Papers by M. Lutfi Firdaus
Deep Sea Research Part I: Oceanographic Research Papers, 2018
The two pairs of geochemical twins, Zr-Hf and Nb-Ta, have similar chemical properties, leading to... more The two pairs of geochemical twins, Zr-Hf and Nb-Ta, have similar chemical properties, leading to their limited fractionation throughout the igneous processes and thus useful and widely used to elucidate rock and mineral formation. In contrast to the analysis of solid samples (e.g. igneous rocks), however, reports of these elements from aquatic samples (e.g. seawater) are very limited due to difficulties in analyzing their very low concentrations in seawater compared to those in solid samples (up to 6 orders of magnitude different). Recent developments of clean sampling techniques coupled with pre-concentration and ICP-MS determination have made trace elements analysis in seawater reliable. Here we report the first vertical distribution of dissolved Zr, Hf, Nb and Ta in the Indian Ocean in addition to those in the Atlantic Ocean, Andaman Sea and Gulf of Thailand. In the Atlantic and northeastern Indian Ocean, Zr, Hf, Nb and Ta show surface depletion and deep water enrichment. The average deepwater Zr/Hf molar ratios in the western North Atlantic, eastern North Atlantic and northeastern Indian Ocean were 270, 315 and 280, respectively. Compared to North Pacific Ocean Zr/Hf ratios of~500, strong intra-and inter-ocean fractionation, a term that describe a difference between concentration of trace metals in deep Atlantic and deep Pacific seawater, is observed to occur in the global ocean. However, the inter-ocean fractionation of Nb/Ta is weaker due to a more uniform distribution of Nb and Ta in seawater. In contrast to open ocean seawater, Zr, Hf, Nb and Ta concentration at stations close to the continent in the Andaman Sea and Gulf of Thailand were highest in surface water decreasing through deep water, with Zr/Hf and Nb/Ta closer to continental crust ratios indicating significant terrestrial inputs of these elements to seawater. Results suggest that, in spite of the similar chemical properties of these geochemical twin pairs generating coherent fractionation in igneous rocks, strong fractionations of Zr-Hf and Nb-Ta takes place in aquatic environments such as seawater.
Alotrop, 2018
The objective of this research was to utilize bintaro shell waste (Cerbera odollam). The morpholo... more The objective of this research was to utilize bintaro shell waste (Cerbera odollam). The morphology of bintaro shell is similar with coconut shell and the contains of lignin and cellulose is higher than coconut. Bintaro shell waste used as activated charcoal to remove environmental pollution caused by synthetic dyes waste of batik industry. The adsorbents were then applied to remove of Reactive Red-120 (RR) and Reactive Blue-198 (RB) dyes in aqueous solution using Visible Spectrophotometer analysis method. Bintaro shell was dried, cut and carbonized at 400°C for 1 hour, then activated with ZnCl 2 20% for 24 hours at 27°C and dryed in oven at 105°C for 30 minutes. The activated charcoal of bintaro shell has proven afford to adsorbing RR and RB dyes. The optimum conditions (pH, contact time, adsorbent weight and temperature) were determined to obtain best adsorption capacity. The optimum of conditions for RR occured at pH 2, contact time of 40 minutes and adsorbent weight 100 mg while RB occurred at pH 11, contact time of 60 minutes and adsorbent weight 50 mg and with each the temperature 30°C. At optimum conditions the adsorption isotherm followed Freundlich model with maximum adsorption capacity obtained for RR and RB were 332.6 and 243.9 mg/g, respectively.
Alotrop, 2017
The problem of environmental polution caused by waste of batik industry lately is increasing, so ... more The problem of environmental polution caused by waste of batik industry lately is increasing, so it needed a method to overcome that problem. The aim of this study was to determine the ability of activated charcoal from coconut fiber palm in adsorbing Reactive Red-120 and Direct Green-26 dyes in waste of batik along with determining the parameters of isotherms adsorption using UV-Vis Spectrophotometer analysis method. Variations of pH, contact time, adsorbent weight and temperature were carried out as variable to obtain optimum conditions of the adsorption process. The optimum of conditions for Reactive Red-120 occured at pH 3 and a contact time of 30 minutes, while Direct Green-26 occurred at pH 4 and a contact time of 40 minutes, with each adsorbent weight 150 mg and the temperature 30 °C. Adsorption isotherms determined by Freundlich and Langmuir models with maximum adsorption capacity (Qmax) were obtained for the Reactive Red-120 was 400 mg/g, while Direct Green-26 is 169 mg/g.
IJORER : International Journal of Recent Educational Research, 2021
This research is to precieve the learning outcomes and student responses to the applied models an... more This research is to precieve the learning outcomes and student responses to the applied models and applications. The type of research carried out was experimental research using a one group pretest-posttest design with the research subjects were 29 students of the fifth semester of 2019/2020 academic year who took Capita Selecta Chemistry Course. The data collection technique was carried out by means of test techniques, namely learning outcomes as seen from the pretest and posttest scores, as well as non-test techniques as seen from observation, interview and student response questionnaires to the application used via google form. The t test was carried out with the help of the SPSS 23 program. Based on the research conducted, there was an increase in student learning outcomes from a value of 65.172 (pretest average score) to 84.586 (posttest average score). The N-Gain score of 0.557 is included in the moderate category, indicating that there is a significant increase in student...
Papan gipsum yang kurang baik dapat diperbaiki dengan menambahkan serat dalam produlrsinya, salah... more Papan gipsum yang kurang baik dapat diperbaiki dengan menambahkan serat dalam produlrsinya, salah sattmya pengganaan sabut kelapa dan boraks. Penelitian ini bertujuan untuk mengetahui: 1. pengaruh penambahan serat sabut kelapa dan boraks terhadap sifat mekanik papan gipsum. 2. perbedaan hasil belajar fisika fisis dan siswa, antara y"ig diaiarknn menggtmakan metode eksperimen dengan pembelajaran konvensional pada keias X IpA SAIA Negeri 2 Kota Benglailu. Serat sabut kelapa variasi 0 %, 0,5 o/o, I l,s %o, 2 %o dan 2,5 % merupakan pengganti serat sintetk dalam pembuatan papqn gipsum, sedangkan borala variasi 0% da1 1% merupakan campuran dalam pembuatan -pipon*[rytu*. o/o, pengujian yang dilakupan meliputi densitas, daya serap air, kuat lentur dan kuat tekan. Hasil pengujian ii|"t ptb papan gipsum meliputi densitas dan daya serap air berkisar antara t2-1,24 g/cm3 dan 32-39%. Hasil pengujign sifat mekanis papan^ gipsum meliputi kuat lentur dan kuat tekan antara 0,22-A,4g Kgf/cm...
Proceedings of the International Conference on Educational Sciences and Teacher Profession (ICETeP 2018), 2019
Indonesia is the largest palm oil producer in the world, of which 19 Palm Oil Mills (POM) are in ... more Indonesia is the largest palm oil producer in the world, of which 19 Palm Oil Mills (POM) are in Bengkulu Province. POM in Bengkulu generally processes palm fruit bunches into Crude Palm Oil (CPO) with the by-products of Palm Oil Mill Effluent (POME) which contains CPO residues (CPO-res) as much as 0.6-1.2%. CPO-res are cheap raw materials for the manufacture of biofuels. The purpose of this study was to develop a module based on laboratory research of synthesis of biofuel. Synthesis of biofuels was done by esterification with an acid catalyst, followed by a trans esterification using a base catalyst, both reactions are carried out with ultrasonic irradiation assistance at a frequency of 45 kHz, temperature 60°C, for 30 minutes. This laboratory research was then developed as a module; the module was then used in learning chemistry after being validated by expert judgment. The biofuel has a density of 0.852 g / mL, kinematic viscosity of 1.692 cSt, fog point = 8.84 ° C, pour point = 11°C, acid number = 1.122 mg KOH / g oil and water content = 0.739%. Modules developed from research into biofuel production after being validated by expert judgment on good value (4.71) at the level of trustworthy validation trust (0.846) can be used in learning organic chemistry.
Bencoolen Journal of Science Education and Technology, 2020
The goal of this study was to describe the differences in students learning outcome, between thos... more The goal of this study was to describe the differences in students learning outcome, between those who use the jigsaw learning model with those who study conventionally in analytical chemistry learning. This research used quasi-experimental method with a non-equivalent design and control grup design. The research conducted at chemistry study program fifth semester. In the non-equivalent control group design, the sample was not chosen randomly but by purposive sampling technique. The sample was chosen by purposive sampling technique. The research used two classes, i.e. class A as the experimental-class and class B as the control-class. Both classes were given pretest to find out the student's initial ability before being given a lesson and a posttest to find out the student's final ability. This research was conducted in three meetings in accordance with the material to be delivered. In experimental-class, we used jigsaw learning model. In this learning model there were stage...
PENDIPA Journal of Science Education, 2020
Silica is one of the potential minerals to be developed and applied in various industrial fields.... more Silica is one of the potential minerals to be developed and applied in various industrial fields. High purity of silica can be obtained by utilizing natural materials such as beach sand. In this research the solid-liquid extraction (leaching) method was used in three main steps. Bengkulu beach sand as precursors reacted with NaOH (alkaline fusion) at 95°C to form Na2SiO3, then addition of HCl to form Si(OH)4, and drying the silica gel becomes SiO2. Based on the initial content analysis in Bengkulu sand contained 69.87% silica and other compounds with a lower percentage. The extracted silica was characterized using XRF and the purity of silica increase to 97.3%. The XRD characterization results showed that the silica formed was in the amorphous phase. Si-O-Si and Si-O bonds which are characteristics of SiO2 were identified in the FT-IR spectrum with absorption bands of 798.8 cm-1 and 475.1 cm-1 respectively.
Proceedings of the 3rd Asian Education Symposium (AES 2018), 2019
A module for laboratory practice in quantitative analytical chemistry subject has been developed.... more A module for laboratory practice in quantitative analytical chemistry subject has been developed. The method uses digital image colorimetry as a basis for low-cost spectrophotometry analysis. Reduction-oxidation reaction of silver nanoparticle and mercury (II) ion was used as a case study for the colorimetric experiment. The yellow color of silver nanoparticle was faded linearly to colorless with the addition of mercury ion as an analyte. The color change was then recorded with a digital camera and processed through computer software to extract the color information in the form of Red, Green and Blue. The module of laboratory practice was then applied to students in chemical education study program. The gain of the learning process was measured using pre-test and post-test. The results of the study indicate that the students were able to understand the concept of spectrophotometry by using the developed module of digital image colorimetry. Therefore, we conclude that laboratory practice of digital image colorimetry is applicable as an alternative to the traditional spectrophotometry.
Jurnal Teknologi Industri Pertanian, 2018
Palm oil mill effluent (POME) is a liquid waste by product of fresh fruit bunches processing (FFB... more Palm oil mill effluent (POME) is a liquid waste by product of fresh fruit bunches processing (FFB) in palm oil factory (POF). POME contains oil residue of 0.7% (from treated FFB). The purpose of this study was to convert oil residue of POME into biogasolin with the help of ultrasonic irradiation and catalytic cracking. The convertion was performed by reacting oil residue of POME with methanol in an esterification and transesterification reaction with the aid of ultrasonic irradiation. The reaction product was further reacted in the catalytic cracking reaction using zeolite-based catalysts (Ni/HZa and Mo-Ni/HZa). The overall reaction results were characterized using GCMS to determine the constituent components. The components found using Mo-Ni/HZa catalyst were 51.22% biogasoline and other products of kerosene and diesel as well as long chain methyl ester components, whereas using Ni/HZa catalyst was found a component equivalent to diesel at 2.44%.
PENDIPA Journal of Science Education, 2020
Development of teaching material based on laboratory research is one way that can be done to impr... more Development of teaching material based on laboratory research is one way that can be done to improve students' creative thinking abilities in meeting the challenges of 21 st century learning. The aims of this study were to determine the feasibility of the developed environmental chemistry modules, to improve of students' thinking abilities and determine the students' responses to the use of modules in environmental chemistry lectures. Module development by R and D methods 4D model, namely Define, Design, Develop and Disseminate. Module quality is determined by expert validation test. Based on the results of expert validation, the module developed obtained 90.91% percentage of eligibility with a very good category. Based on the N-Gain value obtained, an increase in students' creative thinking abilities on the aspect of flexibility was 0.47, and the aspect of elaboration was 0.64 with medium category. The student responses to the use of modules in learning environmental chemistry obtained a percentage of 83.82% with very good category.
PENDIPA Journal of Science Education, 2019
ABSTRACT[Implementation of Discovery Learning Model on Electromagnetic Wave Application Material ... more ABSTRACT[Implementation of Discovery Learning Model on Electromagnetic Wave Application Material of Various Palm Oil Impurity Analysis With Spectrophotometry UV-Vis].The aims of this study was to describe the differences between the learning outcomes of students who learn to use the learning model of Discovery Learning with students studying physics learning conventionally onwaves electromagnetic material. The method used quasi experimental research with Pretest-Posttest Control GroupDesign research conducted at SMA Negeri 8 Lubuklinggau. Sample research used 2 classes i.e. class X.3 as a experimental class and class X.2 as a control class. Based on the results of data analysis it can be concluded that there was a difference between learning outcomes of students who learn to use the learning model of Discovery Learningwith students studying in conventional method. The data views from the average final value obtained after being given the treatment. The average value of experimental...
PENDIPA Journal of Science Education, 2019
Improvement of students learning outcomes by applying the video of coffee-mixture identification ... more Improvement of students learning outcomes by applying the video of coffee-mixture identification using UV-Visible Spectroscopy]. The purpose of this study was to evaluate the differences of student learning outcomes on electromagnetic wave materials and how students respond to the learning videos. This research was an experimental research which applies video coffee-mixture identification. The study was conducted in grade X islamic high school consisting of experimental class and control class. Based on the data analysis, the average post-test grade of the experimental class was 82.11 and the mean posttest control grade was 72.88 with t count = 0,038 which is lower than the value of significance (0,05). The N-gain values of both classes indicate that the experimental class (0.72) is better than the control class (0.61). This suggests the adoption of a coffee-mixture identification video on electromagnetic wave material able to improve greater learning outcomes than control class that did not apply the video to the learning process. The result of questionnaire analysis shows that the student response to video implementation is good, as seen from the average score of responses of students who answered strongly agree at 40% level, while the answer agree at 53.83% level, not agree at 5.43% level and who answered very disagreeing 0.74% of all students.
PENDIPA Journal of Science Education, 2018
PENDIPA Journal of Science Education, 2018
Penelitian ini bertujuan untuk mengetahui potensi air tanah di sekitar perkebunan sawit di Desa P... more Penelitian ini bertujuan untuk mengetahui potensi air tanah di sekitar perkebunan sawit di Desa Pondok Kelapa-Bengkulu yang dilakukan dengan menggunakan resistivity-meter metode geolistrik, konfigurasi elektroda Wenner. Data pengukuran muka air tanah dan hasil kualitas air diperoleh pada 4 lokasi penelitian. Interpretasi kurva resistivitas dengan Res2dinv menunjukkan bahwa daerah Pondok Kelapa masih memiliki potensi air tanah dengan jarak 0,5 m. Keempat lokasi diantaranya: (1) pada rata-rata kedalaman 1,967 m dengan pH 6, besi 0,0021 mg/L dan kekeruhan 54,16 NTU; (2) pada rata-rata kedalaman 2,935 m dengan pH 6, besi 0,0022 mg/L dan kekeruhan 37,12 NTU; (3) pada rata-rata kedalaman 2,240 m dengan pH 5,8, besi 0,0021 mg/L dan kekeruhan 35,65 NTU; dan (4)pada rata-rata kedalaman 2,678 m dengan pH 5,7, kandungan besi 0,0011 mg/L dan kekeruhan 19,02 NTU. Hasil penelitian menyimpulkan bahwa terdapat kecenderungan hubungan terbalik antara kualitas air dan muka air tanah dari segi kekeruhan. Hasil penelitian ditampilkan sebagai penunjang proses pembelajaran Fisika yakni pengembangan LKPD berbasis service learning materi Hukum Ohm penerapan pengukuran geolistrik yang berorientasi pada pengembangan reflective thinking dengan desain ADDIE (Analisys, Design, Development, Implementation, and Evaluation). Kemampuan hasil belajar 21 siswa SMK kelas X-ATP (Agribisnis Tanaman Perkebunan) didapat dengan peningkatan hasil N gain antara nilai pretest dan posttest sebesar 0,66 yakni berada dalam kategori sedang.
PENDIPA Journal of Science Education, 2018
ABSTRACT[Innovation of microbial fuel cell stack system using cow rumen waste substrate and its i... more ABSTRACT[Innovation of microbial fuel cell stack system using cow rumen waste substrate and its implementation as a learning media]. The aims of this study are to: 1) describe the difference of Electric Motion (GGL), 2) describe the difference of electric power per unit area of the anode (Pa) which is produced between the series design MFC type series, parallel, mixed type 1 and mixed type 2, and 3) describe the significant difference of learning outcomes between the PBL learning model using MFC media with PBL learning model by using the electrical kit medium on dynamic electrical concept in SMA Muhammadiyah 4 Bengkulu. The free variable of this research are MFC stack system design (series, parallel, mixed types 1 and 2) and the dependent variable is GGL and electric power per unit of anode surface area. The results are obtained difference GGL and Pa between series design, parallel, mixed types 1 and 2 by comparison are 3: 1: 1,5: 2 whereas Pa ratio is 1: 10: 6: 2 with maximum GGL i...
Analytical Sciences, 2017
Novel green-chemistry synthesis of silver nanoparticles (AgNPs) is introduced as a low-cost, rapi... more Novel green-chemistry synthesis of silver nanoparticles (AgNPs) is introduced as a low-cost, rapid and easy-to-use analytical method for mercury ion detection. Aqueous fruit extract of water apple (Syzygium aqueum) was used for the first time as bioreductant to synthesize stable AgNPs. The prepared AgNPs have a yellowish-brown color with a surface plasmon resonance peak at 420 nm. The addition of Hg(II) ions then changes the AgNPs color to colorless. The color change was in proportion to the concentration of Hg(II) ions. The presence of other metal ions in the system was also evaluated. The proposed method shows good selectivity and sensitivity towards Hg(II) ions. Using UV-visible spectrophotometry, the detection limit of the developed method was 8.5 × 10-7 M. The proposed method has been successfully applied for determination of Hg(II) ions in tap and lake water samples with precision better than 5%.
Indonesian Journal of Chemistry, 2016
Typhoid fever caused by Salmonella typhi is an important issue for public health in the world. La... more Typhoid fever caused by Salmonella typhi is an important issue for public health in the world. Laboratory methods for rapid and sensitive diagnosis are very important for disease management. The purpose of this study was to determine the performance of nested PCR–voltammetric DNA biosensor using flagellin gene (fla) of S. typhi as a marker. The differential pulse voltammetry using pencil graphite electrode was applied to measure the guanine oxidation signal of probes vs synthetic target stDNA and probes vs fla PCR product hybridizations. The probe DNA selectivity was examined by hybridized probes vs non-complementary sequence. The result showed that the first round nested PCR product can not be visualized by agarose electrophoresis, whereas using the voltammetric biosensor methods can be detected both for the first or second round nested PCR product. The average peak current of hybridized probe vs first and second round of PCR product was 2.32 and 1.47 μA respectively, at 0.9 V. Det...
This study aims to (1) determining the effect of leaf extract Thespesia Populnea (L.) Soland ex c... more This study aims to (1) determining the effect of leaf extract Thespesia Populnea (L.) Soland ex correa as an anti-malaria drugs in Mus musculus animal that have been infected by Plasmodium berghei (2) knowing the characterization of the isolation result of Thespesia Populnea (L.) Soland ex correa leaves using Infrared Spectroscopy (IR). The antimalaria activity of these leaves was tested by using Mus muculus males that have been infected with Plasmodium berghei, and it was observed within sixth day. Thespesia Populnea (L.) Soland ex correa leves extract could reduce malaria parasites in animal Mus musculus infected with Plasmodium berghei with increasing of percent barrier for 6 days, with dose suggested 0.056 g / kg. From the characterization of the isolated compounds using IR, it is assumed that secondary metabolites such as flavonoid was one of the metabolites that inhibit the growth of malaria parasites.
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Papers by M. Lutfi Firdaus