Ahmad Hafizullah Ritonga
@medistra.ac.id
Chemistry
Institut Kesehatan Medistra Lubuk Pakam
EDUCATION
Doctor in Chemistry
RESEARCH INTERESTS
Polymer Chemistry, Material Chemistry
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Debby Endriani, Nor Faizah Bawadi, Aazoki Waruwu, and Ahmad Hafizullah Ritonga
IOP Publishing
Abstract Improvements to the bearing capacity of the soil have been carried out and developed at this time, one of which is the stabilization of clay soils. There are several alternatives to solve low soil bearing capacity, one of which is using geo-synthetic materials but has a weakness in terms of high cost. Another alternative is to add palm shell ash as a stabilizing agent. The effect of adding palm shell ash has not been thoroughly studied, so further research is needed. The material added is palm shell ash with a variation of 0%, 4%, 8%, 10%, and 12% in each test. The tests carried out in the laboratory were water content (w), specific gravity test (Gs), Atterberg limit test, sieve analysis (sieve analysis), soil compaction test, and CBR (California Bearing Ratio) test. The CBR test was carried out by curing the soil for 1, 3, 5, and 7 days with a mixture of palm shell ash before compaction. The soil in this study belongs to the A-7-5 group. The CBR (California bearing ratio) value increased with the increase in the palm shell ash percentage in the mixture after curing the soil. The highest CBR value was in the variation of 12% palm shell ash with a 7-day curing period of 6.92% with a soil bearing capacity of 5.06.
Tamrin, Ahmad Hafizullah Ritonga, and Barita Aritonang
Elsevier BV
Gusliani Eka Putri, Syukri Arief, Ahmad Hafizullah Ritonga, Wiya Elsa Fitri, Eliza Arman, Arniat Christian Telaumbanu, and Rahmi Novita Yusuf
Universitas Gadjah Mada
The approach to the synthesis of cerium oxide nanoparticles (CeO2NPs) using plants as capping agents has been widely researched because of its eco-friendly, low-cost, simple, effective, and reusability. In this research, we used Moringa oleifera leaf extract-mediated CeO2NPs. CeO2NPs were characterized by XRD, FTIR, SEM, TEM, and DRS UV-vis. The photocatalytic activity of CeO2NPs was tested using a phenol dye concentration of 7 mg/L with variations in photocatalyst weight of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 mg under UV irradiation, respectively, with time variations of 15, 30, 45, 60, 75, 90, 105, 120, 135, and 150 min. SEM and TEM morphology results showed that the CeO2NPs were spherical and agglomerated. The crystal structure is cubic, with a crystal size of 18 nm with a band gap of 2.87 eV. CeO2NPs showed high photo-degradation phenol dye of 94.45% under visible light in 120 min irradiation time. The results show that M. oleifera leaf extract could be as inexpensive and safe for synthesizing other metal oxide nanoparticles, potentially having applications in the biomedical and environmental fields.
Ahmad Hafizullah Ritonga, Barita Aritonang, Gusliani Eka Putri, Khairiah Khairiah, Enzo Wiranta Battra Siahaan, and Debi Meilani
Universitas Gadjah Mada
A plastic composite consisting of polylactic acid (PLA), linear low-density polyethylene (LLDPE), oleic acid-grafted linear low-density polyethylene (LLDPE-g-OA) compatibilizer, and organo-precipitated calcium carbonate (O-PCC) have been successfully made in the molten state. This study aims to characterize the mechanical, physical, thermal, and morphological characteristics of the PLA/LLDPE/O-PCC plastic composite in the presence of an LLDPE-g-OA compatibilizer. The plastic composite was prepared by blending PLA, LLDPE, LLDPE-g-OA, and O-PCC using an internal mixer with a heating of 160 °C and a rotation of 100 rpm. LLDPE and LLDPE-g-OA are put together into the inner mixer chamber until melted, followed by PLA and O-PCC. The most optimum plastic composite composition is PLA/LLDPE/LLDPE-g-g-OA/O-PCC (67.5:22.5:5:5). The mechanical properties showed an increase in tensile strength of 9.78 MPa. The physical properties showed that the minimum water absorption was 0.74%, the biodegradation in humus soil showed a degradation rate of 0.09% per day, and the thermal properties showed better stability with a melting point of 146.5 °C. The FTIR spectrum is similar to the polymer blend without O-PCC. The morphology indicates that the composite is compatible and homogeneous. This semi-biodegradable plastic composite has significant implications for reducing the accumulation of plastic waste in the environment.
Rudi Kartika, Ahmad Hafizullah Ritonga, Lilik Sulastri, Siti Nurliana, Deddy Irawan, and Partomuan Simanjuntak
International Journal of Technology
Boy Isfa, Novesar Jamarun, Emriadi Emriadi, Syukri Arief, Ahmad Hafizullah Ritonga, Denny Akbar Tanjung, and Vivi Sisca
International Journal of Technology
Ahmad Hafizullah Ritonga, Novesar Jamarun, Syukri Arief, Hermansyah Aziz, Denny Akbar Tanjung, and Boy Isfa
International Journal of Technology
Denny Akbar Tanjung, Novesar Jamarun, Syukri Arief, Hermansyah Aziz, Boy Isfa, Ahmad Hafizullah Ritonga, and Vivi Sisca
International Journal of Technology
B. Isfa, N. Jamarun, Emriadi, S. Arief, A.H. Ritonga, and V. Sisca
Rasayan Journal of Chemistry
This study optimized the Precipitated Calcium Carbonate (PCC) and lithopone mixture (50:50) as substitution pigments of titanium dioxide (TiO2) in matt-type water-based paint. Matt-type water-based paint has been made in two steps; (1) mill base paste preparation and (2) water-based paint production (layout process). Pigment characterization showed that PCC/lithopone mixture produced a white solid of 95.57%, crystallinity degree of 91.5%, and a diameter small size particle of 198.29 nm. Application of PCC/lithopone mixture as pigment into matttype water-based paints has resulted in good dispersibility and hiding power while exhibiting the same whiteness quality as TiO2 and glossy better than TiO2. Keywords: PCC; Lithopone; TiO2; Pigment
M. Supeno, B. Aritonang, A.H. Ritonga, R. Gurusinga, K. Harefa, and R. Tambun
Rasayan Journal of Chemistry
The mixture of bioethanol with gasoline (gasohol) as vehicle fuel can increase the research octane number (RON) to perfect combustion and reduce carbon monoxide pollution from exhaust gases. The difference in electronegativity polarity causes the two fuels to be incompatible. This study aims to produce a homogeneous and compatible mixture of gasoline (85%) and bioethanol (15%) after the addition of crude palm oil (CPO) gum using degumming and distillation methods. The RON index calculation and physical properties of gasohol E-85 showed that the existence of CPO gum in bioethanol reduced the boiling point from 78 °C to 69 °C and the RON from 120 to 109. FTIR results showed that gasohol E-85 contains phosphatides, hydrocarbons, carboxylic acids, and tocopherols characteristic of CPO gum. The DSC results obtained a melting point of 43.8 °C which indicated that the CPO gum had mixed with bioethanol in gasohol E-85. The GC results of gasohol-85 obtained seven peaks indicating the presence of butylated hydroxytoluene, 1,9-decadiene, 4,4,7,7-tetramethyl, n-hexadecanoic acid, hexadecanoic acid, 2-hydroxy-1-(hydroxyl methyl) ethyl ester, 1-(3-methyl-2-butenyl)-2-phenylcyclopropane, and 9,9-bis(1"-indazolyl) -thioxanthene.
Ahmad Hafizullah Ritonga, Novesar Jamarun, Syukri Arief, Hermansyah Aziz, Denny Akbar Tanjung, and Boy Isfa
AIP Publishing
Ahmad Hafizullah Ritonga, Novesar Jamarun, Syukri Arief, Hermansyah Aziz, Denny Akbar Tanjung, Boy Isfa, Vivi Sisca, and Hendri Faisal
Elsevier BV
Ahmad Hafizullah Ritonga, Novesar Jamarun, Syukri Arief, Hermansyah Aziz, Denny Akbar Tanjung, and Boy Isfa
Universitas Gadjah Mada
This study investigates the improvement of the mechanical, thermal, and morphological properties of linear low-density polyethylene (LLDPE)/cyclic natural rubber (CNR) after the addition of organo-precipitated calcium carbonate (O-PCC). The impact on the properties of the LLDPE/CNR/LLDPE-g-OA/O-PCC composites was investigated by a series of empirical experiments. First, the polymer composite was blended in the molten state using an internal mixer with a heating temperature of 160 °C and a rotation speed of 100 rpm. The LLDPE was placed in a chamber of internal mixer until melted, followed by CNR, LLDPE-g-OA, and O-PCC. The polymer composites with an O-PCC concentration of 5% obtained the optimal mechanical properties compared to other variations, with a tensile strength of 17.17 MPa and Young's modulus of 252.68 MPa. The presence of O-PCC resulted in better thermal stability and a change in the melting point temperature of 124 °C. The FTIR spectra of the polymer composite showed the specific characteristics of O-PCC at 872.1 cm–1. The morphology of the polymer composite indicates that the O-PCC is evenly dispersed in the polymer composite.
Denny Akbar Tanjung, Novesar Jamarun, Syukri Arief, Hermansyah Aziz, Ahmad Hafizullah Ritonga, and Boy Isfa
Universitas Gadjah Mada
The addition of LLDPE-g-MA into the compound of sago starch/LLDPE was studied to improve its mechanical, morphology, degradation performance, and water absorption properties. Thermoplastic Sago Starch was composed of a mixture of sago starch and glycerol. LLDPE-g-MA was prepared in varied concentrations based on the weight of TPSS (0, 6, 8, 10, and 14 wt.%) by reacting LLDPE, maleic anhydride, and benzoyl peroxide using an internal mixer. The results showed an increase in values obtained from mechanical tests, i.e., tensile strength was improved from 0.6902 to 3.6187 N/mm2 with the addition of LLDPE-g-MA at 10 wt.%. The addition also resulted in a 1.44% increment in elongation at break and 251 N/mm2 for Young's Modulus. The surface morphology of the sample demonstrated an excellent interfacial adhesion reaction or LLDPE dispersion over the entire surface of the matrix (starch). The water absorption test continued to decrease with the increase in the LLDPE-g-MA concentration from 53 wt.% (without LLDPE-g-MA) to 14 wt.% at 10 wt.% LLDPE-g-MA concentration. The degradation performance showed that the sample could be degraded under all three conditions for up to 30 days.
D.A. Tanjung, N. Jamarun, S. Arief, H. Aziz, A.H. Ritonga, and B. Isfa
Rasayan Journal of Chemistry
This study aims to improve the mechanical and physical properties of the thermoplastic sago starch blends with the addition of polypropylene (PP). PP concentrations were given starting from 10, 15, 20, 25, and 30 percent (%), with the addition of a PP-g-MA compatibilizer as a coupling agent. From the mechanical properties, it is known that the tensile strength and elongation at break increase with increasing PP concentration, whereas Young's modulus decreases with increasing PP concentration. The Thermogravimetry Analysis (TGA) did not show a significant reduction in degradation on each temperature increase. From the morphological results, it could be seen that the PP is dispersed into the TPSS matrix with the help of this compatibilizer, evidenced by the absence of flocculants on the surface. The rate of degradation indicates that the addition of PP to the sago starch matrix could still be degraded by environmental elements such as freshwater, seawater, and soil burial.