Didik Prasetyoko

Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite

Niobic acid, , has been supported on the titanium silicalite by impregnation method. The obtained materials were characterized by X-ray diffraction, infrared, and ultra-violet—visible diffuse reflectance spectroscopy, temperature programmed reduction, pyridine adsorption, and field emission scanning electron microscopy techniques. It was demonstrated that the tetrahedral titanium species still retained after impregnation of niobic acid. The results revealed that niobium species interacted with hydroxyl groups on the surface of TS-1. The niobium species in the catalysts are predominantly polymerized niobium oxides species or bulk niobium oxide with the octahedral structure. All catalysts showed both Brønsted and Lewis acid sites. The catalysts have been tested for epoxidation of 1-octene with aqueous hydrogen peroxide. It was found that the presence of niobic acid in the catalysts enhanced the rate of the formation of epoxide at the initial reaction time. Diol as a side product was also observed due to the acidic properties of the catalysts.

Surface modification of banana stem fibers via radiation induced grafting of poly(methacrylic acid) as an effective cation exchanger for Hg(II)

A low cost adsorbent, banana stem fibers (BSFs), was used for modification by grafting with methacrylic acid via three free radical generation methods. The presence of poly(methacrylic acid) on the adsorbent surface was verified by FTIR, ESR and TG analyses. BSFs grafted via β-radiation (BSF-β) were proven to have a higher grafting yield which led to a higher Hg(II) adsorption capacity. A slight decrease in the equilibrium pH after the adsorption process was probably due to BSF-β acting as an acid-form ion-exchanger. The adsorption equilibrium uptake fitted well with the Freundlich isotherm model implying that Hg(II) adsorption occurred heterogeneously on the adsorption sites. The kinetics of adsorption follows a pseudo-first order model with an activation energy of 13.7 kJ mol−1 indicating that the adsorption undergoes an ion-exchange process. Thermodynamic studies illustrated that that the Hg(II) adsorption process was endothermic and non-spontaneous. Spent BSF-β was effectively regenerated with 0.1 M HCl and could be reused without any significance efficiency loss over at least six cycles of adsorption. The present investigation shows that BSF-β is a promising adsorbent for the removal and recovery of Hg(II) ions from aqueous solutions.

Improving the quality of patchouli oil by adsorption process using surfactant modified of natural zeolite

This research concerns with the development of natural material i.e. natural zeolite. Natural zeolite were modified by surfactant treatment. Material modification has been done using cetyltrimethyllammonium bromide as cationic surfactant for mesopore template. The physicochemical characters of natural material modified and unmodified was investigated by using XRD, FTIR, nitrogen physisorption, and SEM-EDX. The XRD was used to show crystallinity structure of natural material modified and unmodified. Surfactant treatment caused decreasing crystallinity of natural zeolite. The FTIR spectra showed characteristic peaks for natural zeolite modified and unmodified, the bands around 3400-3500 cm−1 and 1635-1641 cm−1 correspond to adsorbed water and bands around finger print area were characteristic for silica and alumina. Meanwhile physisorption nitrogen profiles gave information that the pore modification by surfactant. The morphologies of natural material modified and unmodified as well as chemical composition ...

The effect of aging temperature on natural zeolite modification

This study investigated the effect of aging temperature on the development of natural zeolite. Natural zeolite was modified by surfactant treatment using cetyltrimethylammonium bromide as the cationic surfactant for mesopore template. Characterization materials used XRD, FTIR and nitrogen physisorption. XRD diffractograms showed variations aging temperature caused the crystallinity and mesopores structure of natural zeolite (MZ). All FTIR spectra showed the presence of silanol and siloxane in the sample MZ and modified of natural zeolite (MMZ). It is proved that all the samples MZ and MMZ on any variation is economical silica-based material. Meanwhile, physisorption nitrogen profiles gave information that the addition of aging temperatures increased the surface area of the modified material but at a temperature of 100°C, the surface area of MMZ becomes smaller due to the water loss system.

Three-step crystallization in synthesis of ZSM-5 without organic template

ZSM-5 was synthesized without organic template through three steps crystallization by adding seed solution. ZSM-5 crystals was characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy and nitrogen adsorption/ desorption technique. XRD and FTIR showed that this method produced the ZSM-5 and quartz as byproduct. Nitrogen adsorption/desorption technique was as certained the formulation of micro-meso porosity of hierarchical ZSM-5.

AMMONIUM REMOVAL USING BATCH AND FIXED BED COLUMN BY ZEOLITE A-CARBON SYNTHESIZED FROM COAL BOTTOM ASH

Bottom ash is coal ash waste released due to the usage of coal in the electric power plant. According to data reported by Ministry of Environment Indonesia, bottom ash waste was about 58 ton/day (Said, 2010). The coal ash waste is clasified as hazardous and dangerous waste under Indonesian regulation (PP85/1999), because it could cause self burning and negative impact to human health. Therefore, the ash waste must be utilised such as by converting the ash to become zeolite-carbon. On the other hand, ammonium is one of the significant contaminant of wastewater. The excessive presence of ammonium could cause eutrophication of stuaries, rivers, lakes and coastal seas, corrosion or biological fouling problem in industrial water system (Widiastuti et al, 2011). Zeolite is a potensial material to remove ammonium from wastewater. The zeolite framework generates one negative charge on the framework owing to the substitution of aluminum (Al3+) atom for silicon (Si4+) in the three dimensional framework of aluminosilicate tetrahedral (Englert and Rubio, 2005). The negative charge in the zeolite framework is balanced by cations such Na+, that can be exchanged by the ammonium ion. Zeolite A is a type of zeolite that has Si/Al ratio of 1 resulting in high ion exchange. This research focuses on the effectiveness of ammonium removal using batch and fixed bed column by zeolite A-carbon synthesized from coal bottom ash. The zeolite A-carbon was synthesized by fusion method in nitrogen atmosphere followed by a hydrothermal treatment (Yanti, 2009). Adsorption capacity of the synthesized zeolite was determined in batch by varying contact time (Figure 1), initialconcentration of ammonium and pH. The theoritical aspect of adsorption including adsorption isotherm and kinetics were also studied (Table 1).