Effect of Aluminium Content in Aluminium Pillared Montmorillonite on Its Surface Acidity Properties

Aluminium pillared montmorillonites from Indonesian natural montmorillonite has been prepared using Al13 Keggin ion pillaring precursor in varied concentrations. Herein we studied their characterization and catalysis application for esterification reaction. X-ray diffraction (XRD), energy dispersive x-ray analysis (EDX), and BET gas sorption analysis were employed to characterize the prepared materials besides the characterization on surface acidity by pyridine and n-butylammine adsorptions and FTIR analysis. The result showed that significant improvement on physicochemical character data was obtained by a pillarization process. Such a process also provided improvements on catalytic activities in esterification reactions. The effect of aluminium content on material characters was discussed in this paper. It was observed from the catalytic activity tests that pillared montmorillonite samples demonstrated higher activity in esterification reaction relative to the raw montmorillonite. It was found that surface profile of materials consist of specific surface area, pore volume and Lewis acidity were significantly affect the catalyst activity

COLLABORATIVE TRIAL AND QUALITY CONTROL IN CHEMICAL ANALYSIS

Abstract                                                             This paper deals with some practical problems related to the quality of analytical chemical data usually met in practice. Special attention is given to the topic of quality control in analytical chemistry, since analytical data is one of the primary information from which some important scientifically based decision are to be made. The present paper starts with brief description on some fundamental aspects associated with quality of analytical data, such as sources of variation of analytical data, criteria for quality of analytical method, quality assurance in chemical analysis. The assessment of quality parameter for analytical method like the use of standard materials as well as standard methods is given. Concerning with the quality control of analytical data, the use of several techniques, such as control samples and control charts, in monitoring analytical data in quality control program are described qualitatively.  In the final part of this paper, some important remarks for the preparation of collaborative trials, including the evaluation of accuracy and reproducibility of analytical method are also given Keywords: collaborative trials, quality control, analytical data Abstract                                                             This paper deals with some practical problems related to the quality of analytical chemical data usually met in practice. Special attention is given to the topic of quality control in analytical chemistry, since analytical data is one of the primary information from which some important scientifically based decision are to be made. The present paper starts with brief description on some fundamental aspects associated with quality of analytical data, such as sources of variation of analytical data, criteria for quality of analytical method, quality assurance in chemical analysis. The assessment of quality parameter for analytical method like the use of standard materials as well as standard methods is given. Concerning with the quality control of analytical data, the use of several techniques, such as control samples and control charts, in monitoring analytical data in quality control program are described qualitatively.  In the final part of this paper, some important remarks for the preparation of collaborative trials, including the evaluation of accuracy and reproducibility of analytical method are also given Keywords: collaborative trials, quality control, analytical dat

EFFECT OF K2SO4 TO THE PORE PROPERTIES OF PRODUCTS IN THE SYNTHESIS OF MESOPOROUS SILICATES MCM-41

Researchs about the effects of K2SO4 to the pore properties of the products in the synthesis of mesoporous silicates MCM-41 has been done. MCM-41 was synthesized by hydrothermal treatment of the mixture containing : 9.31 of sodium silicate solution, 8.67 g of cetyltrimetylammoniumbromide (CTMAB) and 29 g of distilled water (molar ratio of 8 Na2SiO3 : CTMAB : NaOH : 400H2O). The hydrothermal treatment was carried out at 100 oC in a teflon-lined stainless steel autoclave heated in the oven for 36 h. The solid phase was filtered, washed with distilled water, and dried in the oven at 100 oC for 2 h. The surfactant CTMAB was removed by calcinations at 550 oC for 10 h with heating rate of 2 ºC/min. The as-synthesized MCM-41 was characterized by using FTIR spectroscopy and X-ray diffraction, while calcined-MCM-41 was characterized by using FTIR spectroscopy, X-ray diffraction; and N2 physisorption methods. The same procedure was carried out, with the addition of 17.4 g of K2SO4 and 21.6 ml of distilled water to obstain the molar composition of the gel of: 8Na2SiO3 : CTMAB : NaOH: 400H2O : 2 K2SO4. The results showed that the addition of K2SO4 increased the crystalinity. MCM-41 prepared with K2SO4 has a higher specific surface area of 972.812 m2 g-1 compared to the MCM-41 prepared without K2SO4 (i.e., 946.607 m2 g-1), higher mean pore diameter of 3.714 nm compared to the MCM-41 prepared without K2SO4 (i.e. 3.357 nm), and thicker pore walls of 0.830 nm compared to the MCM-41 prepared without K2SO4 (i.e. 1.176 nm).Key words : MCM-41, K2SO4, pore propertie

EFFECT OF DIATOMEAOUS EARTH TREATMENT USING HYDROGEN CHLORIDE AND SULFURIC ACID ON KINETICS OF CADMIUM(II) ADSORPTION

In this research, treatment of diatomaceous earth, Sangiran, Central Java using hydrogen chloride (HCl) and sulfuric acid (H2SO4) on kinetics of Cd(II) adsorption in aqueous solution has been carried out. The work was conducted by mixing an amount of grounded diatomaceous earth (200 mesh in size) with HCl or H2SO4 solution in various concentrations for two hours at temperature range of 100 - 150oC. The mixture was then filtered and washed with water until the filtrate pH is approximately 7 and then the residue was dried for four hours at a temperature of 70oC. The product was used as an adsorbent to adsorb Cd(II) in aqueous solution with various concentrations. The Cd(II) adsorbed was determined by analyzing the rest of Cd(II) in the solution using atomic absorption spectrophotometry. The effect of treatment was evaluated from kinetic parameter of adsorption rate constant calculated based on the simple kinetic model. Results showed  that before equilibrium condition reached, adsorpstion of Cd(II) occurred through two steps, i.e. a step tends to follow a reaction of irreversible first order  (step I) followed by reaction of reversible first order (step II). Treatment with acids, either hydrogen chloride or sulfuric acid, decreased adsorption rate constant for the step I from 15.2/min to a range of 6.4 - 9.4/min.  However, increasing concentration of acid (in a range of concentration investigated) did not give significant and constant change of adsorption rate constant. For step II process,  adsorption involved physical interaction with the sufficient low adsorption energy (in a range of 311.3 - 1001 J/mol).     Keywords: adsorption, cdmium, diatomaceous earth, kinetics

EFFECT OF ACID CONCENTRATION ON CHARACTERS OF SILICA GEL SYNTHESIZED FROM SODIUM SILICATE

In this research, synthesis and characterization of silica gel from sodium silicate through sol-gel process using H2SO4, HCl, and citric acid have been investigated. Synthesis was carried out by mixing and stirring  20 mL of H2SO4, HCl or citric acid  at certain concentration with 50 mL of sodium silicate solution (Na2O 0.17 M and SiO2 0.61 M) for one hour and let to form gel.  The gel was washed with distillated water, and dried in an oven at 100 oC. Characterization of silica gel was carried out by determination of acidity, water adsorption capacity, and water content. Identification of functional group and structure were identified using x-ray diffractometer (XRD) and infrared (IR) spectrophotometer, respectively.  Results showed that at a range of investigated concentration (0.6 - 3.0 M) the increase of concentration, formation of gel with H2SO4 tended to be faster, but with HCl and citric acid to be slower. The increase of acid concentration caused water content, water adsorption capacity, and acidity of the silica gel resulted with HCl and citric acid tended to be increased, increased, and increased, but with H2SO4 to be decreased, increased, and decreased, respectively. Based on the IR spectra and XRD data, it could concluded that the synthetic silica gels contained silanol (Si-OH) and siloxane (Si-O-Si) and were amorphous, showing similar pattern to kieselgel G 60 produced by Merck.   Keywords: silica gel, adsorption capacity, sodium silicate, acidit

Encapsulation Of Horseradish Peroxidase-Glucose Oxidase (Hrp-Gox) In Silica Aquagel Synthesized From Rice Hull Ash For Enzymatic Reaction Of Glucose

In recent years, the sOl-gel technique has attracted increasing interest as a unique approach to immobilize biomolecules for bioanalytical applications as well as biochemical and biophysical studies. In this research, encapsulation of Horseradish peroxidase-Glucose oxidase (HRP-GOx) enzymes in silica aquagel from rice hull ash by sol.gel process has been carried out. In addition,. the effect of several parameters (weight ratio of HRP to GOx, pH, temperature, sodium ion concentration) on enzyme activity was studied, as well. Rice hull ash, which was produced by ashing at 700 .C, was extracted it\u27s silika by NaOH solution 1 Mat 100 .C for two hours to produce sodium silikate (Na2Si03J solution. The Na2Si03 solution with pH of 13 was added with a strong cation exchanger resin, to produce sol solution with the pH of 4. Encapsulation was emphasized by mixing sol solution and phosphate buffer pH 7 containing HRP-GOx solution at volume ratio of buffer to sol solution 1:5. The mixture was transferred into 96-microwell plate and was aged for 24 hours Enzymatic reaction was carried out by adding chromogenic solution of phenol and 4-aminoantipyrine (4-AAP) and fJ-D-glucose solution (as substrate) into the microwel\u27. enzymatic activity was examined by measuring absorbance of product solution at 490 nm with ELISA reader. Result of enzymatic activity for encapsulated enzymes (SGE) was compared to that for free enzymes (EB). Results showed that at the investigated condition, HRP-GOx enzymes gave high activity at weight ratio of HRP to GOx 10:1 and pH 7 for both SGE and EB. Encapsulation caused the enzymes activity decrease to 53.0:tO.2 %. However, SGE was observed to be more stable on pH and temperature changes than eB. Study on the effect of sodium concentration showed that the increase of sodium concentration from 0.10 to 0.37 M decreased the enzymatic activity to 56:tO.2%. Reusability test showed that the synthesized SGe was reusable with activity decrease of 60% within 23 days

IMPREGNATION OF 2-MERCAPTOBENZOTHIAZOLE ON DIATOMACEOUS EARTH AND ITS APPLICATION AS MERCURY(II) ADSORBEN IN AQUEOUS MEDIUM

An adsorbent was prepared by impregnating 2-mercaptobenzo-thiazole onto polystirene treated diatomaceous earth support. This adsorbent was then applied to adsorb mercury(II) in aqueous medium. The mercury(II) adsorption characteristics of the adsorbent was studied by the use of the original diatomaceous earth as reference. Interaction of mercury(II) and both of diatomaceous earth as well as MBT-diatomaceous were performed in a aqueous batch system to include the following parameters: (a) medium acidity and (b) mercury(II) adsorption characteristic on MBT-diatomaceous with and without the present of other metal ions. In the present work quantification of mercury(II) adsorption was done by determining the mercury concentration left in the solution after adsorption. A cold vapour-generation atomic absorption spectroscopy technic was used in this determination.The experiment results show, that the adsorption affinity of MBT-diatomaceous is higher than the original diatomaceous earth. The total adsorption energy of mercury(II) for diatomaceous earth (24.702 kJ/mol) and MBT-diatomaceous (46.942 kJ/mol) suggest that the interaction is chemisorption. The mercury(II) maximum adsorption on diatomaceous earth is obtained at pH 6, while similar adsorption on MBT-diatomaceous practically was not influenced by pH changes. The present of other metals, i.e. Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and Zn(II) in solution does not give any appreciable influence to the adsorption affinity of MBT-diatomaceous to mercury(II); the total sum of the mercury(II) adsorbed is constantly high, almost 100 %. Keyword: Impregnation, MBT-diatomaceous, adsorption, mercury(II