The ubiquitous problem of pesticide in aquatic environment are receiving worldwide concern as pesticide tends to accumulate in the body of the aquatic organism and sediment soil, posing health risks to the human. Many pesticide formulations had introduced due to the rapid growth in the global pesticide market result from the wide use of pesticides in agricultural and non-agricultural sectors. The occurrence of pesticides in the water body is derived by the runoff from the agricultural field and industrial wastewater. Soluble pesticides were carried away by water molecules especially during the precipitation event by percolating downward into the soil layers and eventually reach surface waters and groundwater. Consequently, it degrades water quality and reduces the supply of clean water for potable water. Long-time exposure to the low concentration of pesticides had resulted in non-carcinogenic health risks. The conventional method of pesticide treatment processes encompasses coagulation-flocculation, adsorption, filtration and sedimentation, which rely on the phase transfer of pollutants. Those methods are often incurred with a relatively high operational cost and may cause secondary pollution such as sludge formation. Advanced oxidation processes (AOPs) are recognized as clean technologies for the treatment of water containing recalcitrant and bio-refractory pollutants such as pesticides. It has been adopted as recent water purification technology because of the thermodynamic viability and broad spectrum of applicability. This work provides a comprehensive review for occurrence of pesticide in the drinking water and its possible treatment.

Chitosan (Cs) composites with carbon nanotube (Cs/CNT) and with activated carbon (Cs/AC) were prepared, characterised and applied for adsorption of thionine dye. Optimum adsorption conditions were adsorbent dose 0.1 g, dye concentration 30 mg/L, solution pH 5 and adsorption time 120 min. The overall results confirm the adsorption ability of Cs/CNT > Cs/AC > Cs where the adsorption ability of pure Cs reached 59.3%, 73.7% with Cs/AC and reached its maximum value of 98.5% with Cs/AC adsorbent material. Adsorption isotherm was studied by three isothermal models, and the results indicate the adsorption of thionine dye using the three adsorbents fit Freundlich > Langmuir > Dubinin–Radushkevich (D–R) model. The correlation coefficient (R²) obtained from Langmuir model did not fit the experimental data of thionine dye where (R²) obtained from Freundlich model indicate a multilayer adsorption with physicosorption type. The results of D–R isotherm model indicate that the physisorption nature of thionine dye was less than 8 kJ mol⁻¹ indicating the physisorption nature of adsorption using Cs, Cs/AC and Cs/CNT.

The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 2,5-dichloro-p-phenylendiaminium decachlorotricadmate(II) hexahydrate complex, (C₆H₈Cl₂N₂)₂[Cd₃Cl₁₀]·6H₂O, has been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge-sharing [CdCl₆]²⁻ octahedra in linear polymeric chains spreading along the a-axis, while the organic cations surround these latters. The inspection of the Hirshfeld surface analysis helps to discuss the strength of hydrogen bonds and to quantify the inter-contacts, which reveal that H…Cl/Cl…H (38.9%), H…H (13.9%), and Cd…Cl/Cl…Cd (12.4%) are the main interactions that govern the crystal packing of the studied structure. SEM/EDXwas carried out and the powder XRD confirmed the good crystallinity of the material. FT-IR and the DFT calculation reveal the good correlation between the experimental and the theoretical wavenumbers. The HOMO-LUMO energy gap was used to predict the electric conductivity of the compound. Finally, the thermal TGA/DTA analysis shows stability until 380 K.

The slow solvent evaporation approach was used to create a single crystal of (C₇H₆N₃O₂)₂[ZnCl₄] at room temperature. Our compound has been investigated by single-crystal XRD which declares that the complex crystallizes in the monoclinic crystallographic system with the P2₁/c as a space group. The molecular arrangement of the compound can be described by slightly distorted tetrahedral ZnCl₄²⁻ anionic entities and 5-nitrobenzimidazolium as cations, linked together by different non-covalent interaction types (H-bonds, Cl…Cl, π…π and C–H…π). Hirshfeld’s surface study allows us to identify that the dominant contacts in the crystal building are H…Cl/Cl…H contacts (37.3%). FT-IR method was used to identify the different groups in (C₇H₆N₃O₂)₂[ZnCl₄]. Furthermore, impedance spectroscopy analysis in 393 ≤ T ≤ 438 K shows that the temperature dependence of DC conductivity follows Arrhenius’ law. The frequency–temperature dependence of AC conductivity for the studied sample shows one region (E_a = 2.75 eV). In order to determine modes of interactions of compound with double stranded DNA, molecular docking simulations were performed at molecular level.