Binder-Free Modification of a Glassy Carbon Electrode by Using Porous Carbon for Voltammetric Determination of Nitro Isomers

Biomass-Derived Carbon-Based Electrodes for Electrochemical Sensing: A Review

The diverse composition of biomass waste, with its varied chemical compounds of origin, holds substantial potential in developing low-cost carbon-based materials for electrochemical sensing applications across a wide range of compounds, including pharmaceuticals, dyes, and heavy metals. This review highlights the latest developments and explores the potential of these sustainable electrodes in electrochemical sensing. Using biomass sources, these electrodes offer a renewable and cost-effective route to fabricate carbon-based sensors. The carbonization process yields highly porous materials with large surface areas, providing a wide variety of functional groups and abundant active sites for analyte adsorption, thereby enhancing sensor sensitivity. The review classifies, summarizes, and analyses different treatments and synthesis of biomass-derived carbon materials from different sources, such as herbaceous, wood, animal and human wastes, and aquatic and industrial waste, used for the construction of electrochemical sensors over the last five years. Moreover, this review highlights various aspects including the source, synthesis parameters, strategies for improving their sensing activity, morphology, structure, and functional group contributions. Overall, this comprehensive review sheds light on the immense potential of biomass-derived carbon-based electrodes, encouraging further research to optimize their properties and advance their integration into practical electrochemical sensing devices.

Synthesis of Activated Porous Carbon from Red Dragon Fruit Peel Waste for Highly Active Catalytic Reduction in Toxic Organic Dyes

In this study, an alternative precursor for production of biomass-derived activated carbon was introduced using dragon fruit (Hylocereus costaricensis) peels. Chemical activators such as FeCl3, MgCl2, ZnCl2 were used in the thermal carbonization process to convert carbon into porous carbon (PC). However, heteroatom-doped PC catalysts including N-, B-, and P-doped carbon catalysts in the field of dye removal is highly desirable. Several approaches (XRD, FE-SEM/TEM, XPS, FT-IR, EDS, and elemental mapping) were employed to examine the surface morphology, surface properties, and elemental composition of the PC catalyst. The catalytic activity of metal-free PC catalyst was demonstrated for methylene blue (MB), crystal violet (CV), and Nile blue (NB) in a mild environment The corresponding rate constant (kapp) values were estimated as 0.2473, 0.3248, and 0.3056 min−1, respectively, for MB, CV, and NB, which were significantly greater than those of numerous reports. It exhibited the best catalytic activity and recyclability. Moreover, the approach proposed here could create new opportunities for the remediation of organic dyes in lakes and industrial wastewater.

A comparative study of novel spectrophotometric methods for simultaneous determination of nitroaniline isomers in their binary mixtures with highly severe overlapping spectra

In the present work, four simple and economic spectrophotometric methods, namely constant center (CC), ratio difference (RD), H-point standard addition method (HPSAM), and ratio H-point standard addition method (RHPSAM) were employed for the simultaneous determination of meta and para-nitroaniline with severely overlapping spectra without unitizing the preliminary physical separation techniques. In each method, the parameters affecting the resolution of the spectra were optimized to determine the cited isomers in a binary mixture with a high accuracy. Under the optimized conditions, the results obtained showed that from cited methods used, the CC and RD methods have the least errors in determination of the concentration of highly spectral overlapping species. The mean percentage recovery values for the binary mixture of meta- and para-nitroaniline were found to be 95.98 and 98.78 using the RD method, and 101.85 and 100.23 using the CC method, respectively. For comparison of the powerful multivariate methods including the principal component regression (PCR) and partial least squares (PLS) were also applied. The mean percentage recovery values for the binary mixtures of the cited isomers were found to be 101.62 and 101.47 using the PCR method, and 101.00 and 101.36 using the PLS method, respectively. A statistical comparison of the methods demonstrated that there was no significant difference between the RD, CC, PCR, and PLS methods and the reported HPLC method regarding both accuracy and precision. The proposed methods have an admissible precision and accuracy for determination of the two isomers in their binary mixtures in tap water as a real sample.

Cobalt molybdate nanorods decorated on boron-doped graphitic carbon nitride sheets for electrochemical sensing of furazolidone

A nanorod-like structured CoMoO₄ embedded on boron doped-graphitic carbon nitride composite (CoMoO₄/BCN) has been developed by a simple sonochemical method for electrochemical detection of furazolidone (FUZ). Interestingly, the impedance of CoMoO₄/BCN fabricated screen-printed carbon electrode (SPCE) possesses a lower resistance charge transfer (R_ct), which favors superior electrochemical detection of FUZ. Such CoMoO₄/BCN/SPCE exhibits an ultralow detection limit of 1.6 nM with a concentration range of 0.04-408.9 μM, and high sensitivity of 11.6 μA μM^-1 cm^-2 by DPV method. In addition, biological and water samples were used for demonstration of practical application of CoMoO₄/BCN/SPCE towards electrochemical detection of FUZ, and the result exhibits a satisfactory recovery.Graphical abstract.

Design strategy of rGO–HNT–AgNPs based hybrid nanocomposite with enhanced performance for electrochemical detection of 4-nitrophenol

We report a highly precise and sensitive electrochemical sensor to detect 4-nitrophenol based on halloysite nanotubes with silver nanoparticles decorated on reduced graphene oxide.