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Studying of the optical properties of poly (vinyl alcohol) films using Aluminum sulphate as additive by measuring allowed direct transition energy gap
دراسة الخصائص البصريه لشرائح افلام بولي فينيل الكحول باستخدام مضافات كبريتات الالمنيوم عن طريق قياس فجوة الطاقه للانتقال المباشر

Author: Atheel H. Alwash أثيل حسن علوش
Journal: Baghdad Science Journal مجلة بغداد للعلوم ISSN: 20788665 24117986 Year: 2011 Volume: 8 Issue: 1 Pages: 103-109
Publisher: Baghdad University جامعة بغداد

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Abstract

The change in the optical band gap and optical activation energy have been investigated for pure Poly (vinyl alcohol)and Poly (vinyl alcohol) doped with Aluminum sulphate to proper films from their optical absorption spectra. The absorption spectra were measured in the wave range from (200-700) nm at temperature range (25-140) 0C. The optical band gap (Eg) for allowed direct transition decrease with increase the concentration of Aluminum sulphate. The optical activation energy for allowed direct transition band gap was evaluated using Urbach- edges method. It was found that ∆E increases with increasing the concentration of Al2 (SO4)3 and decreases when temperature increases.

تم فحص التغيير في فــجوة الطاقه المحضورة وطاقة التنشــيط قد تم فحصها لشرائح مركب PVA النقي والمشوب من خلال الامتصاص البصري للاطوال الموجية من (200-700) نانوميتر وبدرجة حرارة تتغير بمعدل (25-140) م0 .ان فــجوة الطاقة المحضورة تقل بزيادة تركيز ملح سلفات الالمنيوم وان طاقة التنشــيط للانتقال المباشر تم حسابها باستخدام طريقة Urbach-edges ووجد انها تزداد بزيادة تركيز ملح ســلفات الالمنيوم وتقل بزيادة درجة الحرارة.


Article
Synthesis of Activated Carbon from Eichhronia Crassipes Plant as Adsorbent for the Removal of Phenol from Aqueous Solution

Authors: Atheel H. Alwash --- Dheaa Zageer --- Hussain Mohammed Ali
Journal: Al-Nahrain Journal of Science مجلة النهرين للعلوم ISSN: (print)26635453,(online)26635461 Year: 2019 Volume: 22 Issue: 1 Pages: 46-54
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

For a friendly environment, adsorbents are prepared from harmful natural sources to reduce their impact on the environment. The preparation of activated carbon from the Eichhornia crassipes was done by carbonization at 450C°, followed by activation step at 800C°. The adsorption processes were carried out by the batch system to determine the optimal conditions for the removal of phenol from the aqueous solutions. Different parameters were used in batch experiments such as initial concentrations of phenol (in the range from 10-100 ppm), pH (from 2-12), temperature (from 298-328k), AC dosage (from 0.09-0.4g). All the adsorption experiments were carried out in thermostat shaker at 150 rpm. The removal percentage of phenol on activated carbon was 98.2% at optimum conditions of 10 ppm initial phenol concentration, 25 minutes, pH=7, 308 k, 0.2 g of AC dosage). The thermodynamic functions of phenol adsorption were studied at different temperatures. The values of Gibbs free energy (∆G) at maximum removal with temperatures (298, 308, 318 and 328K) was (-5.17, -6.83, -8.22, -8.48) respectively and enthalpy ∆H, entropy ∆S values was 29.22 and 0.114. The activated carbon extracted from Eichhornia crassipes has a double benefit. first, to remove various organic pollutants such as phenols in aqueous solutions and the second, to create a clean water environment free of this plant found in Iraqi waters.

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