Adsorption of Lead from Aqueous Solution Using Activated Carbon Derived from Rice Husk Modified with Lemon Juice

Abstract

In the present work, activated carbon (RHAC-LJ) was synthesized utilizing rice husk as a carbon source that is activated with lemon juice. Moreover, the adsorptive capacity of RHAC-LJ in removing Pb(II) from aqueous solution was investigated. FTIR analysis revealed the presence of amides, alkenes, carboxyl and hydroxyl groups in RHAC-LJ. SEM micrographs illustrate that activation with lemon juice resulted in high pore volume and greater pore diameter. Activation using acid from lemon juice can remove impurities from the adsorbent surface. The surface area and pore volume of RHAC-LJ were determined to be 112.87 m2·g−1 and 0.107 cm3/g, respectively. Adsorption kinetics followed the pseudo-second-order equation (R2 = 0.9941) with a rate constant of 3.3697 g/mg·min for Pb (II), which indicates chemisorption to be the rate-determining step of the process. The BBD model using RSM was applied in studying the effects of pH, stirring speed and adsorbent dosage and their interactions on the removal efficiency of RHAC-LJ. Analysis of variance was used to examine the significance of the model, independent parameters, and their interactions. Moreover, a removal efficiency of 98.49% can be attained using the following optimal conditions: 197 rpm, pH 5.49, and adsorbent dosage of 0.3487 g. Overall, the present work illustrates RHAC-LJ as a potential low-cost adsorbent for the removal of Pb(II) from synthetic wastewater.