Colloidal stability of the coated gold nanoparticles synthesized from spent coffee ground extract and qualitative modeling of nucleation and growth of gold nanoparticles

การเคลือบอนุภาคนาโนทองคำที่สังเคราะห์ด้วยสารสกัดจากกากกาแฟและการสร้างแบบจำลองเชิงคุณภาพของการกระจายขนาดอนุภาคทองคำ

Name: Nichayanan Manyuan

keyword: Gold nanoparticles

; Localized surface plasmon resonance

; Spent coffee ground extract

; Steric stabilization

; Electrostatic stabilization

Abstract: Gold nanoparticles (AuNPs) were synthesized using cold-brew spent coffee grounds extract. The synthesized AuNPs with two average sizes, using 1.8 mM HAuCl4 (1.8AuNPs and 4.0 mM HAuCl4 (4.0AuNPs), were compared for their enhancement of colloidal stability to withstand several conditions, including mechanical, chemical, thermal, and acid-base disturbances. Furthermore, the synthesized AuNPs were coated with polyethylene glycol 400 and 6000 (PEG400 and PEG600) to enhance steric stability, SDS to enhance electrostatic stability, and sodium alginate to enhance both the steric and electrostatic stabilities. The colloids were characterized by UV-vis spectrophotometry and transmission electron microscopy. The average diameters of 1.8AuNPs and 4.0AuNPs were 13.33 and 18.86 nm, corresponding to the absorbance peak at 533 and 539 nm, respectively. The colloidal stability was studied using the results from spectrophotometry. The aggregation of as-synthesized AuNPs, reflected by the red shift of the spectrum, occurred after the centrifugation at 10000 rpm for 10 minutes, but this was prevented after coating with 5%w/v PEG400, 5%w/v PEG6000, 0.1%w/v alginate, and 0.5%w/v SDS solutions. Electrostatic stabilization using alginate and SDS could withstand up to three times of centrifugation, while steric stabilization using PEG400 and PEG6000 could withstand the disturbance of Ca2+ more effectively. The smaller AuNPs were more affected by Ca2+ than the larger ones. In highly acidic solutions, all coated AuNPs showed the red shift and SDS-coated AuNPs were the most effective against acid disturbance, and in highly basic solutions, all coated AuNPs showed the blue shift. Besides, the coated AuNPs were still stable at 52ºC. Furthermore, the theoretical study of growth and nucleation of AuNPs was done. The modeling of nucleation and growth via a coalescence of two nanoparticles were simplified using reaction kinetics of the diffusion-controlled reaction. The frequency factor and activation energy were approximated and the set of differential equations were solved using Polymath. The concentrations of nanoparticles of discretized radii ranging from 1 to 12 nm were obtained at different reaction times. Therefore, the size distribution of the AuNPs could be obtained. Qualitatively, the effect of the concentration of gold precursor (1.8 and 4.0 mM) on the size distributions was observed consistent with the experimental results

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Panu Danwanichakul

Role: advisor

Created: 2021

Modified: 2023-02-09

Issued: 2023-02-09

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2021.35

eng

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Chemical Engineering

Grantor: Thammasat University

©copyrights Thammasat University

ลำดับที่.	ชื่อแฟ้มข้อมูล	ขนาดแฟ้มข้อมูล	จำนวนเข้าถึง	วัน-เวลาเข้าถึงล่าสุด
1	10409nichayanan.pdf	6.66 MB

ใช้เวลา

0.015362 วินาที