<p>Nanopartikel magnetit merupakan suatu material dengan sifat magnet yang stabil dan memiliki luas permukaan tinggi. Penyalutan nanopartikel magnetit dengan asam humat (AH) dilaporkan dapat meningkatkan stabilitas, kapasitas adsorpsi, dan kemudahan pemisahan pasca adsorpsi. Penelitian ini bertujuan untuk melakukan sintesis Nanopartikel Magnetit tersalut Asam Humat (NpMAH) dengan metode ko-presipitasi dan menentukan parameter adsorpsinya sebagai adsorben <em>Methylene Blue</em> (MB) dengan metode <em>batch</em>. Keberhasilan sintesis ditunjukkan oleh karakterisasi NpMAH dengan FT-IR, XRD, SEM, dan VSM. Parameter isoterm adsorpsi mengindikasikan bahwa adsorpsi terjadi secara lapis tunggal dengan kapasitas adsorpsi sebesar 56,96 mg/g dan energi adsorpsi sebesar 26,31 kJ/mol pada pH optimum 6,0. Parameter kinetika menunjukkan bahwa adsorpsi mengikuti model kinetika Ho (<em>pseudo</em> orde kedua) dengan konstanta laju adsorpsi (<em>k<sub>Ho</sub></em>) sebesar 12688,71 g/molmenitdan perhitungan MB yang teradsorpsi pada kesetimbangan (<em>q<sub>e</sub></em>) sebesar 2,96×10<sup>-5</sup> mol/g. Perhitungan energi adsorpsi menggunakan model kinetika Santosa dan RBS berturut-turut 25,67 kJ/mol dan 41,25 kJ/mol.</p>
Carbonated calcium hydroxyapatite (CHAp) exhibits excellent biocompatibility with bone and teeth, making it an ideal candidate for orthopedic and dental application. However, the study of CHAp synthesis from natural material is still scarce. The purpose of this research is to synthesize and characterize of CHAp, using Rebon shrimp (Acetes erythraeus) as a calcium source. The synthesis was conducted by hydrothermal method with the variation of Ca/P ratios 1.61; 1.67; 1.73. The as-prepared CHAp was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray (SEM-EDX). The FT-IR results show that synthesized material exhibited characteristic CHAp band of hydroxide at 3448 and 1635 cm-1, carbonate at 872 and 1427 cm-1, and phosphate at 1049; 606; and 570 cm-1. The diffractogram pattern assigned the all observed peak of CHAp are in good agreement compared to CHAp database with the nano-scale size. It also observed that the high Ca/P ratio will decrease the crystallinity of CHAp. The as-prepared CHAp micrograph is agglomerates spherical form with size between 5-20 nm which build up from 18–26 nm crystallite particles. The result of this research confirmed that Rebon shrimp is the promising materials for calcium source in CHAp production.
Ecoprint is a technique for printing colors and shapes on fabric using natural materials. Ecoprint techniques have been introduced to junior high school students because they can capture the material and teacher's instructions independently, think critically and creatively. The purpose of the ecoprint introduction activity is to provide knowledge about ecoprint and students' skills in utilizing local potential through natural materials or plants around the school. The methods used are lectures, demonstrations, practice, and evaluation. The questionnaires and direct observations on ecoprint products were used as evaluations for this activity. Students have been able to print motifs and colors from leaves and flowers on a cloth to produce ecoprint products according to their respective creativity.
Plastics become the biggest environmental problem when it accumulate in landfills because its nonbiodegradable properties. To handle the problems, the plastics were processed to produce liquid fuels by means pyrolysis method which was in this case with and without a catalyst. In this work, polypropylene was used as a precursor and SiO 2 , zeolites, CaO, Fe as catalysts. FTIR spectrum of pyrolized polypropylene with and without catalysts both have shown C = C functional group at 1648 cm -1. GCMS analysis confirmed the availability of chain length of hydrocarbon between C 7 -C 27 which is mixture of kerosene and diesel fractions. Catalysts can lower the temperature and time reaction of pyrolysis process as they increase rendement (%) of product. Liquid fuels that produced from polypropylene pyrolysis without catalyst was 72.06%, and with catalysts were 79.59% (SiO 2 ), 74.76%, (zeolite), 76.80% (CaO), and 76.83% (Fe).
Platinum is a valuable metal that is widely used in industry, electronics, and catalysts. The use of Platinum has a significant impact on the production of waste, necessitating effective metal recovery. This study investigated Platinum (IV) recovery from wastewater using a positively charged and magnetically separable Magnetite/Silica-Ammonium (MSA). The MSA was prepared by co-precipitation procedure of silica-decorated quaternary ammonium in the Fe3+/Fe2+ solution. The characterization result of the MSA by FT-IR, X-ray diffraction (XRD), SEM-EDX, and Vibration Sample Magnetometer (VSM) demonstrated the success of MSA synthesis. The application of MSA to the Pt (IV) solution occurred at pH optimum 6,0 with the easy and quick retraction of MSA-loaded Pt (IV) by 29.3 emu/g magnetic strength of an external magnet. The adsorption isotherm study followed the Freundlich model (R2=0.9895) with the KF=2.57×10-2 mol/g. The monolayer capacity by Langmuir showed the remarkable performance of 139.09 mg/g adsorption capacity through the ion exchange interaction mechanism based on the Dubinin-Radushkevich energy (ED-R=8,3 kJ/mol). The kinetics study was fitted well to the Pseudo-second-order model indicated the fast adsorption of Pt (IV) into the MSA surface.
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