Per- and polyfluoroalkyl substances (PFAS) are ever-present pollutants in the environment. They are persistent and bio-accumulative with deleterious health effects on biota. This study assesses the levels of PFAS in environmental matrices along the Nairobi River, Kenya. An aggregate of 30 PFAS were determined in water, while 28 PFAS were detected in sediments and plants using solid phase extraction then liquid chromatography–mass spectrometric techniques. In water, higher levels of perfluoroundecanoic acids of up to 39.2 ng L⁻¹ were observed. Sediment and plant samples obtained in the midstream and downstream contained higher levels of perfluorooctanoic acid of up to 39.62 and 29.33 ng g⁻¹, respectively. Comparably, levels of long-chain PFAS were higher in water and sediments than in plants. Sediment/water log distribution of selected PFAS ranged between 2.5 (perfluoroundecanoic acid) and 4.9 (perfluorooctane sulfonate). The level of perfluorooctane sulfonate (1.83 ng L⁻¹) in water is above the acceptable level in surface water posing high human health and ecological risks. The observed PFAS concentrations and distribution were attributed mainly to multi-industries located along the river, among other sources. The knowledge of PFAS occurrence and distribution in Nairobi River, Kenya, provides important information to local regulatory agencies for PFAS pollution control.

Molecular simulations have been used as a screening tool to identify promising zeolites for the removal of selected pharmaceutical pollutants. 40 zeolites with different structural and chemical configurations were studied. Galophosphate cloverite (CLO) of the chemical formula, F₂₄Ga₉₆P₉₆O₃₇₂(OH)₂₄, with pores of 20 rings and the lowest observed bulk density, showed exceptionally preferred adsorption of diclofenac [2-(2,6-dichlorophenyl)amino benzeneacetic acid), ciprofloxacin [1,3,7-Trimethylpurine- 2,6-dione] and chloramphenicol [2,2-dichloro-N-[(IR,2IR)-1, 3-dihydroxy-1-(4-nitrophenyl) propan-2-yl acetamide]. This selectivity was attributed to the geometry and structural composition of the cavities. We also investigated the most stable adsorbed compositions of the pollutants in the CLO zeolite. Our calculations show that diclofenac, ciprofloxacin and chloramphenicol molecules are adsorbed into the pores with adsorption energies of − 78.23, − 173.68 and − 84.46 kcal/mol respectively. Additional calculations were also made to obtain detailed information on desorbed products. It is seen that dechlorination is the most energetically preferred process compared to dehydrogenation and dehydroxylation.

This study reports the kinetic studies of aqua complexes (Ru1–Ru6) as well as the calf-thymus DNA (CT-DNA) and bovine serum albumin binding studies of their chloro derivatives (Ru7–Ru11). The rate of substitution of the aqua ligand(s) in Ru1–Ru6 by thiourea nucleophiles (thiourea, N,N-dimethylthiourea and N,N,N′,N′-tetramethylthiourea) in 0.1 M HClO₄/NaClO₄ aqueous medium was investigated as a function of nucleophile concentration and temperature under pseudo-first order conditions. The reactivity of the binuclear and mononuclear complexes decreased in the order Ru3 > Ru4 > Ru5 > Ru6 and Ru1 > Ru2, respectively. The trend in reactivity of the binuclear complexes showed a dependence on the electronic and static factors of the rigid N,N-chelate bridging ligand in the complexes. The reactivity trends are well supported by the DFT-calculated data. The activation parameters (ΔH^≠ > 0, ΔS^≠ < 0) for the substitution process in all complexes support an associative mechanism of activation. The complexes effectively bind to CT-DNA via intercalation and this was corroborated by the molecular docking results. Likewise, the complexes bind favorably with bovine serum albumin. The order of CT-DNA and bovine serum albumin interactions with these complexes are in line with the trends in aqua ligand substitution.