دراسة امتزاز بعض الأصبغة من المحاليل المائية علي الفحم الفعال المنتج من قشور اللوز

الموضوعات

علوم بحتة وطبيعية

روابط وملفات

التعريف والنوع

رقم الوثيقة

03d9e5aa-817f-4670-a44b-bd18ee5e18d5

رقم العقد

0

نوع الوسائط

Crawler

نوع المحتوى

الرسائل العلمية

صيغة المصدر

رسائل ماجيستير

نوع الملف

pdf text

أسماء الملفات

1967081_1.pdf

بيانات النشر

ترجمة العنوان

STUDY OF ADSORPTION OF SOME DYES FROM AQUEOUS SOLUTIONS ON ACTIVATED CARBONS OBTAINED FROM ALMOND SHELLS

ألقاب المؤلفين

[{"name_ar":"رقية محمد علي سعدون","title_ar":"اعداد","title_en":"Preparation"},{"name_ar":"محمد نصوح علايا","title_ar":"اشراف","title_en":"Supervision"}]

اللغة

Arabic

المصدر والدورية

اسم المصدر

دراسة امتزاز بعض الأصبغة من المحاليل المائية علي الفحم الفعال المنتج من قشور اللوز

المحتوى والصفحات

عدد الصفحات

89

ترجمة الملخص

Adsorbents:The activated carbons (ACs) used in this study were previously prepared in Physical Chemistry Research Laboratory. Known amounts of grounded almond shells were impregnated in aqueous solutions of H3PO4 of varying wt.% (20, 35, 50 and 65 wt.%H3PO4)for 72 h, then dried at 120 oC and carbonized in limited amount of air at 400 oC for 4 h. The 50 wt.%H3PO4-activated sample was also carbonized at 300 -600 oC. The carbonized products were washed thoroughly with bidistilled water until the pH of the filtrate being ~6, then dried at 120 oC. The ACs were designated as APx-y, where x was the wt.%H3PO4 and y indicates the carbonization temperature.Techniques:The pH of the AC surface (pHs) was determined by adding 0.5 g of dry powder AC to 50 mL of bidistillated water, the suspension was boiled for 10 min then filtered, and the filtrate was cooled to 298 K. The pH of the filtrate was measured by pH-meter.The pH of zero point charge (pHzpc) of the used ACs was determined by adding 0.15 g of AC to 50 mL of 0.01 M NaCl solution at pH = 2, 4, 6,...12, left for 48 h, then filtered and the pH of the filtrate was measured. Drawing the final pH against the initial pH, the pHzpc was obtained from the intercept of the curve with the radial line.The cation –exchange capacity (CEC) of the used ACs was determined by adding 20 mL of 0.1 N NaOH solution to 0.1 g of AC. The suspension was agitated for 24 h, then filtered. 5 mL of the filtrate was titrated with o.1 N HCl solution. The consumed amount of NaOH in mmol/g was a measure to CEC of AC.The adsorption of Congo red (CR), rhodamine –B (RB) and eriochromblack T (EBT) dyes from aqueous solutions at 298 K was determined by adding 0.1 g of AC to 50 mL of the respective aqueous solutions of the dye at a given initial concentrations (Co), and shaking for 72 h to attainequilibrium. The equilibrium concentration (Ce) was determined using Jasco spectrophotometer at the wave length of 500, 565 and 530 nm for CR, RB and EBT respectively. The amount of dye adsorbed for 1 g AC, x (mg/g), was calculated for each Ce. The adsorption isotherms were determined by plotting x against Ce. The adsorption data were analyzed by applying Langmuir and Freundlich equations.The kinetics of dyes adsorption on AP50-500, AP50-600 and AP65-400 ACs were studied at 298 K. The thermodynamics functions(∆Go, ∆Ho and ∆So)of the adsorption processes of the dyes on AP50-400 AC were studied by analyzing the adsorption data at 298 and 308 K.Results: Theresults of this study reveal the following points:1-The pHs and pHzpc values are in the range of 2.26 ‒2.47 and 2.00‒ 2.50 respectively, which indicate that the surface of the used ACs are acidic and of type L.2-The cation-exchange capacities are in the range of 3.72‒9.92 mmol/g. CEC decreased with the rise of carbonization temperature, and increased with an increase in wt.% H3PO4. 23-The adsorption isotherms of CR, RB and EBT are of Type L according to the classification of Gils et al. Analysis of the adsorption data indicates that adsorption of CR molecules obeys both Langmuir and Freundlich equations, whereas the adsorption data of RB fit well Langmuir equation, but for EBT fit well Freundlich equation. These observations reveal that the adsorption process of the dyes occurs on heterogeneous surfaces with mostly monolayer coverage. The calculation of monolayer capacities and B constants show the following:(i)The uptake of dyes, qm, are dependent on the percent of activation as well as on carbonization temperature. Thus, the qm values show maxima at 50 wt. %H3PO4 activation for CR and RB, whereas for EBT the maximum uptake observed at 35 wt.%H3PO4. The qm values are maxima for AP50 ACs that carbonized at 400 oC for CR, at 450 oC for RB and at 600 oC for EBT.(ii)The adsorbate/adsorbent interactions as indicated from the values of B constants for the dyes are in the order: RB > EBT > CR. This order due to that RB molecules are zwitterions whereas EBT and CR molecules are anions and CR anion is biggerthan that of EBT anion.(iii)The surface available to dye molecules is small in comparison with the total surface area of the ACs, since the values of S/SBET are 9.16‒ 29.2% for CR and 2.23‒ 15.22% for RB.4-The kinetics of the adsorption of CR, RB and EBT on some selected ACs from aqueous solutions at 298 K obey the pseudo-second order kinetics. The apparent rate constants follow the order: k2(RB) > k2(CR) > k2(EBT). The intraparticle diffusion is not alone the controlling step in the adsorption process.5-The calculation of thermodynamic functions ∆Go, ∆Ho and ∆ Soindicates that the adsorption process of all studied dyes are spontaneous (∆Go<0) and endothermic (∆Ho> 0). The positive values of ∆Soindicate that the dye molecules are more random at liquid-solid interface than in the solution and there are affinity between the surface and the dye molecules.6-The AC sprepared from almond shells by activation with H3PO4 are excellent adsorbents for removal of these dyes from aqueous solutions.

إشراف وإعداد

الإشراف

محمد نصوح علايا

الإعداد

رقية محمد علي سعدون

الاقتباسات الببليوغرافية