Papers by Keyword: Hydrolysis

Abstract: A comparative characterization of chemical reagents Al₂(SO₄)₃, FeSO₄ and FeCl₃ in the process of wastewater treatment of dairies. The colloid-chemical regularities of the course of hydrolysis of chemical reagents depending on the nature, concentration and acidity of wastewater are established. It was found that the greatest degree of purification from ether-soluble substances 87-88% is provided by the addition of FeCl₃ at a concentration of 150-200 mg / l at a pH of 9.5-10.

Abstract: The result of burning hydrogen which is environmentally friendly makes hydrogen as a very attractive fuel. Hydrogen storage is interesting research material. One alternative to hydrogen storage is a metal-hydride as NaBH₄. In this paper, the catalyst for hydrogen production from storage, namely The result of burning hydrogen, which is environmentally friendly, makes hydrogen a desirable fuel. Hydrogen storage is exciting research material. One alternative to hydrogen storage is a metal-hydride as NaBH₄. In this paper, the catalyst for hydrogen production from storage, namely NaBH₄, was synthesized by electrochemical. Ni-B catalyst with hydroxyapatite as catalyst support was prepared by electrochemical. Ni-B/HA catalyst was synthesized at various current densities (namely 67, 133, and 200 mA/cm²) and various electrolysis times (namely 30, 60, and 90 minutes). The resulting catalysts were analyzed by XRD and used as the catalyst for hydrogen production from the hydrolysis reaction of NaBH₄. The fastest hydrogen production was obtained using a catalyst generated at 133 mA/cm² and an electrolysis time of 60 minutes. The reaction rate equation for the hydrolysis of NaBH₄ has a first-order reaction to the concentration of NaBH₄. The resulting reaction rate constant ranged from 233.33 mL/g/min to 861.11 mL/g/min. The relationship between reaction temperature and reaction rate constant can be expressed by the equation k = 2.2x10⁶exp (5534/T).

Abstract: This paper presents a parametric study on the adsorptive property of NaOH-treated polyacrylonitrile (PAN)-kapok fibers for the removal of Pb (II) and Cr (VI) ions in aqueous solutions. Generally, the NaOH-hydrolyzed PAN-kapok favors the adsorption of Pb (II) compared to Cr (VI). The adsorption capacity was in the range of 41.67-83.33 mg/g as the initial Pb (II) concentration was increased from 50 to 100 ppm. Similarly, the adsorption capacity for Cr (VI) was from 8.24 to 15.81 mg/g as the initial concentration was raised from 50 to 150 ppm. The adsorption capacity was also enhanced by increasing the adsorbent dosage. Finally, uptake of Pb (II) at the early stages of the adsorption was fast, with adsorption capacity reaching ~120 mg/g.

Abstract: Enhanced Oil Recovery (EOR) is a promising technology for increasing crude oil production, especially from old wells. Polymer flooding is one of the techniques used in EOR in which the water-soluble polymer is added to increase the viscosity of the injected fluid. However, this technique has not been implemented in Indonesia due to the unavailability of locally-synthesized polymers. Therefore, this research aims to synthesize polyacrylamides and their partially-hydrolyzed derivatives and to study the possibility of their utilization for the EOR application. Various polymerization conditions using potassium persulfate (KPS) as initiators have been realized and the resulting polymers were characterized using FTIR spectroscopy and rheology measurement. It was found that higher monomer concentration resulted in higher viscosity-average molecular weight of polyacrylamide. Further study revealed that the hydrolysis of polyacrylamide by alkaline solution significantly increased the viscosity of 1000 ppm solution from 1.5 to 145.40 cP at room temperature, which is comparable to one of the commercial products. These results showed that the simple synthesis and hydrolysis method could be effectively used to produce water-soluble polymers for the EOR application.

Abstract: The present study investigates the structural, crystallinity index, crystallite size, morphological, and the dimension of Nanocrystalline Cellulose (NCC) extracted from ramie fiber by hydrochloric acid-hydrolysis. NCC was chosen because it has high strength and modulus compared to other natural materials. Ramie fiber was chosen because it has high cellulose content and abundant in Indonesia. The other reason is ramie has a high crystallinity index compared to other natural fibers. The extraction process was carried out into two steps: cellulose purification then followed by hydrochloric acid hydrolysis. The characterizations of extracted NCCs were conducted through Fourier-Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), and Particle Size Analyzer (PSA). The focus of this research was to study the effect of acid concentration on the characteristics of extracted NCCs. The results show that NCCs could be extracted through hydrolysis using hydrochloric acid. Morphological analysis by TEM shows the formation of rod-like shaped NCCs. Hydrolysis by hydrochloric acid does not affect the chemical compound of cellulose. It was found that during hydrolysis, the higher acid concentration being employed had resulted in smaller dimension of NCCs and decreasing crystallinity index.

Abstract: Polydimethylsiloxane (PDMS) is a tamponade substance that is used as vitreous humour substitutes in vitreoretinal surgery. PDMS can be obtained from monomers of Octamethylcyclotetrasiloxane (D4) that was reacted with Hexamethyldisiloxane through polymerization reactions in a base condition. The monomers are very difficult to obtain in Indonesia, therefore another alternative monomer is needed to produce PDMS with specific properties for vitreoretinal surgery. Here, we reported the synthesis of monomer for replacing D4 through hydrolysis process of Dichlorodimethylsilane (DCMS). Furthermore, the synthesized monomer was used to produce PDMS. The process of DCMS hydrolysis assisted by KOH 0.5 M along 18 hours in reflux system. The synthesized monomer has viscosity of 171 mPas, refractive index of 1.4005 and surface tension of 17 mN/m. PDMS was produced using synthesized monomer by ring-opening polymerization. It is found that the properties of PDMS are very similar with that of commercial PDMS of 5500 cSt.

Abstract: In this study, the disintegration of poly(butylene succinate)(PBS) and poly(lactic acid) (PLA) under landfill conditions was investigated. Both polymers were melted, injected into a dumbbell-shape, and buried under the soil for 20 weeks. The morphology of the polymer from the scanning electron microscope (SEM) revealed that, after 6 weeks of the burial, the PBS polymer produced many micro-voids in the bulk of polymer. The amount of the voids increased with time. While the morphology of PLA showed a few voids and some cracks during the degradation process. Moreover, the mechanical properties of the PLA were decreased after 2 weeks following with PBS after 4 weeks of the burial times. The weight loss and the water uptake of PBS and PLA were slightly increased. From the result, it was found that the degradation of PBS and PLA proceeds via random chain scission of the ester bond through bulk erosion mechanism. The degradation of PLA degraded faster than the PBS due to the low crystallinity in the polymer chain. This result can be applied to the design waste management of biodegradable polymer products.

Abstract: Fossil fuels dependencies need to be stopped to safeguard the earth from further damage. This study focuses on the production of hydrogen (H₂) gas using waste aluminum (Al) cans. Al waste cans were fed into disintegrator to produce fine powder. The hydrolysis performance of disintegrated powdered Al cans were compared with the commercial Al powder. The effect of different reaction temperatures (25 - 100°C); type of alkalis (NaOH, KOH and Ba (OH)₂); and type of water sources (tap, deionized, ultrapure and distilled) for the hydrolysis process were analyzed. The Al powders were also characterized using different techniques to understand its behavior. It was found that powdered Al waste cans produced more H₂ compared to commercial Al reported in the literature. The higher the reaction temperature, the higher the rate of H₂ production. Deionized water maximizes the production of H₂ compared to other types of water. Ba (OH)₂ was found to be an unproductive alkaline for H₂ production using powdered Al waste cans. The successful hydrolysis of powdered Al waste can in alkaline condition in this research has demonstrated as a cost-effective, clean and green alternative hydrogen production method.

Abstract: Cassava peel and used newspaper are example of daily solid wastes that continue to increase in Indonesia from year to year. Most of people in Indonesia have not utilized cassava (Manihot Esculenta L.) peel and used newspaper properly, hence they only become untreated wastes. Cassava peel highly contains carbohydrate and starch which is about 44 - 59%, while newsprint contains quite a lot of cellulose which is 61%, so that both wastes have the potential to make bio-ethanol as a one of potential renewable energy source. The focus of this study is to produce bio-ethanol from these two waste materials. There were several stages to produce bio-ethanol, which are hydrolysis with 0.1 N hydrochloric acid (HCl), and fermentation with yeast (Saccharomyces Cerevisiae), and separation of the bio-ethanol by distillation. The content of bio-ethanol produced was analyzed by Gas Chromatography (GC). The bio-ethanol was produced under different variables, which are: amount of yeast (8 g and 10 g), fermentation time (3, 7, and 10 days), and ratio of volume of solution (mL) cassava peel waste : used newspaper (i.e. 80:20; 60:40; 50:50; 40:60). The GC analysis results showed that the bio-ethanol contents were approximately 0%, 6.194%, 8.421% and 8.887% for ratio volume of solution (mL) cassava peel waste : used newspaper of 80:20; 60:40; 50:50; 40:60, respectively. Whereas, the bio-ethanol contents for 3, 7, and 10 days of fermentation time were 6.690%, 8.765%, and 9.472%, respectively. In this study, the highest bio-ethanol content produced (i.e. 9.472%) was in the following variables: amount of yeast 10 g, 10 days fermentation time, ratio volume of solution (mL) cassava peel waste : used newspaper of 50:50.

Abstract: The study investigates the hydrolysis products of lanthanum nitrate, obtained at various pH values and times of the hydrolytic agent addition. It has been found that the structure formation of lanthanum oxyhydroxide is accompanied by capturing the admixture ions, namely, the anions of the reactant salt and carbonate ions. It has been shown that thermal decomposition of the hydrolysis products proceeds in four stages for faster hydrolysis. If hydrolysis is slow, the intervals merge together into three stages of thermal decomposition. The hydrolysis products of lanthanum nitrate, heated up to 500...550 С, actually consist of lanthanum oxide containing nitrate and carbonate, chemically bonded to the oxide matrix, in its inner regions. The composition of the synthesized samples changes if pH varies. The minimal content of admixture ions can be observed at the synthesis pH > 10, if the time of the hydrolytic agent addition equals 24 h. The obtained results suggest that lanthanum nitrate can be used as a precursor for synthesis of structured lanthanum oxide.