Adsorption of Lead Ions from Aqueous Solution by Functionalized Polymer Aniline–Formaldehyde Condensate, Coated on Various Support Materials

Continuous release of heavy metals such as Cadmium, Chromium, Copper, Lead, Manganese, Nickel, Zinc, etc., from different industrial wastewaters has become one of the most alarming threats all over the world due to their adverse effects on the proper ecosystems functioning. Most of the heavy metals do not degrade or degrade very slowly in the environment. A study was conducted for quantifying the metal removal capacity of a functionalized resinous polymer, i.e., aniline–formaldehyde condensate (AFC), which was coated on eggshell, sand, tea leaves, and fly ash separately as support material and divalent lead (Pb⁺²) was taken as the model metal ion. The various parameters affecting adsorption, i.e., reaction pH, adsorption time, and initial concentrations of lead were taken into consideration. A pH range of 3.0–6.0 shows a continuous increase in metal adsorption but at pH > 6.0, the lead precipitates as lead hydroxide, i.e., Pb (OH)₂. The maximum removal of Pb⁺² by AFC coated tea leaves (91.9%), fly ash (91.4%), eggshell (74.5%), and sand (65.8%) was obtained at optimum solution pH of 6.0. For the AFC coated adsorbents, reaction kinetics followed the Lagergren second-order model. Adsorption of lead by the AFC polymer coated on the above support materials could be better described by Langmuir isotherm model with maximum Langmuir monolayer uptake of 96.15, 46.73, 13.62, and 7.07 mg/g for AFC polymer coated on eggshell, tea leaves, fly ash, and sand, respectively. It can be concluded that AFC polymer coated on the above support materials have the efficiency for the removal of lead from waste discharge.