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Nanocarbons for Flexible Sensing Applications
Published in Changjian Zhou, Min Zhang, Cary Y. Yang, Nanocarbon Electronics, 2020
Morgan J. Anderson, Shobhit Kareer, Seyed Esmaeil Mahdavi Ardakani, Seamus D. Thomson, Jessica E. Koehne, Jeongwon Park, Jeongwon Park
Ion-selective electrodes (ISEs) are often used to selectively measure concentrations of specific ions in a solution. Generally, ISEs consist of an electrode isolated by a membrane or polymer film with a high complexation affinity toward a specific ionic species (i.e., H+, Cl−, NO3−, etc.) [75, 99]. When the analyte ions are present, they associate with the ion-selective membrane, shifting the thermodynamic potential of the surface and causing a measurable change in potential relative to a stable reference electrode. The final readout is measured as a voltage, which can then be calibrated to yield a quantifiable value. The most common example of an ISE is the pH meter, which uses a porous glass membrane to detect H+ along with an internal Ag/AgCl reference electrode [75]. Because the functionality of ISEs primarily relies on the chemistry between the target ion and the ion-selective membrane [99, 100], ISEs are easy to adapt to most electrode materials and configurations. Consequently, several flexible nanocarbon-based ISEs have been developed for targets, including NO3− and NH4+ [101], K+ [102, 103], Ca2+ [103, 104], Cd2+ [105], and H+ [103], on substrates ranging from laser-induced graphene, to printed CNT and graphene electrodes, and free-standing graphene paper.
Aptamers in Medical Diagnosis
Published in Rakesh N. Veedu, Aptamers, 2017
Veli Cengiz Ozalp, Murat Kavruk, Ozlem Dilek, Abdullah Tahir Bayrac
Clinical detection assays are most efficient when high sensitivity and miniaturized formats are combined with biorecognition elements and novel microfabrication technologies. Among the sensing formats, electrochemical aptasensors provide high sensitivity at low cost. Several techniques have been used for fabricating electrochemical aptasensors, such as electrochemical impedance spectroscopy, potentiometry, and amperometry. Potentiometric sensors are based on measuring the potential difference between a working and a reference electrode when there is no significant current flowing between them. An ion-selective electrode (ISE) is the most common choice as a transducer to take the advantage of detecting a wide range of ion concentrations, up to five digits of difference with a lower ppm level of detection limit values. Also, continuous measurement property is an important advantage in the fabrication of sensors. Another attractive feature of potentiometric sensors is the high signal levels independent of a sample volume. Aptamer-grafted electrodes can decrease currents due to the interference by the binding events on aptamer molecules. Kim et al. selected DNA aptamers binding to estradiol, and the aptamer was used to develop an electrochemical detection method for chemical sensing by immobilizing it on the gold electrode on the basis of avidin–biotin interaction [38]. In this study, estradiol was detected using a redox mediator where the sensitivity and selectivity of the detection was drastically increased.
Photoelectrochemical Ammonia Production
Published in Anirban Das, Gyandshwar Kumar Rao, Kasinath Ojha, Photoelectrochemical Generation of Fuels, 2023
Arpna Jaryal, Anjali Verma, Kamalakannan Kailasam
Ion selective electrode (ISE) is generally known as specific ion electrode due to its sensitivity toward specific ions or gas concentration in the sample solution.65 ISE operates on the galvanic cell principle consisting of an RE, voltmeter, and ion selective membrane. According to the Nernst equation, the potential difference measured between ion selective membrane and the RE is directly proportional to the ammonium ion concentration.
Fluoride removal in zinc sulfate solution by adsorption on lanthanum silicate
Published in Canadian Metallurgical Quarterly, 2023
Mingyu Wang, Guoqi Zhang, Zhiqin Liao, Guiqing Zhang, Qinggang Li, Zuoying Cao, Wenjuan Guan, Shengxi Wu, Qiuxiang Liu
The concentration of fluorine in the solution was measured by a fluorine ion-selective electrode method. The research conducted by Xu et al. [16] demonstrated that the fluorine ion selective electrode method exhibits high accuracy in determining the concentration of fluorine in zinc sulfate solutions, with a relative standard deviation ranging within 0.26%. The morphology of the adsorbent before and after fluoride adsorption was characterised by SEM-EDS analysis. FTIR analysis was conducted using the United States Nicholas force 5700 Fourier infrared spectrometer. The adsorbent before and after fluoride adsorption was analyzed using XPS (Thermo Scientific K-Alpha, Thermo Fisher) with an Al Kα X-ray source (1486.6 eV of photons). The Zeta potential of the adsorbent was determined using a potentiometric analyzer (Zetasizer Nano-ZS90, Malvern, UK).
Defluoridation of synthetic and industrial wastewater by using acidic activated alumina adsorbent: characterization and optimization by response surface methodology
Published in Journal of Environmental Science and Health, Part A, 2018
Usha Kumari, Sushanta K. Behera, B. C. Meikap
In this article, an attempt was made to prepare sulfuric AAA adsorbent for the defluoridation purpose. Post preparation, the adsorbent was characterized by particle size analysis, SEM, and XRF to ascertain the mean particle size, activation of alumina and fluoride adsorption. Further, the effect of various affecting parameters, like pH, temperature, adsorbent dose and initial fluoride concentration, on fluoride removal from the synthetic wastewater was studied by central composite design (CCD) in RSM. For optimization and model development, all the experiment were performed on a batch scale using synthetic wastewater. The variation of fluoride concentration was analyzed by ion selective electrode. Later, the optimized process parameters were applied on the industrial wastewater to check the applicability of the model.
Novel carbonized bone meal for defluoridation of groundwater: Batch and column study
Published in Journal of Environmental Science and Health, Part A, 2018
Somak Chatterjee, Sanjay Jha, Sirshendu De
Morphological analyses of different carbonized samples were carried out by using scanning electron microscope (SEM model: ESM – 5800, JEOL, Japan). X-ray diffraction (XRD) peaks of various CBM were recorded using a Diffractometer (M/s, PANalytical, model: Xpert Pro, The Netherlands). Weight change of CBM with temperature was studied using thermogravimetric analysis (TGA) by Pyris Diamond, Perkin Elmer, CT, USA. Infrared spectra of CBM (before and after batch adsorption) were recorded using FTIR (Fourier transform infrared spectroscopy) spectrophotometer, supplied by M/s, Perkin Elmer, CT; model: Spectrum 100. Pore volume distribution and Brunner–Emmet–Teller (BET) surface area of CBM were determined by surface area analyzer, manufactured by Quantachrome instruments, Florida, USA (model AUTOSORB-1), using nitrogen as the adsorption medium (degassing temperature: 343 K, time: 24 h). Fluoride concentration in aqueous solution was measured using an ion selective electrode (model: Orion 720A+, Thermo Electron Corporation, Beverly, MA, USA) at a neutral pH (7.0 ± 0.2). Variation in concentration of fluoride species in water (in the presence of other coexisting anions) was determined by dissolving TISAB III in the solution (0.1 times the sample volume). This was done to suppress the interference of other anions with the measurement of fluoride. The average of five measured data was reported. Concentration of different ions was measured by an ion chromatograph (model: 883 Basic IC Plus, Metrohm, Switzerland).