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Electrogenerative gold recovery from cyanide solutions using a flow-through cell with activated reticulated vitreous carbon

Yap CY, Mohamed N

Chemosphere, 2008 Oct;73(5):685-91.
PMID: 18718637 DOI: 10.1016/j.chemosphere.2008.07.014

An electrogenerative flow-through reactor with an activated reticulated vitreous carbon cathode was developed. The influence of palladium-tin activation of the cathode towards gold deposition was studied by cyclic voltammetry. The reactor proved to be efficient in recovering more than 99% of gold within 4 h of operation. The performance of the reactor was evaluated with initial gold concentrations of 10, 100 and 500 mg L-1 and various electrolyte flow rates. Gold recovery was found to be strongly dependent on electrolyte flow rate and initial gold concentration in the cyanide solution under the experimental conditions used.
An electrogenerative process for the recovery of gold from cyanide solutions

Yap CY, Mohamed N

Chemosphere, 2007 Apr;67(8):1502-10.
PMID: 17296217

Traditional methods for the recovery of gold from electronic scrap by hydrometallurgy were cyanidation followed by adsorption on activated carbon or cementation onto zinc dust and by electrowinning. In our studies, a static batch electrochemical reactor operating in an electrogenerative mode was used in gold recovery from cyanide solutions. A spontaneous chemical reaction will take place in the reactor and generate an external flow of current. In this present work, a static batch cell with an improved design using three-dimensional cathodes namely porous graphite and reticulated vitreous carbon (RVC) and two-dimensional cathode materials, copper and stainless steel plates were coupled with a zinc anode. The electrogenerative system was demonstrated and the performance of the system using various cathode materials for gold recovery was evaluated. The system resulted in more than 90% gold being recovered within 3h of operation. Activated RVC serves as a superior cathode material having the highest recovery rate with more than 99% of gold being recovered in 1h of operation. The morphology of gold deposits on various cathode materials was also investigated.
Biodiesel synthesis from oil palm empty fruit bunch biochar derived heterogeneous solid catalyst using 4-benzenediazonium sulfonate

Lim S, Yap CY, Pang YL, Wong KH

J Hazard Mater, 2020 05 15;390:121532.
PMID: 31843399 DOI: 10.1016/j.jhazmat.2019.121532

In this research, biomass from oil palm empty fruit bunch was used as the carbon precursor and sulfonated by 4-benzenediazonium sulfonate (4-BDS) to produce solid acid catalyst. The as-synthesized catalysts were characterized and the performances were tested in esterification of palm fatty acid distillate (PFAD) for biodiesel production. Scanning Electron Microscopy (SEM) showed that clear porous and rough carbon surface was successfully developed after calcination which favored the attachment of sulfonic groups. Thermogravimetric Analysis (TGA) result showed that the catalyst was thermally stable up to 600 °C. Fourier Transform Infrared Spectroscopy (FTIR) proved that SO and SO3H sulfonic groups were successfully attached to the carbon catalyst. From the catalytic activity tests, the results showed that the catalyst which was calcined at 200 °C and sulfonated with 15:1 sulfanilic acid to AC ratio was the optimum catalyst as it provided the highest biodiesel yield. Further investigation showed that the reaction time of 7 h and 20 wt.% of catalyst loading were reported as optimum esterification conditions which provided the highest biodiesel yield at 98.1 %.
Fulltext Family function and health self-management ability among older adults from mountainous areas in China: moderated mediation model in a cross-sectional study

Chen JH, Chen MF, Zain NM, Yap CY, Yusuf A, Ying BH

BMC Public Health, 2025 Apr 05;25(1):1291.
PMID: 40188096 DOI: 10.1186/s12889-025-22472-2

BACKGROUND: Improving the health self-management ability (HSMA) of older adults is a feasible strategy for addressing population ageing and the high incidence of non-communicable diseases. Identifying psychosocial factors that facilitate better self-management of health is key to developing effective interventions. This study explored whether self-efficacy mediates the relationship between family function and HSMA and whether this mediation is moderated by personal income.
METHODS: A multicentre cross-sectional survey was conducted with 596 participants (response rate of 97.2%) in the mountainous Lishui region of China by using a multi-stage, stratified, cluster-sampling procedure. The survey included questions on sociodemographic characteristics, the Adult Health Self-Management Skills (Ability) Rating scale, family APGAR scale and General Self-Efficacy (GSE) scale. Data were analysed using descriptive statistics, Spearman's correlation, and multiple regression analysis with mediation and moderated mediation models.
RESULTS: The average score for HSMA, family function, and GSE were 149.6 ± 18.1 (out of 190), 8.2 ± 2.2 (out of 10), and 24.0 ± 6.0 (out of 40), respectively, which indicate moderate HSMA and family function levels and low GSE among older adults in Lishui. Significant correlations were observed between family function and GSE (rs = 0.150, P