A Review of Fluoride Removal from Groundwater

Most of the arid and semiarid zones of the Indian subcontinent are seriously affected by the fluorosis problem due to high concentration of the fluoride in ground water. Due to leaching of fluoride from the fluoride bearing rocks, the groundwater gets contaminated with fluoride. The different techniques for fluoride removal namely, the Activated alumina, the Nalgonda technique, bone charcoal, contact precipitation, electro-dialysis, reverse osmosis, ion-exchange, clay column, bio-adsorbents and MgO are discussed in detail. Their advantages and disadvantages together with the applicability in actual use also been discussed in the paper

Studies on <em>cis</em> and <em>trans</em> influence in alkylcobaloximes with different axial bases

707-711Thirteen alkyl cobaloximes RCo(L2)B with two equatorialligands L (L=dmgH and dpgH) and with three different bases B (y -picoline, imid and benzimid) have been synthesised (78 complexes in all). The cis influence has been studied using UV -Vis, IR and IH NMR techniques. The results show that the cis influence follows the order: dpgh &gt; dmgH and the result match with those of our previous studies

Synthesis, Characterization, Semiempirical and Biological Activities of Organotin(IV) Carboxylates with 4-Piperidinecarboxylic Acid

Organotin (IV) carboxylates with the general formulae R2Sn(Cl)L [R = Me (1), n-Bu (2), Ph (3)] and R3SnL [R = Me (4), Ph (5)] have been synthesized by the reaction of 4-piperidinecarboxylic acid (HL) with KOH and R2SnCl2 (R = Me, n-Bu, Ph)/R3SnCl (R = Me, Ph) in methanol under stirring conditions. The metal ligand binding site, structure, and stability of complexes have been verified by FT-IR, (1H, 13C) NMR, EI-MS technique, and semiempirical study. The FT-IR data indicate the bidentate chelating mode of the carboxylate ligand which is also confirmed by semiempirical study. In solution state, five and four coordinated geometry around tin was confirmed by NMR spectroscopy. The EI-MS data agreed well with the molecular structure of the complexes. Thermodynamic parameters and molecular descriptors were calculated by using semiempirical PM3 method. HOMO-LUMO calculations show that chlorodiorganotin complexes are more susceptible to nucleophilic attack as compared to triorganotin complexes. Computed negative heat of formation indicates that complexes 1–4 are thermodynamically stable. The organotin(IV) carboxylates displayed powerful antimicrobial activities against various strains of bacteria and fungi and their minimal inhibitory concentration were also evaluated. The complexes exhibited comparatively higher hemolytic activity as compared to free ligand

CuO Nanorods Immobilized Agar-Alginate Biopolymer: A Green Functional Material for Photocatalytic Degradation of Amaranth Dye

The contamination of water is increasing day by day due to the increase of urbanization and population. Textile industries contribute to this by discarding their waste directly into water streams without proper treatment. A recent study explores the treatment potential of copper oxide nanorods (CuO NRs) synthesized on a green basis in the presence of a biopolymer matrix of agar (AA) and alginate (Alg), in terms of cost effectiveness and environmental impact. The synthesized bio nanocomposite (BNC) was characterized by using different instrumental techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), ultra-violet spectroscopy (UV-Vis), scanning electron microscopy-energy dispersive X-ray-elemental analysis (SEM-EDX), transmission electron microscopy (TEM), selected area diffraction pattern (SAED) and X-ray photoelectron spectroscopy (XPS). The optical studies revealed that immobilization of CuO NRs with Alg-Agar biopolymer blend resulted in an increase in light absorption capacity by decreasing the energy bandgap from 2.53 eV to 2.37 eV. The bio nanocomposite was utilized as a photocatalyst for the degradation of amaranth (AN) dye from an aquatic environment under visible light irradiation. A statistical tool known as central composite design (CCD) associated with response surface methodology (RSM) was taken into consideration to evaluate the optimized values of process variables and their synergistic effect on photocatalytic efficiency. The optimized values of process variables were found to be irradiation time (45 min), AN concentration (80 ppm), catalyst dose (20 mg), and pH (4), resulting in 95.69% of dye degradation at 95% confidence level with desirability level 1. The rate of AN degradation was best defined by pseudo-first-order reaction based on the correlation coefficient value (R2 = 0.99) suggesting the establishment of adsorption-desorption equilibrium initially at the catalyst surface then photogenerated &bull;O2&minus; radicals interacting with AN molecule to mineralize them into small non-toxic entities like CO2, H2O. The material used has high efficiency and stability in photocatalytic degradation experiments up to four cycles of reusability

Synthesis and characterization of hetero-bimetallic complexes with 2-mercapto-5-methyl-benzimidazole: theoretical study and biological activities

<div><p>Heterobimetallic complexes have been synthesized by stirring 2-mercapto-5-methylbenzimidazole with carbon disulfide in methanol at room temperature. In the second step, the product was treated with R₂SnCl₂/R₃SnCl (R = Me, <i>n</i>-Bu, Ph) in 1 : 1 M ratio, then organotin(IV) complexes were treated with HgCl₂ in 2 : 1 M : L ratio to yield heterobimetallic complexes. The ligand and complexes have been characterized by elemental analysis, IR, ¹H- and ¹³C NMR spectroscopy, mass spectrometry (EI-MS), and semiempirical study to assess the binding mode of the heterobimetallic complexes. IR data showed the bidentate nature of the dithiocarbamate moiety, which is also confirmed by semiempirical study. Mass spectra correspond to the expected for the complexes. NMR spectroscopy confirmed the four-coordinate geometry in solution. Computed molecular descriptors, thermodynamic parameters, and electrostatic surface potential map of <b>4</b> were calculated by using the PM6 method. Biological screening data indicated that complexes exhibit significant activity against various bacterial and fungal strains with few exceptions. Ligand and <b>6</b> are excellent for phagocyte reactive oxygen species inhibition.</p></div

Synthesis, characterization, HOMO–LUMO study, and antimicrobial activity of organotin(IV) complexes of 4-piperidine carboxamide and its Schiff base

<div><p>A series of organotin(IV) complexes has been synthesized by reacting 4-piperidine carboxamide with CS₂ and R₂SnCl₂/R₃SnCl in 1 : 1 M/L ratio at room temperature. The synthesized complexes were further treated with benzaldehyde to synthesize Schiff bases under stirring. All the complexes were characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR. FT-IR and semi-empirical study confirm the bidentate nature of ligand. The complexes exhibit four-coordinate geometry in solution. Thermodynamic parameters and molecular descriptors were calculated by using semi-empirical PM3 method. HOMO–LUMO calculations show that chlorodiorganotin complexes are more susceptible to nucleophilic attack when compared with triorganotin complexes. Negative heats of formation at 298 K demonstrate that <b>1</b>, <b>4,</b> and <b>7</b> are thermodynamically stable. The antimicrobial results have shown that complexes containing Schiff base exhibit significantly better activity compared to complexes with carboxamide derivatives.</p></div