ASSESSING THE EFFECTIVENESS OF Fe3O4 (MAGNETITE) MODIFIED PINECONE BIOCHAR FOR THE ADSORPTION OF Cd (II) IN AQUEOUS SOLUTION

Over the last decade, there has been an increase in coastal water contamination because of increased natural and anthropogenic activities, hence the need to proffer an efficient method for water remediation. Using engineered biochar obtained from pyrolysis of agricultural wastes is a low-cost and efficient pathway for sustainable water treatment. This study assesses the use of Fe₃O_4-modified pinecone biochar composite (Fe₃O₄-PCBC) prepared by co-precipitation of Fe₃O₄ unto the pinecone biochar for the adsorption Cadmium (II) (Cd²⁺). Several factors, such as adsorbent dosage, shaking speed (rpm), contact time (Kinetics), temperature, and pH, were optimized to determine the maximum adsorption capacity of the prepared adsorbent. The pH study was considered within the range of 3 to 8, contact time of 1mins, 5mins, 10mins, 15mins, 30mins, 60mins, and 120mins, the salinity of 0M, 0.001M, 0.01M, 0.1M, 1M, adsorbent dosage ranges from 0.4 to 4 g/L, and shaking speed was performed within 100 to 250 rpm. Based on the results of the analyses, the adsorption capacities were optimum at pH 6, 0.4 g/L, 25⁰C, at salinity of 0.01M and 250 rpm. Elovich kinetic model best described the Cd²⁺ adsorption onto the Fe₃O₄-PCBC with an R²-value of 0.999 compared to the pseudo-first-order and pseudo-second-order kinetic model with an R²-value of 0.991 and 0.995, respectively. The Freundlich isotherm model best describes Cd²⁺ adsorption on the adsorbent, with an adsorption capacity of 103.67 mg/g.. Characterization of the adsorbent using various analytical instruments revealed that in situ precipitation and surface complexation contributed to the Cd²⁺ adsorption. The results showed that the Fe₃O₄-PCBC composite could be used as an effective and eco-friendly adsorbent for removing Cd²⁺ from aqueous solution and, in extension, coastal waters.