surface methodology

Transcription

1 Applied Mechanics and Materials Submitted: ISSN: , Vol. 66, pp 5-57 Revised: doi:0.408/ Accepted: Trans Tech Publications, Switzerland Online: Response Surface Methodology Approach for Optimization of Biosorption Process for Removal of Binary Metals by Immobilized Saccharomyces Cerevisiae MOHAMAD ZULHELMI Mohd Zawawi,a, RASYIDAH Alrozi*,b, FARAZIEHAN Senusi,c, MOHAMAD ANUAR Kamaruddin,d Faculty of Chemical Engineering, Universiti Teknologi MARA Pulau Pinang, 3500 Permatang Pauh, Penang, Malaysia School of Civil Engineering, Universiti Sains Malaysia, 4300 Nibong Tebal, Penang, Malaysia a helmi.yana@yahoo.com.my, b rasyidah.alrozi@ppinang.uitm.edu.my, c faraziehan@ppinang.uitm.edu.my, d anuar97@yahoo.com Keywords: Binary metal, immobilized, Saccharomyces cerevisiae, response surface methodology Abstract. Biosorption process is considered as economical treatment to remove metal from the aqueous solution compared to other established methods. In this study, Saccharomyces cerevisiae was used as biosorbent and subject to immobilization process which consists of ethanol treatment for the removal of binary metals, lead (II) and nickel (II) from aqueous solution. Response surface methodology (RSM) was used to optimize effective parameters condition and the interaction of two or more parameters in order to obtain high removal of the binary metals. The parameters that have been studied were initial concentration of binary metals solution (0-60 mg/l), biosorbent dosage ( g), ph (ph - ph 6) and contact time ( minutes) towards lead (II) and nickel (II) ions removal. Based on analysis of variance (ANOVA), biosorbent dosage, solution ph and contact time factor were found significant for both responses. Through optimization procedure, the optimum condition for lead (II) and nickel (II) ions removal were obtained at initial concentration of 0.0 mg/l, biosorbent dosage of.0 g, solution ph of ph 6, and contact time of minutes, which resulted in % and.09 % removal of lead (II) and nickel (II) ions respectively. Introduction The presence of the toxic metals in the industrial effluent that is discharge into the water bodies have been the major contributors to the non-point and point source pollutions. Generally, heavy metal such as lead, copper, cadmium, nickel and zinc are commonly used in electroplating, plastic manufacturing, fertilizers, pigments, mining, and metallurgical processes []. Thus, uncontrolled release of heavy metals to the environment can cause hazards to humans, animals, plants, and ecosystems. Different wastewater treatment techniques for heavy metal removal have been developed in recent years such as chemical precipitation, coagulation-flocculation, ion-exchangeand biosorption []. Because of simple and economically attractive, biosorption has been employed in the last decades particularly for heavy metal removal. Generally, biosorption can be used for metal ions binding through functioning of ligands or functional group located at the outer surface []. Saccromyces cerevisiae has a unique characteristics and suitable in biosorption process for heavy metal removal. The presence of vacoule-deficient straints in Saccromyces cerevisiae is capable to bind toxic metal ions such as zinc, manganese, cobalt and nickel. Apart from that, inexpensive growth media and the ability to grown by using unsophisticated fermentation techniques have been one of the reason this process is favorable in waste water treatment [3]. Application of response surface methodology (RSM) in this study was explored in order to develop the model for experimental work. RSM helps to determine to optimize effective parameters condition by minimizing the number of experiment. A standard design of called as central composite design (CCD) has been used for the optimization of binary metal removal (lead All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (#697977, Pennsylvania State University, University Park, USA-6/09/6,3:54:03)

2 5 Applied Solutions of Engineering Science (II) and nickel (II) ions) parameters such as initial concentration of binary metal solution, dosage of biosorbent, ph of the solution and contact time. Material and methods Adsorbate. The adsorbate used in this studies were Nickel(II) Chloride Hexahydrate and Lead(II) Nitrate which are supplied by R&M Marketing, Essex, U.K. Nickel(II) chloride hexahydrate has the chemical formula of NiCl 6H Owhereas lead(ii) nitrate has the chemical formula of Pb(NO 3 ). Preparation of immobilized biosorbent. For immobilization of yeast,.0g of biosorbent (Saccharomyces cerevisiae yeast) was suspended in 50.0 ml distilled water. This suspension was blended with the mixture of.0g of sodium alginate and.0 ml ethanol and dropped into 00 ml of 0. M calcium chloride (CaCl ) solution. The immobilized yeast bead was left in the calcium chloride solution about one hour at 4.0 o C to cure and form more stable cross-linkage between the bonds. Biosorption studies. Batching process was applied to all metal ions solution that has been prepared in the series of Erlenmeyer flask. A total of 30 Erlenmeyer flasks of metal ions solution with different concentration, ph and biosorbent dosage were batched by using top orbital shaker (Model SK-300, Malaysia). This process was carried out in room temperature (7-30 ºC) with agitating speed of 50 rpm until it reached the desired contact time. The percentage removal at equilibrium was calculated based on common equilibrium equation. Design of experiment. RSM was employed in this work because it is capable for modeling vast numbers of numerical experiments. RSM can evaluate the relationship of the controlled experimental factors and measured responses. CCD was applied to study the variables for lead (II) and nickel (II) removal involve in three categories of runs which are n factorial runs, (n) axial runs and 6 center runs where n is the number of the process variables. Independent process parameters in qualitative form were calculated as follows: Y = f ( X, X, X3,... X n) ±. () where Y is the response, f is the response functions, ɛ is the experimental error and X, X, X 3,..., X n are the independent parameter that involve in the experiment [4]. Experimental error and the reproducibility of the data can be obtained by using the center point [5]. The axial point is located at ± α for each of variables where ± α is the distance of the axial point from the center point. Hence, the response that well modeled by linear function can be written as: Y = C 0 + C X + C X C n X n ±. () where Y is the response, C is the coefficient, X is the coded values of the process variables and ɛ is the experimental error. However, when the curvature occurs, the higher order polynomial such as quadratic model may be used. The quadratic equation is written by equation: C i X i + C ii X i C ij X i X j Y = C where Y is predicted response, C o is the constant coefficient, C i is the linear effect, C ii is the squared effect, and C ij is the interaction effect [6]. In this experiment, the process variables that have been investigated were initial concentration (mg/l, X i ), biosorbent dosage (g, X ), ph (ph, X 3 ) and contact time (min, X 4 ). The parameters were coded at three levels of -, 0,, where the center point of the experiment was at 35 mg/l, 0.6 g, ph 4 and 95 minutes of time contact. Table shows the complete design matrix that has been developed with their responses values. (3)

3 Applied Mechanics and Materials Vol Model Fitting and Statistical Analysis.The experimental data was analyzed by using Design Expert software version 6 (Stat-Ease, Inc., Minneapolis) for regression analysis and statistical significance of the equation derived. Table : Experimental design matrix for lead (II) and nickel (II) removal process Run Level Initial concentration [mg/l] Dosage [g] ph Contact time [min] Pb removal [%] Ni removal [%] Results and discussion Development of regression model equation. CCD was used as a polynomial regression in order to determine the interaction between the parameters variables and responses. The quadratic models of lead (II) and nickel (II) removal were suggested by the software. The selection of the quadratic model is based on the higher order polynomial. Equations 5 and 6 list out the final empirical formula models for lead (II) (у ) and nickel (II) removal (у ): y x 9.37x 4.6x3 7.80x4 3.68x 0.33x 3. 0x3 3.7x4 4.x x 0.86x x3 0.4x x4.68xx xx x3x4 (4) y x.8x.75x3 3.7x4.x.70x. 9x3 0.8x4 0.6x x 0.7x x3 0.59xx xx3.3xx4. 48x3x (5) 4

4 54 Applied Solutions of Engineering Science In this study, the R values for Eq. 4 and 5 were and (data not shown) indicated that 90.7% and 95.34% of total variation in the lead(ii) removal and nickel(ii) removal were much closer to the actual value. Statistical analysis. In this study, ANOVA was used to analyze and justify the significance and adequacy of the models. The results of the surface quadratic model of ANOVA are given in Table and Table 3. The model terms are considered as significant if the F-value is relative high and the value Prob.>F is less than Table : Analysis of variance (ANOVA) for lead (II) removal response Source Sum of Degree of Mean square F-value Prob.>F Comment squares freedom Model <0.000 significant x x x <0.000 x <0.000 x x x x x x x x x x x x x x E x 3 x Residual Table 3: Analysis of variance (ANOVA) for nickel (II) removal response Source Sum of squares Degree of Mean square F-value Prob.>F Comment freedom Model <0.000 significant x x <0.000 x <0.000 x <0.000 x x x x x x x x x x x x x x x 3 x Residual The F-value for lead (II) (Table ) was 9.83 and the prob.>f was less than indicated that the model was relevant and significant. Meanwhile, the significant model terms obtained were x, x, x 3, x 4 and x. In contrast, x, x 4, x x, x x 3, x x 4, x x 3, x x 4 and x 3 x 4 were insignificant model terms to the model. In addition, the model for nickel(ii) removal was significant because the F-value of.9 and the prob.>f was less than x, x, x 3, x 4, x 3, x x 3, x x 4 and x 3 x 4 were significant model

5 Applied Mechanics and Materials Vol terms whereas x, x 4, x x 3, and x x 4 were insignificant model terms. The model developed was successful because the predicted values obtained were closer to the actual experimental data. Lead (II) removal. From Table 3, the biosorbent dosage, solution ph and the contact time were most significant factors that contributed to high lead(ii) removal. Meanwhile, the initial concentration of binary metal solution and the quadratic effect of initial concentration were considered least significant. For the lead(ii) removal, the highest F-value was obtained for contact time which was indicated that the greatest effect for lead(ii) removal. Fig. (a) shows the effect of ph and contact time on the lead(ii) removal when initial concentration and dosage was fixed.from Fig. (a), when both variables studied were increased, the lead(ii) removal also increased. The results was supported by previous study that was conducted by Park and Choi [7] which reported that the ph of binary metal solution and time contact were significant effect in order to remove lead(ii) ion from the binary metal solution. However, this relationship was not linear because increasing solution ph can cause precipitation of metal complexes. Meanwhile, the contact time factor also influenced lead(ii) removal by prolong the duration of time contact between the metal ions and the biosorbent [8,9]. (a) (b) Fig.: Three-dimensional response surface plot of (a) lead (II) removal response (effect of ph and contact time, initial concentration = 35 mg/l and dosage = 0.6 g) and (b) nickel (II) removal response (effect of ph and contact time, initial concentration = 35 mg/l and dosage = 0.6 g) Nickel (II) removal. From Table 3, it was observed that contact time, ph and dosage were most significant effects for nickel(ii) removal. The F-value for contact time effects of 95. indicated that the factor was the greatest for the nickel(ii) removal. In addition, quadratic effect of solution ph and interaction between biosorbent dosage and solution ph showed almost similar effects on the response. Fig. (b) shows the effect of ph and contact time on the nickel(ii) removal with initial concentration and dosages were fixed. From Fig. (b), it shows that the percentage of nickel(ii) removal increased as both variables studied also increased. The F-value for contact time effect of 95. (Table 3) showed that the factor played crucial role for nickel(ii) removal. In addition, it was found that by prolong the contact time of metal solution, higher efficiency of metal uptake from the solution could be observed [0]. Al-Rub et al. [] claimed that about 80% of maximum nickel(ii) removal can be obtained during the first 0 minutes. Then, slow decrease of nickel(ii) removal was accounted due to some reaction of active metabolism []. Process optimization. RSM was used to determine the optimum parameters condition to get the maximum lead(ii) and nickel(ii) removal. Therefore Design-Expert software could be used to compromise between these responses. During analysis process, both responses were set as maximum values whereas all the parameters were fixed in the range being studied. Table 4 showed the experimental results and predicted results of lead(ii) and nickel(ii) removal at the optimum condition. The optimum condition for both lead(ii) and nickel(ii) removal was selected based on the higher value of model desirability. The optimum condition was obtained at initial concentration of 0.00

6 56 Applied Solutions of Engineering Science mg/l, dosage of.0 g, ph solution of ph 5.97, and contact time of minutes, respectively resulted in 95.08% and.53% removal of lead(ii) and nickel(ii) respectively. Table 4: Model validation for lead (II) and nickel (II) removal Model Initial concentration, Dosage, ph, Contact time, Predicted Experimental Error (%) desirability x [mg/l] x [g] x 3 x 4 [min] Lead (II) Nickel (II) Conclusion Saccharomyces cerevisiae was found as a suitable biosorbent for lead (II) ions removal but less effective towards nickel(ii) ions removal from the binary metal solution. Response surface methodology (RSM) was successfully used to investigate the parameters that influenced the removal of lead(ii) and nickel(ii) ions from the solution. Based on the parameters that have been studied, dosage of biosorbent, ph of the metal solution and contact time were found significant factors that contribute to the metal uptakes. By using RSM, the optimum condition for lead(ii) and nickel(ii) removal were obtained at initial concentration of 0.00 mg/l, dosage of.0 g, ph of ph 5.97 and contact time of minutes which resulted in 95.08% and.09% removal of lead (II) and nickel (II) removal, respectively. Acknowledgment The authors gratefully acknowledge Research Intensive Faculty Grant (RIF) under Excellent Fund of UniversitiTeknologi MARA, Research Acculturation Grant Scheme (RAGS) under MOHE and Research Management Institute of Universiti Teknologi MARA for the financial support through this project. References [] R. Kumar, R. Singh, N. Kumar, K. Bishnoi and N.R. Bishnoi, Response surface methodology approach for optimazation of biosorption process for removal of Cr (VI), Ni (II) and Zn (II) ions by immobilized bacteria biomass sp. Bacillus brevis, Chem. Eng. J. 46 (009) [] M. Amini, H. Younesi and N. Bahramifar, Biosorption of nickel(ii) from aqueous solution by Aspergillus niger: response surface methodology and isotherm study, Chemosphere. 75 (009) [3] U.K. Garg, M.P. Kaur, V.K. Garg and D. Sud, Removal of nickel(ii) from aqueous solution by adsorption on agricultural waste biomass using a response surface methodological approach, Bioresour. Technol. 99 (008) [4] M.A. Ahmad and R. Alrozi, Optimization of rambutan peel based activated carbon preparation conditions for Remozol Brilliant Blue R removal, Chem. Eng. J. 68 (0) [5] M.Y. Can, Y. Kaya and O.F. Algur, Response surface optimization of the removal of nickel from aqueous solution by cone biomass of Pinus sylvestris, Bioresour. Technol. 97 (006) [6] J. Wang and C. Chen, Biosorption of heavy metals by Saccharomyces cerevisiae: a review, Biotechnology Adv. 4 (006)

7 Applied Mechanics and Materials Vol [7] J.K. Park and S.B. Choi, Metal recovery using Immobilized Cell Suspension from a Brewery, Chem. Eng. J. 9 (00) [8] S. Tonk, A. Maicaneanu, C. Indolean, S. Burca and C. Majdik, Application of immobilized waste brewery yeast cells for Cd + removal: Equilibrium and kinetics, Journal of the Serbian Chem. Society. 76 (0) [9] F. Yang, H. Liu, J. Qu and P. Chen, Preparation and characterization of chitosan encapsulated Sargassum sp. biosorbent for nickel ions sorption, Bioresour. Technol. 0 (0) [0] S. Kalyani, P.S. Rao and A. Krishnaiah, Removal of nickel(ii) from aqueous solutions using marine macroalgae as the sorbing biomass, Chemosphere. 57 (004) 5-9. [] F.A.A. Al-Rub, M.H. El-Naas, F. Benyahia and I. Ashour, Biosorption of nickel on blank alginate beads, free and immobilized algal cells, Process Biochem. 39 (004) [] M.Z. Alam and S. Ahmad, Multi-metal biosorption and bioaccumulation Exiguobacterium sp. ZM-, Annals of Microbiol. 63 (0)