مهندسی شیمی ایران

مهندسی شیمی ایران

تهیۀ آئروژل سیلیکای فوق آب‌گریز با ظرفیت بالای جذب آلاینده‌های آلی

نوع مقاله : مقاله پژوهشی

نویسندگان
1 کارشناس ارشد مهندسی شیمی و پلیمر، دانشگاه یزد
2 استادیار مهندسی شیمی و پلیمر، دانشگاه یزد
چکیده
از آئروژل‌های سیلیکا به‌دلیل ریزساختار متخلخل و خواص برجسته مانند چگالی کم، تخلخل زیاد به‌عنوان جاذب برای حذف آلاینده­های آلی استفاده می­شود. با این حال، کاربرد آن‌ها به‌دلیل هزینۀ بالای تولید محدود شده‌است. بنابراین، استفاده‌از پیش‌مادۀ ارزان‌بهای آب شیشه و فرایند کم هزینۀ خشک‌کردن در فشار محیط پیشنهاد می­شود. در این مطالعه، آئروژل سیلیکای مزومتخلخل آب‌گریز بااستفاده‌از دو پیش‌مادۀ آب شیشه و متیل تری‌اتوکسی سیلان در نسبت مولی 1/5=MTES/WG
با روش خشک‌کردن در فشار محیط تهیه و به‌عنوان جاذب استفاده می­ شود. نتایج نشان داد که شرایط بهینۀ 8/5=
pH، پیرسازی دومرحله‌ای، شست‌وشوی یون سدیم و از همه مهم‌تر استفاده‌از عامل فعال سطحی CTAB منجربه تهیۀ آئروژل­ با خواص برجسته مانند چگالی کم 0/102 گرم بر سانتی­متر مکعب، زاویۀ تماس زیاد 140، تخلخل زیاد 95%، مساحت ویژۀ زیاد 1588متر مربع بر گرم و متوسط اندازۀ حفره‌ها به‌طور متوسط 5/7 نانومتر شد. ظرفیت جذب آئروژل‌ها در 6 حلال مختلف بنزین، نفت، هگزان، تولوئن، کلروفرم و اتانول اندازه‌گیری شد. نتایج ظرفیت جذب نشان داد که ایروژل تهیه‌شده روغن را حدود 20 برابر، بنزین را حدود 5/9 برابر، تولوئن را حدود 4/4 برابر و هگزان را حدود 2/7 برابر بیشتر از کربن فعال جذب کرد. ویژگی‌ جذب تکرارپذیر نیز با انجام آزمایش‌های چرخه‌ای برای نفت خام نشان داد که آئروژل، ‌شکل و ساختار اصلی خود را تا چرخۀ ششم حفظ می‌کند و ظرفیت جذب تا چرخۀ چهارم کاهش بسیار کمی را نشان می­ دهد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Preparation of Superhydrophobic Silica Aerogel with High Adsorption Capacity of Organic Pollutants

نویسندگان English

D. Yaballoie 1
Z. Daneshfar 2
1 M. Sc. of Chemical and Polymer Engineering, Yazd University
2 Assistant Profesor of Chemical and Polymer Engineering, Yazd University
چکیده English

Silica aerogels can be used as adsorbents to remove organic pollutants due to their porous microstructure and outstanding properties such as low density and high porosity. However, their application is limited due to the high cost of production. Therefore, it is recommended to use the inexpensive precursor of glass water and the low-cost ambient pressure drying. In this study, the hydrophobic mesoporous silica aerogel was prepared by water glass (WG) and methyltriethoxysilane (MTES) co-precursor with molar ratio of MTES / WG = 1.5 through the sol-gel method followed by pressure drying which used as an adsorbent.
The results showed that the optimal conditions of pH = 8.5, two-stage aging, sodium ion washing, and most importantly, the use of cetyltrimethylammonium bromide as a surfactant led to the preparation of an aerogel with outstanding properties such as a low density (0.102 g/cm3), high contact angle (140
°), porosity (95%), high specific area (1588 m2/g) , and the average pore size of 5.7 nm. The adsorption capacity of aerogels was measured in 6 different solvents: gasoline, oil, hexane, toluene, chloroform and ethanol. The results of adsorption capacity showed that the prepared airgel absorbed oil about 20 times, gasoline about 5.9 times, toluene about 4.4 times, and hexane about 2.7 times more than activated carbon. Repeatable adsorption characteristics of the samples were also checked by performing cycling tests for crude oil and concluded that the aerogel kept its original shape and structure until the sixth cycle and the absorption capacity showed a very small decrease until the fourth cycle.

کلیدواژه‌ها English

Silica Aerogel
Adsorption
Organic Pollutant
Water Glass
Ambient Pressure Drying
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