Lead Ion Sorption Capacity and the Structural Properties of the Humic Acid Extracts from Evergreen Forests of Different Agro-ecological Zones of Kerala Western Ghats

Abstract

Forest soils are enriched with soil carbon content. The vegetation and precipitation influences it’s chemical structure. The chemical structure directly contributed to its entire properties. Physico-chemical properties play vital role in its soil functioning. The sorption capacity of the humic acid can be applied in the nutrient uptake enhancement and waste water treatment. The study was conducted in the humic acid extract of evergreen forest of different agro-ecological zones of Kerala. Extraction was done by the acidic precipitation method recommended by International Humic Substance Society (IHSS). Determine the chemical structural variations and properties of the humic acid extracts followed by determining the sorption capacity of the material with lead ion. The study revealed the higher percentage of adsorption of lead ion with humic acid extract from evergreen forest of northern high hills –charnockite zone of western  ghats of Kerala. This was the combined effect of enhanced cation exchange capacity and –COOH acidity of the material. These chemical structure and the functional properties to the sorption capacity of the humic acid extract to chelate the lead ion was evaluated .The higher cation exchange capacity and the –COOH acidity favoured the lead ion adsorption. Adsorption isotherm modeling was revealed the multilayer and monolayer adsorption of lead ion on humic acid depends with the heterogeneity of the HA surfaces. Maximum amount of lead ion molecule adsorbed on the HA surface was observed for humic acid from SHH-K agro-ecological zone. This method can be considered as economically viable green method for looking forward technology for waste water treatment.