Biochar was produced by pyrolysing palm tree bark biomass at 500 degrees C for the removal of rhodamine B (RhB) and metronidazole (MET). Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller, X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray analyses were used to characterize the biochar. The biochar obtained was crystalline, mesoporous (SBET: 189.157 m(2) g(-1); pore diameter: 2.207 nm), clustered with prominent O-H and C = O functional groups. The pHpzc of the biochar was 7.98, and it adsorbed RhB and MET maximally at pH 3.4 and 7.2, respectively. The Langmuir and Freundlich isotherms described RhB and MET adsorption, respectively, with maximum adsorption capacities (q(max)) of 31.81-224.30 mg/g for RhB and 95.44-26.76 mg/g for MET from 303 to 313 K. Both adsorbates exhibit favourable physisorption processes with pseudo-second-order kinetics, as the most appropriate. The thermodynamic parameter (-Delta G degrees) demonstrates spontaneous adsorption processes for RhB and MET, with spontaneity increasing with temperature for RhB and decreasing with increasing temperature for MET. The adsorption process was endothermic (+Delta H degrees) for RhB and exothermic (-Delta H degrees) for MET. Given its reusability of 96 and 95% for RhB and MET, respectively, mesoporous biochar derived from palm trees is a more promising adsorbent.

In this study, emerging-recalcitrant water contaminants were examined to determine their impact on water quality and oxidative disruption of antioxidant markers in Clarias gariepinus (African catfish). Fifty C. gariepinus were randomly exposed to fresh water, 250 mg/L acetaminophen (ACT), 0.525 mg/L chromium (Cr) and a mixture of ACT+Cr – dosed water for 21 days. As compared to the control, dosed water did not significantly (p ˃ 0.05) affect dissolved oxygen (DO), but biochemical oxygen demand (BOD) significantly increased in ACT, ACT+Cr, and Cr-dosed water. Levels of ACT in C. gariepinus exposed to different concentrations followed by kidney ˃ gill ˃ liver ˃ heart. Likewise, higher Cr presence was found in C. gariepinus gills exposed to 0.350 mg/L Cr. Accordingly, kidneys and gills were the worst affected organs by ACT and Cr accumulation. All the targeted organs of C. gariepinus exposed to different concentrations of ACT+Cr showed a concentration-dependent reduction in catalase (CAT) activity, indicating the synergistic effects of ACT and heavy metals. Based on these results, ACT and Cr adversely affect the kidneys and gills of C. gariepinus, compromising their physiological activity. As a result, pharmaceutical wastes and heavy metal effluents released into the aquatic environment indiscriminately need to be monitored. Keywords Acetaminophen, Bioaccumulation, Clarias gariepinus, Chromium, Enzymatic antioxidant

Abstract This study investigated the phytostabilization and plant-promoting abilities of silver nanoparticles (AgNPs). Twelve Zea mays seeds were planted in water and AgNPs (10, 15 and 20 mg mL−1) irrigated soil for 21 days on soil containing 0.32 ± 0.01, 3.77 ± 0.03, 3.64 ± 0.02, 69.91 ± 9.44 and 13.17 ± 0.11 mg kg−1 of As, Cr, Pb, Mn and Cu, respectively. In soil treated with AgNPs, the metal contents were reduced by 75%, 69%, 62%, 86%, and 76%. The different AgNPs concentrations significantly reduced accumulation of As, Cr, Pb, Mn, and Cu in Z. mays roots by 80%, 40%, 79%, 57%, and 70%, respectively. There were also reductions in shoots by 100%, 76%, 85%, 64%, and 80%. Translocation factor, bio-extraction factor and bioconcentration factor demonstrated a phytoremediation mechanism based on phytostabilization. Shoots, roots, and vigor index improved by 4%, 16%, and 9%, respectively in Z. mays grown with AgNPs. Also, AgNPs increased antioxidant activity, carotenoids, chlorophyll a and chlorophyll b by 9%, 56%, 64%, and 63%, respectively, while decreasing malondialdehyde contents in Z. mays by 35.67%. This study discovered that AgNPs improved the phytostabilization of toxic metals while also contributing to Z. mays’ health-promoting properties. NOVELTY STATEMENT Enhanced phytoremediation strategies, which use nanoparticles to boost and facilitate the phytoremediation capacity of plants, are being recommended due to the limitations of traditional phytoremediation employing hyperaccumulating plants alone. Nanoparticles enhance phytoremediation potentials by directly reducing phytoavailable pollutants and promoting plant growth. Silver nanoparticles (AgNPs) are recognized as possessing the ability to enhance the phytoremediation of heavy metals HMs by converting them to a less toxic form and immobilizing the remaining phytoavailable HMs. This is in addition to their potential to modify plant biochemical and physiological properties to counteract HM toxicity.

Mesoporous titanium dioxide nanoparticles (TiO2NPs) were evaluated for their adsorption capacity and the mechanism of rhodamine B (RhB) and congo red (CR) removal using molecular docking with density function theory (DFT). Mesoporous TiO2NPs had a pH point of zero charge at pH 7.45 and maximum adsorption occurred at pH 9 and 3 for RhB and CR, respectively. Based on the correlation coefficient (R2) and the root square mean error (RMSE), the Langmuir model was the most appropriate isotherm and pseudo-second-order was the most accurate kinetic mechanism. Adsorption of RhB and CR was feasible, exothermic, physical, and spontaneous, with maximum adsorption capacities of 389.74 and 244.57 mg g  1, respectively. Adsorption, as predicted by molecular docking (DFT), was exergonic involving electron transfer mechanism from RhB and CR to TiO2NPs. The interactions between Ti and RhB-O and CR-N atoms were found to be more significant than those between Ti and the phenyl-H and -C atoms of the dyes. Three complexes were predicted for RhB based on energy and interatomic distances, and two for CR. In this study, an alternative reusable adsorbent that is more effective at removing RhB and CR was biologically synthesized with an identified mechanism.

The application of nanofertilisers in agriculture has been widely utilised due to their distinct characteristics and negative impacts of conventional chemical fertilisers. This study thus examined the influence of calcium nanoparticles (CaNPs) on soil composition vis-à-vis performance parameters in Moringa oleifera L exposed to water, 100 mg Ca(NO3)2kg−1 soil and 100, 75 and 50 mg CaNPs kg−1 soil. Soil morphology was determined with a scanning electron microscope coupled with energy dispersive x-ray (SEM-EDX) and elemental composition in both soils and M. oleifera roots determined with inductively coupled plasma-optical emission spectrometer (ICP-OES). The CaNP-amended soils were more crystalline, more fertile and had reduced salinity. An increase in immobilisation percentage of heavy metals, improvement in physiological parameters (percentage germination, vigour indices, relative water contents, lengths of roots and shoots) and photosynthetic efficiency in M. oleifera were recorded. This study has demonstrated that CaNPs could improve soil composition for better plant performance and can act as nanofertilisers mobilising essential nutrients.