The Adsorption of Cr3+ onto Na+-Saturated Kaolinite

Abstract

Chromium is one of the parameters of the heavy metal pollutant in the environment. An adsorption of chromium can be used to reduce the content of chromium cation. The study aimed to reduce the concentration of Cr cations in the water waste by using adsorbents kaolinite and Na-kaolinite with the pH variation of the solution. The adsorbents used were kaolinite and Na-saturated kaolinite. There were four steps to conduct this study, including the preparation of kaolinite, making waste simulation, testing the adsorbent, and the data analysis of cation adsorbed. Before the adsorbents were used, it was characterized using the FTIR and XRD methods. The results of the characterization by FTIR showed that the kaolinite and Na-kaolinite adsorbents didn't give significant difference; both adsorbents had the uptake of the clusters that were almost the same. While the XRD characterization on the adsorbent kaolinite appeared with spectra of 2θ = 21.23 and 41.93 which indicated the presence of quartz with contrast on Na-kaolinite that was not visible. On the other hand, Na-kaolinite appeared with spectra of 2θ = 12.6, which indicated the presence of halloysite. The percentage of the cation Cr 3+ that adsorbed was increased concurrently along with the increasing of pH. It indicated that the pH gave significant effect toward the adsorption process. The adsorbent of Na-kaolinite was stronger in adsorbing Cr 3+ as compared with kaolinite at low pH, because the addition of Na + on the kaolinite could result in the distance between the layers became larger and the reduced cluster of quartz in the sample.