Mohammad Salim Akhter

Formaldehyde evolves from various household items and is of environmental and public health concern. Removal of this contaminant from the indoor air is of utmost importance and currently, various practices are in the field. Among these practices, indoor plants are of particular importance because they help in controlling indoor temperature, moisture, and oxygen concentration. Plants and plant materials studied for the purpose have been reviewed hereunder. The main topics of the review are, mechanism of phytoremediation, plants and their benefits, plant material in formaldehyde remediation, and airtight environmental and health issues. Future research in the field is also highlighted which will help new researches to plan for the remediation of formaldehyde in indoor air. The remediation capacity of several plants has been tabulated and compared, which gives easy access to assess various plants for remediation of the target pollutant. Challenges and issues in the phytoremediation of formaldehyde are also discussed. Novelty statement: Phytoremediation is a well-known technique to mitigate various organic and inorganic pollutants. The technique has been used by various researchers for maintaining indoor air quality but its efficiency under real-world conditions and human activities is still a question and is vastly affected relative to laboratory conditions. Several modifications in the field are in progress, here in this review article we have summarized and highlighted new directions in the field which could be a better solution to the problem in the future. Graphical Abstract

In the current study the application of organo‐modified bentonite for the adsorption of mycotoxins (aflatoxin B1, citrinin, patulin, and zearalenone) is presented. The modification of clays is carried out using benzyl‐tri‐n‐butyl ammonium bromide (BTB), benzethonium chloride (BTC), and dioctyl sodium sulfosuccinate (DSS). Various experimental parameters such as pH, time, adsorbent dose, and mycotoxins concentration are thoroughly studied. The modified clays (B‐BTB, B‐BTC and B‐DSS) are characterized by X‐ray fluorescence, X‐ray diffraction, and Fourier transform infrared spectroscopy. The results depicted the high detoxification efficiency (≈99%) of modified clays for the removal of mycotoxins under optimized conditions (pH 5, time: 30 min, adsorbent amount: 50 mg). The adsorption capacities of modified clays are found in the order of: B‐BTC (AFB1: 18.02, CIT: 18.35, PAT: 18.21, ZEA: 18.09 mg g⁻¹) > B‐BTB (AFB1: 17.7, CIT: 18.11, PAT: 17.95, ZEA: 17.90 mg g⁻¹) > B‐DSS (AFB1: 17.5, CIT: 18.02, PAT: 17.86, ZEA: 17.80 mg g⁻¹). The obtained results fitted well with thermodynamic, isothermal (Langmuir) and pseudo‐second order kinetics. Low cost organo‐modified bentonite shows the promise in mitigating mycotoxin contamination, which could improve food safety and reduce environmental contamination.

Hydrogen is contemplated as a promising renewable source of energy as compared to the fast depleting fossil fuels. The splitting of water for the generation of hydrogen is a perspective approach to produce sustainable fuel. Titanium dioxide is the most commonly used catalyst, the performance of which depends upon its electronic surface structure, bandgap, and type of radiation. This review article summarizes the state of the art developments about the photocatalytic activity of titanium dioxide for hydrogen production from the splitting of water. Special attention has been devoted to the addition of sacrificial reagents, metal/non-metal doping ions, and composite semiconductors in titania for absorbing visible light and enhancing charge separation on a catalyst surface for efficient energy generation of hydrogen fuel from water splitting.

Metal ions contamination is the leading cause of many health and environmental problems. In order to rectify and remediate the environment from metal ions contamination, simple, efficient and easy to fabricate sensors for the onsite detection of metals ions is obligatory. However, devising a practically applicable sensor that could be compatible to the environment which contains a plethora of other ions than the target metal ions, is very challenging. In this work we report a highly sensitive and selective yet simple and greener electrode for copper ions detection by modifying GCE with amino acid-L-tryptophan. The modifier brings about increase in active surface area of the GCE and effectively binds to the metal ions through the process of chelation utilizing its amino and carboxylic acid functional groups. Cyclic voltammetry (CV), square wave voltammetry (SWV) and square wave anodic stripping voltammetry (SWASV) along with electrochemical impedance spectroscopy (EIS) was conducted to investigate the surface of the electrode and its sensitivity towards detection of Cu ¹⁺ and Cu ²⁺ ions. A number of experimental parameters such as pH, supporting electrolyte, concentration of the modifier, accumulation time and deposition potential were investigated to achieve best response of the metal ions towards the modified electrode. The designed sensor exhibited excellent electrocatalytic activity and sensitivity towards Cu ¹⁺ ions even in the presence of 5-fold higher concentration of different interferents. The LOD (Limit of detection) of 3.13 pM as determined by the calibration curve was found to be much lower than permissible values suggested by the WHO (World Health Organization) and US EPA (Environmental Protection Agency). % age recoveries as estimated from real water samples was found to be within 3% RSD value and proved the validity of the proposed methodology for the designed sensor. Computational studies were carried out using hyperchem 7.5 software with semi empirical PM3 method. The negative value of binding energy of the merged molecule i.e., −3024.181 kcal mol ⁻¹ point towards significant interactions between L-tryptophan and Cu ²⁺ ions which is evident from the change in physicochemical properties upon merging of L-tryptophan with Cu ²⁺ ions. Our computational studies agree well with the experimental results.

Herein, we present a greener approach to achieve an ultrasensitive, selective, and viable sensor engineered by amino acids as a recognition layer for simultaneous electrochemical sensing of toxic heavy metals (HMs). Electrochemical techniques like electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and square-wave anodic stripping voltammetry (SWASV) were applied to demonstrate sensing capabilities of the designed analytical tool. The comparative results of different amino acids demonstrate alanine’s superior performance with a well-resolved and enhanced current signal for target metal ions due to strong complexation of its functional moieties. The working conditions for alanine-modified GCE were optimized by investigating the effect of alanine concentration, different supporting electrolytes, pH values, accumulation potentials, and time. The limits of detection for Zn²⁺, Cd²⁺, Cu²⁺, and Hg²⁺ were found to be 8.92, 5.77, 3.01, and 5.89 pM, respectively. The alanine-modified electrode revealed absolute discrimination ability, stability, and ultrasensitivity toward metal ions even in the presence of multifold interfering species. Likewise, greener modifier-designed electrodes possessed remarkable electrocatalytic activity, cost affordability, reproducibility, and applicability for picomolar level detection of HM ions in real water sample matrixes. Theoretical calculations for the HM–amino acid interaction also support a significantly improved mediator role of the alanine modifier that is consistent with the experimental findings.

The glassy carbon electrode was fabricated with multifunctional bis-triazole-appended calix[4]arene and then used for the simultaneous detection of Zn(II), Pb(II), As(III), and Hg(II). Before applying the square-wave anodic stripping voltammetry, the sensitivity and precision of the modified electrode was assured by optimizing various conditions such as the modifier concentration, pH of the solution, deposition potential, accumulation time, and supporting electrolytes. The modified glassy carbon electrode was found to be responsive up to picomolar limits for the aforementioned heavy metal ions, which is a concentration limit much lower than the threshold level permitted by the World Health Organization. Importantly, the designed sensing platform showed anti-interference ability, good stability, repeatability, reproducibility, and applicability for the detection of multiple metal ions. The detection limits obtained for Zn(II), Pb(II), As(III), and Hg(II) are 66.3, 14.6, 71.9, and 28.9 pM, respectively.

Herein we report for the first time a highly sensitive electrochemical platform for the trace level detection of Pb (ӏӏ) using glassy carbon electrode modified with 1-dodecanoyl-3-phenylthiourea (DPT). The performance of the designed sensor was tested by electrochemical impedance spectroscopy, chronocoulometry, cyclic voltammetry and Square Wave Anodic Stripping Voltammetry (SWASV). The DPT was found to play an efficient role in enhancing the sensing response of the electrode for the detection of lead ions in aqueous samples. A number of experimental conditions such as deposition potential, accumulation time, surfactant concentration, pH, number of scans and supporting electrolytes were examined to optimize conditions for getting intense signal of the target analyte. Linear calibration curve was obtained using SWAS voltammetric data obtained under optimized conditions. The limit of detection with a value of 0.695 μg/L suggests that the designed sensor can sense lead ions even below the permissible concentration level (10 μg/L) recommended by the World Health Organization and Environmental Protection Agency of USA. The designed sensor demonstrated sensitivity, selectivity and stability for the targeted analyte. Percentage recoveries from real water samples with standard deviations of less than 2% suggested precision of the proposed method. Moreover, computational findings supported the experimental outcomes.