پديد آورندگان :
اميري، حميد دانشگاه تربيت مدرس , آيتي، بيتا دانشگاه تربيت مدرس - دانشكده مهندسي عمران و محيط زيست - گروه مهندسي محيطزيست , گنجي دوست، حسين دانشگاه تربيت مدرس - دانشكده مهندسي عمران و محيط زيست - گروه مهندسي محيطزيست
كليدواژه :
راكتور ديسكي آبشاري , رگرسيون غيرخطي , مدل لانگماير , هينشلوود , زبري مصنوعي
چكيده فارسي :
صنايع نساجي بدليل تنوع رنگزاهاي مصرفي و روش هاي توليد، پساب هايي با كميت و كيفيت شيميائي متفاوت توليد مي كنند. بعضي از اين رنگ ها بدليل داشتن ساختار شيميايي پيچيده، نيازمند روش هاي كارا و داراي راندمان تصفيه، نظير روش هاي اكسيداسيون پيشرفته هستند. در اين تحقيق به منظور افزايش كارائي فرايند فتوكاتاليستي در تصفيه پساب حاوي Reactive Yellow (RY81)، از يك راكتور ديسكي آبشاري تثبيت شده با نانوذرات اكسيد روي استفاده شد. در اين راكتور به منظور غلبه بر محدوديت هاي انتقال جرم در راكتورهاي با بستر تثبيتي، سطح ديسك ها بوسيله زبري مصنوعي پوشش داده شد، همچنين به دليل وجود جريان آبشاري، علاوه بر ايجاد اختلاط، هوادهي فاضلاب بصورت خودبخودي انجام مي شد. تاثير پارامترهاي غلظت اوليه رنگزا، pH، ميزان كاتاليست پوشش داده شده و دبي جريان بر حذف رنگزا مورد بررسي قرار گرفت و ميزان بهينه پارامترها، به ترتيب mg/L50، 8، gr/m240 و cc/s80 بدست آمد. نتايج مدل سازي سينتيكي نشان داد كه مدل لانگماير- هينشلوود با ميزان k_(L-H) و K_ads، به ترتيب mg L-1 hr-1 7/17 و mg-1 L 122/0 توانايي زيادي در پيش بيني نرخ واكنش دارد. در انتها به منظور پيش بيني ثابت واكنش شبه درجه اول، رابطه رگرسيون غيرخطي پيشنهاد شد كه با دقت بالايي (R2=0.95) تحت شرايط بهره برداري مختلف توانايي پيش بيني نرخ واكنش را دارد.
چكيده لاتين :
Use of different synthetic dyes in textile industries has increased in recent decade, resulting in release of the dye-containing industrial effluents into natural aquatic ecosystem. Since most of dyes are usually very recalcitrant to microbial degradation, removal of dye from effluent is a main concern in many studies. Different processes are used for treatment of dye effluent. In last few years, studies are focused on advanced oxidation process (AOPs) methods such as UV-ZnO, UV-H2O2, UV-O3 and UV-TiO2. Photocatalytic process such as UV-ZnO is an efficient method that treats non-degradable wastewater by active radicals. The photocatalysis needs a photo-reactor that contacts reactant, products and light. In recent years, different types of photo-reactors have been used for wastewater treatment. In some reactors, nano-photocatalysts are utilized in slurry form, and the other particles are coated on bed. In Photocatalytic reactors with fixed bed, nano-photocatalysts are immobilized on bed and do not need separation unit. However, the main disadvantage of these photo-reactors is the low mass transfer rate between wastewater and nano-photocatalysts. Consequently, Different optimal photo-reactors have been developed for increasing mass transfer rate. In this study, a novel photocatalytic cascade disc reactor coated with ZnO nano-photocatalysts is applied and in order to increase mass transfer rate, artificial roughness are created on the surface of disks. Applying artificial roughness changes mass transfer rate by providing vertical mixing, creating secondary currents and increasing the Reynolds number. This photo-reactor has a number of advantages including: eliminating the need for catalyst separation units as the catalyst is immobilized; creating flow mixing by non-mechanical method; increasing oxygen transport from gas phase to photocatalyst surface by providing the flow cascade pattern. The photo-reactor is used in order to remove Reactive Yellow 81 (RY81) dye from textile industry effluent, by means of UV-ZnO process. RY81 is a reactive dye composed of 10 Benzene rings and two –N=N azo bonds. The effect of initial Concentration of dye, pH, Catalyst surface loading and flow rate on removal efficiency is investigated, and the optimal value of those parameters are reported as 50 mg/L, 8, 40 gr/m2 and 80 cc/s, respectively. A rate equation for the removal of RY81 is obtained by mathematical kinetic modeling. The Langmuir-Hinshelwood kinetic model is one of the most common kinetic models that are used for studying the kinetics of heterogeneous photo-catalysis. Results of reaction kinetic modeling indicate the conformity of removal kinetics with Langmuir-Hinshelwood model, and the constants kL-H and Kads are obtained as 7.17 mg L-1 hr-1, 0.122 mg-1 L, respectively.
Considering various operational parameters into an equation, using regression analysis is appropriate. In this study, nonlinear regression model is developed for prediction pseudo- first order rate constant as a function of initial concentration of dye, pH, catalyst surface loading and flow rate. This equation properly predicts (R2=0.95) the removal rate constant of RY81 removal in the photocatalytic cascade disk reactor under different operational conditions and a good consistency is observed between the calculated results and experimental findings.
