دانشگاه تهران محیط شناسی 1025-8620 40 2 2014 06 22 Purging of Oil Contaminants in Soil Using Combination of Fenton Advanced Oxidation and Sulfate Radical (A Case Study: Masjed Soleiman, Iran) پاک‌سازی آلاینده‌‌های نفتی از خاک با بهره‌گیری از روش اکسایش پیشرفتۀ ترکیبی فنتون و سولفات رادیکال (مطالعۀ موردی: مسجد سلیمان) 277 287 51198 10.22059/jes.2014.51198 FA الهام عظیمیان دانشجوی کارشناسی ارشد زمین‌شناسی زیست‌محیطی، دانشکدۀ علوم طبیعی، دانشگاه تبریز علی کدخدائی استادیار گروه زمین‌شناسی، دانشکدۀ علوم طبیعی دانشگاه تبریز مجید بغدادی استادیار گروه عمران، دانشکدۀ محیط‌زیست دانشگاه تهران اصغر اصغری مقدم دانشیارگروه زمین‌شناسی، دانشکدۀ علوم طبیعی، دانشگاه تبریز رضا مرادی کارشناسی ارشد زیست‌محیطی، دانشگاه چمران Journal Article 2013 11 17 Oil exploration and production zones are very frequently contaminated with petroleum hydrocarbons or its derivatives. The most important exploration and production zones are located in South-west and South of the country, in Iran. Masjed Soleiman city is located on an oil field. The soil of this region has been affected by the petroleum composition. Mach petroleum seepages and springs (asphalt, oil and gas) with active oil and gas wells in Masjed soleiman caused this contamination. Restoration of soil contaminated with hydrocarbons at the sites has become a very interesting scientific challenge, mainly because of the actual complexity of the matrix. A large number of studies have been reported for the treatment of oil contaminated soil. One of the technologies is advanced oxidation. Advanced oxidation processes has the potential for rapidly treating or pretreating of pollution by TPHs. Applying the advanced oxidation processes have proven to be effective in treating and recovering the soil, mainly because they are faster than the other processes and are able to degrade toxic recalcitrant matter. The aim of this study is to evaluate effectiveness of the advanced oxidation process of oil contaminated soil by combination of Fenton and sulfate radical.   Materials and methods The study area is located in the Zagros fold belt, and considered as a part of the Dezful embayment. Masjed Soleiman is located on Aghajari, Mishan, and Gachsaran formations. The Gachsaran formation is located inside the Asmari Formation as one of the largest oil reservoirs in southern Iran. Joint and Fractures systems caused oil spills to the surface. The lithology of these formations is composed of gray marl, limestone, brown to gray sand lime stone and carbonate. Due to the weather conditions, the climate of the region is known as the cold and dry. In this study, soil samples contain two types of soil, Petroleum-contaminated soil and clean soil. Sampling locations are shown in Figure 1. Soil characteristics were determined based on clean soil test. Clean soil passed from a 40 mesh sieve. Physical – chemical properties of the samples were, pH (7.3), organic matter (2.59%), Calcium carbonate (CaCO₃) (18.75%), clay (5.4%), sand (10.2%), silt (84%), and soil texture (silt loam).                                 B     A       Figure 1. A) Location of study area, B) Sampling points       In this study, advanced oxidation process was used for cleaning up the contaminated soil in the Masjed Soleiman. Materials used in the experiment are including: Hydrogen peroxide (Merck, 35%), potassium per sulfate (pxtra, 98, India), Optical Spectrometer (GCB model UV/VIS199), sulfuric acid (98%) and potassium dichromate. Although hydrogen peroxide is highly reactive and capable to oxidize a wide range of pollutants, but the limitations of the peroxide is unstable and rapidly decomposes in the soil texture. Recently, increasing attention has been paid to the sulfate radical due to its high efficiency of mineralization of organic pollutants. On the other hand, one of the systems that contain hydrogen peroxide and per sulfate with H₂O₂ oxidation and stability is resulted from the higher degradation rate of soil. The removal efficiency of contaminants by iron oxide catalyzed by Fenton-like reaction is influenced by parameters such as types and concentrations of iron oxides, H₂O₂ concentration, and the presence of other oxidant-consuming compounds and pH. Initially, experiments were carried out to determine the optimal concentrations of hydrogen peroxide andpotassium per sulfate. To obtain optimal concentrations, different amounts of hydrogen peroxide and potassium per sulfate were added to soil samples. Then, samples were added to the dichromate and sulfuric acid to measure the amount of organic matter remaining in the soil. It is used analyzing samples of the spectrometer. The spectrometer was adjusted on 620 wavelengths. This spectrum is based on the use of dichromate. The results are shown in Table 1 and Figure 2. Concentrations selected for this experiment, 0.15 gr of potassium per sulfate, hydrogen peroxide and 4 cc. Other effective factors are the test: pH, temperature and the amount of catalyst. This experiment was done in neutral pH and temperature of 50°C. The iron oxides were used in the soil as a catalyst potential. We used the experimental stage to increase the removal rate. Hydrogen peroxide and potassium persulfate were added in three steps over three days. Table 1. Different amounts of hydrogen peroxide and potassium persulfate Concentrations persulfate Concentration H₂O₂ 0 1 0.05 2 0.1 4 0.2 6 0.4 8 0.6 10   <br clear="all" /> Figure 2. Results of the optimization of A) hydrogen peroxide and B) persulfate Conclusion   The results of this study have indicated that an advanced oxidation process can be used as a powerful method in this study. This method was able to remove a significant percentage of contamination of soil during three days. The first step was to remove 19 percent of contamination. The next steps were to remove the 45 and 48 percent, respectively. The result is shown in Table 2. Although hydrogen peroxide-based oxidation is more powerful for the removal of contaminants, its oxidative strength cannot exist in a remedial system for a long time due to ease of decomposition of hydrogen peroxide and rapid disappearance of hydroxyl radicals. These experiments indicated that both hydrogen peroxide and potassium persulfate have a positive impact on oxidation of petroleum compounds in soil. According to the most appropriate optimization of hydrogen peroxide and potassium persulfate removal rate, the ratio of 1:0.05 is obtained. It should be noted that although hydrogen peroxide can be activated by ferrous ion and persulfate, ferrous ion is also a scavenger of sulfate and hydroxyl free radicals. Thus, ferrous ion concentrations should be controlled to minimize the adverse effects of ferrous ion on sulfate radical production. In addition, ferrous ion can also decompose persulfate anion according to reaction. Thus, excess addition of ferrous ion may reduce the efficiency of contaminant removal.   Table 2. The result of advanced oxidation process Testing stage amount of number with Optical spectrometer Removal % Removal Averae % temperature C° amount H₂O₂ amount per sulfate Frist Day 146 21 19.2 50 1.3 0.05 Frist Day 153 17 50 1.3 0.05 Second Day 97 47 45.4 50 2.6 0.1 Second Day 106 43 50 2.6 0.1 Third Day 90 51 48.70 50 4 0.15 Third Day 101 45 50 4 0.15 Control 186 0 0 50 0 0 آلودگی خاک مناطقی که روی میدان‌‌های نفتی واقع شده‌اند، از بزرگ‌ترین مشکلات زیست‌محیطی است، زیرا این مناطق همواره تحت تأثیر‌‌ آلاینده‌های نفتی قرار دارند. از آنجا که کشور ما دارای منابع فراوان نفتی و گازی است، شهر‌‌های جنوبی و به خصوص حاشیۀ خلیج‌فارس، تحت تأثیر‌‌ این معضل بوده‌‌اند. فرایند اکسایش پیشرفته از مهم‌‌ترین تکنولوژی‌‌ها، برای اکسید و تخریب طیف وسیعی از آلاینده‌‌های آلی در خاک و آب در مدت کوتاه با بازدهی بالاست. هدف از این تحقیق بررسی تأثیر‌‌ حذف آلاینده‌‌های نفتی از طریق فرایند اکسایش پیشرفته در خاک‌‌های آلوده‌شده در شهرستان مسجد سلیمان است که به وسیلۀ چشمه‌های نفتی در مناطق مسکونی مانند سی برنج و نفتون آلوده شده‌اند. در این راستا با مطالعات خاک‌شناسی و زمین‌شناسی اولیه برای حذف ترکیبات نفتی از خاک، از اکسید‌کننده‌‌های پراکسید هیدروژن و پتاسیم پرسولفات استفاده شده است. استخراج ترکیبات نفتی از خاک به روش سوکسله انجام شد. میزان ترکیبات نفتی در خاک نمونه‌برداری‌شده از طریق روش وزن‌سنجی 8/6 درصد تعیین شد. با توجه به بهینه‌کردن هیدروژن پراکسید و پتاسیم پرسولفات مناسب‌ترین نرخ حذف در نسبت 05/0: 1 به دست آمده است. این مقادیر در حضور مقدار احتمالی آهن در خاک، که برابر 8/2 درصد است، به خاک اضافه شده است. در این آزمایش مشخص‌شده اضافه‌کردن مرحله‌ای عوامل مؤثر در اکسایش پیشرفته سبب افزایش راندمان حذف شده است. تحت شرایط بهینه و مرحله‌‌ای افزودن پراکسید هیدروژن و پتاسیم پرسولفات طی این فرایند، در حدود 50 درصد ترکیبات نفتی از خاک حذف شده است. https://jes.ut.ac.ir/article_51198_954a867d2d0220a7ccfe7870e10f80df.pdf