The Application of Response Surface Methodology for Lead Ion Removal from Aqueous Solution Using Intercalated Tartrate-Mg-Al Layered Double Hydroxides

Layered double hydroxide intercalated with tartrate (tartrate-Mg-Al) was used as an adsorbent to remove lead ions from aqueous solutions. The effects of various optimization parameters such as contact time, solution pH, lead ion concentrations, and adsorbent dosage were investigated by the use of Response Surface Methodology (RSM). The Response Surface Methodology (RSM) based on a four-level four-variable Central Composite Rotatable Design (CCRD) was employed to evaluate the interactive effects of the various optimization parameters. The parameters were contact time (6–10？h), solution pH (1–3), adsorbent dosage (0.06–0.1？g), and lead ion concentrations (10–30？mg/L). The percentage of lead ions removal for each of the parameters studied was determined by Inductively Coupled Plasma-Optical Emission Spectrophotometer. Simultaneously by increasing contact time and amount of dosage of tartrate-Mg-Al used the percentage of lead ions removal from aqueous solution will increase; however, the percentage removal decreases with an increase in pH and concentrations of lead ions. The experimental percentage removal recorded under optimum conditions was compared well with the maximum predicted value from the RSM, which suggest that Central Composite Rotatable Design of RSM can be used to study the removal of lead from aqueous solution by the use of tartrate-Mg-Al as an adsorbent. 1. Introduction The pollution of aqueous solution by high concentrations of metal cations can contribute to a serious environmental problem. The removal of metal cations from aqueous solution to a certain concentration level is therefore becoming an important issue. Adsorption is one of the effective methods to remove metal cations from aqueous solution [1]. Various materials can be used as an adsorbent for the removal of metal cations such as activated carbon [1], biomaterials [2], and clay minerals [3]. In recent years, the use of clay minerals as an adsorbent were found increasing in interest, and numerous studies on the adsorption of metal cations have been carried out by use of the metal oxides [4], metal hydroxides [5], and metal carbonates [6] which are due to their abundance in nature and good metal cations adsorption 1 properties [4–6]. Layered Double Hydroxide (LDH) is one of the clay minerals that have good metal cations adsorption properties with a negatively charged layers, high anion exchange property, and high surface areas. The chemical composition of layered double hydroxides can be described by the formula [M2+1-xM3+x(OH)2]x+(An-)x/n mH2O where M2+ and M3+ are metal