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1 International Research Journal of Applied and Basic Sciences 2016 Available online at ISSN X / Vol, 10 (1): 5-12 Science Explorer Publications Modeling and Statistical Analysis of Malachite Green Dye Removal from Aqueous Solutions by Activated Carbon Powder Prepared from Pine Bark (Modified by Sulfuric Acid) - Application of Response Surface Methodology Ali Almasi 1, Meghdad Pirsaheb 1, Sohrab Allafpour haghighi 1*, Kiomars sharafi 1, 2, Masoud Moradi 1,3, Yahya Jabari 1 1. Environmental Health Engineering Department, Public Health School, Kermanshah University of Medical Sciences, Kermanshah, Iran 2. Environmental Health Engineering Department, Public Health School, Tehran University of Medical Sciences, Tehran, Iran 3. Environmental Health Engineering Department, Public Health School, Iran University of Medical Sciences, Tehran, Iran Corresponding Author sohrab191919@yahoo.com ABSTRACT: Nowadays, the adsorption process has been recognized as one of the best ways to removing of dye pollutants from wastewater industry. This study was to evaluate the efficiency of activated carbon powder processed from pine bark (raw absorbent and adsorbent treated with sulfuric acid), in removing of malachite green dye from aqueous solutions (with application response surface method). Adsorbent was treated using sulfuric acid with a purity of 98% at 1, 6 and 12 normality. Run of experiments (sample size required) was determined using Design of Expert software (DOE). Based on the variables range, 20 Run experiments was obtained for each adsorbent, and considering the use of four adsorbents and three times repetition for each Run, 240 experiments were obtained in total. Experiments were established at follow condition: constant concentration of dye (85 mg/l), adsorbent dose (2.0, 5.0, 8.0, 1.1 and 4.1 g/l), contact time (15, 30, 45, 60 and 75 min) and ph (3, 5, 7, 9 and 11). The results showed that the use of sulfuric acid as a modifier cannot significance increasing of efficiency activated carbon sorbent made from pine trees. And even increasing of sulfuric acid normality for treatment of adsorbent has revers result so that afford reducing of adsorbent efficiency. Therefore, 3 4% increasing of efficiency (with the modify effect of sulfuric acid 1 and 6 normal) cannot be considered as a cost-effective process than the raw activated carbon. Based on the results, the contact time hasn t significant effect on malachite green adsorption by adsorbents. While the ph and adsorbent dosage parameters have significant effect in terms of dye adsorption, and with regard to relevant coefficient of regression models, the effect of adsorbent dosage is greater than the effect of ph. Key words: adsorption, malachite green, activated carbon, pine tree, aqueoussolutions INTRODUCTION Due to limited water resources and increasing industrial units, the increase of industrial wastewater production and contaminated water sources are considered as economic and social problems. The wastewater produced from factories and manufacturing centers due to various combinations at different levels afford the complicated the treatment process. Among the different industries textile (1), pulp and paper (2), pharmaceutical (3) and leather (4) industries are the major cause of environmental pollution due to the use of thousands chemicals dyes. Many of these dyes are resistant to biodegradation processes and existence of them in the wastewater cause prevent sunlight penetration into the water and slow photosynthetic processes in the surface waters. Many of these dyes have carcinogenic effects and in many cases causing genetic mutations occur in living organisms (5). In

2 developing countries, in order to protect human health and environment, the use of inexpensive and economical methods of dye removal from textile wastewater and manufacturing plants of dye production has special importance (6, 7). Various methods were used and evaluated to reduce the wastewater entering surface water include coagulants, oxidizing agents, membranes, photo catalytic, electrochemical, biological processes and adsorption (5-8). Since the adsorption process has priority over other methods, due to inexpensive and simpler implementation ability (5, 6, 8, 9). Nowadays, adsorption process is known as the most suitable technique for the removal of pollutants and improve the quality of industries wastewater for reuse in terms of low cost, simple design, ease of operation and absence of sensitivity to the toxins (6). activated carbon known as The most common and effective adsorbent material, because of the high cost of production and the revival of its commercial form, in developing countries cannot be regarded as a desirable option, Hence its production of the raw material cost and available in the country could be economically justified. Activated carbon produced from organic materials have been studied in many studies. Such as activated carbon from peanut (10), industrial waste (11), kernel of coconut (12) and waste bamboo (13). In all these studies, the activated carbon has significant adsorption ability to removing of studied pollutants.the study of Ahmad and Hameed in Malaysia (2010) was conducted in the case use of activated carbon produced from waste bamboo in removing of reactive azo dyes in batch and continuous status, the thermal chemical method in the presence of phosphoric acid to activate of carbon were used and the maximum adsorption capacity of adsorbent bed was obtained 39.9 mg/g with initial dye concentration 100 mg/l (13). In another study by Gupta and et al (2011) revealed that the old tires were used to produce activated carbon. The maximum adsorption capacity of Acid Blue 113 was obtained 9.2 mg/g at 25 C (14) In a study that conducted by Li in China (2010), the Polygonum oriental was used for the production of activated carbon. The monolayer absorption capacity of Langmuir isotherm model at 25 C for malachite green and rhodamine B was obtained 480 and 556 mg/g respectively (15). Pine tree has most used in Iran as an ornamental tree in parks and resorts, and is compatible with the climatic conditions of different parts of Iran. Therefore, the bark of trees was collected from dried up and cutoff trees and used as initial material for produce of activated carbon. Moreover, with different methods such as doped metal, treated with detergents, acids, alkalis and heat can modify and increase the efficiency of inexpensive activated carbon. Based on the above subjects, This study was to evaluate the effective parameters on the efficiency of activated carbon powder processed from pine bark (treated with sulfuric acid with different normality), in removing of malachite green dye from aqueous solutions (with application response surface method). MATERIALS AND METHODS Absorbent soil preparation and modification Initially, pine bark collected, transported and then crushed in the laboratory. In the next stage, the obtained pieces of pine bark entirely washed to eliminate waste and dust and then was placed in the oven for 1 hour at 100 to 110 C. Activated powdered carbon was treated with sulfuric acid (Merck, Germany) at various normality as fallow: 100 g of pine bark pieces were transferred to 3 flask, subsequently, 250 ml of sulfuric acid 1, 6 and 12 N (98% purity) was then added to flaks and kept at room temperature for 24 hours. Afterwards pine bark pieces completely washed with deionized distilled water, to removing of acid for reach to neutral ph, pieces was placed in the oven (Shimaz, Iran) with C for 14 hours After the above steps, 100 g of obtained pieces was transferred into themetallic reactor (80 mm width, 100 mm length and 90 mm depth), then, Rector placed into electric furnace (Exciton, Iran) so that the temperature gradually reached to 900 C for 3 hours. After reaching to 900 C, the reactor was kept at this temperature for 1 hour, then cooled at home temperature slowly. Obtained carbon sieved with 50 mesh and used as powdered activated carbon. Preparation and testing solutions The malachite green dye with chemical formula C 23 H 26 N 2 CL and molecular weight g/ mol (Merck, Germany) were usedfor preparation of stoke solution. This dye is a cationic organic dye that used in the chemical industry and aquaculture. the carcinogenic effect of this dye afford the its prohibition in many countries (16). For preparation of stoke solution (1000 mg/l), 1 g of malachite green with carefully weighed and then transferred to Erlenmeyer flasks with a 1 L volume, Then reached to volume with deionized distilled. Operating concentration (85 mg/l) was prepared from stoke solution. Experiments were carried out as fallow: 200 ml of sample with 85 mg/l concentration at ambient temperature was mixed with absorbent doses (2.0, 5.0, 8.0, 1.1 and 1.4 g) by stirring electrical device (HACH, Iran) at 200 rpm, ph= 3, 5, 7, 9, 11 (ph adjusted with 0.1 N NaOH and HCL) and contact time (15, 30, 45, 60 and 75 min). After each period of operation, 15 ml of solution was centrifuged at 2000 rpm for 15 min and then residual concentration was measured with the spectrophotometer (Optizen View, South Korea) at 6

3 wavelength 665 nm. It should be noted that the preparation method and testing solutions was conducted according to standard methods for water and wastewater (17). Sampling The Design of Expert software (DOE) was used to determine of Run experiments (sample size required) and 20 Run was obtained according to variables range that listed in Table 1. Given that the effluent from industrial plants containing malachite green will neutralize to ph=7, assuming that after neutralization the dye and other contaminants will be removed as well as with regard to previous studies that surveyed other variables, hence, the range of variables for determining Run of central point (Run with the most frequent) was determined at ph = 7, adsorbent dose 8 g and the contact time 45 min. In all Run, initial concentration of malachite green was considered at 85 mg/l. given the use of four adsorbents, 20 Run for each experiment and three times repetition, 240 experiments were obtained in total. Variables Table 1. the range of considered variables Range and level Contact Time (min) Adsorbent Dosage (gr/l) ph Initial Concentration of Malachite Green Dye (mg/l) 85 mg/l Statistical analysis The Design of Experiments (DOE) software V.7 was used for modeling and study effect of considered parameters in terms of removal efficiency of malachite green using various adsorbents. The one way ANOVA at significant level (α =0.05) was used for comparison of average removal efficiency of 4 adsorbent. RESULTS AND DISCUSSION Table 2 showed the actual and predicted removal of malachite green using raw and treated adsorbent by the normality of sulfuric acid. The difference between the actual and predicted will bring the predictive ability of the model. Considering the slight difference between actual and predicted removal efficiency for each adsorbent, therefore we can say that the resulting model has high predictive ability. Table 2. the amount removal of malachite green using raw and modified adsorbents (actual and predicted level) Raw Activated Carbon Sulfuric Acid (6N) -AC Sulfuric Acid (12N) -AC Variables Sulfuric Acid (1N) -AC (RAC) A B C Actual predicted Actual predicted Actual predicted Actual predicted Run Contact Time (min) Adsorbent Dosage (gr/l) ph % % % % % % % %

4 The study of modify effect of sulfuric acid on efficiency removal of adsorbent Figure 1 showed that tread absorbent with sulfuric acid afford increasing of efficiency removal of malachite green, but this raising is not statistically significant(p=0.895). In other words, sulfuric acid as a modifier cannot significance increasing of activated carbon efficiency, therefore cannot be considered as a cost-effective modifier with aim of increasing efficiency removal of dye using adsorbent. Moreover, according to the results the increase of sulfuric acid normality cannot improved the adsorbent efficiency, even that using of sulfuric acid 12 N with destruction of retaining layer between pores and thereby reduce the absorption sites could reduce the adsorbent efficiency. In addition, given that the malachite green is cationic dye, and because the modify effect of sulfuric acid cause the positively charges of adsorbent that afford repulsion electrostatic between the absorbent and adsorbate, therefore the dye adsorption can be reduced (18, 19).The obtained results were conformity and some studies contrary with other studies. The study of Wang and Zhu (2000) showed that the effect of different acids on Merck activated carbon in removing of methylene blue cause reduce of adsorbent efficiency as follow (Raw- AC> AC- HCl> AC-HNO 3 ) (19). While, the study of Chen-Chia Huang and et al in Taiwan (2008) indicated the effect of different acids on activated carbon for the removal of ammonia has significant effect and was as follow: nitric acid > sulfuric acid > hydrochloric acid (20). The different in effect of acids in terms of increase or reduce the adsorbent efficiency is related to basic structure of raw absorbent (untreated), ion-absorbing agent, absorbent and acid modifier, treatment conditions such as acid concentration, contact time of acid with the adsorbent, etc (18-20). Figure 1. the comparison efficiency of raw and modified adsorbent by sulfuric acid in removing of malachite green from aqueous solution The survey trends of changes of raw and modified absorbents efficiency by changing the considered parameters According to the results of Figure 2, it is clear that efficiency of 4 adsorbents were increased with raising of ph. In other hands, the malachite green adsorption by activated carbon produced by pine trees in alkali condition is more than acidic condition. Results also revealed that the adsorbent efficiency was similar to ph effect, this reason is because the provider of more adsorption sites by increasing of adsorbent dosage. In the case of raw activated carbon, the efficiency removal of dye was reduced with increasing of the contact time. This could be due to adsorption and saturation of adsorption sites that was occur at first few minutes (about 10 minutes), Thus by increasing of contact time, the dye cannot be adsorption and as a result of this subject is the reduction of efficiency. In the case of absorbent treated, this subject is somewhat different with raw adsorbent so that firstly by increase of contact time the efficiency will increase (up to 45 minutes) and then adsorbent efficiency has downward trend. 8

5 Raw Activated Carbon (RAC) Sulfuric Acid (1N) -AC Sulfuric Acid (6N) -AC Sulfuric Acid (12N) -AC Figure 2. the Survey effect of considered variables on the different adsorbent efficiency in removing of malachite green A: Contact Time (min), B: Adsorbent Dosage (gr/l), C: ph In terms of trend changes of absorbent efficiency based on changing in the values of effective parameters, the results of some studies are conformity or contrary with the results of this study. The study of Samarghandi and et al (2010) revealed that removal of Azo dye by treated pumice with hydrochloric acid was increased with increasing of dye concentration and contact time, but dye removal was reduced by increasing of ph and temperature (21). In another study which conducted by Zarrabi and et al (2010) indicated that removal of Acid Red 14 and Acid Red 18 was increased by increasing of contact time and initial dye concentration(22). The study that carried out by Ahmad and et al (2009) showed the optimum condition for dye removal using activated carbon produced from sawdust and bamboo trees and modified with phosphoric acid was ph=7 and contact time= 2.15 h so that maximum adsorption capacity and removal efficiency were obtained mg/g and 69.73% respectively (23). In another study that conducted by Ferial Akbal (2005) revealed that the removal efficiency of dye using pumice was increased by reducing of dye concentration and increasing of contact time and adsorbent dosage (24). The study of Elizalde (2009) in Mexico on the removal of acid orange 7 by the carbon produced from the seeds of guava indicated that best removal of orange 7 was obtained 99% at optimum condition including PH = 6, adsorbent dose = 16 mg/l and 25 (25). Modeling process and compare the effect of various parameters (ph, contact time and adsorbent dose) on efficiency removal of different sorbents The results of modeling process of malachite green adsorption by activated carbon produced from pine (as raw and treated with sulfuric acid) showed that the contact time parameter (factor A in the model) has not significant effect on four adsorbent efficiency (P> 0.05). While the adsorbent dose (factor B) and the ph parameters (factor C) has a significant effect on the efficiency of adsorbents, in other words, adsorbent efficiency is associated 9

6 to dose and ph variables significantly (P<0.05) (Table 4-6). The interactions between variables (simulates effect of two variables) for raw treated adsorbent with sulfuric acid 6 and 12 N, only there was significant effect of adsorbent dosage and ph (B*C) (P <0.05), but there wasn t significant effect in other modes of interaction (P> 0.05). While in case of the treated adsorbent with sulfuric acid 1N, all modes of interactions was significant on the removal efficiency of malachite green (P <0.05). If an interaction (simulates effect of two variables) to be significant, it is showed that simultaneous effect of both variables are significant increase or decrease the adsorption efficiency, although it may be these two variables that forming interaction, both or one of them alone does not have a significant effect on the adsorption efficiency (such as contact time interaction with other variables in the adsorbent treated with sulfuric acid 1N which presented in Table 4). As mentioned earlier, only two variables including adsorbent dose (factor B) and the ph (factor C) parameters has a significant effect on the efficiency of all four considered adsorbents (P <0.05). Given the variable coefficients obtained in the regression models, the effect of adsorbent dose (factor B) is greater than the effect of the ph (factor C) which revealed for improve of adsorbent efficiency, adsorbent dose changing (factor B) can be more effective than the ph (factor C). Table 3. the characteristic of obtained regression model related to removal of malachite green using raw activated carbon Factor P-value Significant/ Not Significant A Not Significant B Significant C Significant AB Not Significant AC Not Significant BC Significant A Not Significant B Not Significant C Not Significant model Significant Removal of Dye by (Raw-AC ) =3.93A+9.98B+9.39C+4.46AB+3.18AC BC-0.84A 2 - Quadratic 7.95B C R-Squared= Adj R-Squared= Pred R-Squared= Adeq Precision= Table 4. the charactization of obtained regression model related to removal of malachite green using AC-Acid-1N Factor P Significant/ Not Significant A Not Significant B < Significant C Significant AB Significant AC Significant BC Significant A Not Significant B Not Significant C Not Significant model Significant Removal of Dye by (AC-Acid-1N) =+3.67A+12.97B+8.49C-4.14AB-4.64AC-8.96BC-4.99A 2 - Quadratic 4.99B C R-Squared= Adj R-Squared= Pred R-Squared= Adeq Precision= Table 5. the charactization of obtained regression model related to removal of malachite green using AC-Acid-6 N Factor P Significant/ Not Significant A Not Significant B < Significant C Significant AB Not Significant AC Not Significant BC Significant A Not Significant B Not Significant C Not Significant model < Significant Removal of Dye by (AC-Acid-6N) =+1.44A+15B+9.25C-2.50AB-3.31AC-9.45BC-4.96A B 2 - Quadratic 5.32C R-Squared= Adj R-Squared= Pred R-Squared= Adeq Precision=

7 Table 6. the charactization of obtained regression model related to removal of malachite green using AC-Acid-12 N Factor P Significant/ Not Significant A Not Significant B < Significant C < Significant AB Not Significant AC Not Significant BC < Significant A Not Significant B Not Significant C Not Significant model < Significant Removal of Dye by(ac-acid-12n) =+0.6A+20.3B+15.63C-0.87AB-1.91AC-16.64BC-7.2A 2 - Quadratic 8.11B C R-Squared= Adj R-Squared= Pred R-Squared= CONCLUSION Adeq Precision= Based on the results, we can conclude that the use of sulfuric acid as a modifier cannot increased significantly the efficiency of activated carbon produced from pine tree and even increasing of sulfuric acid normality afford reduce of adsorbent efficiency. Therefore, 3 4% increasing of efficiency (with the modify effect of sulfuric acid 1 and 6 normal) cannot be considered as a cost-effective process than the raw activated carbon. Based on the results, the contact time hasn t significant effect on malachite green adsorption by adsorbents. While the ph and adsorbent dosage parameters have significant effect in terms of dye adsorption, and with regard to relevant coefficient of regression models, the effect of adsorbent dosage is greater than the effect of ph. Based on the results we can say that time back in the dye malachite green by absorbing tested, can have a significant impactwhile the parameters ph and adsorbent dosage significant impact in this respect, and with regard to relevant factors regression models, the effect of adsorbent dosage is greater than the effect of ph. ACKNOWLEDGMENT This letter resulted from Sohrab Allafpour haghighi s thesis, major Environmental Health Engineering, Kermanshah University of Medical Science, Kermanshah, Iran. REFERENCES Ahmad A, Hameed B, Ahmad A. Removal of disperse dye from aqueous solution using waste-derived activated carbon: Optimization study. Journal of Hazardous materials. 2009;170(2): Ahmad A, Hameed B. Fixed-bed adsorption of reactive azo dye onto granular activated carbon prepared from waste. Journal of Hazardous Materials. 2010;175(1): Akbal F. Adsorption of basic dyes from aqueous solution onto pumice powder. Journal of colloid and interface science. 2005;286(2): Ali M, Sreekrishnan T. Aquatic toxicity from pulp and paper mill effluents: a review. Advances in Environmental Research. 2001;5(2): Almasi A, Omidi M, Khodadadian M, Khamutian R, Gholivand MB. Lead (II) and cadmium (II) removal from aqueous solution using processed walnut shell: kinetic and equilibrium study. Toxicological & Environmental Chemistry. 2012;94(4): Almasi A, Soltanian M, Asadi F, Mohamadi A, Sharafi K. Removal of Tetrachloroethylene by copper-coated pumice Andersen WC, Turnipseed SB, Roybal JE. Quantitative and confirmatory analyses of malachite green and leucomalachite green residues in fish and shrimp. Journal of agricultural and food chemistry. 2006;54(13): Elizalde-González MP, Hernández-Montoya V. Removal of acid orange 7 by guava seed carbon: A four parameter optimization study. Journal of hazardous materials. 2009;168(1): Federation WE, Association APH. Standard methods for the examination of water and wastewater. American Public Health Association (APHA): Washington, DC, USA Fu Y, Viraraghavan T. Column studies for biosorption of dyes from aqueous solutions on immobilised Aspergillus niger fungal biomass. Water SA. 2004;29(4): Gupta V, Gupta B, Rastogi A, Agarwal S, Nayak A. A comparative investigation on adsorption performances of mesoporous activated carbon prepared from waste rubber tire and activated carbon for a hazardous azo dye Acid Blue 113. Journal of Hazardous Materials. 2011;186(1): Ho Y-S. Second-order kinetic model for the sorption of cadmium onto tree fern: a comparison of linear and non-linear methods. Water Research. 2006;40(1): Huang C-C, Li H-S, Chen C-H. Effect of surface acidic oxides of activated carbon on adsorption of ammonia. Journal of hazardous materials. 2008;159(2): Kadirvelu K, Karthika C, Vennilamani N, Pattabhi S. Activated carbon from industrial solid waste as an adsorbent for the removal of Rhodamine- B from aqueous solution: Kinetic and equilibrium studies. Chemosphere. 2005;60(8): Kolpin DW, Furlong ET, Meyer MT, Thurman EM, Zaugg SD, Barber LB, et al. Pharmaceuticals, hormones, and other organic wastewater contaminants in US streams, : A national reconnaissance. Environmental science & technology. 2002;36(6):

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