Chemical and Natural Resources Engineering Journal (Formally known as Biological and Natural Resources Engineering Journal)

COMPARISON STUDY BETWEEN HYDROTHERMAL AND COPRECIPITATION METHOD FOR GREEN SYNTHESIZE OF MAGNETIC SILVER NANOPARTICLES

Mohammad Aiman Hakim Abdullah, Ainul Husna Abdul Aziz, Nurul Sakinah Engliman — Tue, 25 Jun 2024 00:00:00 +0800

Nanoparticle research has been attractive for the past decade due to its unique electronic, mechanical, optical, chemical, and magnetic properties, which can be used in various applications, including sensors, medical, food, and others. Yet, the use of toxic chemicals in the synthesis of nanoparticles limits their potential use in the medical and food industries. The green synthesis of nanoparticles is eco-friendly and well-suited for many applications. However, there are some issues related to it as there are limited comparisons made between nanoparticles synthesized through different routes, and even the physiochemical and morphological properties are also not compared. Therefore, this study attempts to synthesize magnetic silver nanoparticles using the greener technique, which utilized the banana peel waste extract as the reductant during the synthesis of nanoparticles. The banana peel waste extract and the nanoparticles were characterized using a UV-VIS spectrometer, Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscope (FESEM) to analyze the properties of the extract and the fabricated nanoparticles. The results found that the -OH group was present in both banana peel extract as well and the synthesis of silver nanoparticles in FTIR analysis, which is believed to come from the phenolic group that helps in the reduction of silver ions to silver nanoparticles during the synthesis process. VSM analysis indicates that the synthesized silver nanoparticles had ferromagnetic properties of 2.83 emu/g for the coprecipitation method and 3.91 emu/g for a hydrothermal method, which is considered stronger to be utilized for further application. In addition, FESEM analysis shows that the hydrothermal could synthesize the uniformly distributed and mono-dispersed spherical shape compared to the coprecipitation method, which produces uneven shapes like rods, pellets, and spheres. The study concludes that the green-synthesized silver nanoparticles using banana peel waste extracts could produce medium-strength magnetic silver nanoparticles, especially through a hydrothermal process when the diluted precursor ions were used compared to concentrated ones.

SOLID WASTE GENERATION IN SELANGOR DURING THE COVID-19 PANDEMIC (2019-2021)

Tue, 25 Jun 2024 00:00:00 +0800

Selangor, like many other Malaysian states, experienced various disruptions
due to the pandemic. In addition to health and economic challenges, the populous state
also faced notable issues regarding waste production. The COVID-19 pandemic has led to
a dramatic rise in solid waste generation especially in its two largest sources, municipal
solid waste (MSW) and clinical solid waste (CSW). The pandemic resulted in people
staying at home and relying on home deliveries, which led to an escalation in MSW.
Healthcare workers also faced longer hours due to the growing number of COVID-19
patients, causing increased production of CSW. Though, it is unclear which waste source
is more affected by the pandemic. In the present study, the trend of solid waste generation
in Selangor during the pandemic was investigated. A comparison was also made between
the annual generation rates of both MSW and CSW, particularly spanning the period from
2019 to 2021. After collecting relevant numeric data from respective resources, the data is
recorded into Microsoft Excel to generate graphs. The findings showed that in 2019,
Selangor witnessed a generation of 1,358,786 tonnes of MSW, which increased to
1,426,551 tonnes in 2020, and further escalated to 1,484,282 tonnes in 2021. As for CSW,
Selangor generated a total of 7,343 tonnes in 2019, 9,703 tonnes in 2020, and 12,993
tonnes in 2021. The analysis uncovered that MSW exhibited an average annual generation
rate of 4.5%, whereas CSW demonstrated a higher average generation rate of 33%. An
upward trend was seen in both MSW and CSW generation in Selangor from 2019 to 2021,
with CSW demonstrating a significantly higher generation rate.

ELUCIDATING THE PHYSICOCHEMICAL PROPERTIES OF STINGLESS BEE HONEY AS CRYOPROTECTANT AND THERMOREGULATED CONSTITUENTS

Tue, 25 Jun 2024 00:00:00 +0800

Stingless bee honey had been studied for their unique properties and their potential in medical aspects. In this study, the physicochemical properties of the stingless bee honey of Heterotrigona itama and Geniotrigona thoracica were investigated for their potential as cryoprotectant. The water content of the stingless bee honey was determined through water removal process where G. thoracica and H. itama contained 26.8% and 29.68% of water, respectively. The freezing point and properties of the stingless bee honey under different temperatures between 0?C, -20?C and -80?C were studied and the results showed that G. thoracica stingless bee honey had a slower freezing rate compared to H .itama. Thawing experiment of the stingless bee honey was conducted at room temperature in order to find the rate of thawing for the stingless bee honey. It was found that the melting rate of H. itama was slower compared to G. thoracica. Image analysis was done in order to analyze the freezing and melting rate of the stingless bee honey from G. thoracica and H. itama. DSC analysis thermograms of pure G. thoracica and pure H. itama stingless bee honey showed that the T_g value for G. thoracica was 36.64?C and H. itama was 58.06?C, while the T_m value of G. thoracica was 122.33?C and H. itama was 153.27?C. Finally, the T_c value for G. thoracica was 89?C, while for H. itama, the value was 129.47?C. Our study has shown that these stingless bee honey contained high water content and low T_g value. Stingless bee honey’s amorphous solid physicochemistry merit for study and should be further elucidated for its potential in cells and macromolecules such as mRNA and DNA protection and preservation under low temperature and extreme conditions.