STUDI KINETIKA, MEKANISME, DAN EFESIENSI ADSORPSI PEWARNA INDIGO CARMINE DARI AIR LIMBAH MENGGUNAKAN BIOCHAR BERBASIS LIMBAH BIOMASA BIJI ASAM JAWA

Pewarna sintetik seperti Indigo Carmine (IC) dari limbah cair dapat membahayakan manusia atau lingkungan, bahkan pada konsentrasi rendah. Penelitian ini menyelidiki karakteristik fisikokimia, kinetika adsorpsi, dan mekanisme adsorpsi dari adsorben biochar yang dipreparasi melalui pemanfaatan limbah biji asam jawa dalam mereduksi pewarna dari larutan berair. Biochar disiapkan melalui karbonisasi pada suhu 250°C selama 5 jam dan dikarakterisasi untuk ukuran dan morfologi partikel, gugus fungsi, dan luas permukaan yang masing-masing menggunakan intrumen Scanning Electron Microscope (SEM), spektroskopi Fourier Transform Infrared (FTIR), dan Brunauer-Emmett-Teller (BET). Uji adsorpsi batch dilakukan dengan memvariasikan ukuran partikel biochar berbasis biji asam jawa yang berbeda (500, 1000, dan 2000 µm). Beberapa variabel meliputi ukuran partikel (500, 1000, dan 2000 µm), waktu kontak (5-60 menit), konsentrasi awal IC (40–100 mg/L), massa adsorben (0,1-0.5 g), dan pH awal larutan IC (1, 7, dan 13) juga dipelajari. Parameter kinetika dan isoterm adsorpsi diskemakan dengan metode linear melalui pencocokan data pada 2 model kinetika adsorpsi (seperti pseudo-first-order dan pseudo-second-order) dan pada 4 model isoterm adsorpsi (seperti Langmuir, Freundlich, Temkin, dan Dubinin-Radushkevich). Hasil karaktersasi SEM menunjukkan bahwa bioadsorben biochar memiliki permukaan berpori dengan ukuran partikel tidak homogen untuk semua variasi ukuran partikel. Hasil BET menunjukkan bahwa luas permukaan dari biochar berbasis biji asam jawa meningkat seiring menurunan ukuran partikel dan tipe porinya dikonfirmasi sebagai tipe III. Kemudian, analisis gugus fungsi menunjukkan keberadaan hidroksil, alkil, alkena, karbonil, karbon-heteroatom (C-N). Berdasarkan hasil karakterisasi fisikokimia ini, biochar dari biji asam jawa berhasil dipreparasi. Hasil eksperimen menunjukkan bahwa persentase penghilangan pewarna IC meningkat seiring penurunan ukuran partikel adsorben, kenaikan waktu kontak adsorpsi, kenaikan massa adsorben, dan penurunan pH. Namun, persentasi penghilangan pewarna IC ini menurun seiring dengan peningkatan konsentrasi awal larutan adsorbat. Karakteristik adsorpsi IC menunjukkan bahwa adsorpsi mengikuti model Freundlih untuk adsorben biochar berukuran 500 µm dan mengikuti model Dubinin-Radushkevich untuk biochar berukuran 1000 dan 2000 µm. Kemudian, model kinetika orde dua semu adalah model terbaik yang dapat diterapkan untuk menggambarkan kinetika adsorpsi untuk seluruh jenis ukuran partikel adsorben. Penelitian menunjukkan bahwa limbah agro yang digunakan dalam penelitian ini adalah prekursor yang memungkinkan untuk memproduksi adsorben secara lokal dengan biaya rendah. Namun, agar mencapai efesiensi adsorpsi yang baik, perlu adanya modifikasi permukaan pada adsorben biochar jenis ini. Synthetic dyes such as Indigo Carmine (IC) from wastewater can be harmful to humans or the environment, even at low concentrations. This study investigated the physicochemical characteristics, adsorption kinetics, and adsorption mechanism of biochar adsorbents prepared by utilizing tamarind seed waste in reducing dyes from aqueous solutions. Biochar was prepared by carbonization at 250°C for 5 hours and characterized for particle size and morphology, functional groups, and surface area respectively using Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and Brunauer- Emmett-Teller (BET). Batch adsorption tests were carried out by varying the particle sizes of different tamarind seed-based biochar (500, 1000, and 2000 µm). Several variables include particle size (500, 1000, and 2000 µm), contact time (5-60 minutes), initial concentration of IC (40–100 mg/L), mass of adsorbent (0.1-0.5 g), and initial pH IC solutions (1, 7, and 13) were also studied. Parameters of adsorption kinetics and isotherms were schematized using the linear method by matching data to 2 adsorption kinetics models (such as pseudo-first-order and pseudo-second-order) and to 4 adsorption isotherm models (such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) . SEM characterization results show that the biochar bioadsorbent has a porous surface with inhomogeneous particle sizes for all variations in particle size. BET results showed that the surface area of tamarind seed-based biochar increased with decreasing particle size and the pore type was confirmed as type III. Then, functional group analysis showed the presence of hydroxyl, alkyl, alkene, carbonyl, carbon-heteroatom (C-N). Based on the results of this physicochemical characterization, biochar from tamarind seeds was successfully prepared. The experimental results showed that the percentage of IC dye removal increased as the adsorbent particle size decreased, the adsorption contact time increased, the adsorbent mass increased, and the pH decreased. However, the percentage of IC dye removal decreased with increasing the initial concentration of the adsorbate solution. The IC adsorption characteristics showed that adsorption followed the Freundlih model for 500 µm biochar adsorbents and followed the Dubinin-Radushkevich model for 1000 and 2000 µm biochar. Then, the pseudo second order kinetic model is the best model that can be applied to describe the adsorption kinetics for all types of adsorbent particle sizes. The research shows that the agro-waste used in this study is a precursor that makes it possible to produce adsorbents locally at low cost. However, in order to achieve good adsorption efficiency, it is necessary to modify the surface of this type of biochar adsorbent

Economic Perspective in the Production of Silver Nanoparticles on the Bacterial Cellulose Membrane as Antibacterial Material

Silver nanoparticles (Ag NPs) are the most frequently studied material with superiority as antibacterial that currently increasing the production of Ag NPs. Hence, feasibility study is needed for the development on the production of Ag NPs in industrial scale, especially in Indonesia and other developing countries. The chemical reduction with sodium citrate is used to produce Ag NPs. The purpose of this study is to analysis the prospect of large-scale industrial production in engineering perspective and economic evaluation. This study also gave recommendations for profitability of the production. Perspective of engineering in the production gave information about capability of large-scale production because the easy process and low-cost apparatuses of production can be done. Various economic parameters were used to completed the analysis. Then, the ideal condition to the worst issues of production was estimated to completed the calculation of economic evaluation by effects of raw materials. From this study, those all parameters gave positive result which mean it has good profitability. However, further analysis of strategies in sales and investment must be done in the future to developing the production of Ag NPs that promising in capability on large-scale production

Techno-economic Analysis for the Production of Silica Particles from Agricultural Wastes

The purpose of this study was to evaluate the feasibility studies on the production of silica from agricultural wastes (i.e. rice husk, rice straw, bagasse, and corn cob) from engineering and economic perspectives. The engineering perspective was done by calculating stoichiometry, mass balance, and the preliminary plant design evaluation, whereas the economic perspective analysis was performed by calculating various economic parameters (i.e., Gross Profit Margin, Internal Rate Return, Break Even Point, Payback Period, and Cumulative Net Present Value) under various conditions. The results from engineering perspective showed that the project is applicable even in the home-scale production. The project is potentially scaled up since it can be executed using commercially available and inexpensive equipment. Economic analysis showed that various agricultural wastes gave positive impacts on profitability, confirmed by the various economic evaluation parameters. Based on the evaluation from various agricultural wastes, rice husk is the best raw materials for gaining the highest interest, whereas corn cob is the worst. To confirm the analysis, various economic conditions under different raw material costs, utility costs, labor, and sales, as well as taxes, were added into the calculation, and they showed positive values for the potential production of silica particles. Although the evaluation confirmed for the excellent economic parameter values, further analysis of this project must be carried out to determine the uncertainty of conditions existing during the realistic project

Desain Reaktor untuk Produksi Nanopartikel Nikel Ferit (NiFe2O4)

Tujuan dari penelitian ini adalah untuk merancang reaktor sederhana tipe Continous Stirred Tank Reactor (CSTR) dan menganalisis reaktor melalui analisis komputasi dengan menghitung reaktor, pengaduk yang digunakan dan neraca massa menggunakan Microsoft Excel. Berdasarkan hasil perhitungan dimensi reaktor CSTR, diperoleh tekanan design sebesar 44,61 psig, tebal dan tinggi tabung silinder masing-masing 0,14 in dan 85,46 in, ketebalan tutup atas dan bawah tabung silinder adalah 0,15 in dan 0,23 in begitu pun ketinggian tutup atas dan bawah tabung silinder sebesar 9,63 in dan16,47 in serta tinggi reaktor sebesar 114,06 in. Tidak hanya itu, reaktor juga dilengkapi 1 pengaduk dengan diameter, tinggi, panjang dan lebar berturut-turut 28,49 in, 18,99 in, 7,12 in dan 5,70 in dengan daya pengadukan pada prosesnya sebesar 32,73 Hp. Penulisan artikel ini diharapkan menjadi referensi yang bermanfaat sebagai metode pembelajaran perancangan reaktor untuk menghasilkan produk nanopartikel nikel ferit (NiFe2O4) yang berpuluh ribu kali lebih besar dari skala laboratorium