Flax fiber based semicarbazide biosorbent for removal of Cr(VI) and Alizarin Red S dye from wastewater.

In the present study, flax fiber based semicarbazide biosorbent was prepared in two successive steps. In the first step, flax fibers were oxidized using potassium periodate (KIO4) to yield diadehyde cellulose (DAC). Dialdehyde cellulose was, then, refluxed with semicarbazide.HCl to produce the semicarbazide functionalized dialdehyde cellulose (DAC@SC). The prepared DAC@SC biosorbent was characterized using Brunauer, Emmett and Teller (BET) and N2 adsorption isotherm, point of zero charge (pHPZC), elemental analysis (C:H:N), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The DAC@SC biosorbent was applied for the removal of the hexavalent chromium (Cr(VI)) ions and the alizarin red S (ARS) anionic dye (individually and in mixture). Experimental variables such as temperature, pH, and concentrations were optimized in detail. The monolayer adsorption capacities from the Langmuir isotherm model were 97.4 mg/g and 18.84 for Cr(VI) and ARS, respectively. The adsorption kinetics of DAC@SC indicated that the adsorption process fit PSO kinetic model. The obtained negative values of ΔG and ΔH indicated that the adsorption of Cr(VI) and ARS onto DAC@SC is a spontaneous and exothermic process. The DAC@SC biocomposite was successfully applied for the removal of Cr(VI) and ARS from synthetic effluents and real wastewater samples with a recovery (R, %) more than 90%. The prepared DAC@SC was regenerated using 0.1 M K2CO3 eluent. The plausible adsorption mechanism of Cr(VI) and ARS onto the surface of DAC@SC biocomposite was elucidated.

Design, structural, spectral, DFT and analytical studies of novel nano-palladium schiff base complex.

A novel nano-palladium (II) Schiff base complex (C1) is synthesized by the reaction between palladium chloride and the Schiff base N, N'-1, 2-phenylene) bis (3 -aminobenzamide (A1). The prepared compounds were characterized by elemental analysis, Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Thermogravimetric Analysis (TGA). A combined solvent sublation-ICP OES methodology has been studied for the preconcentration, separation and determination of trace palladium (II) in media of diverse origin using the Schiff base ligand (A1). The different experimental variables that affect the sublation efficiency (S, %) were thoroughly investigated viz.: pH of sample solution; amounts of A1, Pd (II) and TBAB; type and amounts of surfactants, types of organic solvent, temperature and stirring time. The method involves the determination of trace palladium (II) after selective separation by solvent sublation, thus eliminating the effect of foreign ions and increasing the sensitivity. Also, palladium is determined directly in the organic phase, which decreases the determination time and its loss during determination. At optimum conditions, the linear range of Pd (II) was 10.0-100.0 ngmL-1. The coefficient of determination, the limit of detection (LOD) and limit of quantification (LOQ) were 0.9943, 21.29 ngL-1 and 64.5 ngL-1, respectively. This sublation method was applied to real samples and recoveries of more than 95% were obtained in the spiked samples with a preconcentration factor of 100. The mechanism of solvent sublatation of the TBA.[PdII-(A1)2] ion pairs is discussed. The computational studying was estimated to approve the geometry of the isolated solid compounds.

A novel cerium(iii)-isatin Schiff base complex: spectrofluorometric and DFT studies and application as a kidney biomarker for ultrasensitive detection of human creatinine.

In this paper, a new isatin-Schiff base L1 was prepared via a simple reaction of isatin with 2-amino-3-hydroxypyridin. Subsequently, cerium(iii)-Schiff base complex C1 was obtained through the reaction of the prepared Schiff base L1 with cerium chloride via a hydrothermal method. The prepared L1, as well as C1, were fully characterized using many spectroscopic techniques, such as mass spectra, elemental analysis, UV-vis, FT-IR, 1H-NMR, 13C-NMR, FE-SEM/EDX, and HR-TEM. A photoluminescence study (PL) was carried out for the prepared complex C1. The promising photoluminescence results revealed that C1 could be used for the detection of creatinine in different human biological samples as a selective optical biosensor. The results showed that C1 after excitation at 370 nm has a strong emission band at 560 nm. The calibration graph was obtained in a wide concentration range between 2.5 and 480 nM creatinine with limits of detection (LOD) and quantitation (LOQ) of 1.07 and 3.25 nM, respectively. In addition, the correlation coefficient (r 2) was found to be 0.9890. The PL spectra indicate that C1 has high selectivity toward creatinine without interference from other different analytes and can be successfully used as an optical sensor for creatinine detection. The mechanism of quenching between the Ce(iii) complex and creatinine was a dynamic type. The geometry of Schiff base L1 and its cerium(iii) complex C1 was proven by using density functional theory (DFT). The energy of the LUMO and HOMO, energy gap, dipole moment and structure-activity relationship were determined and confirmed.