BENTONITE MODIFICATION USING SURFACTANT FOR ION ADSORPTION PB(II) OF THE SOLUTION

• Main Author: Nabilah Putri Setiawan, Azizah
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/65043
• Institution: Institut Teknologi Bandung

The presence of metallic lead in water can be harmful to health because of its toxic nature. The lead ion is separated by adsorption method where the adsorbent used is bentonite. Bentonite has a negative charge on its surface and has the ability to swell so that it is effectively used for the separation of metal ions. Bentonite modification was carried out to increase the adsorption capacity with Benzalkonium Chloride which is a cationic surfactant having a quaternary ammonium group. Infrared characterization of bentonite was found to absorb at wave numbers 3412 cm-1 and 3628 cm-1 which are functional groups of structural OH, 1037 cm-1 and 1629 cm-1 which are typical peaks, namely stretching vibrations of Si-O-Si and buckling of water and 476 cm-1 which is the buckling vibration of Si-O-Si on bentonite. Infrared characterization of modified Bentonite found absorption at wave number 1460 cm-1 which is the peak of the bending vibration of N-H, 2852 cm-1 and 2924 cm-1 which is the vibration of C-H which indicates that the methyl present in the surfactant has entered into bentonite. XRD characterization showed that there was a d-spacing value in the modified bentonite, which was 14.48 Å to 17.29 Å which indicated that the bentonite had swollen. Adsorption was carried out using two adsorbents, namely Bentonite and Modified Bentonite to compare their capacities by optimizing them first. Optimization parameters are pH, temperature, analyte concentration, adsorbent mass, and contact time. Optimization of the Bentonite adsorbent was obtained at a contact time of 90 minutes, pH 4, temperature 45oC, adsorbent mass of 0.1 grams, and analyte concentration of 100 ppm. Optimization of the modified bentonite adsorbent was obtained at a contact time of 105 minutes, pH 4, temperature 45oC, adsorbent mass of 0.1 grams, and analyte concentration of 100 ppm. The Cation Exchange Capacity (CEC) in sodium bentonite is 64.3 meq/100 gram. The absorption capacity of modified bentonite is greater than that of pure bentonite where the Qe value for pure bentonite is 59,839 mg/g and modified bentonite is 88,516 mg/g. Under optimum conditions, an adsorption isotherm analysis was carried out in which the two samples, namely bentonite and modified bentonite, followed the Langmuir Isotherm model, this isotherm illustrates that the adsorption system is monolayer. Determination of adsorption kinetics in both samples, namely bentonite and pure bentonite, both followed pseudo-second order. Based on deeper exploration, it shows that adsorption does not only go through one stage but two stages, namely starting with film diffusion followed by intraparticle diffusion. Thermodynamic analysis was carried out to determine the spontaneity of the reaction, where for the two samples, namely bentonite and modified bentonite, the trend value of ?G° was that the higher the temperature, the smaller ?G°, and the value of ?G° obtained (-) where the reaction proceeded spontaneously. The value of the second order reaction rate constant was 0.0044 g/mg.min for bentonite and 0.01173 g/mg.min for modified bentonite. In thermodynamics, the values of ?S° and ?H° for bentonite are 169.037 J/K.mol and 9.235 KJ/mol. Meanwhile, for modified bentonite, the values of ?S° and ?H° are 240,732 J/K.mol and 32,638 KJ/mol.