Influence of Humic Acid on the Sorption of Heavy Metal Cations on Clay

الموضوعات

علوم بحتة وطبيعية

الملخص

The aim of the present study was to investigate the effects of the interactions between two important soil components, clay minerals and HSs, on the sorption of heavy metals cations under laboratory conditions selected to model the soil systems. The model system used in this study consisted of clay minerals (Kaolinite and Montmorillonite) and an extracted soil humic acid (HA). Cadmium and lead were taken as heavy metal contaminants model. Humic acid extracted from Egyptian soil by using recommended procedures by international Humic Substance Society. HA was characterized using elemental analysis and different spectroscopic methods (NMR and FT-IR spectroscopy) to obtain more information on the chemical structure and function groups of the macromolecule. Kaolinite and Montmorillonite were characterized using elemental analysis by EDAX, calculating the surface area and cation exchange capacity (CEC) value. It was found that, the Si: Al ratio of Kaolinite is 1:1, however in case of Montmorillonite it was 2:1. Moreover, Montmorillonite has higher surface area (35.2 m2/g) and CEC (85 meq/100 g) values than Kaolinite (10 and 4, respectively). The adsorption of soil extracted HA on colloidal-sized clay mineral sparticles was investigated to elucidate how the solution chemistry affects the formation and nature of organic surface coating. A systemic study of the affects of pH and ionic strength on HA adsorption was performed. Humic acid adsorption isotherm followed Langmuir-type (L) curve. The amounts of HA adsorbed onto clay minerals (Kaolinite and Montmorillonite) at high pH and low salt concentration are in a relatively stretched form on the surface and the adsorption was low, however, at low pH and high salt concentration a substantial fraction of the adsorbed HA is collapsed on the surface, which results in a relatively high adsorbed amount. In general, the surface complexation ligand exchange is the most important adsorption mechanism of HA onto the clay minerals (Kaolinite and Montmorillonite) particles regardless of solution chemistry. By using the scanning electron microscope, the clay minerals (Kaolinite and Montmorillonite) particles were studied after adsorption of HA noted that clay minerals particles size increases, this means that HA acts as a binding agent and as nucleus in formation aggregation. Clay minerals (Kaolinite and Montmorillonite) particles were studied by FT IR spectroscopy in presence and absent of HA and this explained that adsorption of HA on clay minerals particles carried out through carboxylic groups. The sorption results of cadmium and lead cations on native clay minerals (Kaolinite or Montmorillonite) and on clay mineral-HA complex’s under different pH and ionic strength, revealed that the adsorption amount decreased in medium of lower pH and higher ionic strength, this refers to the competition of H+ and Na+ for the adsorption sites with Cd (II) and Pb (II). Heavy metals (cadmium and lead) sorption isotherm can be described as linear isotherm at pH = 5.5 but at pH= 6.5, and the adsorption isotherm followed langmuir-type (L)curve in Montmorillonite and Montmorillonite-humic complex particles, but in case of Kaolinite and Kaolinite-humic complex particles, sorption isotherm can be described as Langmuir-type (L) isotherm at pH = 5.5 and 6.5. Also, the results revealed that presence of HA would enhancing the adsorption of heavy metals (cadmium and lead) on clay minerals (Kaolinite and Montmorillonite) under the studied conditions. Also, the results indicated that Pb (II) was more adsorbed than Cd (II) at the same conditions on clay minerals in presence or absence of HA

روابط وملفات

التعريف والنوع

رقم الوثيقة

0c8873f7-3e48-4ac0-9477-ff8c40098825

رقم العقد

0

نوع الوسائط

Crawler

نوع المحتوى

الرسائل العلمية

صيغة المصدر

رسائل ماجيستير

نوع الملف

pdf text

أسماء الملفات

0c8873f7-3e48-4ac0-9477-ff8c40098825_1.pdf

بيانات النشر

ترجمة العنوان

تأثير حمض الهيوميك على امتزاز كاتيونات العناصر الثقيلة على الطفلة

ألقاب المؤلفين

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اللغة

English

المصدر والدورية

اسم المصدر

Influence of Humic Acid on the Sorption of Heavy Metal Cations on Clay

المحتوى والصفحات

عدد الصفحات

0

كلمات الباحثين

Humic Acid - Sorption - Heavy Metal Cations

إشراف وإعداد

الإشراف

أبو الفتوح السيد مراد , سعيد السيد محمد حجي

الإعداد

محمد عيد عبد الحميد السيد, مصطفى محمد رضا خلف

الاقتباسات الببليوغرافية