دوماه نامه

نوع مقاله : مقالات پژوهشی

نویسندگان

دانشگاه صنعتی اصفهان

چکیده

در این تحقیق، میزان پتانسیل حذف فلز سنگین کروم (VI) از محلول­های آبی توسط پوسته میوه تمبرهندی اصلاح شده با اسیدسولفوریک بررسی شد. روش سطحی پاسخ بر اساس روش D-optimal برای بهینه­سازی جذب کروم (VI) توسط ذرات پوسته میوه تمبرهندی اصلاح شده به کار رفت. پنج متغیر مستقل از جمله، دز جاذب برابر (1-7g/L)، سرعت لرزاننده (شیکر) برابر (50-200rpm)، pH اولیه محلول برابر (10-1)، غلظت اولیه محلول کروم (VI) برابر ((5-150mg/L و زمان تماس برابر (30-120min) برای پیش­بینی بازدهی حذف فلز سنگین کروم (VI) به کار رفت. اهمیت متغیرهای مستقل و تقابل آنها توسط آنالیز واریانس (ANOVA) بررسی شد. با استفاده از بهینه­سازی به مقادیر بهینه دز جاذب برابر 3g/L، سرعت لرزاننده برابر 200rpm، pH برابر 1، غلظت محلول کروم برابر 150mg/L و زمان تماس برابر 90min به بیشینه ظرفیت جذب محلول کروم (VI) برابر 23mg/g دسترسی پیدا کردیم؛ نتایج آزمایشات جذب با مدل ایزوترم فرندلیچ سازگاری بیشتری داشت.

کلیدواژه‌ها

عنوان مقاله [English]

Design and Optimization of Heavy Metal Chromium (VI) from Aqueous Solutions by Tamarind Fruit Shell Activated with Sulfuric Acid

نویسندگان [English]

  • Morteza Shahmoradi
  • Amir Taebi
  • Hasti Hasheminejad

Isfahan university of Technology

چکیده [English]

Introduction: The industries of leather, plating, metal processing, wood production, painting, textile, steel making and bottling are the main industries for pollution of heavy metal chromium. Chromium in the two main oxidation states consists of chromium (VI) and chromium (III). Chromium (VI) is more dangerous, more cancerous and toxic for living organisms compared with chromium (III). In addition, low chromium (VI) concentration can cause health problems, including damage to the liver, as compared with chromium (III). In addition, lower concentrations of chromium (VI) can cause health problems including liver damage and skin cancer. Acceptable limits of chromium (VI) for discharging to surface water and drinkable water are 0.1 and 0.05 mg L-1, respectively. Therefore, wastewater treatment for reaching the desired level of chromium (VI) is essential. There are several methods including chemical oxidation-reduction, ion exchange, electro dialysis, electrochemical treatment, evaporation, solvent extraction, reverse osmosis, chemical treatment and adsorption to reduce chromium (VI) from aqueous and sewage solutions. The main drawback of many of these methods is the high operating cost and remaining sludge disposal problems. Among the techniques, the adsorption method is preferred because of its simplicity, medium-performance and economic conditions. In the adsorption process, the physical and chemical properties of adsorbent are very important for achieving high adsorption efficiency. In the present study, activated particles with sulfuric acid were used to improve the removal of chromium (VI) from aqueous solution. In the adsorption process, the removal of chromium (VI) metal depends on several process variables in a discrete system such as the initial concentration of chromium (VI) solution, adsorbent dose, solution pH, vibrational speed and contact time. Optimizing process variables is necessary to achieve the maximum process efficiency for removing pollutants. A laboratory statistical design approach is necessary to reduce the number of experiments, create an appropriate model for process optimization and also evaluate the effect of response variability. Recently, several types of test design methods have been used to optimize the multivariate chemical process. Response surface of methodology is a set of statistical and mathematical methods for designing experiments in this field. Nevertheless, no study has been carried out on the optimization of the removal of chromium (VI) by particles of the shell modified with sulfuric acid.
Materials and Methods: Chromium (VI) solution was prepared by dissolving potassium dichromate (K2Cr2O7) in distilled water. It should be noted that the dominant form of chromium solution in terms of pH and chromium (VI) contaminant concentrations is (HCrO4) – and (CrO4) 2- in this study.
Preparation of modified tamarind fruit shell: Tamarind fruit shells were prepared from the central part of Iran (Isfahan province). The shells were washed with distilled water and placed in an oven at 110 °C for 4 hours. The dried shells were crushed and then passed through a filter with a size of 200 microns. The resultant particles were contacted with concentrated sulfuric acid (98 % w/w) for chemical activation and H+ ion saturation in a 1: 1 weight ratio and in an oven at 150 ° C for 24 hours. The particles were then washed with distilled water and placed in a 1% sodium bicarbonate solution for 2 days. The material was then washed with distilled water and dried at 100 ° C for 5 hours. With this activation operation, H+ ions are located on the adsorbent surface and increase the adsorption of chromium samples. In this study, chromium samples are more (HCrO4) - and (CrO4) 2- which have an electric charge. These negative samples are definitely adsorbed to the shells by placing H+ ions on the surface of the adsorbent.
Adsorption­-Tests: The effect of 5 independent variables on chromium (VI) adsorption of aqueous solution was investigated by the particles of tamarind fruit shells in a discrete medium. All experiments were performed in accordance with the D-optimal matrix method. To adsorb chromium (VI) by tamarind fruit shells, different weights of the tamarind fruit shell (1-7 gr/L) were combined with 50 ml of chromium (VI) solution and different concentrations (50-150 mg/L). The chromium aqueous solution (VI) was prepared by dissolving preset amounts of K2Cr2O7 powder in distilled water. The pH of the solution was adjusted by a solution of 1 M hydrochloric acid or 1 M sodium hydroxide over the range of 1-10. The residual concentration of chromium ions (VI) in the soluble phase was determined by spectrophotometer detection of UV rays at 540 nm by the formation of diphenyl carbazide color. Adsorption Capacity (mg g-1) of the bimetallic system was calculated as follows:
where C0 and Ce are the primary and final concentrations of chromium (VI) (mg L-1), respectively. V and W represent the volume and mass of the solution containing the tamarind fruit shell particles, respectively.
Results: The adsorption of heavy metal chromium (VI) by the modified tamarind fruit shell as a sorbent was studied by changing the pH of the solution, the adsorbent dose, the initial concentration of chromium (VI), contact time and vibrational velocity (shaker). The design of the D-optimal experiment, along with the response surface procedure modeling, was used to maximize the removal of chromium (VI) from the aqueous solution by the particle of the tamarind fruit shell.
 

کلیدواژه‌ها [English]

  • Tamarind fruit shell
  • Hexavalent chromium
  • D-optimal
  • Optimization
  • Response surface methodology
Abrowski D., Hubicki Z., Podko Scielny P., and Robens E. 2004. Selective of the heavy metal ions from waters and industrial wastewater by ion-exchange method. Chemosphere, 56: 91-106.
2- Ahmad R. 2004. Sawdust: Cost effective scavenger for the removal of chromium (iii) ions from aqueous solutions. Water, Air and Soil Pollution, 163: 169-183.
3- Alaerts G.J., Jitjaturant V., and Kelderman P. 1989. Use of coconut shell based activated carbon for chromium (VI) removal. Water Science Technology, 21: 1701–1704.
4- Alam M.Z., Muyibi S.A., and Toramae J. 2007. Statistical optimization of adsorption processes for removal of 2, 4-dichlorophenol by activated carbon derived from oil palm empty fruit bunches. Journal Environment Science, 19: 674–677.
5- Aliabadi M., Irani M., Ismaeili J., and Najafzadeh S. 2014. Design and evaluation of chitosan/ hydroxyapatite composite nanofiber membrane for the removal of heavy metal ions from aqueous solution. Journal Taiwan Inst Chem Engineering, 45: 518-526.
6- American Public Health Association. 1998. Standard methods for examination of water and wastewater.
7- Annadurai G., Juang R.S., and Lee D.J. 2001. Adsorption of heavy metals from water using banana and orange peels. Water Science Technology, 47: 185–190.
8- Babu B.V. 2008. Adsorption of Cr (VI) using activated neem leaves: kinetic studies. Springer Science+Business Media, 14: 85-92.
9- Celevi O., Uzum C., Shahwan T., and Erten H.N. 2007. A radiotracer study of the adsorption behavior of aqueous Ba2+ ions on nanoparticles of zero-valent iron. Journal Hazardous Materials, 148: 761–767.
10- Cimino G., Passerini A., and Toscano G. 2000. Removal of toxic cations and Cr (VI) from aqueous solution by hazelnut shell. Water Research, 34: 2955–2962.
11- Dinesh M., and Charles U. 2006. Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water. Journal of Hazardous Materials, 137: 762-811.
12- Gunaraj V., and Murugan N. 1999. Application of response surface methodology for predicting weld bead quality in submerged arc welding of pipes. Journal Mater. Process. Technology, 88: 266–275.
13- Gupta Suresh., and Babu B.V. 2009. Utilization of waste product (tamarind seeds) for the removal of Cr (VI) from aqueous solutions: Equilibrium, kinetics, and regeneration studies. Journal of Environmental Management, 90: 3013–3022.
14- Gupta V.K., Shrivastava A.K. and Jain N. 2001. Biosorption of chromium (VI) from aqueous solutions by green algae spirogyra species. Water Research, 25: 4079-4090.
15- Hamadi N.K., Chen X.D., Farid M.M., and Lu M.G.Q. 2001. Adsorption kinetics for the removal of chromium(VI) from aqueous solution by adsorbents derived from used tyres and sawdust. Chem. Engineering Journal, 84(2): 95–105.
16- Hamilton M.J., and Mann-Whitney U. 2004. September 2 Sample Test (a. k. a. Wilcoxon Rank Sum Test), Department of Anthropology. University of New Mexico, Albuqueque, NM, USA.
17- Kobya M. 2004. Removal of Cr (VI) from aqueous solutions by adsorption onto hazelnut shell activated carbon: kinetic and equilibrium studies. Bioresour. Technology, 91: 317–321.
18- Liu H.L., and Chiou Y.R. 2005. Optimal decolorization efficiency of Reactive Red 239 by UV/TiO photocatalytic process coupled with response surface methodology. Chem. Engineering Journal, 112: 173–179.
19- Low K.S., Lee C.K., and Ay N.G. 1999. Column study on the sorption of Cr (VI) using quaternized rice hulls, Bioresour. Technology, 68: 205–208.
20- Mahvi A.H., Naghipour D., Vaezi F., and Nazmara S. 2005. Teawaste as an adsorbent for heavy metal removal from industrial wastewaters. American Journal of Applied Sciences, 2: 272-275.
21- Mohan D., and Pittman Jr Ch. 2006. Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water, Journal Hazardous Materials, 137: 762–811.
22- Myers R.H., and Montgomery D.C. 2001. Response Surface Methodology, second edWiley.
23- Periasamy K., Srinivasan K., and Murugan P.R. 1991. Studies on chromium (VI) removal by activated ground nut husk carbon. Indian Journal Environment Health, 33: 433–439.
24- Ricou-Hoeffer P., Lecuyer I., and Lecloires P. 2001. Experimental design methodology applied to adsorption of metallic ions on to fly ash. Water Research, 35: 965–976.
25- Sahu J.N., Acharya J., and Meikap B.C. 2009. Response surface modeling and optimization of chromium (VI) removal from aqueous solution using Tamarind wood activated carbon in batch process, Journal Hazardous Material, 172: 818–825.
26- Selomulya C., Meeyoo V., and Amal R. 1999. Mechanisms of Cr (VI) removal from water by various types of activated carbons. Journal Chem. Technology Biotechnology, 74: 111–122.
27- Selvi K., Pattabhi S., and Kadirvelu K. 2001. Removal of Cr (VI) from aqueous solution by adsorption onto activated carbon. Bioresour. Technology, 80: 87–89.
28- Singh K.P., Malik A., Sinha S., and Ojha P. 2008. Liquid-phase adsorption of phenols using activated carbons derived from agricultural waste material. Journal Hazardous Material, 150: 626–641.
29- Srinivasan K., Balasubramanian N., and Ramakrishnan T.V. 1988. Studies on chromium removal by rice husk carbon. Indian Journal Environment Health, 30: 376–387.
30- Srinivasan K., Balasubramanian N., and Ramakrishna T.V. 1991. Studies on chromium (VI) removal by activated groundnut husk carbon. Indian Journal Environment Health, 33: 433–439.
31- Tan I.A.W., Ahmad A.L., and Hameed B.H. 2008. Optimization of preparation conditions of activated carbons from coconut husk using response surface methodology. Chem. Engineering Journal, 137: 462–470.
32- Xiangyu W., Chau C., Ying C., and Huiling L. 2009. Dechlorination of chlorinated methanes by Pd/Fe bimetallic nanoparticles. Journal Hazardous Material, 161: 815–823.
CAPTCHA Image