Elimination des nitrates contenus dans les solutions aqueuses par adsorption sur un matériau végétal

الموضوعات

علوم تطبيقية وتكنولوجية

الملخص

Notre étude porte sur l'adsorption des nitrates sur un matériau végétal. Nous avons testé plusieurs matériaux végétaux tels que : écorce d'orange, la paille, le résidus de mais et les tiges de dattes et il s'est avéré que les tiges de dattes constitue un meilleur adsorbant des nitrates. Une étude paramétrique a été effectuée pour examiner l'influence de la concentration du polluant, la masse et la granulométrie de l'adsorbant, le pH et la température de la solution sur le rendement d'adsorption. Le meilleur rendement d'adsorption (90%) est obtenu dans les conditions opératoires suivantes : Concentration des nitrates = 125 mg/l, pH = 2, concentration de l'adsorbant = 5g/l, granulométrie = 50µm. L'étude cinétique a montré que l'équilibre d'adsorption est atteint au bout des premières 20min de contact. L'isotherme d'adsorption du polluant sur les tiges de dattes obéit au modèle de Langmuir (R2 = 0.99), et la vitesse de la réaction est du pseudo second ordre.L'étude thermodynamique a montré que le processus d'adsorption des nitrates est spontané ( G<0), endothermique ( H>0) et l'affinité du matériau pour l'adsorption des nitrates est représenté par S>0. Les paramètres opératoires influences sont optimisées par un modèle trouvé par la méthode des plans des expériences

روابط وملفات

التعريف والنوع

رقم الوثيقة

ed4e5b82-6e75-449a-81bd-2ee9b86a49ea

رقم العقد

0

نوع الوسائط

Crawler

نوع المحتوى

الرسائل العلمية

صيغة المصدر

رسائل ماجيستير

نوع الملف

word

أسماء الملفات

1376738_1.docx, 1376738_2.pdf

بيانات النشر

ألقاب المؤلفين

[{"name_ar":" Z. Sadaoui ","title_ar":"اشراف","title_en":"Supervision"},{"name_ar":"Ouiza Allalou","title_ar":"اعداد","title_en":"Preparation"}]

اللغة

French

المصدر والدورية

اسم المصدر

Elimination des nitrates contenus dans les solutions aqueuses par adsorption sur un matériau végétal

المحتوى والصفحات

عدد الصفحات

0

ترجمة الملخص

The present investigation is devoted to study the removal of nitrate from synthetic aqueous solution by using natural adsorbents (orange barks, straw, waste of com) in particular date stems. This agricultural by-product is available in large amount in Algeria. The preliminary results showed that washing the adsorbents with demineralised water involve a low level of nitrate elimination. Thus all the adsorbents were used in a rough state without undergoing any treatment. This paper reports the feasibility of using an agricultural waste to remove nitrates from synthetic solution under different experimental conditions. Effect of various process parameters, namely, pH, adsorbent dose, particle size, initial nitrates concentration, temperature and contact time has been studied in batch systems. The first results of this study enabled us to select the date stems like a better adsorbent of nitrates. The results obtained revealed rate of nitrates elimination about 78, 45%. A parametric study was conducted to examine the influence of some operating parameters on the performance of adsorption as follows: the initial concentration of nitrate, the mass and size of adsorbent, pH and temperature of the solution. The results are very promising. Indeed, a yield of 90% adsorption is obtained in the following operating conditions: initial concentration of nitrate = 125mg / l, pH = 2, mass of adsorbent = 5g and a particle diameter of 50μm Moreover, the kinetic study showed that adsorption equilibrium is reached after the first 20min of contact. The adsorption isotherm of nitrate on the stems of dates was studied by examining the application of two models: Langmuir and Freundlich. The results indicate that the Langmuir model adequately describes the experimental results (R2 = 0.99). In addition, the study of adsorption kinetics shows that the velocity of reaction is the pseudo second order. The determination of thermodynamic parameters showed that the adsorption of nitrate process is spontaneous (ΔG < 0), endothermic (ΔH > 0) and the stems of dates have good affinity for the adsorption of nitrate as the value of the entropy is found positive ΔS> 0. In addition, the value of the heat of adsorption obtained, permit us to conclude that it is a physical adsorption. Finally, the method of design of experiments led to a rapid and effective modelling in the experimental study. The search for an optimal area to optimize the parameters affecting the performance of adsorption of nitrates on the stems of dates. However, the mathematical model which has been deducted can’t predict the value of the adsorption efficiency of nitrate outside the field of study.

كلمات الباحثين

adsorption kinetics, Adsorption, Cinétique chimique, Nitrate, Nitrates, Solutions aqueuses (chimie), stems of dates, النترات, حركية الامتصاص, سيقان التمر

إشراف وإعداد

الإشراف

Z. Sadaoui

الإعداد

Ouiza Allalou

الاقتباسات الببليوغرافية