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"Objectives of this research are mainly to study impacts of acidity strength (by varying amount of precipitant and loading Al-Si) and the effect of nickel particle size (by varying calcinations temperature) on decomposition reaction performances. In this research, high-nickel-loaded catalyst is prepared with two methods. Ni-Cu/Al catalysts were prepared with co-precipitation method. While the Ni-Cu/Al-Si catalyst were prepared by combined co-precipitation and sol-gel method. The direct cracking of methane was performed in 8mm quartz fixed bed reactor at atmospheric pressure and 500-700°C. The main results showed that the Al content of catalyst increases with the increasing amount of precipitant. The activity of catalyst increases with the increasing of catalyst?s acidity to the best possible point, and then increasing of acidity will reduce the activity of catalyst. Ni-Cu/4Al and Ni-Cu/11Al deactivated in a very short time hence produced fewer amount of nanocarbon, while Ni-Cu/15Al was active in a very long period. The most effective catalyst is Ni-Cu/22Al, which produced the biggest amount of nanocarbon (4.15 g C/g catalyst). Ni catalyst diameter has significant effect on reaction performances mainly methane conversion and product yield. A small Ni crystal size gave a high methane conversion, a fast deactivation and a low carbon yield. Large Ni particle diameter yielded a slow decomposition and low methane conversion. The highest methane conversion was produced by catalyst diameter of 4 nm and maximum yield of carbon of 4.08 g C/ g catalyst was achieved by 15.5 nm diameter of Ni catalyst."

"Objectives of this research are mainly to study impacts of acidity strength (by varying amount of precipitant and loading Al-Si) and the effect of nickel particle size (by varying calcinations temperature) on decomposition reaction performances. In this research, high-nickel-loaded catalyst is prepared with two methods. Ni-Cu/Al catalysts were prepared with co-precipitation method. While the Ni-Cu/Al-Si catalyst were prepared by combined co-precipitation and sol-gel method. The direct cracking of methane was performed in 8mm quartz fixed bed reactor at atmospheric pressure and 500-700°C. The main results showed that the Al content of catalyst increases with the increasing amount of precipitant. The activity of catalyst increases with the increasing of catalyst?s acidity to the best possible point, and then increasing of acidity will reduce the activity of catalyst. Ni-Cu/4Al and Ni-Cu/11Al deactivated in a very short time hence produced fewer amount of nanocarbon, while Ni-Cu/15Al was active in a very long period. The most effective catalyst is Ni-Cu/22Al, which produced the biggest amount of nanocarbon (4.15 g C/g catalyst). Ni catalyst diameter has significant effect on reaction performances mainly methane conversion and product yield. A small Ni crystal size gave a high methane conversion, a fast deactivation and a low carbon yield. Large Ni particle diameter yielded a slow decomposition and low methane conversion. The highest methane conversion was produced by catalyst diameter of 4 nm and maximum yield of carbon of 4.08 g C/ g catalyst was achieved by 15.5 nm diameter of Ni catalyst."

"Penggunaan gas hidrogen sebagai sumber energi pada sel bahan bakarmenjadikannya sebagai potensi sumber energi di masa depan Salah satu permasalahan yang cukup perlu diperhatikan pada pemanfaatan hidrogen sebagai sumber energi ini adalah media penyimpanannya Untuk dapat menyimpan hidrogen dalam jumlah besar diperlukan tekanan operasi yang sangat tinggi dan temperatur yang sangat rendah Penyimpanan hidrogen dapat ditingkatkan dengan pemanfaatan fenomena adsorpsi gas hidrogen pada media berporos seperti Carbon Nanotube CNT Kapasitas adsorpsi hidrogen pada CNT ini juga dapat ditingkatkan dengan menyisipkan unsur doping pada CNT Salah satunya adalah dengan menyisipkan senyawa alkali metal seperti Lithium Simulasi dinamika molekuler proses adsorpsi hidrogen pada CNT dengan Lithium sebagai unsur doping ini memberikan perkiraan bahwa kapasitas adsorpsi hidrogendapat meningkat hingga 100 dibandingkan dengan kapasitas adsorpsi hidrogen pada CNT tanpa doping Lithium pada tekanan 40 atm dan temperatur 293 K dari sebelumnya 1 wt menjadi 2 wt

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The uses of hydrogen gas as energy resources in fuel cell let it to be future energy resources potential One of the problems which need to be concerned about the uses of hydrogen gas as energy resources is its storage medium To be able to store hydrogen gas in large amount very high operational pressure and very low operational temperature are required Hydrogen storage capacity can be improved by using adsorption phenomena of hydrogen gas on porous medium like Carbon Nanotube CNT Hydrogen adsorption capacity of CNT can be improved too by inserting alkaline metal such as Lithium into CNT Molecular dynamic simulation of hydrogen adsorption process on Lithium doped CNT predicts that its hydrogen adsorption capacity can be improved until 100 compared to its hydrogen adsorption capacity without Lithium at pressure of 40 atm and temperature of 293 K from 1 wt become 2 wt"

"Fabrikasi Carbon Nanotube CNT secara komersial terhalang oleh biaya produks meliputi: sumber karbon, katalis, dan energi. Stainless steel merupakan substrat potensial untuk fabrikasi CNT, kandungan Fe dan Ni menjadikan stainless steel berfungsi ganda sebagai substrat sekaligus katalis. Pada penelitian ini stainless steel di preparasi dengan HCl 37,8 dan oxidative heat treatment 850 oC selama 30 menit. Penelitian ini bertujuan mengidentifikasi pengaruh oxidative heat treatment pada stainless steel dalam pembentukan CNT. Identifikasi dilakukan menggunakan sumber karbon asetilena dan kamper. Substrat stainless steel 304 divariasikan atas foil, pelat, dan wiremesh. Hasil penelitian dengan asetilena selama 20 menit pada ketiga variasi menghasilkan carbon loss diatas 90. Hal ini disebabkan peningkatan persentase Cr menghambat pembentukan nano partikel katalis. Dengan bantuan ferrocene substrat foil, pelat, dan wiremesh menghasilkan CNT dengan massa 0,0573 gram; 0,0701 gram; dan 0,1246 gram disertai penurunan carbon loss mencapai 30. Penggunaan substrat stainless steel 316 dengan kandungan Cr lebih rendah dan tambahan waktu sintesis menjadi 60 menit menghasilkan massa 0,6325 gram dan carbon loss 2,76. Identifikasi dengan menggunakan kamper selama 60 menit menghasilkan peningkatan massa CNT pada stainless steel 304 foil 0,831 gram; pelat 1,856 gram; wiremesh 2,6305 gram dan 316 pelat 2,1075 gram .

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Commercial CNT fabrication is hindered by its production costs including carbon sources, catalysts, and energy. Stainless steel is potential for CNT fabrication as Fe and Ni contents function as substrate and catalyst. Stainless steel is prepared with HCl 37,8 and 850 oC oxidative heat treatment for 30 minutes. This study aims at identifying oxidative heat treatment effect on stainless steel in CNT formation performed using the carbon sources of acetylene and camphor. 304 stainless steel substrates are varied including foil, plate, and wiremesh. By using acetylene for 20 minutes results in carbon loss above 90 increasing the Cr inhibiting the formation of nano particles catalyst. The addition of ferrocene decrease the carbon loss up to 30 and CNT of 0,0573 gram 0,0701 gram and 0,1246 gram are formed in foil, plate, and wiremesh. The use of 316 stainless steel substrate with lower Cr content and additional time of synthesis to 60 minutes yield a mass of 0,6325 gram and carbon loss 2,76 . The 60 minutes identification using camphor results in CNT mass increase in the 304 stainless steel foil 0,831 gram plate 1,856 wiremesh 2,6305 gram and 316 plate 2,1075 gram."

"Ampas tebu merupakan limbah perkebunan dengan kandungan serat selulosa yang dapat dimanfaatkan sebagai bahan penyusun komposit. Komposit serat alami dengan matriks epoksi memiliki beberapa kelebihan diantaranya sifat mekanis yang baik. Penambahan carbon nanotube (CNT) pada komposit diketahui melalui banyak penelitian dapat meningkatkan sifat mekanik. Perlakuan alkali dengan NaOH dilakukan pada serat untuk menghilangkan pengotor pada permukaan serat serta mengaktivasi gugus hidroksil dari serat. Mild acid oxidation dilakukan pada CNT menggunakan HNO3 dan H2O2 untuk mengfunsionalisasi CNT menjadi CNTOH. Perlakuan silane coupling agent (GLYMO) dilakukan terhadap serat dan CNT untuk meningkatkan kompabilitas dengan matriks. Pada penelitian ini dilakukan penambahan carbon nanotube pada komposit serat ampas tebu (bagasse) dengan matriks epoksi sebanyak 0,5%, 1% dan 1,5% terhadap berat matriks yang digunakan. Pengujian FTIR membuktikkan keberhasilan proses perlakuan alkali, mild acid oxidation dan perlakuan silane coupling agent dengan menunjukkan terbentuknya gugus hidroksil, karboksil dan silanol. Selain itu, pengujian Uv-Vis Spektroskopi juga menunjukkan keberhasilan proses fungsionalisasi CNT dengan meningkatkan dispersitas kelarutan CNT sebesar 5%. Hasil uji tekuk yang didapatkan dari penelitian adalah meningkatkan kekuatan lentur komposit sebesar 150,65%, 87,61%, dan 72,73% pada penambahan CNT 0,5%, 1% dan 1,5% berat. Dapat disimpulkan bahwa penambahan CNT akan meningkatkan kekuatan lentur komposit hingga titik optimum penambahan CNT sebesar 0,5% berat dan komposit yang terbentuk dapat dimanfaatkan dalam industri otomotif untuk bahan interior mobil.

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Sugarcane bagasse is a plantation waste containing cellulose fiber which can be used as a composite material. Natural fiber composites with epoxy matrices have several advantages including good mechanical properties. The addition of carbon nanotubes (CNT) to composites known through many studies can improve mechanical properties. Alkali treatment with NaOH is carried out on the fiber to remove impurities on the surface of the fiber and activate hydroxyl groups from the fiber. Mild acid oxidation is carried out on CNT using HNO3 and H2O2 to functionalize CNT become CNT-OH. The silane coupling agent (GLYMO) treatment was performed on fiber and CNT to improve compatibility with the matrix. In this study, the addition of carbon nanotubes on bagasse fiber composites (bagasse) with epoxy matrix as much as 0.5%, 1% and 1.5% of the weight of the matrix used. FTIR result proves the success of the alkali, mild acid oxidation and silane coupling agent treatment by showing the formation of hydroxyl, carboxyl and silanol groups. In addition, Uv-Vis Spectroscopy also showed the success of CNT functionalization process by increasing CNT solubility dispersion by 5%. The bending test obtained from the study were to increase the flexural strength of composites by 150.65%, 87.61%, and 72.73% on the addition of CNT 0.5%, 1% and 1.5% by weight. It can be concluded that the addition of CNT will increase the flexural strength of the composite with the optimum value of adding CNT by 0.5% by weight and the composite formed can be utilized in the automotive industry for car interior materials."

"Tandan Kosong Kelapa Sawit (TKKS) mengandung serat selulosa yang dapat dimanfaatkan sebagai bahan penyusun komposit. Penambahan carbon nanotube pada komposit diketahui melalui banyak penelitian dapat meningkatkan sifat mekanik. Pada penelitian ini dilakukan penambahan carbon nanotube pada komposit serat TKKS dengan matriks epoksi. Bentuk serat divariasikan menjadi chopped strand, chopped strand mat, dan woven rovings. Untuk meningkatkan kompabilitas, fungsionalisasi dan perlakuan carbon nanotube dilakukan dengan metode mild acid oxidation dengan menggunakan asam nitrat yang dilanjutkan dengan hidrogen peroksida. Silane coupling agent digunakan untuk meningkatkan ikatan antar komponen dalam material komposit. Hasil yang didapatkan dari penelitian ini adalah peningkatan modulus Young material komposit sesuai dengan penambahan 0,5% (%massa) CNT dan modifikasi serat strand, fiber mat, woven rovings sebesar 10,98%, 38,90%, dan 62,29% relatif terhadap komposit tanpa penambahan CNT. Komposit 0,5% CNT dan 40% serat TKKS woven rovings yang dihasilkan memiliki peluang untuk dikembangkan menjadi bumper mobil dengan nilai modulus Young sebesar 6,80 GPa.

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Empty palm oil fruit bunch is the side product of palm oil cultivation which contains cellulose fiber. Cellulose fiber is usually used as the composite reinforcement. The addition of carbon nanotube in composite has been known that increase mechanical properties from many researches. In this research, carbon nanotube is added to the composite material which has epoxy as its resin and empty palm oil fruit bunch fiber as the reinforcement. The fiber form is variated to chopped strand, chopped strand mat, and woven rovings. To increase the compability, a functionalization of carbon nanotube in mild acid oxidation method with nitric acid and continued by hydrogen peroxide is performed. Silane coupling agent is used to strengthen the bond of composite components. The result obtained from this research is the increasing of composite materials? Young modulus as the addition of 0.5% (%mass) CNT and woven rovings fiber modification which equals 10.98%, 38.90%, 62.29% relative to the composite without CNT addition. The composite with 0.5% CNT and 40% woven rovings fibber has a chance to be developed into car bumper with 6,80 GPa Young modulus."

"Botol air mineral dan minuman ringan merupakan sumber sampah terbesar di Indonesia dengan jenis plastik Polypropylene (PP). Teknologi nano merupakan salah satu cara untuk mengatasi masalah sampah plastik. Metode pirolisis digunakan untuk mengubah sumber karbon PP dalam bentuk padatan agar menjadi gas sebagai bahan baku sintesis. Akan tetapi, hasil penelitian pirolisis PP sebagai sumber karbon untuk CNT di Departemen Teknik Kimia Universitas Indonesia belum memperoleh kualitas dan kuantitas yang baik. Hal ini disebabkan karena metode konvensional tidak memperhatikan efek interaksi antar parameter. Oleh karena itu, peneletian ini menggunakan metode respon permukaan atau response surface methodology orde II dengan Central Composite Design (CCD), dan menggunakan ANOVA full quadratic untuk menganalisis signifikansi parameter proses terhadap hasil pirolisis PP, yang nantinya akan mengoptimasi hasil yang sebelumnya dilakukan dengan metode konvensional. Hasil penelitian menunjukkan aplikasi metode respon permukaan pada eksperimen mendapatkan konversi optimum pada suhu reaksi suhu 525,6°C dan waktu 30,4 menit, dengan hasil konversi metana sebesar 99,9%.

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Bottled mineral water and soft drinks are the largest source of waste in Indonesia with Polypropylene (PP) plastic. Nano technology is one way to overcome the problem of plastic waste. Pyrolysis method is used to convert PP carbon sources in the form of solids to become gas as raw material for synthesis. However, the results of PP pyrolysis research as a carbon source for CNTs at the Department of Chemical Engineering, University of Indonesia have not obtained good quality and quantity. This is because conventional methods do not pay attention to the effects of interactions between parameters. Therefore, this research uses a surface response method or response surface methodology of Order II with Central Composite Design (CCD), and uses a full quadratic ANOVA to analyze the significance of the process parameters to the results of PP pyrolysis, which will later optimize the results previously done with conventional methods . The results showed the application of the surface response method in the experiment obtained the optimum conversion at a reaction temperature of 525.6 ° C and a time of 30.04 minutes, with the result of 99.9% methane conversion."

"Reaktor unggun terfluidakan memiliki transfer panas dan massa yang lebih baik dibandingkan dengan reaktor unggun tetap untuk produksi carbon canotube (CNT) pada metode chemical vapor deposition (CVD). Pada penelitian ini dilakukan uji coba reaktor unggun terfluidakan untuk produksi CNT dari Liquefied Petroleum Gas (LPG) menggunakan katalis Fe-Co-Mo/MgO dan mendapatkan pengaruh waktu reaksi, suhu reaksi, dan laju alir LPG terhadap yield, diameter, morfologi, luas permukaan, volume pori, dan kristalinitas dari CNT. Hasil CNT yang berhasil diproduksi berjenis MWCNT. Peningkatan waktu reaksi dari 30 menit menjadi 90 menit meningkatkan yield CNT dari 33,07% menjadi 38,83% (gr CNT/gr katalis (%)) tetapi diameter luar meningkat dari 14-29 nm menjadi 14-44 nm. Peningkatan suhu reaksi menyebabkan yield, diameter, kristalinitas CNT meningkat. Suhu setting sebesar 900 ⁰C (suhu real= 600-820 ⁰C) menghasilkan yield yang tertinggi sebesar 50,5% dengan diameter dalam sebesar 9-20 nm dan 18-37 nm diameter luar. Penambahan laju alir LPG dari 260 mL/menit menjadi 390 mL/menit menaikan yield dari 50,5% menjadi 82,77% dan meningkatkan diameter luar dari 18-37 nm menjadi 20-44 nm. Sedangkan, luas permukaan dan volume pori dari CNT menurun dengan meningkatnya waktu reaksi, suhu reaksi, dan laju alir LPG.

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Fluidized bed reactor has better heat and mass transfer compared to fixed bed reactor for production of carbon nanotube (CNT) using chemical vapor deposition method (CVD). The aim of this research is to trial fluidized bed reactor for CNT production from Liquefied Petroleum Gas (LPG) using Fe-Co-Mo/MgO catalyst and to study the influence of reaction time, temperature, and LPG flow rate on yield, diameter, morphology, surface area, pore volume, and cristallinity of CNT. The result showed that MWCNT has been sucessfully produced. Increasing reaction time from 30 minutes to 90 minutes improved yield of CNT from 33.07% to 38.83% (gr CNT/gr catalyst (%)) and outer diameter from 14-29 nm to 14-44 nm. Improving reaction temperature increased yield, diameter, and cristallinity of CNT. The setting temperature of 900 ⁰C (real temperature = 600-820 ⁰C) produced the highest yield, i.e 50,5%, with 9-20 nm of inner diameter and 18-37 nm of outer diameter. Improving LPG flow rate from 260 mL/minutes to 390 mL/minutes increased yield from 50.50% to 82.77% and outer from 18-37 nm to 20-44 nm. Meanwhile, surface area and pore volume of CNT decreased with increasing reaction time, temperature, and LPG flow rate."

"CNT memiliki kecenderungan untuk beragregasi, sehingga diperlukan fungsionalisasi untuk menggunakan CNT dalam aplikasi biomedis. Minyak zaitun dan CTAB bertindak sebagai surfaktan yang dapat memodifikasi permukaan MWCNT. Proses fungsionalisasi dengan tahapan pencampuran, pendispersian pada water bath ultrasonik, penyaringan, hingga pengeringan. Karakterisasi FTIR MWCNT dengan minyak zaitun ataupun dengan CTAB menghasilkan gugus fungsional baru, yaitu C=O pada 1600 cm-1 dan O-H pada 2430 cm-1, kedua gugus tersebut merupakan gugus polar yang memiliki sifat hidrofilik. Hasil SEM menunjukkan morfologi MWCNT + minyak zaitun yang didominasi oleh minyak zaitun, sedangkan morfologi MWCNT + CTAB terlihat adanya modifikasi permukaan MWCNT dan terpisah satu tube dengan tube lainnya. Karakterisasi EDX menghasilkan persentase berat unsur C yang terkandung pada MWCNT + minyak zaitun 100ml dan 200ml secara beruturut-turut mengalami penurunan sebesar 30,5% dan 31,09%. Namun penambahan O sebesar 84,97% dan 85,22%. Sedangkan untuk MWCNT + CTAB, terjadi penurunan C sebesar 5,37% dan O sebesar 71,31% yang dikarenakan munculnya unsur baru pada MWCNT + CTAB, yaitu Br dan N. Karakterisasi XRD menunjukkan intensitas kristalin unsur C paling tinggi berada pada MWCNT + CTAB, MWCNT murni, MWCNT + 100ml minyak zaitun, dan MWCNT + 200ml minyak zaitun secara berturut-turut. Intensitas ini berbanding lurus dengan diameter rata-rata MWCNT.

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CNT has their tendency to aggregate, it could be overcome to use the functionalization of CNTs for biomedical applications. Olive oil and CTAB acts as a surfactant to modify the surface of the MWCNT. There are several stages on functionalization process, mixing, dispersing in an ultrasonic waterbath, filtration, then drying. FTIR spectrum shows MWCNT that had functionalization with olive oil or CTAB have new functional group, C=O at 1600 cm-1 and O-H at 2430 cm-1.

SEM micrographs shows morphology MWCNT + olive oil are dominated by olive oil, meanwhile morphology MWCNT + CTAB show the occurance of surface modification of MWCNT on the outer surface wall and separated from one tube to another tube. EDX shows the percentage of the C elements contained in the MWCNT + 100ml and 200ml olive oil is decreasing, 30.5% and 31.09%, respectively. But increasing O, 84.97% and 85.22%, respectively. As for MWCNT + CTAB, C and O are decreasing for 5.37% and 71.31%. This is due to the emergence of new elements from CTAB, Br and N. The results from XRD characterization are the highest intensity of crystalline C is MWCNT + CTAB, pristine MWCNT, MWCNT + 100ml, and MWCNT + 200ml olive oil."

"Pada penelitian nanofluida yang dilakukan akhir-akhir ini molekul Carbon Nanotube (CNT) merupakan salah satu molekul nano yang sering digunakan, hal ini karena CNT memiliki nilai konduktivitas termal yang tinggi dan memiliki karakterisasi yang unggul, CNT sendiri dibagi menjadi dua jenis berlapisan tunggal atau single-walled CNT (SWCNT) dan multi-walled (MWCNT). Dalam penelitian ini menggunakan MWCNT as-received yang dikarakterisasi dengan menggunakan Energy Dispersive Spectroscopy (EDS) dan Scanning Electron Microscope (SEM). Nanofluida berbasis CNT disintesis dengan menambahkan konsentrasi CNT sebesar 0,1%, 0,3%, dan 0,5% serta surfaktan sodium dodecylbenzenesulfonate (SDBS) sebanyak 10%, 20%, dan 30% pada fluida dasar yaitu air distilasi yang kemudian didispersikan menggunakann alat ultrasonikasi selama 15 menit. Kemudian nanofluida akan dikarakterisasi nilai zeta potensial dan konduktivitas termalnya di suhu ruang (25oC). nanofluida sebanyak 100ml yang sudah dikarakterisasi kemudian akan digunakan untuk proses quenching atau perlakuan panas pada baja S45C, sebelumnya baja S45C sudah diaustenisasi di suhu 900oC. Baja S45C hasil perlakuan panas akan dikarakterisasi menggunakan mikroskop optik dan rockwell hardness C. Penambahan konsentrasi CNT tanpa surfaktan pada nanofluida menaikan konduktivitas termal nanofluida, namun penambahan surfaktan konsentrasi tinggi (10%, 20%, dan 30%) pada nanofluida menurunkan konduktivtas termal nanofluida. Nilai zeta potensial dari nanofluida meningkat seiring dengan bertambahnya konsentrasi surfaktan, zeta potensial dapat mengukur stabilitas nanofluida. Hubungan konduktivitas termal dan kekerasan baja S45C hasil perlakuan panas menggunakan nanofluida tidak dapat dihubungkan secara linier walaupun terlihat tren semakin tinggi konduktivitas termal, maka nilai kekerasan akan semakin tinggi. Hal tersebut terjadi karena proses perlakuan panas dilakukan di temperatur tinggi yang dapat mempengaruhi stabilitas nanofluida. Mikrostruktur Baja S45C hasil perlakuan panas dengan media quench dengan konsentrasi SDBS 0% hingga 10% memiliki mikrostruktur yang didominasi martensite, sedangkan untuk konsentrasi SDBS 20-30% mikrostruktur baja didominasi dengan pearlite, ferrite dan sedikit widmanstätten ferrite.

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In recent nanofluid research, Carbon Nanotube (CNT) are one of the nano-molecules that are often used in studies, this is because CNT’s have a high thermal conductivity value and have superior characterization. There are two kinds of CNT, Single-walled CNT (SWCNT) and multi-walled (MWCNT). In this study, the as-received MWCNT is characterized by using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscope (SEM). CNT-based nanofluids were synthesized by adding 0.1%, 0.3%, and 0.5% CNT and as much as 10%, 20%, and 30% surfactant sodium dodecylbenzenesulfonate (SDBS) in the base fluid, namely distilled water which was then dispersed. using ultrasonication tool for 15 minutes. Then the nanofluid will be characterized by its zeta potential value and thermal conductivity at room temperature (25oC). 100ml of nanofluid that has been characterized will then be used for the quenching process or heat treatment on S45C steel, previously S45C steel has been austenized at 900oC. Heat treated S45C steel will be characterized using an optical microscope and rockwell hardness C. The addition of CNT concentrations without surfactants in nanofluids increased the thermal conductivity of nanofluids, but the addition of high concentrations of surfactants (10%, 20%, and 30%) in nanofluids decreased the thermal conductivity of nanofluids. The zeta potential value of nanofluids increases with increasing surfactant concentration, the zeta potential can measure the stability of nanofluids. The relationship between thermal conductivity and hardness of the heat treated S45C steel cannot be linearly related, although the trend is that the higher the thermal conductivity, the higher the hardness value. This happens because the heat treatment process is carried out at high temperatures which can affect the stability of the nanofluid. The microstructure of the heat treated S45C steel with nanofluids quenchant with a concentration of 0% to 10% SDBS has a predominantly martensite microstructure, while for an SDBS 20-30% concentration the steel microstructure is dominated by pearlite, ferrite and a little widmanstätten ferrite."