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Selective and simultaneous detection of cadmium, lead and copper by tapioca-derived carbon dot-modified electrode

Pudza MY, Abidin ZZ, Abdul-Rashid S, Yasin FM, Noor ASM, Abdullah J

Environ Sci Pollut Res Int, 2020 Apr;27(12):13315-13324.
PMID: 32020456 DOI: 10.1007/s11356-020-07695-7

The need for the sensing of environmental pollutants cannot be overemphasized in the twenty-first century. Herein, a sensor has been developed for the sensitive and selective detection of copper (Cu2+), lead (Pb2+) and cadmium (Cd2+) as major heavy metals polluting water environment. A screen-printed carbon electrode (SPCE) modified by fluorescent carbon dots (CDs) and gold nanoparticles (AuNPs) was successfully fabricated for sensing Cu2+, Pb2+ and Cd2+. Differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were deployed for the analysis of ternary analytes. CV was set at a potential range of - 0.8 to + 0.2 V at a scan rate of 100 mV/s, and DPV at a potential range of - 0.8 to + 0.1 V, scan rate of 50 mV/s, pulse rate of 0.2 V and pulse width of 50 ms. DPV technique was applied through the modified electrode for sensitive and selective determination of Cu2+, Pb2+ and Cd2+ at a concentration range of 0.01 to 0.27 ppm for Cu2+, Pb2+ and Cd2+. Tolerance for the highest possible concentration of foreign substances such as Mg2+, K+, Na+, NO3-, and SO42- was observed with a relative error less than ± 3%. The sensitivity of the modified electrode was at 0.17, 0.42 and 0.18 ppm for Cd2+, Pb2+ and Cu2+, respectively, while the limits of detection (LOD) achieved for cadmium, lead and copper were 0.0028, 0.0042 and 0.014 ppm, respectively. The quality of the modified electrode for sensing Cu2+, Pb2+ and Cd2+ at trace levels is in accordance with the World Health Organization (WHO) and Environmental Protection Agency (EPA) water regulation standard. The modified SPCE provides a cost-effective, dependable and stable means of detecting heavy metal ions (Cu2+, Pb2+ and Cd2+) in an aqueous solution. Graphical abstract .
Fulltext Eco-Friendly Sustainable Fluorescent Carbon Dots for the Adsorption of Heavy Metal Ions in Aqueous Environment

Yahaya Pudza M, Zainal Abidin Z, Abdul Rashid S, Md Yasin F, Noor ASM, Issa MA

Nanomaterials (Basel), 2020 Feb 12;10(2).
PMID: 32059384 DOI: 10.3390/nano10020315

The materials and substances required for sustainable water treatment by adsorption technique, are still being researched widely by distinguished classes of researchers. Thus, the need to synthesize substances that can effectively clean up pollutants from the environment cannot be overemphasized. So far, materials in bulk forms that are rich in carbon, such as biochar and varieties of activated carbon have been used for various adsorptive purposes. The use of bulk materials for such purposes are not efficient due to minimal surface areas available for adsorption. This study explores the adsorption task at nano dimension using carbon dots (CDs) from tapioca. The properties of carbon structure and its influence on the adsorptive efficacy of carbon nanoparticles were investigated by energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HrTEM), and atomic force microscopy (AFM). The results implied carbon present in CDs are good adsorbents for effective adsorption of heavy metal ions (lead) with removal efficiency of 80.6% in aqueous environment. The adsorption process as explored by both Langmuir and Freundlich isotherms have proven favorability of the adsorption process. Langmuir form two and three have correlation coefficients R2 at 0.9922 and 0.9912, respectively. The Freundlich isotherm confirms CDs as having defined surface heterogeneity and the exponential distribution of active sites. The adsorption of lead unto CDs obeyed the second order kinetic model with coefficient of determination, R2 of 0.9668 and 0.9996 at an initial lead concentration of 20 mg/L and 100 mg/L, respectively. The findings validated the efficiency of CDs derived from tapioca as an excellent material for further utilization in the environmental fields of wastewater pollution detection and clean up, bio-imaging, and chemical sensing applications.
The readiness of the Asian research ethics committees in responding to the COVID-19 pandemic: A multi-country survey

Karbwang J, Torres CE, Navarro AM, Wongwai P, Jimenez EB, Shetty Y, et al.

F1000Res, 2024;13:19.
PMID: 39165349 DOI: 10.12688/f1000research.143138.1

BACKGROUND: COVID-19 is a highly challenging infectious disease. Research ethics committees (RECs) have challenges reviewing research on this new pandemic disease under a tight timeline and public pressure. This study aimed to assess RECs' responses and review during the outbreak in seven Asian countries where the Strategic Initiative for Developing Capacity in Ethical Review (SIDCER) networks are active.
METHODS: The online survey was conducted in seven Asian countries from April to August 2021. Two sets of online questionnaires were developed, one set for the chairs/secretaries and another set for the REC members.The REC profiles obtained from the REC members are descriptive in nature. Data from the chairs/secretaries were compared between the RECs with external quality assessment (SIDCER-Recognized RECs, SR-RECs) and non-external quality assessment (Non-SIDCER-Recognized RECs, NSR-RECs) and analyzed using a Chi-squared test.
RESULTS: A total of 688 REC members and 197 REC chairs/secretaries participated in the survey. Most RECs have standard operating procedures (SOPs), and have experience in reviewing all types of protocols, but 18.1% had no experience reviewing COVID-19 protocols. Most REC members need specific training on reviewing COVID-19 protocols (93%). In response to the outbreak, RECs used online reviews, increased meeting frequency and single/central REC. All SR-RECs had a member composition as required by the World Health Organisation ethics guidelines, while some NSR-RECs lacked non-affiliated and/or layperson members. SR-RECs reviewed more COVID-related product development protocols and indicated challenges in reviewing risk/benefit and vulnerability (0.010), informed consent form (0.002), and privacy and confidentiality (P = 0.020) than NSR-RECs.
CONCLUSIONS: Surveyed RECs had a general knowledge of REC operation and played a significant role in reviewing COVID-19-related product development protocols. Having active networks of RECs across regions to share updated information and resources could be one of the strategies to promote readiness for future public health emergencies.

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