Cepi Kurniawan
@unnes.ac.id
Chemistry Department
Universitas Negeri Semarang
RESEARCH INTERESTS
Electrochemistry, Inorganic chemistry, coordination chemistry
Scopus Publications
Scopus Publications
Widi Astuti, Irene Nindita Pradnya, Ria Wulansarie, Dhoni Hartanto, Triastuti Sulistyaningsih, Cepi Kurniawan, Miftakhul Hidayah, Lu'lu' Fitriana, Muhammad Arief Mahardhika, and Evin Fajri Irchamsyah
College of Graduate Studies, Walailak University
To address the separation problems and produce the reusable adsorbent, cassava peel magnetic activated carbon (MAC) prepared via microwave-assisted activation has been proposed to replace activated carbon (AC) for naphthol blue-black removal. To create MACs, ACs were embedded with nano-sized magnetite particles using co-precipitation methods. In this sense, 2 different activating agents (i.e., H3PO4 and KOH) have been used. H3PO4 activation provides a larger pore size and more functional groups, while KOH activation provides a larger surface area and higher porosity. The increase of H3PO4 concentration from 40 to 60 % leads to an increase in porosity as well as an increase in the weight ratio of KOH to char from 1 to 3. Impregnation magnetite to the ACs reduces surface area from 457.76 to 337.94 m2 g-1 for KOH activation, and from 360.65 to 232.74 m2 g-1 for H3PO4 activation, decreasing adsorption capacity from 97.5 to 97 % for KOH activation and from 99 to 98 % for H3PO4 activation. However, the adsorbent is easy to separate under the magnetic influence. The adsorption data of MAC by H3PO4 activation show suitability with the Redlich-Peterson isotherm model, suggesting that naphthol blue-black removal is not ideal monolayer adsorption, but a combination of physisorption and chemisorption processes that exhibit heterogeneity of naphthol blue-black adsorption on the surface of adsorbent. Meanwhile, for MAC by KOH activation, the Langmuir isotherm is more suitable. HIGHLIGHTS Cassava peel was used in the preparation of magnetic activated carbon The effect of microwave-assisted H3PO4 and KOH activation was discussed Prediction of isotherm models was proposed and compared GRAPHICAL ABSTRACT
Rikson Siburian, Liang Wei Tang, Yatimah Alias, Alfred Iing Yoong Tok, Ronn Goei, Crystina Simanjuntak, Kerista Tarigan, Suriati Paiman, Boon Tong Goh, Isa Anshori,et al.
Elsevier BV
Nanik Wijayati, Nurul Kholifati Faizah, Dante Alighiri, Cepi Kurniawan, Willy Tirsa Eden, Senda Kartika Rakainsa, and Retno Ariadi Lusiana
AIP Publishing
Woro Sumarni, Sigit Priatmoko, Cepi Kurniawan, and Agung Tri Prasetya
AIP Publishing
Cahya Fadilah, Cepi Kurniawan, Muhammad Ridwan, Muhammad Al Muttaqii, Egi Agustian, Agustina Sus Andreani, Adid Adep Dwiatmoko, and Indri Yati
Springer Science and Business Media LLC
Sri Kadarwati, Riska Nurfirda Annisa, Evalisa Apriliani, Cepi Kurniawan, and Samuel Budi Wardhana Kusuma
College of Graduate Studies, Walailak University
The bio-oil produced from the pyrolysis of biomass is highly corrosive due to the high content of organic acids. These organic acids could be removed through an appropriate upgrading process, i.e., esterification using alcohols to form less polar esters. In this study, the bio-oil used as the feedstock in the esterification was produced from the pyrolysis of Sengon wood with a particle size of 297 µm at 600 °C. The esterification was performed at 70 °C in the presence of a trichloro acetic acid (TCA)-modified Indonesian H-zeolite catalyst with various weight ratios of bio-oil-to-methanol and reaction times under a constant stirring rate of 500 rpm. The esterification progress was indicated by the decrease in the total acid number of the bio-oil after esterification. No significant coke formation (< 0.05 wt%) was observed indicating that the suppression of repolymerisation could be achieved. This study showed that the esterification underwent in a fast rate, indicated by the decrease in the total acid number of the bio-oil by 47.85 % only over a 15-min esterification. Compared to the uncatalysed esterification, the TCA/zeolite-catalysed esterification showed a higher decrease in the total acid number of the bio-oil up to 65.83 %, due to the conversion of the carboxylic acids to esters. HIGHLIGHTS The TCA-modified Indonesian natural zeolite catalyst has been successfully prepared The presence of the TCA/Indonesian natural zeolite during the esterification of bio-oil produced from the pyrolysis of Sengon wood could greatly suppress the severe repolymerisation leading to coke formation The TCA/Indonesian natural zeolite-catalysed esterification of Sengon bio-oil underwent in a fast rate The TCA/Indonesian natural zeolite catalyst showed a good performance in this study in comparison with the uncatalysed esterification GRAPHICAL ABSTRACT
Isa Anshori, Ghani Faliq Mufiddin, Iqbal Fawwaz Ramadhan, Eduardus Ariasena, Suksmandhira Harimurti, Henke Yunkins, and Cepi Kurniawan
Elsevier BV
Nur Husnina Nasaruddin, Shahrul Nizam Ahmad, Siti Syaida Sirat, Kong Wai Tan, Nurul Aili Zakaria, Cepi Kurniawan, and Hadariah Bahron
Elsevier BV
C Kurniawan, R R Wati, A T Prasetya, S Priatmoko, K Kasmui, and H Bahron
IOP Publishing
The development of selective and sensitive chemical sensors to overcome fluoride ions is needed, especially for applications in chemical and biological processes. One of the chemical compounds that can act as sensors is the Schiff base compound group. This study aims to synthesis a Schiff base based on salicylaldehyde and as a fluoride ion sensor. The one-pot synthesis approach was carried out in room terms by mixing salicylaldehyde with hydrazine hydrate or phenylenediamine with a molar ratio of 2: 1 in ethanol solvent under stirring for 24 hours. The bright yellow crystal was obtained with a yield of 80% for salicylaldazine (SB). The compounds in the dimethyl sulfoxide (DMSO) solvent tend to be colorless, but in the presence of F-ions, the solution turns orange. The results indicate an interaction between SB1 with F-ions in solution.
E Cahyono, C Kurniawan, and U Anggraito
IOP Publishing
The utilization of natural products that potentially act as anti-cancer has been widely investigated. Our previous study in 2019 on microencapsulation of several essential oils, including citral with aldehyde moiety and citronellal from lemongrass, and cinnamaldehyde from cinnamon, has proved remarkably successful to prevent cancer risk (chemo-prevention). The study is then extended to produce tea-based products with citral and cinnamaldehyde oil additives as cancer risk prevention drink drinks. The study will aim to optimizing the mixer parameters to overcome the volatility rate of essential oil. The research was designed with the Analysis, Defining, Development, Implementation and Evaluation (ADDIE) model. It was conducted to make sure that all the machine parameters work efficiently. The developed machine is equipped with a heater tank and mixer. The heater tank and mixer capacities are 2.2 L and 4.0 L, respectively. The maximum pressure tank is up to 4.0 bar, and the recommended pressure works are 2.0 bar. The heating temperature maximum is 170 °C, and it will also keep the essential oil stability. The vapor-solid mixed gently at 20 rpm to produce a well-mixed product. Power consumption up to 1500 watts at 220 V (50 Hz). However, the product at the mixing time of 60 seconds with the gas flow 2 bar was perfectly obtained.
S Kadarwati, T Qurrochman, C Kurniawan, Jumaeri, and Kasmui
IOP Publishing
S Moreta, E Cahyono, N D N Affandi, F Fadil, and C Kurniawan
IOP Publishing
C Kurniawan, S Haryani, S Kadarwati, and E Cahyono
IOP Publishing
Ida Nurhazwani Abdul Rahman, Roswanira Abdul Wahab, Naji Arafat Mahat, Joazaizulfazli Jamalis, Mohamad Afiq Mohamed Huri, and Cepi Kurniawan
Springer Science and Business Media LLC
To overcome the drawbacks and high costs of the synthetic route to produce pentyl valerate (PeVa), i.e., a fuel additive, the biotechnological route of utilizing Rhizomucor miehei lipase conjugated to magnetite carrier support (RML-CS/CH/MNPs) is proposed. The magnetized RML-CS/CH/MNPs were developed for enabling high yield production of PeVa at relatively short reaction time $$(<$$(< 3 h), while facilitating easy removal of excess RML-CS/CH/MNPs. Efficacy of the developed RML-CS/CH/MNPs biocatalyst was assessed for relevant esterification factors, viz. time, enzyme loading, temperature, substrate molar ratio and stirring speed. The highest yield of PeVa (96%) was reached under an optimized condition ($$50\\,^{\\circ }\\hbox {C}$$50∘C, using valeric acid/pentanol molar ratio of 1:2, with a lipase loading of 1.5 mg/mL, incubation time of 3 h), thus indicating the RML was catalyzing at its fullest potential due to improved activity and stability after immobilization onto CS/CH/MNPs. RML-CS/CH/MNPs retained a 90% activity after 40 days of storage and leached an initial 3.5% of the lipase likely due to insufficient rinsing during preparation. Since the RML-CS/CH/MNPs was prepared without the use of acids, it appears to be a greener catalyst for the esterification production of PeVa and presumably for other types of commercially important esters, too.
Raden Angga Kartiwa, Hulya Cut Septiyani, Astriviani Switania Sari Dirgahayu, Susi Heryati, Irawati Irfani, Paramita Pandansari, Basril Abbas, Nur Atik, M Fadhlillah, Toto Subroto,et al.
IOP Publishing
Dewi Selvia Fardhyanti, Megawati, Cepi Kurniawan, Retno Ambarwati Sigit Lestari, and Bayu Triwibowo
EDP Sciences
The utilization of biomass as a source of new and renewable energy is being carried out. One of the technologies to convert biomass as an energy source is pyrolysis which is converting biomass into more valuable products, such as bio–oil. Bio–oil is a liquid which produced by steam condensation process from the pyrolysis of coconut shell. The composition of biomass such as hemicellulose, cellulose and lignin will be oxidized to phenol as the main content of the bio–oil. Production of bio–oil from coconut shell was investigated via fast pyrolysis reactor. Fast pyrolysis was carried out at 500 °C with a heating rate of 10 °C and 1 hour holding time at pyrolysis temperature. The Bio-oil chemical composition was investigated using GC–MS. Percentage value of phenol, 2–methoxy phenol, 3–methoxy 1,2–benzenediol, and 2,6–dimethoxy phenol was 45.42%, 13.37%, 10.09%, and 11.72% respectively.
Taufiq Hidayat, Endang Susilaningsih, and Cepi Kurniawan
Elsevier BV
Abstract Students are to be prepared to face the challenges of 4th industrial revolution by having creative thinking skills and problem-solving. Study of preliminary show that test used in school has not been oriented to creative thinking skills and problem-solving. The purpose of this study is to develop enrichment test instruments which can be used to measure creative thinking skills and problem-solving that achieve valid and reliable criteria. The study belongs to research and development applying the 4D model. Stages which were developed involved preliminary studies, product design, development, and publication. The technique of data analysis used was qualitative and quantitative data analysis. Qualitative data analysis was done based on the investigate instrument validity sheet. Besides, quantitative data analysis aimed at finding out reliability level and test instruments effectiveness. The instrument validity is declared valid by experts and regarded reliable on each trial of development stage. Enrichment test instruments were effective to measure students’ creative thinking skills and problem-solving based on the analysis of creative thinking and problem-solving competence, mean of learning result increases, and completeness proportion which achieved 100%. It is inferred that the enrichment test instruments developed can measure students’ creative thinking skills and problem-solving.
Ida Nurhazwani Abdul Rahman, Nursyafreena Attan, Naji Arafat Mahat, Joazaizulfazli Jamalis, Aemi S. Abdul Keyon, Cepi Kurniawan, and Roswanira Abdul Wahab
Elsevier BV
The chemical-catalyzed transesterification process to produce biofuels i.e. pentyl valerate (PeVa) is environmentally unfriendly, energy-intensive with tedious downstream treatment. The present work reports the use of Rhizomucor miehei lipase (RML) crosslinked onto magnetic chitosan/chitin nanoparticles (RML-CS/CH/MNPs). The approach used to immobilize RML onto the CS/CH/MNPs yielded RML-CS/CH/MNPs with an immobilized protein loading and specific activity of 7.6 mg/g and 5.0 U·g-1, respectively. This was confirmed by assessing data of field emission scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis and Fourier transform infrared spectroscopy. A three-level-four-factor Box-Behnken design (incubation time, temperature, substrate molar ratio, and enzyme loading) was used to optimize the RML-CS/CH/MNP-catalyzed esterification synthesis of PeVa. Under optimum condition, the maximum yield of PeVa (97.8%) can be achieved in 5 h at 50 °C using molar ratio valeric acid:pentanol (1:2) and an enzyme load of 2 mg/mL. Consequently, operational stability experiments showed that the protocol adopted to prepare the CS/CH/MNP nanoparticles had increased the durability of RML. The RML-CS/CH/MNP could catalyze up to eight successive esterification cycles to produce PeVa. The study also demonstrated the functionality of CS/CH/MNP nanoparticles as an eco-friendly support matrix for improving enzymatic activity and operational stability of RML to produce PeVa.
N Widiarti, U S Sari, F W Mahatmanti, Harjito, C Kurniawan, D Prasetyoko, and Suprapto
IOP Publishing
The aims of current studies is to investigate the effect of strontium oxide content (SrO) on synthesized zeolite. Zeolite was synthesized from Tetraethyl orthosilicate (TEOS) as precursors of SiO2 and aluminum isopropoxide (AIP) precursors. The mixture was aged for 3 days and hydrothermally treated for 6 days. The SrO content was added by impregnation method. The products were then characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Surface Area Analyzer (SAA). The diffractogram confirmed the formation of Faujasite-like zeolite. However, after the addition of SrO, the crystallinity of zeolite was deformed. The diffractograms shows the amorphous phase of zeolite were decrease as the SrO content is increase. The structural changes was also observed from FTIR spectra which shows the shifting and peak formation. The surface area analysis showed that the increasing loading of SrO/Zeolites reduced the catalyst surface area.
R Ujiningtyas, E Apriliani, I Yohana, L Afrillianti, N Hikmah, and C Kurniawan
IOP Publishing
S Haryani, C Kurniawan, and Kasmui
IOP Publishing
Synthesis of complex compound is one field of research which intensively studied. Metal-dithiocarbamate complexes find wide-ranging applications in nanomaterial and metal separation science, and have potential use as chemotherapeutic, pesticides, and as additives to lubricants. However, the information about is reaction kinetic and mechanism are very much lacking. The research and analyzes results show that reaction synthesis ligand DBDTC and complex compounds Cu-DBDTC. Optimum reaction condition of formation of complex compounds Cu with DBDTC at pH=3, [DBDTC] = 4.10-3 M, and the time of reaction 5 minutes. Based the analysis varian reaction of complex compounds at pH 3 and 4, diffrence significance at the other pH: 5; 5,5; 6; 6,5 ; 7; and 8. The various of mole with reactants comosition difference sigbificance, those the time reaction for 5 and 6 minutes diffrence by significance with the other time, it is 3,4,8, and 10 minutes. The great product to at condition pH 6, the time optimum at 5 minutes and molar ratio of logam: ligand = 1:2. The reaction kinetic equation of complex compound Cu with chelathing ligand DBDTC is V=0.917106 [Cu2+]0.87921 [DBDTC]2.03021. Based on the kinetic data, and formed complex compounds estimation, the mechanism explaining by 2 stages. In the first stage formation of [Cu(DBDTC)], and then [Cu(DBDTC)2] with the last structure geomethry planar rectangle. The result of this research will be more useful if an effort is being done in reaction mechanism by chemical computation method for obtain intermediate, and for constant "k" in same stage, k1.k2. and compound complex constanta (β).
S Haryani, Masfufah, N Wijayati, and C Kurniawan
IOP Publishing
The aim of this research is to know the influence of PBL application to the improvement of metacognitive skill and students' reasoning ability on Constanta solubility product (Ksp). The research used mix method with concurrent triangulation strategy and pretest-posttest control group design. Metacognitive skills are known from the results of written tests and questionnaires with N-Gain analysis, t-test, whereas reasoning ability is known from observations and interviews with descriptive analysis. The results showed that the N-Gain effect of PBL on metacognitive skills is 0,59 with medium category and N-Gain value of PBL influence on reasoning ability is 0.71 with the high category. The steps in the PBL affect the metacognitive skills and can train learners to develop their reasoning skills in the solving problems.