Adsorption of cadmium ion on humic acid extracted from laterite soils of Kannur district, Kerala
Abstract
Humic acids are highly stable and functionalized portions of soil organic matter. Because of it’sstructural heterogeneity and surface porosity, it act as a catalyst in soil nutrient enrichment and palnt growth. Besides, humic acid sequestrate the heavy metal ions on it’ssurfaces by pore filling and multilayer adsorption. The study focused the structural behavior and the physico-chemical properties of the humci acid extracted from the laterite soils of Kannur district of Kerala. And evaluated the sorption performance of the humic acid with cadmium ion. Efficacy of the removal of the cadmium ion by humic acid will leads to an green technology for water purification and the sustainable use of the natural resources.
Keywords
Download Options
Introduction
The importance of humic substances are because of the organic carbon content and the effect on soil fertility, soil structure, water acidity, transportation and mineral weathering. Structural variety of this material directly influence the functioning on the soil [1]. Based on the solubility indifferent pH, the humic substances is classified into mainly three, fulvic acid (soluble in acidic and alkaline conditions), humic acid (soluble in alkaline condition), humin (insoluble in acidic and alkaline conditions). So the extraction of the material deals with the different pH of the extracting solution. From the three compounds, the highly stable and functioning material is humic acid. It is a dark coloured material. The role of humic acid on plant growth and soil nutrient capacity is extensively reviewed [2]. The structure of the humic acid consisit of carboxylic group, methenolic group, phenolic group and methoxy groups. The different carbon functionalities create a reaction potential to this molecule. The cation exchange capacity, total and carboxylic acidities and higher surface area are the unique properties of the humic acids. Effect of humic acid on plant root growth, plant growth hormone production, soil nutrient capacity and carbon cycle are documented by previous researchers. Highly porous and macromolecular structures of the humic acid help them to associate with other metal ion through adsorption on the surfaces [3]. Application of the material for environmental and agricultural purposes may increase the potential of the material. Instead of these, using a natural material like humci acid for impurity removal makes a green chemical approach.
The present study investigates the properties and structure of the humci acid extract from laterite soil of Kerala. The study monitors the cadmium ion removal efficacy of the humic acid and looking a forward technology for wastewater treatment.
Conclusion
The humic acid extracted from laterite soil, Kannur is consisted with carbon function groups such as phenolic, carboxylic, ketonic and carbon ring structure. The stability of the material indicates the highly stable material with good cation exchange capacity and –COOH acidity. The supramolecular carbon dominated species have the potential to remove the heavy metal ion, cadmium. Lower initial concentration favours the maximum percentage of adsorption of Cd2+ ion and relatively higher initial concentration of Cd2+ ion leads the higher qevalue. The percentage of adsorption and qare higher in the lower pH than the max higher pH. As earlier reports of humic acids, the material from laterite soil always shows the same reaction performance as a sorbent. The results insights the pristine role of the humci acid in soil system to rich fertile environment.