Efficient removal of ciprofloxacin and ofloxacin from aqueous solutions using a novel nano-scale adsorbent: Modeling, optimization, and characterization.

In the fascinating realm of water purification, our study unveils the remarkable potential of a cutting-edge nano-scale adsorbent-combining graphene oxide (GO), chitosan (CS), and polydopamine (PDA)-in efficiently remove ciprofloxacin (CPF) and ofloxacin (OFL) from aqueous solutions. Our exploration delves deep into the adsorbent's character, utilizing a range of analytical techniques including SEM, RAMAN, FTIR, TGA, BET, XRD, and Zeta potential analyses provided insights into the adsorbent's properties. Modeling the adsorption process with Response Surface Methodology (RSM), Artificial Neural Network (ANN) and General Regression Neural Network (GRNN) indicated excellent predictions by GRNN, with RMSE = 0.0200 and 0.0166, MAE = 0.0082 and 0.0092, as well as AAD = 0.0002 and 0.0006, highlighting its modeling power. Optimization using genetic algorithm (GA) revealed maximum CPF removal efficiency of approximately 95.20% under pH = 6.3, sonication time = 9.0 min, adsorbent dosage = 2.10 g L⁻1, temperature = 45 °C and initial CPF concentration = 90.0 mg L⁻1. Similarly, OFL removal reached about 95.50% under pH = 6.30, sonication time = 8.0 min, adsorbent dosage = 2.0 g L⁻1, temperature = 45 °C and OFL concentration = 115.0 mg L⁻1. RSM optimization closely aligned with GA results. Pseudo-second-order (PSO) kinetic model and Langmuir isotherm model best fitted the experimental data for both antibiotics. Thermodynamic analysis indicated a favorable and spontaneous adsorption process for CPF and OFL. The study concludes that the proposed adsorbents show effectiveness in removing CPF and OFL at lower doses and shorter sonication times compared to various reported adsorbents.

catena-Poly[[diiodidomercury(II)]-µ(2)-2-amino-pyrazine-κN:N].

In the crystal of the title polymeric compound, [HgI(2)(C(4)H(5)N(3))](n), the Hg(II) cation is located on a twofold rotation axis and is coordinated by two I(-) anions and two 2-amino-pyrazine ligands in a distorted HgI(2)N(2) tetra-hedral geometry. In the crystal, the 2-amino-pyrazine ligand is equally disordered over two positions about an inversion center, and bridges the Hg(II) cations with pyrazine N atoms to form a polymeric chain running along the c axis. In the polymeric chain, the amino groups link to the coordinated I(-) anions via inter-molecular N-H⋯I hydrogen bonds.

FeNH4(SO4)2·12H2O (alum)-catalyzed preparation of 1,4-dihydropyridines: improved conditions for the Hantzsch reaction.

ABSTRACT: FeNH4(SO4)2·12H2O (alum) efficiently catalyzes the one-pot three-component reaction of dimedone, aldehydes, and 3-aminocrotonate to afford 1,4-dihydropyridines. The work-up is easy, and the products are obtained in good to excellent yields and high purity.