An improved electrochemical sensor based on triton X-100 functionalized SnO₂ nanoparticles for ultrasensitive determination of cadmium

Highlights

• Fabrication of SnO₂ nanoparticles through an effective aqueous chemical growth method.

• Exploitation of Triton X-100 as functionalizing and stabilizing agents in preparation of SnO₂ nanoparticles.

• Characterization of TX-100/SnO₂ nanoparticles through FTIR, SEM and XRD.

• Utilization of engineered sensor for the low-level electrochemical determination of Cd⁺² ions.

• Evaluation of fabricated TX-100/SnO₂/GCE for determination of Cd⁺² in real water bodies.

Abstract

The drastic increases in the concentration of heavy metals ions in the environment have become a serious concern for a number of years. Heavy metals pose serious impacts on human and aquatic life and cause severe health hazards. Amongst heavy metals, cadmium is known for its lethal effects on human health as it easily reacts with enzymes and creates free radicals in the biological system that causes carcinogenicity and other serious diseases. Thus, to tackle this challenge, TX-100 SnO₂ nanoparticles based chemically modified sensor is introduced to assess the quantity of Cd⁺² in the water system. The engineered SnO₂ nanoparticles were electrochemically characterized through cyclic voltammetry and electrochemical impedance spectroscopy to ensure the better charge transfer kinetics and electrocatalytic properties of fabricated sensors. Under the optimized conditions e.g., scan rate 80 mV/s, PBS electrolyte pH 7, and potential window (−0.2 to −1.4 V), the engineered TX-100/SnO₂/GCE-based sensor manifested a phenomenal response for cadmium ions in water media. The LOD and LOQ of developed TX-100/SnO₂/GCE were calculated in the nanomolar range as 0.0084 nM and 0.27 nM. The recovery values of the proposed method for Cd⁺² were found in an acceptable limit that witnesses the effectiveness of the fabricated sensor. Moreover, the excellent stability and anti-interference behavior of the sensor highlights its dynamic profile to be commercially utilized for the determination of Cd⁺² ions in water bodies.

Introduction

Heavy metal ion concentrations in the environment have sparked considerable concern, notably in drinking water and soil (Karimi et al., 2022). Cadmium (Cd) has a higher toxicity than other harmful heavy metals. Cadmium (II) is the most dangerous heavy metal since it is widely distributed, non-biodegradable, and carcinogenic, posing a significant environmental risk (Lemos and de Carvalho, 2010; Shahat et al., 2021). It can quickly move throughout the environment and may cause pollution due to its high water solubility (Gumpu et al., 2015; Siddeeg et al., 2020). As a result of its bioaccumulation in humans, it reacts with enzymes and creates free radicals, causing major health problems (Liu et al., 2021). It has recently been examined as a human “Type I″ carcinogen, i.e., a biomarker for primary detection of cancer, which is important for public health (Salgado et al., 2011; Chanihoon et al., 2021). It is an element that is not required for human survival (Bhardiya et al., 2021). In general, industrial effluents from paints, plastics, and hardware fittings are common sources of Cd (II) in the environment. The effects of Cd (II) exposure on human body organs include liver enlargement, bone softening (itai-itai), cardiovascular, lungs, reproductive and immune systems (Trnkova et al., 2015). In the light of these negative consequences for the environment and human health, precise, rapid, quantification of even low levels of Cd (II) and sensitive detection in water has become a critical issue and a challenge for the scientific community. Numerous conventional analytical procedures have been established for the detection of Cd (II) in water, such as inductively coupled plasma-atomic emission spectroscopy (Pehlivan et al., 2008), solid-phase extraction (Farajvand et al., 2018), atomic absorption spectroscopy (Shirani et al., 2019), ion chromatography (Ding and Wang, 2018) and inductively coupled plasma spectrometry (Vyhnanovský et al., 2019). However, these instruments are extremely expensive, take a long time to prepare samples, are costly, time-consuming, and require expert workers (Hussain et al., 2021; Mehmandoust et al., 2021; Ghalkhani et al., 2022). Among these approaches, the electrochemical method is a more attractive choice since it is easy, repeatable, and provides very sensitive and quick analytical outputs (Taherkhani et al., 2014; Jajuli et al., 2020; Karimi-Maleh et al., 2022a, 2022c, 2022d). Furthermore, they do not necessitate expensive equipment and allow for in situ and analyzed results. Now day's nanomaterials play vital role in sensing material (Zhang et al., 2020; Buledi et al., 2021; Karimi-Maleh et al., 2021; Khand et al., 2021). Moreover, Tin oxide (SnO₂) is an n-type semiconductor material with a broad band gap of approximately 3.6–4.0 eV. Due to broad band gap, SnO₂ nanoparticles are used in a wide range of applications, including solar cell (Chen et al., 2019), solid gas sensor (Mahdavian, 2013; Song et al., 2020; Zhou et al., 2021), oxidation catalysts (Bhosale et al., 2013; Liu et al., 2019a), electronic devices (Das et al., 2018), catalyst (Maheswari et al., 2017) and lithium ion batteries (Liu et al., 2019b). Furthermore, the nanoparticles have an exact nanometric size and narrow size distribution for the numerous applications in the different fields (Karimi-Maleh et al., 2022b). While the stability of nanoparticles for long term use remained a bottle neck for the modern researchers (Doan et al., 2021; Smaali et al., 2021; Berkani et al., 2022; Nguyen et al., 2022; Seid et al., 2022; Vasseghian et al., 2022). To tackle out this issue, different surfactants such as sodium dodecyl sulfate, cetrimonium bromide, polyvinyl pyrrolidine, polyvinyl alcohol and Triton X-100 have been widely utilized to control the size and to enhance the activity of metal oxide nanoparticles (Karaman et al., 2022). Amongst, the surfactants, Triton X-100 is known as nonionic surfactant and got wide attention from the modern research because of its outstanding properties, and it works as reducing agent as well as stabilizing agent during the synthesis of nanoparticles and prevents the particles growth and aggregation in aqueous medium (Khataee et al., 2018; Sohrabi et al., 2021; Tümay et al., 2021). While doing so, this surfactant retains the stability of nanoparticle to be exploited for long term use, by enhancing the catalytic activity of nanoparticles (Panhwar et al., 2021; Buledi et al., 2022b; Hyder et al., 2022). However, there are some important advantages of the Triton X-100 such as it forms CMC in the water and can be stabilize the nanoparticles. While considering these advantages, Triton X-100 was utilized as stabilizing to improve the catalytic capabilities of tin oxide nanoparticles.

Herein, we report an effective and simple synthesis of Triton X-100 functionalized SnO₂ nanoparticles (TX-100 SnO₂) followed by the fabrication of TX-100 SnO₂/GCE for the ultra-sensitive determination of cadmium.