Sri Hilma Siregar

Bio: Sri Hilma Siregar is an academic researcher. The author has contributed to research in topics: Montmorillonite & Kraft process. The author has an hindex of 2, co-authored 4 publications receiving 6 citations.

Pulp synthesis using bamboo raw materials through unbleached and bleached processes

Abstract: This study aims to see the potential of bamboo as a new raw material for the Indonesian pulp industry, specifically for the manufacture of pulp products, because in Indonesia, the import value for dissolving is still high, and the raw materials used still use wood plants. This study consists of three stages: the pre-hydrolysis stage using water, the cooking stage with the kraft pulping method, and bleaching using the elemental chlorine-free (ECF) method. Bamboo flakes that run into the pre-hydrolysis process decreased the Kappa Number value of pulp produced, which ranges from 4.63% - 14.52% compared to bamboo flakes that do not run into the pre-hydrolysis process. The brightness increase to 0.844% - 2.96% compared to bamboo flakes that do not run into the process of pre-hydrolysis. For pulp products, the value of Alpha Cellulose obtained is around 89.18% - 90.32%.

Eco-friendly Edible Film from Chicken Bone Waste and Tapioca Starch

Abstract: The manufacture of edible film from chicken bone gelatin incorporated with starch is essential for Indonesia, where most Muslims are. This is related to Shari’a law which requires Muslims to consume only halal food. Gelatin made from chicken bones is guaranteed to be halal. This study aimed to determine the process of extracting chicken bone waste with acid solvents, making the edible film, and the characterization of chicken bone edible film. This research started with extracting gelatin from chicken bone waste. The 5 g of extracted chicken bones were mixed with 40% w/v glycerol, starch (0, 5, 10, 15% w/v), and distilled water, then heated at 50°C. The mixture was printed in a petri dish (15 cm in diameter) and dried for 24 hours. The edible films were evaluated for physicochemical and mechanical properties, such as tensile strength, elongation, thickness, water resistance, WVTR, and degradation test. Edible film characterization used FTIR, SEM, XRD, and TGA. The optimum condition of the extraction procedure was obtained by using 5% HCl, which produces 8.22172% yield of gelatin with pH of 6.0, water content of 8%, and ash content of 0.945%. In the thickness test, the more significant the starch concentration added, the greater the thickness of the edible film produced. The edible film exhibited a decrease in tensile strength and an increase in elongation along with increasing starch concentration. The results of the WVTR test were only starch concentrations of 0 and 15% that meet the standards, while all concentrations in the water resistance did. The results of FTIR chicken bones with variations in starch and the addition of glycerol as a plasticizer have functional groups N-H, O-H, C-O, C=O, C-H, C-N. Edible films without the addition of starch were utterly degraded within 30 days.

Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications

Abstract: Abstract Physical and chemical methods have been developed for water and wastewater treatments. Adsorption is an attractive method due to its simplicity and low cost, and it has been widely employed in industrial treatment. In advanced schemes, chemical oxidation and photocatalytic oxidation have been recognized as effective methods for wastewater-containing organic compounds. The use of magnetic iron oxide in these methods has received much attention. Magnetic iron oxide nanocomposite adsorbents have been recognized as favorable materials due to their stability, high adsorption capacities, and recoverability, compared to conventional sorbents. Magnetic iron oxide nanocomposites have also been reported to be effective in photocatalytic and chemical oxidation processes. The current review has presented recent developments in techniques using magnetic iron oxide nanocomposites for water treatment applications. The review highlights the synthesis method and compares modifications for adsorbent, photocatalytic oxidation, and chemical oxidation processes. Future prospects for the use of nanocomposites have been presented.

Recyclable Clay-Supported Heteropolyacid Catalysts for Complete Glycolysis and Aminolysis of Post-consumer PET Beverage Bottles

Abstract: In this investigation, the use of phosphotungstic acid (PWA) and phosphomolybdic acid (PMA) as well as Zn2+ containing kaolin and bentonite explored for chemical recycling of post-consumer poly(ethyleneterephthalate) (PET) wastes have been explored. The clay supported catalysts containing 5wt% of the metals and heteropolyacids (HPAs) synthesized using wet impregnation method. Nitrogen adsorption and desorption studies, SEM–EDX mapping, powder XRD, FTIR and XPS analysis have evaluated effect of metal ions and HPAs loading on the surface area, pore volume, elemental composition and crystalline nature. Total surface area of BET increased with a loading of 5 wt% of Zn2+, PWA and PMA on kaolin and bentonite, while the pore volume and pore diameter remain unchanged. SEM and EDAX mapping images showed that the heteropolyacids crystals are well dispersed on the surface and occupied interlayer spaces of the clay support. SEM–EDX showed that bentonite showed a better loading of PWA and PMA compared to kaolin. PET waste water bottles collected from the local market used for the chemical recycling process. The aminolysis reaction using Zn2+ and PWA loaded on bentonite showed complete depolymerisation of PET wastes to produce 87–98% of BHETA. The glycolysis reaction using the above catalysts showed complete depolymerisation at 180–210 °C and yielded 78–90% of BHET. When comparing the clay, bentonite performed well in terms of heteropolyacid loading and afforded a higher yield of BHET and BHETA because of higher loading of Zn and HPA, as supported by SEM–EDX and XPS. We also examined reusability of the catalysts for glycolysis.

Removal of Acidic Dye from Aqueous Solution Using Surfactant Modified Bentonite (Organoclay): Batch and Kinetic Study

Abstract: Modified bentonite has been used as effective sorbent material for the removal of acidic dye (methyl orange) from aqueous solution in batch system. The natural bentonite has been modified using cationic surfactant (cetyltrimethyl ammonium bromide) in order to obtain an efficient sorbent through converting the properties of bentonite from hydrophilic to organophilic. The characteristics of the natural and modified bentonite were examined through several analyses such as Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Surface area. The batch study was provided the maximum dye removal efficiency of 88.75 % with a sorption capacity of 555.56 mg/g at specified conditions (150 min, pH= 2, 250 rpm, and 0.5 g/100 ml). The-results-showed that with the Freundlich isotherm model the sorption data was accurately described with (R2≥0.94) in comparison with the Langmuir model under the studied conditions. The kinetic studies were revealed that the sorption follows a pseudo-second-order kinetic model which indicates chemisorption between sorbent and sorbate molecules.