ADSORPTION MECHANISM STUDY OF C.I REACTIVE RED 141 TEXTILE DYE ONTO NATURAL LOCAL CLAY

• Main Author: Listyendah Zahra, Nurulbaiti
• Format: Theses
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/32096
• Institution: Institut Teknologi Bandung

The decline in the availability of clean water bodies and high water consumption of textile industry in Bandung region and its surrounding area has prompted the conservation of water resources. The adsorption method can be used to treat the effluent of textile waste water treatment plant (WWTP) in order to increase its quality thereby it can be reused as process or clean water. The main objective of the treatment is removing color that still remains in the textile WWTP effluent, which derived from textile dye such as C.I. Reactive Red 141 (RR 141). Clay is one of materials that can be used as alternative adsorbent for removing color because clay is a natural substance which its existence is abundant in nature, can be found in various countries, cheap and has the availability to remove pollutants through adsorption and ion exchange mechanisms. However, the information and study related to the application of Indonesian local clay as adsorbent are still limited. Therefore, natural local clay derived from three regions in Indonesia were used in this study, namely Arcamanik clay which is a lacustrine deposit, Citatah clay which is a karst soil and Dago clay which is volcanic soil. The objective of this study is to investigate the adsorption mechanism of RR 141 onto natural local clay. Determination of the adsorption mechanism is based on the results of analysis of the characteristics of clays and dye, the effect of various factors on adsorption process, adsorption data compatibility with the kinetic and equilibrium isotherms models, adsorption thermodynamics parameter values and the changes of molecular structure of the local clay during the process of adsorption using FTIR spectroscopy (Fourier Transform Infra Red) method. The results showed that Citatah clay, which its mineral structure has predominantly 2 : 1 layer (montmorillonite), performed better sorption. The optimum color removal of Arcamanik and Dago clay were achieved at dosage of 10 g/L whereas Citatah clay at dosage of 8 g/L and the removal efficiency were 65.93%, 65.93% and 76.65%, respectively. At the optimum dosage, the equilibrium adsorption of Arcamanik and Citatah clay were achieved in 60 minutes and Dago clay in 120 minutes. It was observed that adsorption process performances were better at low pH through the electrostatic force between the clay surface that becomes positive at low pH (S-OH2 +) with SO3 - anionic groups of dye RR 141. The adsorption kinetic of RR 141 dye onto natural local clays fitted well with pseudo second order model. The sorption rate constant (K2) of Arcamanik, Citatah and Dago clay at optimum dosage were 12.422, 13.318 and 10.958 g mg-¹ menit-¹, respectively. The equilibrium adsorption data of Arcamanik clay were well described by Freundlich isotherm model with the value of KF was 0,036 mg/g whereas Citatah and Dago clay were well described by Langmuir isotherm model with the monolayer maximum adsorption capacity (qm) of Citatah clay was 0,053 and Dago clay was 0,038 mg/g. The changes of free energy of Arcamanik, Citatah and Dago clay were -6.286; -7.048 and -6.030 kJ/mol, respectively. The value of the change of Gibbs free energy of Arcamanik, Citatah and Dago clay were -4.794, -7.048 dan -4.234 kJ/mol, respectively, which indicates physisorption. FTIR analysis results showed the involvement of functional groups bonding on the adsorption of RR 141 dye onto Citatah and Dago clay.The possibility of adsorption mechanism of the RR 141 dye onto local clays were through physisorption, namely van der Waals forces and chemisorption through the formation of surface complexes between sulphonic groups of dye RR 141 with metal hydroxide or mineral ion of Si, Al or Fe in the broken edges of clay crystal or in the interlayer sites of clay crystal.