Rhodamine B (RB) and Methylene Blue (MB) dyes adsorption using adsorbent ZSM-5 synthesized from Bangka kaolin were investigated in this study. The effects of the initial concentration, contact time and temperature on the adsorption process were also analyzed. The effect of the initial concentration and contact time played an important role in the adsorption process; however, the effect differs significantly in both dyes. The temperature plays little role in the dye adsorption process. The results showed the adsorption process occurred in ZSM-5 adhere to Langmuir isothermal adsorption model showing that the adsorption process occurred to be monolayer. Based on the kinetics studies, the pseudo-first-order kinetic model represents the adsorption kinetics that occurs for both dyes onto the synthesized ZSM-5. Thermodynamic parameters namely Gibbs free energy (ΔG°), standard entropy changes (ΔS°) and standard enthalpy (ΔH°) reveal that the adsorption process onto ZSM-5 for both dyes was spontaneous and exothermic.

Carbon doped TiO₂ have been successfully synthetized in this study using sol-gel method and followed by carbonization in hypoxic condition. Titanium (IV) isopropoxide and isopropanol were used as starting material without addition of external carbon precursor. The carbon doped TiO₂ were synthetized with different calcination temperature at 200, 300, 400 and 500°C under hypoxic condition. The physical properties of carbon doped TiO₂ were characterized by Fourier Transformation Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Diffuse reflectance UV-Vis Spectroscopy (DRUVS). The synthetized material shows carbon related peak at 1540 and 1400 cm⁻¹ that can be ascribed as carboxylic (COO⁻) and carbonyl (CO₃^2-) vibration respectively from FTIR spectra. Based on XRD result, it can be infered that TiO₂ with anatase phase were initially formed at calcination temperature 200°C showed by amourphous phase with single peak at 25,30° and crystal growth along with increasement of temperature. Rutile phase as impurities was formed at calcination temperature 500°C. The DRUVS result shows significant red shift in spectra that indicate decrease bandgap of synthetized carbon doped TiO₂ compared to conventional anatase TiO₂. The carbon doped TiO₂ in this study show ability to absorb at visible light radiation as suggested by DRUVS spectra. It is hoped that our work could be applied as visible light photocatalyst in industrial and enviromental application and provided valuable information in synthesis of non-metal doped TiO₂.

A hierarchical zeolite ZSM-5 with micro and meso-pore was prepared by optimising the most affecting parameter in sequence of desilication and dealumination. The physicochemical properties of zeolite were characterised with XRD, nitrogen adsorption–desorption, FTIR and SEM. The potential of this zeolite for decolorisation of CR, RY, MB, RhB, DB-1 and DB-14 was evaluated with adsorption isotherm, thermodynamics, kinetics, and influencing parameter for adsorption. The unique modification of ZSM-5 resulted in lower crystallinity, easier porosity control, rich terminal silanol and unbridged silanol groups which assisted in higher adsorption capacity. The adsorption capacity of the optimum ZSM-5 was 323, 435, 589, 625, 61 and 244 mg/g for CR, RY, MB, RhB, DB-1 and DB-14, respectively. The dye adsorption progressed through pseudo-first-order kinetic and close to the Langmuir model. The adsorption mechanism is proposed mainly through interaction between deprotonated silanol site and the electron-rich dye site.

The influence of the molar ratio H2O/SiO2 in the synthesis directly from Bangka Belitung’s Kaolin has been studied by performing synthesis of ZSM-5 with a variation of the molar ratio H2O/SiO2 is different at 15, 25, 30, and 35. Weighing 3.980 g Bangka’s kaolin are added other material so obtained molar composition 10Na2O: 120SiO2: 2Al2O3: 1800-4200H2O, and 1% of silicalite seed, subsequent hydrothermal process of 175°C for 24 hours. The result of solids was analyzed by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) and SEM EDX to the analyzed morphology of ZSM-5 crystal. The synthesis of ZSM-5 was directly optimum with molar ratio H2O/SiO2 of 30 having the highest cristallinity and largest crystal size of 59.44% and 3.795 µm, respectively.

ZSM-5’s adsorption study of kaolin Bangka without organic template using congo red with initial concentration of 50-250 mg / L with variation of contact time of 40-180 minutes. The results of the adsorption of Congo Red (CR) dye at 30oC-50oC with pH 7, the increase in contact time causes the dye to decrease significantly. In addition, an increase in adsorption rate at first step then slows down as it approaches to the equilibrium point. The experimental results using each temperature variation, showing the equilibrium time of the adsorption process at contact time of 100 minutes. Four isotherm adsorption models were used to analyze and measure the results of experimental data adsorption. The ZSM-5 adsorption capacity of Bangka kaolin is exhibited for the reds of Congo isotherm adsorption. The results of isotherm adsorption studies on three temperatures showed the fitting into Langmuir isotherms adsorption type which means the adsroption occured physically monolayer, the kinetics of adsorption clearly follows the first-pseudo-order reaction kinetics with higher R2 closes to 1. The adsorption thermodynamics analysis show that the adsorption chategorized as exthormic reaction (negative value of ), this conclusion is supported by adsortion capacity data in 180 min contact times which demostrate that the increasing adorption temperature decreasing amount adsorbate being adsorbed. The (Gibb’s Energy) of adsorption are negative in several temperature which demonstrates that the adsroption are spontanously occured in ech temperature. The adsorption study can be used as a reference for ZSM-5 adsorption optimization.

TiO₂ photocatalyst is one of the Advanced Oxidation Processes (AOPs) methods which is very potential to be applied to treat wastewater. Modification of TiO₂ with the addition of ZSM-5 as supporting material can increase the adsorption capacity and conductivity of water molecules. Those properties enable TiO₂/ZSM5 composites to conduct photodegradation process within dye waste. TiO₂/ZSM5 composites were prepared by sol gel method. The synthesized materials were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray Scanning Electron Microscopy (SEM-EDX), and Brunauer-Emmett-Teller (BET). The effect of 2-Propanol to TiO₂/ZSM-5 Composite Morphology was studied. The results from X-Ray Diffraction analysis revealed that the peak indicating the presence of anatase TiO₂ on sample 2.5;5; and 10% TiO₂/ZSM-5 composite. The increasing effect of Titanium precursors to TiO₂/ZSM-5 composite carried out agglomerates on external surface of ZSM-5 as seen in SEM which was supported by surface area data from BET.