Yusmardhany Yusuf
Universitas Pembangunan Nasional "Veteran" Yogyakarta

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Mathematical Model of Water Absorption in Arrowroot Starch-Chitosan Based Bioplastic Yusmardhany Yusuf; Fauzan Irfandy; Alit Istiani
Eksergi Vol 19, No 1 (2022)
Publisher : Prodi Teknik Kimia, Fakultas Teknologi Industri, UPN "Veteran" Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31315/e.v19i1.6310

Abstract

Expansion of the size of the weight of bioplastics often occurs in daily use. This phenomenon happens because the material from bioplastics can absorb significant amounts of water. This process can lead to accumulation of swelling degree. Therefore, a mathematical model is needed to quantify this mechanism to predict the dynamics of changes in the weight of bioplastics with respet to time while contact with water to help practitioners during application design for the use of bioplastics. This study aims to build a mathematical model derived from the mass sense validated by experimental data through curve fitting. The experiment was conducted by observing the rate of change in the mass of bioplastic made from starch and chitosan by measuring the change in mass concerning time immersed in water under atmospheric conditions. The immersion time was varied between 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40,50, and 60 minutes. As a result, it can be concluded that starch-chitosan-based biofilms can absorb water up to ±10.9174 gr-water/gr-bioplastic, and also this phenomenon can be quantified by a mathematical equation that derived from mass balance with an average percent error of 1.13% and R-squared coefficient of 0.9981. 
Risk Analysis Related to the Possibility of Using CNG in Trans Jogja Buses Perwitasari Perwitasari; Heni Anggorowati; Yusmardhany Yusuf
CHEESA: Chemical Engineering Research Articles Vol 5, No 1 (2022)
Publisher : Universitas PGRI Madiun

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25273/cheesa.v5i1.10824.28-39

Abstract

One of the issues in urban areas such as DI Yogyakarta province is air pollution. The pollution level is high, as shown by the quality index value of about 85.25 in 2019. Vehicle emissions are the most significant source of this pollution in urban areas and can be decreased by using fuel with minimum carbon emission. Compressed Natural Gas (CNG) is an environmentally friendly fuel. However, a safety study is required because CNG is stored under high pressure. Therefore, this research aims to analyze the risk of using CNG in the Trans Jogja bus. The research method collects secondary data and then processes them using FTA, ETA, ALOHA software, and a risk matrix. The result shows that the risk value for CNG usage in the Trans Jogja bus is low to a moderate level or acceptable.