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Adsorption of Ni(II) from aqueous solution by using the butane tetracarboxylic acid (BTCA) modified peanut shell cellulose as sorbent was examined in the batch system. The optimal modification conditions of cellulose were butane tetracarboxylic 0.05 g/g, sodium dihydrogen phosphate 0.15 g/g, reaction temperature 140°C, and reaction time 90 min. The nickel ions removal rate by the BTCA-modified cellulose increased with the increasing temperature in the range of 20°C–45°C. Ni(II) adsorption onto the BTCA-modified cellulose was successfully described by the pseudo-second- order kinetic and Langmuir isotherm models. According to the thermodynamic parameters, the results indicated that Ni(II) adsorption onto the BTCA-modified cellulose was spontaneous and endothermic in nature. [ABSTRACT FROM AUTHOR]

Two MX2 (M = Ni, Zn; X = Cl, Br) dimethyl N-cyanodithioiminocarbonate compounds and one CrCl2 triphenylphosphine oxide complex were isolated and elucidated by single crystal X-ray crystallography. NiCl2[(CH3S)2C=NC=N]2 (1) features inversionrelated hydrogen bonded dimers linked into chains interacting through C--H...Cl growing layers along [110] whose junction into a 3D structure is enabled by H-bonds. ZnBr2[(CH3S)2C=NC=N]2 (2) also exhibits inversion-related H-bonded dimers. In contrast with 1, the structure of 2 comprises chains along [110], connected via C--H...Br and C--H...S into a 2D layer along [-110]. CrCl2(OPPh3)2 (3) obtaining undergone redox processes, oxidizing [CH3C(O)CH2PPh3]+ to form PPh3PO, and reducing Cr from CrVI to CrII. In the structure, each molecule is linked to height neighbors through H-bonds affording a 3D network. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine phosphoric acid activated hazelnut husk carbon (HHPAAC) feasibility in removing Cu(II), Ni(II) and Co(II) ions from aqueous solutions. The effects of various parameters including, pH of the aqueous phase, contact time and initial metal ion concentration were studied in batch adsorption experiments. Adsorption of Cu(II), Ni(II) and Co(II) ions was found to be favorable at a pH of 6.0 and reached equilibrium at 600 min. Adsorption equilibrium of Cu(II), Ni(II) and Co(II) ions was found to be compatible with the Langmuir isotherm model. The maximum adsorption capacity of HHPAAC for Cu(II), Ni(II) and Co(II) ions were calculated to be 24.3, 16.3 and 17.3 mg g−1, respectively, from the Langmuir equation. The kinetic behavior of Cu(II), Ni(II) and Co(II) adsorption was well expressed by the pseudo-second-order model. Adsorbed Cu(II), Ni(II) and Co(II) ions were quantitatively desorbed from the HHPAAC surface using 0.1 M nitric acid solution. HHPAAC exhibits green and cheap procedures for the treatment of wastewater including heavy metals such as Cu(II), Ni(II) and Co(II) ions. [ABSTRACT FROM AUTHOR]

Attapulgite (ATP) and its organically modified products have been investigated for potential applications in environmental remediation. In this work, a variety of modifiers with different functional groups, including saturated sodium chloride solution (NaCl), cetyltrimethyl ammonium bromide (CTAB) and humic acid (HA), were used to treat attapulgite clay firstly, and then with the modified ATP as adsorbent and acrylamide (AAm) as monomer, polyacrylamide/modified attapulgite (PAAm/modified ATP) composite hydrogel which could adsorb heavy metal ions Ni(II) and organic pollutants phenol were synthesized. The structure of the raw ATP and modified ATP was specified with Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Transmission electron microscope (TEM). The experiments indicated that the modified ATP and composite hydrogel possessed good adsorption properties for Ni(II) ions and phenol. The adsorption capacity of PAAm/HA-ATP hydrogel for Ni(II) was as high as 64.3 mg/g, which was 194.9% of pure hydrogel. The adsorption isotherm of HA-modified ATP (HA-ATP) and adsorption kinetics of PAAm/HA-ATP composite hydrogel was particularly concerned. The adsorption isotherm equation fitted well on the Langmuir model and RL values ranged from 0.04 to 0.12 with different temperatures, indicated that the HA-ATP was a suitable adsorbent for adsorption of Ni(II) ions from wastewater. The obtained kinetics data for Ni(II) ions adsorption onto the PAAm/HA-ATP were described well by the pseudo-second-order model (R2 > 0.99). As for the adsorption of phenol, double-modification proved to be the most effective method, and its optimal adsorption capacity was obtained on PAAm/CTAB-HA-ATP hydrogel. [ABSTRACT FROM AUTHOR]

In this work, to separate Fe(III) and Ni(II) in radioactive wastewater simulation solution, various parameters on adsorption and desorption efficiency were investigated by a novel nuclear anion resin. Considering the poor radiation resistance of separation materials, a commercial product nuclear grade ZG A NR 170 resin as an ion exchanger used in the process with excellent radiation resistance was utilized for the treatment of radioactive wastewater. A very good separation effect can reach by ZG A NR 170 resin. Through the ion exchange process, in the adsorption stage, more than 99% of iron can be adsorbed on the resin column, the β(Ni/Fe) of penetrating fluid can reach 1,223.93. In the desorption process, the desorption rate of iron is up to 98%, the β(Fe/Ni) of the desorption solution can reach 1,120.39. The volumetric mass-transfer coefficient of the static adsorption process can reach 0.032 s–1 and it shows excellent adsorption performance for five cycles under optimal conditions. [ABSTRACT FROM AUTHOR]

• Ni(II) was efficiently removed from strongly acidic wastewater using DDTC. • Dithiocarbamate groups of DDTC react with Ni(II) to form DDTC Ni precipitates. • High-purity NiO can be obtained by calcination of DDTC Ni precipitates. • NO 2 , CS 2 , H 2 O, CO 2 , and SO 2 were released during the calcination process. Strongly acidic wastewater produced in nonferrous metal smelting industries often contains high concentrations of Ni(II), which is a valuable metal. In this study, the precipitation of Ni(II) from strongly acidic wastewater using sodium dimethyldithiocarbamate (DDTC) as the precipitant was evaluated. The effects of various factors on precipitation were investigated, and the precipitation mechanism was also identified. Finally, the nickel in the precipitates was recovered following a pyrometallurgical method. The results show that, under optimised conditions (DDTC:Ni(II) molar ratio = 4:1; temperature = 25 °C), the Ni(II) removal efficiency reached 99.3% after 10 min. In strongly acidic wastewater, the dithiocarbamate group of DDTC can react with Ni(II) to form DDTC Ni precipitates. Further recovery experiments revealed that high-purity NiO can be obtained by the calcination of DDTC Ni precipitates, with the nickel recovery efficiency reaching 98.2%. The gas released during the calcination process was composed of NO 2 , CS 2 , H 2 O, CO 2 , and SO 2. These results provide a basis for an effective Ni(II) recovery method from strongly acidic wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

The cloud point technique was effectively utilized for extraction and pre-concentration of nickel(II) in urine samples before measurement by UV-Vis spectrophotometer and AAS techniques. The metal response to a para-aminophenol (PAP) reagent in a non-ionic surfactant Triton X-114 medium was to form the Ni-PAP complex. The adopted concentration for PAP, concentration of Triton X-114, pH effect and water bath temperature, incubation time, salt effect, and interference effects were all optimized. The calibration curve was linear over the range of (0.0625–1.25) mg L–1 with a correlation coefficient r2 of 0.9682 for the UV-Vis spectrophotometer at a λmax of 629 nm. The limit of detection was 0.005 mg/L. The relative standard deviation for six replicates was 1.07%. This method was applied successfully to determine copper (II) concentrations in 44 urine samples of occupational worker samples as determined by UV-Vis spectrophotometry and FAAS techniques.

Mining is the most common activity that introduces heavy metal ions into aquatic ecosystems, especially in low income-developing nations where governments are implementing stricter regulations for industrial wastewater. In this context, this work is focused on the application of xanthate-modified alginates for the removal of Pb(II) and Ni(II) from aqueous solutions. In order to confirm the presence of xanthate groups alongside alginate chains, characterization by second-derivative FT-IR was carried out and significance evidence attributed to xanthate groups was found at around 1062–1079 cm−1, 829–845 cm−1 and 620–602 cm−1. In addition to this, thermogravimetric analysis and differential scanning calorimetry were employed to explore thermal properties of modified alginates. According to these results, enthalpy changes (∆H) characteristic of dehydration and collapse of biopolymeric structure were estimated as +11.41 J/g and −6.83 J/g, respectively. Furthermore, the presence of S element was confirmed by EDS mapping technique, whereas FESEM image showed a cracked and homogeneous surface distribution. On the other hand, the effect of important parameters such as pH, dosage, initial concentration as well as Langmuir and Freundlich isotherm were deeply discussed. Finally, rheological measurements were performed aiming to investigate the gel-like viscoelastic features associated to nickel xanthate compound. [Display omitted] • Suitable xanthate-modified alginates were prepared for Pb(II) and Ni(II) removal. • The presence of xanthate group was deeply studied by second derivative FT-IR. • Nickel xanthate compound behaves as gel-like viscoelastic material. • Enthalpy change values were calculated by using thermal methods. [ABSTRACT FROM AUTHOR]

A novel Schiff base 4-{(E)-[(3-methyl-5-sulphanyl-4H-1,2,4-triazol-4-yl)imino]methyl}benzaldehyde (MSTB) and its complexes with Ag(I), Hg(II), Cu(II), Ni(II) and Co(II) have been prepared. MSTB is prepared by the condensation reaction between triazole and terephthaldehyde. In complexes, MSTB molecules are found to link with the metal ion, through thiolsulphur after deprotonation and the nitrogen of the azomethine group. The composition of the complexes are found to be ML where M =Ag, ML2 where M=Zn, Hg and ML2(H2O)2 where M= Co, Ni. Linear polymeric structure is proposed for Ag(I) complex, tetrahedral structure is proposed for Zn(II) and Hg(II) complexes and octahedral structure is proposed for Co(II) and Ni(II) complexes. [ABSTRACT FROM AUTHOR]

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel Schiff base ligand (L) has been synthesized using 4-(2-amino ethyl) benzene-1,2-diol (Dopamine) and 1,4 benzoquinone. Co(II), Ni(II), Cu(II) and Zn(II) complexes with this hexadentate ligand have been synthesized with metal:ligand (1:1) stoichiometry. The Schiff base ligand and its metal complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared and electronic spectra, ESR, NMR, Mass spectra, powder X-ray diffraction and SEM studies. Molar conductance showed that all complexes are non-electrolytic in nature. The Co(II), Ni(II), Zn(II) complexes are found to be octahedral and distorted octahedral structure for Cu(II) complex. Powder X-ray diffraction reveals that Schiff base ligand and its metal complexes are nano-crystalline in nature but Co(II) complex is amorphous. Different morphologies of synthesized compounds are identified by SEM images. Schiff base ligand and its metal complexes were screened against gram-positive bacteria, gram-negative bacteria and one fungus strain. The data show that the ligand and its metal complexes have significant activity. Copper(II) complex shows better activity than other complexes. The Schiff base ligand and its copper(II) complex are evaluated for the antiinflammatory by HRBC membrane stabilization method. The anti-cancer activity of Schiff base ligand and its copper complex was also studied against human breast cancer cell line by MTT assay method. The anti-diabetic activity of Schiff base ligand and its copper(II) complex is also studied by alpha-amylase method. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of disease diagnosis and environmental monitoring, it is desirable to detect the concentration of proteins and metal ions simultaneously, since the current popular diagnostic platform can only detect proteins or metal ions independently. In this work, we developed a colorimetric microfluidic paper-based analytical device (µPAD) for simultaneous determination of protein (bovine serum albumin, BSA) and metal ions [Fe(III) and Ni(II)]. The µPAD consisted of one central zone, ten reaction zones and ten detection zones in one device, in which reaction solutions were effectively optimized for different types of chromogenic reactions. Fe(III), Ni(II) and BSA can be easily identified by the colored products, and their concentrations are in good accordance with color depth based on the established standard curves. The detection limits are 0.1 mM for Fe(III), 0.5 mM for Ni(II) and 1µM for BSA, respectively. Best of all, we demonstrated the efficiency of the µPAD with accurate detection of Fe(III), Ni (II) and BSA from river water samples within 15 minutes. The µPAD detection is efficient, instrument-free, and easy-to-use, holding great potential for simultaneous detection of cross type analytes in numerous diagnostic fields. [ABSTRACT FROM AUTHOR]

Two new isostructural M(II) (M = Ni, Co) complexes with 2,2’-dipyridylamine (dipya) and dianion of terephthalic acid (H2tpht), [M(dipya)2(H2O)2](tpht)∙2H2O, have been synthesized by ligand exchange reaction and characterized by single-crystal X-ray diffraction, FTIR spectroscopy, TG/DSC analysis and magnetic measurements. The crystal structures of [M(dipya)2(H2O)2](tpht)∙2H2O consist of discrete complex units in which M(II) adopts deformed octahedral geometries. Two dipya ligands and two water molecules are coordinated to M(II) atom, tpht acts as a counter ion, while additional two water molecules remained uncoordinated. By numerous hydrogen bonds, all structural fragments are connected in three different chains which extend along [100], [010] and [001] directions, giving as a result a complex 3D network. The stabilization of 3D structure is accomplished by non-covalent face to face π-π interactions among pyridyl ring of dipya and benzene ring of tpht from adjacent chains. Towards the applied magnetic field, the both complexes exhibited almost perfect paramagnetic behavior.

A corn stalk cellulose-based adsorbent was reasonably designed and synthesized by two steps of modification to effectively remove Cd(II) and Ni(II) from wastewater of nickel-cadmium (Ni-Cd) and nickel-metal hydride (Ni-MH) batteries. Glycidyl methacrylate (GMA), N,N-methylene-bisacrylamide (MBA), and potassium persulfate (KSP) was selected as the grafting monomer, cross-linking agent and initiator, respectively, in the first step to introduce enough epoxy groups and generate three dimensional (3D) network structures on the cellulose (Cell) surface. Under the optimum conditions of weight ratio of GMA: Cell = 3:1, 20 mmol L-1 KSP, 5.0 wt.% of MBA to Cell and 60°C for 2 h, the maximum grafting efficiency and the amount of epoxy groups could reach 93.69% and 4.96 mmol g-1, respectively. Then this grafted and cross-linked product (Cell-g-GMA-c-MBA) was further reacted with diethylenetriamine (DETA) to introduce amino groups on the adsorbent. The final adsorbent (Cell-g-GMA-c-MBA-DETA) with the maximum amount of 7.20 mmol g-1 amino groups was obtained under the optimized amination conditions. The experiment results showed that the maximum adsorption capacity of Cd(II) and Ni(II) on Cell-g-GMA-c-MBA-DETA could reach 367.3 and 295.9 mg g-1, respectively at 45°C and pH = 4.5. The detailed investigation on relationships between microstructures and adsorption performances of Cell-g-GMA-c-MBA-DETA proved that the introduced sufficient amino groups were the major adsorption sites to adsorb Cd(II) and Ni(II). Cd(II) was inclined to be adsorbed by forming chelation complexes with 2-3 mmol N atoms from amino groups while the adsorption of Ni(II) would require at least 1 mmol N atom from amino groups by accepting lone-pair electrons and forming coordinate bonds. This modified cellulose also displayed a good reproducibility, whose regeneration efficiency for adsorbing Cd(II) and Ni(II) after sixth cycles were still 80% and 82%, respectively. It could be considered as a promising material for effective removal of Cd(II) and Ni(II) from batteries wastewater. [ABSTRACT FROM AUTHOR]

Two novel sorbents, obtained as a result of surface modification of silica gel for the Cu(II), Co(II) and Ni(II) removal from aqueous solutions were proposed. For the modification, 3-chloropropyltrimethoxysilane, N'-hydroxy-N,N-dioctylpyridine-3-carboximidamide and N'-hydroxy-N,N-dioctylpyridine-4-carboximidamides were used. A series of basic tests on the sorption of Cu(II), Co(II) and Ni(II) were carried out and the presented results indicated that the novel sorbents were able to remove all tested metals ions from the aqueous solutions, and the removal efficiency was dependent on the functionalised agent structure, dosage, metal ions concentration and pH. The Langmuir model also assumed that a monolayer sorption occurred. [ABSTRACT FROM AUTHOR]

The precise analysis of redox chemistry of MN4-based macrocyclic complexes is of great importance because of stabilization of unusual oxidation states of metal ions by macrocyclic ligand and thus have various applications in biochemistry, electrochemistry, electrocatalysis, pharmaceuticals etc. In this work, MN4-macrocyclic complexes of Co (II) and Ni(II) transition metal ions have been synthesized by using template condensation method. Further, the MN4-macrocyclic complexes were characterized by elemental, molar conductance and multiple spectroscopic analysis. The spectral and elemental analysis suggested that both complexes would possess the saddle shape distorted octahedral geometry. Further, the electrochemical investigation of both complexes was carried out by cyclic voltammetry. Both complexes showed quasi-reversible one-electron transfer redox process indicating the stabilization of oxidation state of central metal ions. Moreover, the MN4-macrocyclic complexes have shown to have good antimicrobial activity against the various pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus). [ABSTRACT FROM AUTHOR]

In this study, nanoparticles of CuFe2O4@SiO2@PTMS@Tu@Ni(II) as the reusable magnetic catalyst were prepared. Synthesis of the Ni(II)–CuFe2O4 system was carried out through a five-step procedure including the preparation of CuFe2O4 as the prime magnetic core, layering of silica, 3-chloropropyltrimethoxysilane and thiourea and finally the immobilization of Ni(OAc)2·4H2O. The prepared nanocomposite system was then characterized using FT-IR, SEM, EDX, XRD, VSM, ICP-OES and TGA/DSC analyses. Catalytic activity of CuFe2O4@SiO2@PTMS@Tu@Ni(II) was further studied toward synthesis of biscoumarin materials by a domino Knoevenagel–Michael reaction of 4-hydroxycoumarin with aromatic and heterocyclic aldehydes under solvent-free conditions (70 °C) within 15–30 min. The applied nanocomposite system was easily and magnetically separated from the reaction mixture and reused for six consecutive cycles without the significant loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Kenaf is a renewable resource that has recently attracted great interest owing to its fast growth which makes a large volume of raw material in a short time. Due to its large surface area and high water adsorption, kenaf cellulose was readily prepared as a substrate immobilized with dimethylglyoxime (DMG) for specific Ni(II) sensor. Herein, a simple and highly sensitive colorimetric detection of Ni(II) using kenaf cellulose-based 3D printed device was successfully created. The large volume (1.0 mL) of Ni(II) solution can be applied on a kenaf cellulose-based 3D printed sensor coupled with a multilayer of adsorption pads. This system provides a wide linear range (0.1–100 mg/L) with an extremely low limit of detection (40 μg/L), significantly improved from a conventional filter paper-based device (1.0 mg/L) for 25 uses, and it enables highly sensitive colorimetric detection of Ni(II) contamination in industrial wastewater without any use of external instruments validated with a standard ICP-OES method. [ABSTRACT FROM AUTHOR]

The objective of this study was the deposition of thin films of 8-hydroxyquinolin (8-HQ) Cobalt(II) and Nickel(II) complexes onto glass substrates using the chemical bath deposition (CBD) method. The deposition experiments were carried out under the effect of some physicochemical factors such as solution temperature (25 °C–55 °C), medium pH (1–6), metal: ligand molar stoichiometric ratio (1:1–1:3), and immersion time (in the range 10–60 min). The obtained thin films were characterized using many analytical methods (UV-Vis spectrophotometry, infrared spectrophotometry, optical microscopy, scanning electron microscopy, and X-ray diffraction). The study of the optical properties of the obtained thin films showed that the complexes [Ni(8-HQ)2(H2O)2] and [Co(8-HQ)2(H2O)2] have strong absorbance in UV area corresponding to a π-π* or n-π* electronic transition between the HOMO and the LUMO with a gap's energy in the range 4.1 and 4.4 eV. In the light of the optical measurements, [Ni(8-HQ)2(H2O)2] and [Co(8-HQ)2(H2O)2] complexes can be considered as semiconductors. [ABSTRACT FROM AUTHOR]

This paper presents a simple coordinating behavior of Schiff base ligand with Ni(II), Cu(II), Co(II) and Fe(III) ions. A Schiff base ligand;1-(N-ortho-hydroxyacetophenimine)-ethan-2-ol was reported in our previous literature, synthesized by the condensation of 2-hydroxyacetophenone and ethanolamine. Various metal ions such as Cu(II), Co(II), Ni(II) and Fe(III) were reacted with this receptor in 1:2 molar ratio to form their corresponding complexes. These complexes were characterized by elemental analysis, powder X-ray diffraction, spectroscopic methods (FT-IR, UV-Vis, Mass spectrometry, conductance measurements) and thermogravimetric analysis, which confirmed the formation of [Cu(L)2(H2O)2]Cl2, [Co(L)2(H2O)2](NO3)2,[Ni(L)(NO3)](NO3) and [Fe(L)2]Cl3 complexes (where L is Schiff base ligand). [ABSTRACT FROM AUTHOR]

In this experimental study, Ni(II) biosorption onto the dry waste nitrification organisms (NO), which was drawn from the biological nitrification reactor, was investigated in the batch units with respect to the temperature, initial Ni(II) concentrations, pH, and biosorbent doses. Experimental results indicated that the NO could be successfully used to remove Ni(II) ions from the solution. Quick sorption process reached to equilibrium in about 3 hours with a maximum sorption at the pH of 7.0. With the increase of the solution temperature, limited increase of the Ni(II) biosorption onto NO was determined and the highest qe value (13,4 mg Ni(II)/g NO) occurred at the temperature of 55°C. The highest correlation coefficients were obtained using the Langmuir model. A comparison of the kinetic models on the sorption rate demonstrated that the system was best described by the pseudo second-order kinetic model. The thermodynamic parameters ΔG°, ΔH°, and ΔS° were determined in order to predict the nature of biosorption. The results confirmed that the adsorption reaction of Ni(II) onto the NO was thought to be exothermic. The temperature and pH of the solution affected the release organic matter and NH+4-N from the biomass. [ABSTRACT FROM AUTHOR]

In this study, we have synthesized magnetically nanoparticles (MNPs) of CuFe2O4@SiO2@AAPTMS@Ni(II) and CuFe2O4@SiO2@AAPTMS@Cu(II). The prepared nanocomposite systems were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller analysis, vibrating-sample magnetometer and inductively coupled plasma optical emission spectroscopy. Catalytic activity of CuFe2O4@SiO2@AAPTMS@Ni(II) and CuFe2O4@SiO2@AAPTMS@Cu(II) MNPs was also studied toward one-pot the Knoevenagel–Michael reaction of aromatic aldehydes with 4-hydroxycoumarin. All reactions were carried using 40 mg of the nanocatalysts in refluxing H2O within 12‒45 min to afford biscoumarin materials in 84–96% yield. The obtained results exhibited that catalytic activity of the Ni(II)-composite system was higher than the Cu(II)-analogue. Moreover, reusability of the nanocatalysts was examined for five consecutive cycles without the significant loss of the catalytic activity. [ABSTRACT FROM AUTHOR]

This research investigates the adsorption capacity of a novel composite material, namely nano zero-valent iron coated coffee grounds (nZVI-CG), for removal of zinc (Zn) and nickel (Ni). nZVI particles were synthesized and immobilized to the surface of waste coffee grounds (CG) using the ultrasonic-assisted liquid phase method. Characterization of synthesized nZVI-CG composite and bare CG showed that nZVI coating has increased the surface area significantly. Batch tests were conducted to examine the effects of pH, reaction time and initial metal concentrations on Zn2+ and Ni2+ removal. At an initial metal concentration of 10 mg-Ni/L and 10 mg-Zn/L, nZVI-CG removal rates for Zn2+ and Ni2+ were observed as 98.89% and 97.29%, respectively; while removal rates of bare CG have remained at 51% (Zn2+) and 48.1% (Ni2+). Moreover, acidic conditions were observed to deteriorate Ni2+ and Zn2+ adsorption since most functional groups of the metals were protonated. Increasing initial nickel and zinc concentrations decreased removal rates. While the model fittings improved with increasing pH, in the case of nZVI-CG, Langmuir isotherm gave the best fits for Ni2+ and Zn2+ at pH 5 and 7. Also, our experimental results followed the pseudo-second-order kinetic model, regardless of the used adsorbent. Consequently, our results showed that nZVI-CG composite material is a promising alternative adsorbent for pilot scale metal removal/recovery applications. [ABSTRACT FROM AUTHOR]

Two new Ni(II)-based complexes synthesized and used as an efficient photocatalyst for antibiotics photodegradation. [Display omitted] Two new Ni(II) complexes having compositions [Ni(phen)(HL)(H₂O)] (1) and [Ni 2 (phen) 2 (H₂L) 2 (H₂O) 6 ·2H₂L] (2) (H 3 L = 4′-(3,4-dicarboxylphenyloxy)-4-biphenyl carboxylic acid; phen = 1,10-phenanthroline), have been successfully synthesized solvothermally and characterized by microanalyses, FTIR and single crystal X-ray diffraction. The single crystal X-ray diffraction analyses revealed that both 1 and 2 possess distorted octahedral geometry and displayed varied types of non-covalent interactions to stabilize their solid state frameworks. Further, these complexes have been used as photocatalysts for the photodegradation of antibiotics. The photocatalysis experiments reveal that 1 is relatively a better photocatalyst than 2 for photo-decomposing dimetridazole (DTZ) upto 92.5 % in time spans of 45 min. Additional investigation on 1 suggests that it retains its photocatalytic activity after six catalytic cycles indicating its efficient catalytic activity and reusability. The plausible photocatalytic mechanism have been addressed with the help of density of states plots and Hirshfeld surface analyses. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis, characterisation and DFT analysis of an N,O bidentate Schiff base, ((E)-(4-methoxybenzylimino)methyl)phenol, (L1c) and its Ni(II) and Pd(II) complexes. The structures were elucidated via elemental analysis, UV–Visible, NMR, IR and single crystal X-ray diffraction. Complexation of L1c with Ni(II) and Pd(II) was observed to induce different degrees of bathochromic effect on n → π∗ and π → π∗ electronic transitions. A comparison of the experimental data of UV–Visible, NMR, IR and X-ray with those calculated using DFT and TD-DFT methods where five hybrid functionals were tested in gas, IEF-PCM and SS-PCM models was also carried out. The results show that the reproduction of maximum absorption bands n → π∗ and π → π∗ is strongly related to the tested hybrid functionals and solvatochromic effects. Relatively good concordance was obtained between experimental and calculated NMR chemical shifts, IR and X-ray parameters. A bioactivity evaluation against HCT116 and Escherichia coli displayed that the parent ligand L1c is a more superior anticancer and antibacterial agent than the positive controls of 5FU and gentamicin respectively. However, both complexes showed poor activity as anticancer agent and no activity observed against tested bacteria.

The development of analytical methods of histamine using Ni (II) and alizarin red S reagents by UV-Vis spectrophotometry has been done. The objective of this research is to determine the ability of Ni(II) and alizarin red S to form color complex compound with histamine and it will be used to detect the presence of histamine qualitatively and quantitatively as well. Absorbance was measured at a maximum wavelength of 604 nm. In this method, it has been carried out optimization of analytical parameters such as the concentration of Ni(II), the concentration of alizarin red S, pH, and respond time. Analytical parameter optimization showed concentration of Ni(II) is 20 ppm, alizarin red S 75 ppm, pH 8, and a respond time of 15 minutes. Method validation indicated that the coefficient of variation, detection limit, and the limit of quantitation are 0.245%; 9.49 ppm; and 31.62 ppm respectively with a sensitivity of 0.0063/ppm and linearity of 0.99. Accuracy to histamine with a concentration of 50, 75, and 125 ppm are 105.87%, 101.06%, 97.21%, respectively.

C- Styrenyl functionalized Ni(II)(cyclam) was prepared in a two step sequence from Ni(II)(HMD) and these new complexes were characterized with structural and voltammetric methods. The reaction between [Ni(HMD)](OTf) 2 (HMD = 5,7,7,12,14,14-hexamethyl-1,4,8,11-teraazacyclotetradeca-4,11-diene) and benzaldehyde in the presence of NaOH afforded the 5,7-di(styrenyl) derivative [Ni(HMD-Styr)](OTf) 2 (1), which was converted to the corresponding cyclam complex [Ni(HMC-Styr)](OTf) 2 (2) upon NaBH 4 reduction. Addition of NaBPh 4 to the reduction reaction mixture led to the isolation of [Ni(HMC-Styr)](BPh 4) 2 (2′). Single crystal X-ray diffraction studies of 1 and 2′ revealed a square planar NiII center in both [ 1 ]2+ and [ 2 ]2+, which is characteristic of a low spin NiII d 8 center. Complexes 1 and 2 remain low spin in acetonitrile solution as evidenced by their 1H NMR spectra and Vis absorption spectra. Complex 1 displayed two irreversible one-electron reductions between −1.4 and −1.8 V (versus Fc(+1/0)) under Ar in 20% aqueous acetonitrile, and exhibited a new peak around −1.9 V under CO 2 , indicating a mild activity towards CO 2 reduction. In contrast, complex 2 displayed a reversible one-electron reduction at −1.59 V (versus Fc(+1/0)) under Ar, and a less reversible reduction under CO 2 without shift in potential, revealing the lack of activity towards CO 2. [ABSTRACT FROM AUTHOR]

A new polyiodide compound [Ni(bpy) 3 (H 2 O) 2 ]·bpy·2H 2 O·2I 3 − with the rare 1D → 3D interdigitated architecture has been synthesized by hydrothermal method. A new polyiodide compound [Ni(bpy) 3 (H 2 O) 2 ]·bpy·2H 2 O·2I 3 − (1), where bpy is 4,4′-bipyridine, has been synthesized by hydrothermal method. In 1 , the adjacent Ni(II) ions are bridged with the bpy ligand to form a 1D chain, which is further extended to be a 3D supramolecular framework by π – π interactions. This 3D supramolecular framework is a rare 1D → 3D interdigitated architecture. Compound 1 has been characterized by X-ray crystallography, elemental analysis, IR, PXRD and TG. The variable-temperature magnetic studies indicate very weak antiferromagnetic interactions in 1. [ABSTRACT FROM AUTHOR]

The present study investigated the preparation of nitric acid modified powder activated carbon (MPAC) and its adsorption of trace amounts of Ni(II) from aqueous solution. Results showed that raw powder activated carbon modified with 15% nitric acid (MPAC-15%) had the most developed pore structure and the highest adsorption efficiency for Ni(II) in aqueous solution. For MPAC-15%, the pore width was dominated by micropores with pore width about 1 nm and the total amount of chemical functional groups of MPAC-15% was 0.6630 mmol/g. Ni(II) adsorption tests indicated that the highest adsorption efficiency of MPAC-15% was 98%. The adsorption saturation time of MPAC-15% was about 120 min and the pH-dependent adsorption test showed that neutral conditions (6.5 < pH < 7.5) were suitable for Ni(II) adsorption. The adsorption kinetic analysis revealed that the pseudo-second order adsorption model fitted the adsorption process significantly. Thus, Ni(II) adsorption by MPAC-15% was dominated not only by physical adsorption via highly developed micropores but also by chemical adsorption between Ni(II) and surface functional groups. Adsorption isotherm analysis illustrated the Langmuir model was favorable for the adsorption of with R² = 0.9874. [ABSTRACT FROM AUTHOR]

A new adsorbent modified from walnut shell (MWNS) was prepared by grafting aspartic acid onto walnut shell (WNS). Two samples (MWNS1, MWNS2) were characterized through SEM, elemental analysis, XPS, point of zero charge analysis and N2-BET analysis. The adsorption behaviors of Ni(II) onto WNS, MWNS1 and MWNS2 were studied. The results showed that the adsorption kinetics of Ni(II) onto MWNS1 and MWNS2 followed the pseudo-second-order model, while the ones onto WNS followed the pseudo-first-order model. The adsorption mechanism was investigated using the intraparticle diffusion model. The equilibrium data of Ni(II) adsorption onto MWNS2 were analyzed using the Langmuir, Freundlich and Dubinin-Redushkevich (D-R) models. Meanwhile, the mean feature concentration (Ce') correlated with temperature was determined. The values of the mean free energy (E) obtained from the D-R model indicated the adsorption process was conducted by monolayer chemisorption for Cee' and followed by physical adsorption for Ce>Ce'. The thermodynamic parameters (ΔG, ΔH and ΔS) showed that the Ni(II) adsorption onto MWNS2 was spontaneous, endothermic and entropy driven. Recycling property of MWNS2 was studied. [ABSTRACT FROM AUTHOR]

Valsartan (VAL) can be analyzed at the mercury electrode in the presence of nickel (II) yielding a sensitive cathodic peak at − 0.7 V which may be attributed to the reduction of the complex formed between nickel and VAL. Low LOD and LOQ were achieved (7.6 and 23 nM, respectively) permitting the analysis of VAL not only in its pharmaceutical formula, but also in human urine. The influence of adding transition metal, Ni(II), to the electrolyte containing VAL, on the voltammetric response was studied. Differential-pulse voltammetry, using working electrode: hanging mercury drop electrode (HMDE), was applied to elucidate and confirm the possible complexation reaction that could occur between VAL and nickel which aids in the determination of VAL in tablets and human urine. A simple cleanup procedure was applied for urine samples that involves the use of solid-phase extraction with the elution of VAL with methanol. The polarographic peak, which corresponds to the reduction of Ni(II) in the formed complex with VAL, was a function of the concentration of VAL, pH of the medium and Ni(II) concentration at the electrode surface. At Britton–Robinson buffer pH 6 and using 800 µM Ni(II), the reduction peak current linearly varied with the VAL concentration over the ranges of 25–150 and 25–200 nM in tablets as well as urinalysis, respectively. [ABSTRACT FROM AUTHOR]

Abstract In this study, nanochitin-contained magnetic chitosan (FPCC) microfibers were prepared successfully via continuous injection gelation method and employed to remove Ni(II) ion from aqueous solution. Firstly, Fe 3 O 4 -nanoparticles were encapsulated into ε-caprolactam (CL) monomer solution in the presence of polystyrene (PSE), followed by CL anionic ring-opening polymerization and PSE removal, and obtained magnetic polyamide 6 (PA 6) microparticles (FP). After that, the economical FPCC microfibers can be prepared by adding FP microparticles and nanochitin (n-CT) into poly(vinyl alcohol)/chitosan hybrids (PVA/CTS). The obtained FPCC microfibers had shown significant advantages in production, separation, and adsorption when compared to the hydrogel beads prepared by the traditional method (instantaneous gelation method). Within 10 h, 99.7% Ni(II) could be adsorbed by FPCC magnetic microfibers (adsorbent dosage: 1 g, pH: 4.1, and temperature: 293 K). More attractively, the hybridized microfibers could be easily separated from the aqueous solution through a magnetic separation method after Ni(II) adsorption. Ni(II) adsorption behaviors of the hybrid microfibers conform to the Langmuir isotherm model and pseudo-second-order kinetic model. Besides, the possible adsorption mechanism was also discussed. Graphical abstract Unlabelled Image Highlights • Magnetic microfiber adsorbents were prepared via continuous injection gelation method. • Magnetic microparticles endow hydrogels with remote separation capacity. • Microfibers showed significant advantages in production, separation and adsorption. • The maximum Ni(II) removal percentage was 99.7%, higher than other reported sorbents. • Adsorption occurs via pseudo-second-order kinetic and Langmuir isotherm models. [ABSTRACT FROM AUTHOR]

Graphical abstract Three new tetranuclear square Cu(II) and Ni(II), [2 × 2] grid complexes comprising Symmetrical ditopic open chain ligands with terminal carboxylate/oxime functions and central pyrimidine ring are reported. These [2 × 2] square grids are dominated by intramolecular antiferromagnetic exchange coupling. Highlights • Synthesis of symmetrical ditopic open chain ligands with terminal carboxylate/oxime functions and central pyrimidine ring are reported. • Three new tetranuclear square Cu(II) and Ni(II), [2 × 2] grid complexes have been isolated and structurally characterized. • Reported complexes show dominantly intramolecular antiferromagnetic exchange coupling. • The reported ligands demonstrate the propensity for expanded cluster growth, if the right combination of donor components and reaction conditions are chosen. Abstract The successful synthesis of new pyrimidine based organic ligands with terminal carboxylate and oxime functional groups, followed by their employment in metallogrid self-assembly has yielded three tetranuclear [Ni 4 (L1) 4 ]∙2CH 3 CN∙4CH 3 OH·4H 2 O (1), [Cu 4 (HL1′) 4 ]∙8CH 3 OH·28H 2 O (2) and [Ni 4 (H 2 L2) 4 ](CF 3 SO 3) 8 ∙4CH 3 NO 2 ·8H 2 O (3), [2 × 2] metallogrid complexes. The complexes have been well characterized by elemental analyses, IR spectra, UV-vis spectra and X-ray structural analyses. Variable temperature magnetic measurements/studies done on these three complexes followed by magnetic data fitting suggest that all the three complexes are dominated by intramolecular antiferromagnetic exchange coupling. [ABSTRACT FROM AUTHOR]

The conditions of the simultaneous preconcentration of Ti(IV), V(V), Mo(VI), and Ni(II) on a double-layer support and their sequential determination using organic reagents are studied by diffuse reflectance spectroscopy. Disks of polyacrylonitrile fiber filled with an anion exchanger (PANV–AV-17) or a cation exchanger (PANV–KU-2) are used as supports. The determination of titanium and nickel on PANV–KU-2 disks is based on the successive interaction of nickel with dimethylglyoxime (DMG) and titanium with 2,7-dichlorochromotropic acid (DCCA). The determination of vanadium and molybdenum on PANV–AV-17 disks is based on the interaction of vanadium with 8-hydroxyquinoline-5-sulfonic acid (HOS) and 0.1 M HCl and molybdenum with phenylfluorone (PF). The dependences of the analytical signals of Ti‒DCCA and Ni‒DMG complexes on PANV‒KU-2 and V‒HOS and Mo‒PF complexes on PANV‒AV-17 on the pH of solutions in sorption in the dynamic mode are studied. The optimal pH value of the solutions for the simultaneous sorption of four elements is 3.5 ± 0.1. The influence of accompanying elements in the mixture on the determination of Ti, V, Mo, and Ni is studied. Characteristics of the sorption-spectroscopic determination of elements are given, i.e., the sequence of the treatment of support disks with reagent solutions, the conditions for eliminating the signal of the previous element, the coefficients of calibration equations and the linearity ranges of the calibration curves, and the limits of detection of elements. Selectivity factors are determined and a procedure for the sorption-spectroscopic determination of Ti, V, Mo, and Ni on their simultaneous presence is developed. The results of analysis of model solutions with different ratios of elements are presented; RSD < 15%. [ABSTRACT FROM AUTHOR]

The aim of our study was to evaluate the po­tential of a white rot fungi (Phanerochaete chryso-sporium) immobilized on sepiolite, in a continuous flow removal of trace heavy metals. The present work proposes the use of a white rot fungi (Phan­erochaete chrysosporium) immobilized on sepiolite as a new sorbent in trace metal determination. The procedure is based on the biosorption of Cr(III), Ni(II) and Cd(II) ions on a column of sepiolite loaded with dried, dead fungi components prior to their determination by atomic absorption spectro­photometry. The effects of pH, amount of solid phase, eluent type and volume of the sample solu­tion, flow rate of solution on the retention of the metal ions have been studied. The optimum pH value of quantitative sorption for Cr(III), Ni(II) and Cd(II) was found to be 5. These metal ions can be desorbed with 1 M HCl (recovery 95-100 %). The effects of some interfering ions were also studied. The optimum experimental parameters were deter­mined to be pH 5, concentration of 10 mg/L, con­tact time of 30 min and 0.2 g of adsorbent for a quantitative adsorption of the metals. The optimum flow rate was found as 2.5 mL/min for all metal ions. Each column can be used up to 20 successive analyses without considerable change in recoveries of metal ions. This procedure was applied to Cr(III), Ni(II) and Cd(II) determination in aqueous solutions, including tap water system. These metal ions can be desorbed with 1 M HC1 (recovery 95-100 %). The results indicate advantages of high metal biosorp­tion capacity and satisfactory recovery of Cr(III), Ni(II)andCd(II). The proposed method is very good as regards simplicity, sensitivity, selectivity, precision, accura­cy and column stability. [ABSTRACT FROM AUTHOR]

Abstract In this study, the effects of interlayer on Ni(II) sorption at the vermiculite-water interface was investigated by combining batch technique, surface complexation model (SCM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS) analyses. The results showed that alkali cations can enter the interlayer of vermiculite, and cause the collapse of vermiculite interlayer to different extent mainly due to the different ionic radii and hydrated energies. XRD patterns confirmed the order of collapse extent following the trend of Cs+ ≈ Rb+ > K+ > Na+. Subsequently, the sorption edges of Ni(II) on vermiculite were exhibiting the same trends as the interlayer collapse extents in different electrolytes. SCM confirmed that the sorption was mainly controlled by ion exchange (IE) in low pH region, while the inner-sphere complexes (ISCs) and surface-induced precipitates became the dominant species in high pH region. Both XPS and EXAFS analyses have confirmed that the formations of Ni-precipitates and Ni Al layer double hydroxide (Ni Al LDH) were indeed enhanced after the interlayer collapsed. Therefore, the sorption mechanisms of Ni(II) could be regulated by the interlayer of vermiculite. These findings are of great importance to understand the sorption mechanisms of heavy metals at the expandable clay-water interfaces and their environmental behaviors. Highlights • The sorption mechanism of Ni(II) on vermiculite was explored combining EXAFS and surface complexation model. • The regulation of alkaline cations on the interlayer of vermiculite • The regulation of interlayer on the sorption species of Ni(II) on vermiculite • Research findings facilitated the assessment of Ni(II) migration and fate in the environment. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Activated carbon (AC) derived from Phragmites Australis (PA) with phosphoric acid activation as a low-cost adsorbent is extensively used in water treatment. In this study, a novel manganese formate hydrate (MFH) in-situ modified activated carbon (AC-MFH) has been proposed and investigated. The physical and chemical characteristics of adsorbents were characterized by N 2 adsorption/desorption, Fourier transform infrared (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that AC-MFH had more microporous structures and surface oxygen-containing functional groups than AC. The Ni(II) adsorption behaviors of adsorbents were investigated by batch experiments, the results suggested that AC-MFH showed 20% higher Ni(II) adsorption capacity than that of AC and the associated adsorption isotherms and kinetics well fitted to the Langmuir model and pseudo-second-order model, respectively. The Ni(II) adsorption mechanisms of AC-MFH were investigated by FTIR and XPS analysis. These results indicated that the adsorption of Ni(II) mainly depended on the surface chemistry between the Ni(II) and surface oxygen-containing functional groups. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract To improve the adsorption properties of activated carbon (AC), powder-hydrolyzed feathers (PHF) bio-modifier and Trapa natans husks (TH) were used for AC preparation to enhance its physicochemical and adsorption properties. The physicochemical properties of the original activated carbon (AC) and PHF-modified activated carbon (ACF) were systematically examined by N 2 adsorption/desorption, elemental analysis, Boehm titration, and X-ray photoelectron spectroscopy (XPS) techniques. The ACF exhibited higher S mic /S BET (35.97%) and V mic /V tot (45.61%) than that of AC (16.68% and 6.56%), although only slightly decreases in the S BET and V tot observed for the ACF after PHF modification. Meanwhile, ACF shows more functional groups (O/N-containing functional groups) due to in situ modification. Furthermore, the batch adsorption experiments revealed that ACF showed much higher adsorption capacity for Cd(II) and Ni(II) (50.25 and 46.73 mg/L) than that of AC (33.90 and 31.15 mg/L). According to the results of fitting of adsorption models and the XPS analysis, microporous entrapment surface complexation, cation exchange and electrostatic attraction play key roles in Cd(II) and Ni(II) removal. [ABSTRACT FROM AUTHOR]

Macrocyclic complexes with bivalent metal ions Co(II), Ni(II), Cu(II) have been synthesized by [2+2] condensation of 2,6 pyridine di carboxylic acid and thiourea by template method in ethanolic medium. The synthesized complexes have been characterized with the help of various physico-chemical techniques viz. elemental analyses, magnetic susceptibility, conductivity measurements and spectral (IR, UV and EPR) techniques. The low value of molar conductivity indicates the non-electrolyte nature of the complexes. All the complexes are of high-spin type. On the basis of above studies an octahedral geometry has been assigned for Co(II) and Ni(II) complexes whereas tetragonal geometry around the Cu(II) ion. The biological activities of the metal complexes have been tested in vitro against a number of bacterial species to assess their inhibiting potential. Cu(II) complexes were found to more active as compared to Co(II) and Ni(II) complexes. [ABSTRACT FROM AUTHOR]

In this study, two novel supported liquid membranes (SLMs) was developed by using Trioctylphosphine oxide (TOPO) and N-(furane-2-iylmethyl)-N'-hydroxy-2-oxo-2-(4-phenylphenyl) eteneimideamide (BKOF) as a carrier that have different functional groups, each dissolved in the organic phase N-N-dimethyl formamide. Hydrophobic polyvinylidene fluoride (PVDF) and polyamide microporous membranes were used as support to prepare these membranes. Developed membranes were characterized with several analytical methods, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and thermal gravimetric analysis (TGA). Characterization processes confirm the novelty of membranes due to different surface morphologies of prepared SLMs, compared to the PVDF and polyamide supports. Performance of prepared SLMs were evaluated by rejection tests for Ni(II) and Fe(III)) from aqueous solutions by using Donnan dialysis method. The highest flux values were obtained when the feed phase concentration of 1.0x10-1 M NiCl2.6H2O or 1.0x10-1 M Fe(NO3)3.9H2O, the strip phase concentration of 1.0x10-1 M HCl or 1.0x10-1 M HNO3, respectively. [ABSTRACT FROM AUTHOR]

Carbon nanofibers (CNFs) have been extensively investigated due to their strong uptake and complexation ability. In this work, CNFs was characterized by using SEM, TEM, FTIR, XPS and Raman spectra. The uptake of Co(II) and Ni(II) on bacterium-derived CNFs as a function of contact time, pH, ionic strength and temperature was investigated using batch techniques. The pH-dependent uptake indicated that the uptake of Co(II) and Ni(II) onto CNFs was significantly higher at high pH values than that at low pH values. The uptake of Co(II) and Ni(II) onto CNFs was hardly affected by ionic strength, suggesting the formation of inner-sphere surface complexation of Co(II) and Ni(II) onto CNFs over a wide pH range. The Langmuir model described the uptake of Co(II) and Ni(II) onto CNFs better than the other models did. According to regeneration experiments, CNFs displayed good recoverability and recyclability in the Co(II) and Ni(II) uptake process. The findings presented herein play a significant role in the scavenging of metal ions on inexpensive and available CNFs in environmental cleanup applications. [ABSTRACT FROM AUTHOR]

Abstract The Ni(II) derivative, namely Ni [L]⋅ClO 4 (1) is afforded incorporating the Schiff base precursor, (HL) = [2-((E)-(2-(2-aminoethylamino)ethylimino)methyl)-6-methoxyphenol]. Single crystal X-ray structure reveals that in 1 , the central Ni(II) atom is surrounded by N 3 O donor set and possesses on a distorted square-planar environment. EPR spectra confirms that compound 1 is diamagnetic due to square-planar geometrical nature having a spin state S = 0. DFT computational studies are in good agreement with the structural and spectral data. The electrochemical study of compound 1 shows one quasi-reversible oxidative peak at 0.92 V vs Ag/AgCl due to a redox couple of Ni(II)/Ni(III); nd a weak oxidation peak at −0.72 V vs Ag/AgCl which might be assigned to Ni(I/II) couple. Highlights • Mononuclear NiII complex with a tetradentate Schiff base precursor is afforded. • Interestingly, three different N atoms of N 3 O donor set are coupled to NiII atom. • EPR study confirms the diamagnetic nature of the compound having a spin state S = 0. • TD-DFT computation supports the electronic nature of metal ion. • Redox study affirms one quasi-reversible oxidative peak of Ni(II)/Ni(III) and a weak oxidative peak of Ni(I/II) couple. [ABSTRACT FROM AUTHOR]

The removal of Ni(II) using Uludag fir (Abies nordmanniana subsp. bornmuelleriana Mattf.) was investigated as a function of severeal parameters such as initial Ni(II) concentrations, solution pH, adsorbent dosage, temperature and contact time by batch experiments. Experimental data were analysed using the Langmuir and Freundlich isotherms. It was found that the isotherm data was best fitted with Langmuir isotherm (R²= 0.97). Kinetic studies indicated that the pseudo second order kinetic model fit better than the pseudo first order kinetic. Also the thermodynamic parameters (ΔG°, ΔH°, ΔS°) were performed and the results indicated that the adsorption process was feasible, spontaneous and endothermic in nature. The results obtained that use the waste to treat the waste. The results suggested that Uludag fir (Abies nordmanniana subsp. bornmuelleriana Mattf.) is a potent candidate for efficient biosorbent for removing Ni(II) from aqueous streams. [ABSTRACT FROM AUTHOR]

Animal bones are natural and rich source of calcium hydroxyapatite (HAP), which was found to be a good sorbent material for heavy metals and radionuclides. Various treatments can reduce the content of bone organic phase and improve sorption properties. In this study, sorption capacities of raw bovine bones (B) and samples obtained by chemical treatment with NaOH (BNaOH), by heating at 400 oC (B400) and by combined chemical and thermal treatment (BNaOH+400), were compared, using Ni(II) ions as sorbates. Maximum sorption capacities increased in the order B