Solvation and equilibrium studies of some compounds containing azo and nitroso chromophores

Valorization of agro-industrial biowaste to green nanomaterials for wastewater treatment: Approaching green chemistry and circular economy principles

Water pollution is one of the most critical issues worldwide and is a priority in all scientific agendas. Green nanotechnology presents a plethora of promising avenues for wastewater treatment. This review discusses the current trends in the valorization of zero-cost, biodegradable, and readily available agro-industrial biowaste to produce green bio-nanocatalysts and bio-nanosorbents for wastewater treatment. The promising roles of green bio-nanocatalysts and bio-nanosorbents in removing organic and inorganic water contaminants are discussed. The potent antimicrobial activity of bio-derived nanodisinfectants against water-borne pathogenic microbes is reviewed. The bioactive molecules involved in the chelation and tailoring of green synthesized nanomaterials are highlighted along with the mechanisms involved. Furthermore, this review emphasizes how the valorization of agro-industrial biowaste to green nanomaterials for wastewater treatment adheres to the fundamental principles of green chemistry, circular economy, nexus thinking, and zero-waste manufacturing. The potential economic, environmental, and health impacts of valorizing agro-industrial biowaste to green nanomaterials are highlighted. The challenges and future outlooks for the management of agro-industrial biowaste and safe application of green nanomaterials for wastewater treatment are summarized.

Synthesis, characterization, and sorption activity of novel azo-colorants derived from phloroglucinol and antipyrine and their metal complexes

Two novel azo-colorants derived from phloroglucinol and antipyrine as well as 10 metal complexes with Co(ii), Ni(ii), Zn(ii), Cu(ii), and Cd(ii) were isolated and studied by a set of methods (1H, 13C NMR, IR, UV-VIS, EPR, X-ray structure determination). The azo-coupling of phloroglucinol with a 5-pyrazolone amino-derivative led to the isolation of a colorant H3L1 which was presented in the hydroxy-azo tautomeric form. At nitrosation of H3L1, the product H3L2 was isolated, which can be described as tri-oxo di-hydroxylamino hydrazone. According to the X-ray structure determination, the Cd-complex of H3L1 exhibited the dimeric form with two unionized organic ligands in the inner sphere. It was also found that chloride anions bridge two cadmium cations to form dimers. According to EPR spectra, the Cu-complex with H3L1 exhibited distorted tetragonal symmetry associated with the d x 2-y 2 ground state rather than d z 2 , and the corresponding Cu-H3L2 complex was described by a cubic symmetry of the coordination medium. Both H3L1, H3L2, and their metal complexes show coloristic activity towards wool, polyamide, and polyacetate fibers, which are strongly resistant towards UV-irradiation. The H3L2 compound possessed good sorption activity towards heavy metal cations from aqueous solutions of trace concentrations both under static and dynamic conditions.