Characterization and Efficacy Studies of Activated Charcoal Produced from Animal Bones for Heavy Metal Adsorption from Waste Water using Concentrated Hydrochloric Acid as Activating Agent

Abstract

Study’s Excerpt

• Activated charcoal was synthesized from cow and sheep bones.
• The activated charcoal was characterized using FT-IR and SEM.
• The activated charcoal synthesized was effective in cleaning heavy metals from waste waters via adsorption.
• The charcoal can be used in industrial water treatment and purification.
• The method employed is environmentally friendly.

Full Abstract

This research work is designed to study and analyse the efficacy and also characterization of the activated charcoal produced from cow, sheep and goat bones using concentrated hydrochloric acid as an activating agent for toxic metals adsorption using chromatographic techniques. The aim of this research is to provide an eco-friendly adsorbent which will also reduce environmental waste for being converted to the activated charcoal. The bones undergone carbonization with the aid of furnace for one hour (1hr) at 600^°C. The bone charcoal was activated with concentrated hydrochloric acid for a period of 4 hrs at a ratio of 10.0 ml per 50.0 g. The activated bone charcoals produced were characterized using scanning electron microscope (SEM) and infrared spectroscopy (FT-IR) before and after adsorption, the results obtained from SEM shows the porosity owing to the breakage in the surface of the adsorbents before adsorption while after adsorption the porosity reduce for both adsorbents. The FT-IR results indicated the existence of functional groups OH, C-H, C=O and PO₄^3- with some changes in the vibration frequency before and after adsorption. Column adsorption shows that the percentage adsorption for both metals increase with increase in initial metal concentrations. As the concentration of Lead increase from 20, 30 to 40ppm there was corresponding swift increase in adsorption from 46.2 %, 61.58 % to 71.13 % for ACBC (Activated Cow Bone Charcoal) and increase from 25.13 %, 35.65 % to57.70 % for ASBC. For Copper there was increased in adsorption from 37.30 %, 55.90 % to 64.53 % for ACBC, 39.10 %, 56.55 % to 64.90% for ASBC (Activated Sheep Bone Charcoal), for Zinc there was an increase from 35.60%, and 56.45% to 67.03% and similarly for Iron 16.60%, 45.03% to 58.53% for ACBC. The equilibrium data for ASBC-Pb, ACBC-Fe and ASBC-Fe with high regression coefficient value (R²) 0.999 each fit well to the Langmuir isotherm model. For ACBC-Pb, ACBC-Cu, ASBC-Cu, ACBC-Zn and ACBC-Zn with high regression coefficient value (R²) 0.999, 1.0, 0.999, 0.999 and 1.0 respectively fit well to the Freundlich isotherm model. Therefore, the adsorption occurs through multilayer formation on the adsorbent surfaces. The indices of the separation factor K_L for Langmuir indicate that the adsorption processes are favourable with the exception of ASBC-Fe which is unfavourable. The Fruendlich isotherm constant n_f for the adsorption of ACBC-Pb, ACBC-Cu, ASBC-Cu, ACBC-Zn, and ASBC-Zn displays adsorption on heterogeneous surfaces. This uncovers that the bone charcoals can be used for the removal of heavy metals by adsorption from aqueous media and can be serve as an efficient adsorbent for water purification and treatments in industries.