DFT FUKUI DESCRIPTOR-BASED PREDICTION OF ARSENIC ADSORPTION ON GRAPHENE

Arsenic poisoning from groundwater has caused serious health hazards to the exposed population globally. The human body is contaminated by arsenic through drinking water and food, causing skin manifestations, neurological disorders, gastrointestinal disorders, cancer, etc. In the present study, a total of n = 286 household handpump water samples and food consumed (wheat and rice) by the studied subjects and each household member's biological samples (hair and nail) were collected for arsenic quantification. The hazard quotient (HQ) and cancer risk (CR) study was evaluated in the exposed studied population from the consumed wheat and rice. Arsenic content in 14% of water samples, 44% of wheat samples, and 3% of rice samples have exceeded their respective permissible limits of 10μg/L, 100μg/kg, and 200μg/kg. In the studied subjects, 69% had arsenic contamination in their hair samples more than the permissible limit (200μg/kg), while 11% had arsenic contamination in their nail samples more than the permissible limit (500μg/kg). Arsenic contamination in the participants' household water, hair, and nail samples was positively correlated with one another by a correlation coefficient study. The food samples showed a significant correlation between the subjects' hair and nail samples and rice and wheat. In the six districts of Bihar, the geospatial analysis of all the variables revealed a considerable level of arsenic contamination. The health risk assessment also showed a high risk of arsenic contamination through wheat rather than rice. The risk assessment revealed elevated hazard quotient (HQ) and cancer risk (CR) in the six districts of Bihar's arsenic-exposed population. The present study thus concludes that arsenic contamination in water and food grains is causing health hazards in the studied exposed population of Bihar. Therefore, there is an urgent need to initiate an effective mitigation plan to safeguard the health of the exposed population.

The broadly parametrized self-consistent tight-binding quantum chemical method – GFN2-xTB was employed to investigate the impact of Co, Ni, and Cu metal doping on the structural and electronic properties of single-walled carbon nanotube (CNT). Computational results for interaction energy, bond order, and Mulliken atomic charge indicated that the doped metals form chemical bonds with the CNT surface through metal-carbon bond formation. Significant charge transfer from the metal atoms to the CNT was observed, most notably in the case of Cu/CNT. Analysis of ionization energy (IP), electron affinity (EA), and global electrophilicity index (GEI) values revealed that the presence of metals increases IP, EA, and GEI values compared to the pristine CNT. The Lewis acidity of the studied systems increases in the order of Ni/CNT < Co/CNT < Cu/CNT. Calculations of the fractional occupation number weighted density (FOD) indicated that in the metal-doped CNT systems, the density of hot and chemically active electrons is predominantly concentrated on the metal atoms. Molecular orbital analyses demonstrated the contribution of metal atoms to the HOMO and LUMO of the system. Additionally, the centroid distance (Dij) between the HOMO and LUMO of the M/CNT (M = Co, Ni, Cu) is influenced by metal doping. Among the studied systems, Co/CNT exhibits the lowest energy gap between the LUMO and HOMO and the highest Dij value, suggesting its suitability for photocatalytic applications. For citation: Pham Thi Be, Phan Tu Quy, Bui Cong Trinh, Nguyen Thi Kim Giang, Nguyen Thi Thu Ha Understanding the impact of metal doping (Co, Ni, Cu) on the structural and electronic properties of single-walled carbon nanotubes: theoretical insights. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 12. P. 73-79. DOI: 10.6060/ivkkt.20246712.7115.

In this work, a new asymmetric ligand, N‐trans‐cinnamylidene‐1,2‐phenylenediamine via the condensation reaction of 1,2‐phenylenediamine and trans‐cinnamaldehyde, and its complexes have been successfully synthesized. The ligand and its complexes were characterized by spectroscopic techniques including FT‐IR, 1H NMR, 13C NMR, ESI‐mass, UV‐vis, and physicochemical methods, such as molar conductivity, elemental analysis, and melting point. Based on the identification results, the general formula of MLX2 (X = Cl−, Br−, and M = Zn2+, Hg2+, Cd2+) was proposed for the complexes. Differential scanning calorimetric analysis was also used to investigate the thermal properties of the as‐synthesized compounds. Further, theoretical studies were performed on the ligand and its complexes. Molecular electrostatic potential surface analysis was done to distinguish the electrophilic and nucleophilic sites of the products. Nonlinear optical properties of the ligand and complexes were calculated and then compared with the standard nonlinear optical material. The frontier molecular orbitals were theoretically determined and the energy gap, global electrophilicity index, electronic chemical potential, ionization potential, absolute electronegativity, electron affinity, absolute hardness, and softness were calculated. Finally, thermodynamic properties of the compounds were evaluated. Moreover, the assessment of cytotoxicity effects of all compounds against HCT116 cancer cells was performed by the MTT assay. In vitro studies showed that HgLCl2 could considerably reduce cell viability and increase induction apoptosis and cell cycle arrest.

A detailed computational analysis of acridine derivatives viz. acridone, 9-amino acridine hydrochloride hydrate, proflavin, acridine orange and acridine yellow is done in terms of conceptual density functional theory (CDFT). CDFT-based global descriptors-ionization potential, electron affinity, HOMO-LUMO gap, hardness, softness, electronegativity and electrophilicity index of acridine derivatives for ground state as well as excited state are estimated with the help of different hybrid functionals B3LYP/6-31G (d, p), B3LYP/6-311G (d, p), B3LYP/DGDZVP and B3LYP/LANL2DZ. Acridine derivatives show higher values of ionization potential and electron affinity in excited state as compared to ground state, indicating that these compounds are willing to accept electrons in excited state rather than donating electron. Acridone shows the maximum HOMO-LUMO energy gap in ground and excited state which implies that one-way electron transfer is most feasible with this compound. Our computed results emphasize the pronounced electron acceptor behaviour of the acridine derivatives in the excited state which has already been experimentally verified. It is observed that the trend in the computed values of the descriptors is not much improved on refinement of the basis set.

Arsenic contamination in groundwater and its impact on human health has been reported as one of the world's biggest natural groundwater calamities to the mankind. In Assam, Arsenic concentration in groundwater above the permissible level has been reported from 20 districts, of which, maximum level of Arsenic concentration was found in Jorhat, Lakhimpur, Nalbari and Nagaon districts. In the present study Arsenic and Iron contamination of groundwater in Narayanpur Block and Sakhomato Block of North Bank Plain Zone of Assam was determined. Eighty seven numbers of ground water samples from Narayanpur Block and forty seven numbers from Sakhomato Block were collected from tubewells (15 feet to 75 feet deep) at different locations of the Blocks. The Arsenic content of analyzed samples from Narayanpur Block varied from 0 (zero) ppb to 102 ppb, of which, 48 (55.17%) samples were found below the WHO guideline value for drinking (less than 10 ppb); while 39 (44.83%) samples contained Arsenic above the guideline value (more than 10 ppb, WHO, 2011). In case of Sakhomato Block, all the 47 samples contain Arsenic below the critical limit of 10 ppb and hence found safe for drinking. Iron concentration of the samples having Arsenic concentration above the critical limit of 10 ppb from Narayanpur Block was analyzed with a view to ameliorating Arsenic toxicity through removal of Iron. The Iron concentration of the samples ranged from 10 ppm to 58.4 ppm. However, no significant correlation between Iron and Arsenic concentration was observed (r2=0.0403).

Arsenic contamination in water supplies continues to increase in many countries, especially in developing nations, thereby creating both environmental and health hazard. Its sources and effects are multiple and diffused in nature and it requires detailed assessment and policy. This paper discusses the global extent of the problem, its sources and effects and explores different policy options. Sources and pathways of interaction require comprehensive assessment and policy. Innovation in low cost technologies offers possibilities for reducing abatement cost and for economic efficiency. To reduce arsenic in water resources, incentive policies such as taxing and subsidising can be used to reduce arsenic levels in point sources through creation of appropriate incentives. The paper also identifies opportunities for enhancing self-protection efforts through education and information sharing. Under a self-protection policy, though the damages decline to a greater extent, there is a possibility of an increase in arsenic emission. Finally, a combination of policies is proposed that involve low cost technology, education and awareness to mitigate the damage from arsenic contamination at a watershed scale. It is also necessary to enforce these policies through appropriate institutional changes that involve coordination and cooperative efforts to mitigate arsenic contamination.

Among physiologically active compounds isolated from marine organisms, the pyrroloquinoline alkaloids (PQAs) family consisting of damirone A/C, batzelline A/D, makaluvamine O and makaluvone exhibit numerous biological activities derived from the inimitable highly-fused structures. Their structural and electronic properties were investigated through intramolecular interactions, electron affinities (EA), reduction potentials (E°) and complexation of compounds with magnesium and guanidinium cations (ionic and hydrogen bond interactions) using quantum mechanical calculations in the gas phase and solution. For both series of complexes, the most and least stable ones correspond to damirone A and batzelline D, respectively. The energy data, geometrical parameters, and the minima of electrostatic potentials (Vmin) are in good correlation with the results of population analyses. The localized molecular orbital energy decomposition analyses (LMO-EDA) demonstrate that the electrostatic interaction is the most important stabilizing component. The EA values are positive in the gas phase and solution, and are evaluated with the increase in the dielectric constant of solvent. Increase in the EA values and decrease in the E° values are observed after complexation with guanidinium and magnesium cations. Those changes are higher for electron-rich compounds compared to electron-deficient ones, containing halogen substituents.

Arsenic pollution in water primarily occurs in the inorganic forms of As+ and As⁵+, posing significant health hazards even at trace concentrations. Therefore, the continued progress of effective arsenic removal techniques is essential. This review comprehensively explores recent advancements in adsorbent technologies aimed at the treatment of arsenic species from water, addressing a critical global environmental and public health challenge. Adsorption remains one of the most promising arsenic remediation strategies due to its effectiveness, simplicity, and efficacy compared to alternative methods such as membrane filtration, coagulation, ion exchange, and biological treatment. This paper highlights a wide array of adsorbent materials, including mineral materials, activated carbon, metal oxides, polymers, biosorbents, core-shelled, graphene, and industrial by-products, focusing on their adsorption capacities, surface characteristics, and performance under varying conditions, such as pH, removal capacities, surface area, initial ion concentrations, pH, adsorption kinetics, and isotherms. Understanding these factors is vital for evaluating, modifying, and enhancing the adsorption process to address diverse water treatment challenges. Integrating these critical factors into adsorption analysis deepens understanding of its complexities, aiding the development of customized and efficient arsenic treatment methods. The review also emphasizes the importance of optimizing adsorbent regeneration, environmental sustainability, and real-world applications. It concludes with suggestions for future research, calling for the development of more efficient, selective, and eco-friendly adsorbent materials to combat arsenic contamination in water, thereby ensuring safer water sources for affected populations.

The extent of arsenic contamination in the groundwater has been estimated using artificial neural network (ANN) based on multi-layer perceptron (MLP) architecture. The input data to the ANN comprised samples collected from different arsenic affected blocks of Malda district, West Bengal, India. Each data sample consisted of the amount of arsenic contaminant observed in the groundwater together with other geochemical parameters believed to have some relationship with the corresponding arsenic contaminant. Here, the inputs to the ANN were observed values for pH (acidic-alkalinity ratio), specific conductivity, total dissolved solids (TDS), salinity, dissolved oxygen (DO), redox potential (Eh), and depth of tube well water, while the expected output for training the ANN was the amount of corresponding arsenic contaminant observed in the groundwater. Using the back propagation technique, the ANN model was trained with a subset of the input data. The trained ANN model was then used to estimate the arsenic contamination in groundwater beyond the specified training data. The quality of the ANN simulations was evaluated in terms of three different error measures; namely, the root mean square error, the mean absolute error, and the percent mean relative error for proper interpretation of the results. We have also used two other methods for prediction; namely, multiple linear regression and active set support vector regression. Amongst the three methods, the ANN model exhibited better prediction results for predicting the arsenic contamination in groundwater. Based on this methodology, it is possible to show that a four-layer feed-forward back propagation ANN model could be used as an acceptable prediction model for estimating the arsenic contamination in groundwater.

Late Quaternary stratigraphy, geomorphology, and sedimentation in the entrenched channels and floodplains of the upper, middle, and lower Ganga plains in the states of Uttar Pradesh, Bihar, Jharkhand, and West Bengal have control on groundwater arsenic contamination. Arsenic analysis was done through atomic absorption spectrometry, and Iron was analyzed by the use of UV spectro-photometer. Arsenic contamination in groundwater above 50 µg/L is reported in Unnao and Allahabad districts in the upper Ganga plain. In the middle Ganga plain, 66% of tubewells from Buxar, Ghazipur, Varanasi, and Mirzapur districts and 89% of tubewells from Vaishali, Patna, Bhojpur, and Ballia districts have arsenic > 10 µg/L (WHO guideline). Most of the arsenic-affected villages are located close to abandoned or present meander channels of the Ganga River. In contrast, tubewells located in Kanpur, Allahabad, Mirzapur, Chunar, Varanasi, Saidpur, Ghazipur, Muhammadabad, Ballia, Buxar, Ara, Chhapra, Patna, and Hazipur towns are arsenic-safe in groundwater because of their positions on the Pleistocene Older Alluvium upland surfaces. In the middle Ganga plain, 77% of tubewells are located in shallow depth (21–40 m). About 40% of tubewells have arsenic > 50 µg/L within the depth of 17–50 m. The iron content in tubewell water samples varies from 0.1 to 13 mg/L. In the lower Ganga plain, arsenic contaminated aquifers (arsenic >10 μg/L) are confined in the Holocene entrenched channels and floodplains of the Bhagirathi River.KeywordsArsenicTubewell waterNewer alluviumOlder alluviumFluvial geomorphology

Arsenic contamination in groundwater is a severe and widespread environmental and public health challenge. Recent years have witnessed rapid advances in catalytic remediation technologies, particularly those integrating advanced oxidation processes (AOPs), bifunctional materials, and field-scale applications. This comprehensive review synthesizes recent developments, emphasizing the synergy between catalytic oxidation and adsorption, the design of innovative and recyclable materials, and the practical translation of laboratory findings to real-world remediation scenarios. Key breakthroughs include dual-function catalysts for combined contaminant removal, scalable systems compatible with renewable energy, and hybrid strategies integrating conventional and catalytic routes. Case studies from arsenic hotspots worldwide demonstrate not only technological feasibility but also highlight knowledge gaps and sustainability challenges. By evaluating catalytic mechanisms, operational performance, and environmental impact, this review identifies promising directions for the next generation of arsenic remediation and offers a critical roadmap to guide future research and practice.

Arsenic contamination in groundwater represents one of the most significant environmental and public health challenges worldwide, affecting millions of people across various continents. This review synthesizes current knowledge on the sources, mechanisms, health impacts, and remediation strategies associated with arsenic in groundwater. Natural geological processes, primarily the weathering of arsenic-bearing minerals, constitute the primary source of contamination, though anthropogenic activities significantly contribute to the problem. Chronic exposure to elevated arsenic levels leads to severe health consequences, including various cancers, cardiovascular diseases, and developmental disorders. This paper examines the geochemical processes governing arsenic mobilization, discusses the most affected regions globally, evaluates detection and monitoring technologies, and reviews both conventional and emerging remediation approaches. Understanding the complexity of arsenic contamination is crucial for developing effective mitigation strategies and protecting vulnerable populations.

The electron affinities ( EA s) of manganese compounds including , and (X=O, S, and Se; n =0 to 6) species were calculated. The calculated EAs of neutral species are positive, while the EA values of anions remain negative. The increase of the EA value among the number of X atoms for the neutral species was observed so that ( EA =+5.04 eV), ( EA =+4.61 eV), and ( EA =+6.58 eV) all revealed superhalogen property. To interpret the variation of EA with n and number of X atoms, the change in the partial charges of atoms, the electrostatic surface potential (ESP) of species, the strength of Mn−X bonds, the delocalization energy, and the energy components of electronic energy of species were examined. The positive EA of some neutral species is attributed to the increase of delocalization energy due to the added electron. In contrast, for some species, the decrease of delocalization energy is observed despite having a positive EA . For these species, the decomposition of electronic energies provides a reasonable interpretation of the positive EA value.

Is organic matter a source or redox driver or both for arsenic release in groundwater?

Energies, geometries and electronic structures of cyclopentadiene (1), silole (2), germole (3) and their radical anions (RAs) 1a–3a have been studied by quantum-chemical methods at the G2(MP2, SVP) and DFT B3LYP/6-31G(d,p) levels. According to G2(MP2, SVP) calculations 1–3 have negative electron affinities (EAs) equal to −1.09, −0.06 and −0.15 eV, respectively, and hence their RAs are unstable in the gas phase. 1,2,3,4-Tetraphenylcyclopenta-1,3-diene (4) and 2,3,4,5-tetraphenylsubstituted-2 (5) and 3 (6) and their radical anions (4a–6a) were studied at the B3LYP/6-31G(d)//AM1 level. Substitution of cyclodienes results in significant stabilization of RAs 4–6 because of the effective delocalization of an extra electron within phenyl groups, especially those in positions 2 and 5, so 4–6 all have a positive EA. Our best estimates give for 4, 5 and 6 EA values 0.98, 1.30 and 1.13 eV respectively. The calculated hyperfine coupling (hfc) constants a(H) for radical anions 4a–6a are in a good agreement with experimental values. Variation of group 14 element (C, Si, Ge) in the series 1–3 and 4–6 do not produce a monotonous change of EA and hfc values.