A simple approach for synthesizing needle‐shaped α ‐Ni(OH) 2 nanoparticles adorned on graphene oxide, α ‐Ni(OH) 2 ‐GO, is described. The nanocomposite was isolated as an air‐stable black powder and characterized by various instrumental techniques. The interweaved needle‐shaped morphology and the average particle diameter ~7 nm of the adorned α ‐Ni(OH) 2 nanoparticles were ascertained by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) analysis, respectively. The catalytic potential of the nanocomposite was scrutinized in the synthesis of monosubstituted ketones via a hydrogen autotransfer strategy and synthesis of azines via dehydrogenative pathway. The products of both reactions were isolated in excellent yields and characterized by nuclear magnetic resonance (NMR) spectroscopy. α ‐Ni(OH) 2 ‐GO could be segregated and recycled for up to five cycles. The operational simplicity, broad substrate scope, non‐toxic side products, recyclability, and superior catalytic potential of the catalyst are some of the remarkable features of this protocol.

An efficient and base-free approach has been described for the synthesis of an array of quinoxalines by the annulation reaction of terminal alkynes with o-phenylenediamines in the presence of cobalt-doped-magnesium oxide (Co-MgO) as a heterogeneous nanocatalyst. This method has been successfully employed for the synthesis of a wide range of functionalized quinoxalines in high yields (70-90 %). All products were isolated either as solid or liquid and fully authenticated by 1H and 13C NMR spectral data. Operationally, the reaction protocol is simple, mild, and base-free. The Co-MgO catalyst can be successively reused for four runs with a negligible loss in catalytic activity. Five green chemistry metrics, i.e., AE, E-Factor, CE, PMI, RME for the reaction were calculated and found to be in close proximity to the ideal values, suggestive of environmental acceptability of the reaction protocol. The broad functional group tolerance and a mechanistically different approach may be a potent supplement to conventional methods for the synthesis of quinoxalines.

A visible-light-induced efficient methodology has been developed for the C-H selenylation of pyrazolo[1,5-a]pyrimidine derivatives employing erythrosine B as the photocatalyst. This is the first report on the regioselective selenylation of pyrazolo[1,5-a]pyrimidines. The efficiency of this methodology for the selenylation of different electron-rich heterocycles like pyrazole, indole, imidazo[1,2-a]pyridine, imidazo[2,1-b]thiazole, and 4-(phenylamino)-2H-chromen-2-one has been also demonstrated. The exploration of erythrosine B as a photocatalyst with a simple and mild procedure, wide substrate scope, and practical applicability and the employment of eco-friendly energy, oxidant, and solvent are the attractive characteristics of this methodology.

A new biocomposite of chitosan, chitosan-supported di(pyridine-2-yl)methanone-Ni(II) complex, CS-DPM-Ni, is synthesized for the first time. The biocomposite is thoroughly characterized by FTIR, PXRD, XPS, FESEM, EDX, TGA, ICP-OES, and elemental analysis. The synthesized composite is successfully used as a heterogeneous catalyst in the synthesis of a library of xanthone derivatives by the intermolecular catalytical coupling of 2 substituted benzaldehydes and phenols. The catalyst could be retrieved from the reaction mixture by simple filtration and reused for up to four catalytic cycles. All products were isolated in good to high yields (65-90 %) with good turnover numbers (TONs), and fully characterized by 1H and 13C{1H} NMR spectroscopy. The green chemistry metrics values for the reaction were discerned and found to be close to the ideal values.

A new composite, cucurbit[6]uril (CB[6])-supported magnetic nanoparticles, Fe3O4-CB[6], was synthesized via a co-precipitation method in air and fully characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, inductively coupled plasma-mass spectrometry, and vibrating sample magnetometry techniques. It has been found to be a highly efficient, economic, and sustainable heterogeneous catalyst and has been employed for the first time for the synthesis of a series of biologically important 2-substituted benzimidazoles from various benzyl alcohols and 1,2-diaminobenzenes under solvent-free conditions via acceptorless dehydrogenative coupling to afford the corresponding products in good to excellent yields (68-94%). The magnetic nature of the nanocomposite facilitates the facile recovery of the catalyst from the reaction mixture by an external magnet. The catalyst can be reused up to five times with negligible loss in its catalytic activity. All the isolated products were characterized by 1H and 13C{1H} NMR spectroscopy.

The reducibility of iron ore with coke is an important parameter in a blast furnace process which significantly affects the production of pig iron. When iron ore and coke mixed with developed high energetic additive in blast furnace it promotes low temperature iron ore reduction and leads to coke saving. Results of proximate analysis values for moisture, ash, volatile matter and fixed carbon content were 15.28%, 16.62%, 1.02% 67.07% and 14.15%, 15.29%, 0.48% and 70.07% respectively with and without additive. Additive increased metallization of iron (Fe) content from 48.61% to 51.89% and decreased the ferrous oxide (FeO) from 12.26% to 9.28%. Additive reduced the CaO, SiO2, Al2O3 and MgO by 10.90%, 8.31%, 2.79%, and 1.47% respectively which showed improvement of quality of sinter and further reduction of the pig iron sulphur content from 0.22 to 0.08% which reflected improvement in metal product quality. Additive increased the slag chemical composition of CaO, SiO2, MgO, Al2O3 and MnO by 4.79%, 2.62%, 7.35%, 2.82 % and 19.56% respectively and decreased the FeO by 32.23%. Additive reduced the consumption of coke by 700 kg and increased production by 2% resulting saving of coke by 91 kg per ton of pig iron production. Additive increased reducibility, quality and productivity of pig iron with decrease in batch maturing period. Further it exhibited better performance in sintering process and reduced the un-agglomerated material. This paper describes the effect of additive used in the blast furnace process during industrial pig iron production.

A new N-heterocyclic carbene (NHC) copper(I) complex supported on graphene oxide (GO-NHC-Cu) was synthesised and thoroughly characterised by various instrumental techniques such as FT-IR, FT-Raman, PXRD, XPS, FESEM, EDX, HRTEM, TGA and ICP-OES. The catalytic activity of the supported complex was explored in the N-alkylation of anilines with alcohols under solvent-free and aerobic conditions to afford monoalkylated products in good to excellent yields (20 products, 83–96%). All products were isolated and characterised by 1H and 13C{1H} NMR spectroscopy. The catalyst was recuperated from the reaction mixture by simple filtration and reused for up to five successive cycles with insignificant loss in the catalytic activity. The control experiments showed that the reaction proceeded in aerobic conditions. The green chemistry metrics for the reaction were found to be fairly close to the ideal values: carbon efficiency (95.9%), E-factor (0.15), atom economy (92.14%), process mass intensity (1.15) and reaction mass efficiency (86.80%). The air stability, selectivity, recyclability of the catalyst, and the high yields of the products under solvent-free conditions are some of the salient features of the reported methodology.

A copper-triazine-dendrimer-functionalized graphene oxide (CTD-GO) is synthesized for the first time. The structure of the dendrimer is confirmed by Fourier transform infrared (FT-IR), Fourier transform (FT) Raman, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), elemental mapping, atomic absorption spectroscopy (AAS), and thermogravimetric analysis (TGA). The catalytic activity of the CTD-GO is demonstrated in green synthesis of a series of propargylamine derivatives in high yields via A(3)-coupling of aldehyde, alkyne, and amine in water. After the reaction, the catalyst was easily recuperated from the reaction mixture and reused up to four times without any significant loss in its catalytic activity. Operational simplicity, high yields of product, use of green solvent, facile recovery and recyclability of the catalyst, and easy workup are the salient features of this procedure.

Silver (Ag) is extensively used in manufacturing of electronic goods due to its low cost and conductivity. In view of the escalating demand, stringent, environment rules, and limited sources of Ag, the present paper is focused on the development of hydrometallurgical process flow-sheet to extract Ag from scrap computer keyboards. These keyboards contain ~0.4% of Ag. Initially, keyboards were dismantled to separate the Mylar sheets scontaining Ag. The same were pyrolyzed at 300 °C for 2 h to get enriched metallic part. About 99.99% Ag was leached using 2 M HNO3 at 60 °C within 30 min in close and proper condensed system. Separation techniques (precipitation/cementation) could be used to obtain pure Ag salt/metal. Based on the laboratory-scale experiments, the process flow-sheet developed is economical, eco-friendly, and has potential to be translated to industry for commercial exploitation after scale up/pilot trial.

Synthesis of a series of quinazolines using β-Ni(OH) 2 -CB[6] as a heterogeneous nanocatalyst.

Vapor phase dehydrocyclization reaction of acetaldehyde and ammonia was investigated over K salts of 12-tungstophosphoric acid as catalysts in a continuous flow fixed bed reactor at 350-450 degrees C The yield of 2-methylpyridine and 4-methylpyridine were found to be in the range of 38.0-64.5%. The 2-methylpyridine and 4-methylpyridine are used for the preparation of insecticides, poultry drugs, cattle drugs and anti-tuberculosis drugs, veterinary analgesics etc. respectively. The reaction conditions such as temperature, contact time, and molar ratio for achieving optimal yield with respect to 2-methylpyridine and 4-methylpyridine were discussed. Catalysts were characterized through BET surface area, FT-IR, XRD and TGA. NH3-TPD studies exhibit the moderate acidity. The morphology of the catalysts was also studied by FESEM.

Cu2O NPs immobilized on graphene oxide are used as a heterogeneous catalyst for the synthesis of a series of 1,2,4-triazoles and imidazo[1,2-a]pyridines under solvent-free conditions.

Cobalt, an exceptional cathode material present in lithium-ion batteries (LIBs), is an essential element for the production of energy storage devices. But, the lifespan of rechargeable batteries is decreasing day-by-day, which become obsolete after reaching their end of life. Therefore, an enormous amount of discarded LIBs are generated. Keeping in mind the above, a novel approach has been made to selectively recover cobalt from sulfate leach liquor of discarded LIBs containing 1.4 g/L Cu, 1.1 g/L Ni, 11.9 g/L Co, 6.9 g/L Mn, and 1.2 g/L Li. Initially, Cu and Ni were extracted by solvent extraction techniques using 10% LIX 84-IC. Almost complete precipitation of cobalt occurred from leach liquor at pH ~3 using ammonium sulfide solutions. Cobalt from the precipitated product was further dissolved in H2SO4 in presence of H2O2 at elevated temperature. The leach liquor obtained was evaporated to get the cobalt sulfate with a purity of more than 98%.

The first example of a one-pot three-component tandem annulation approach is described for the synthesis of 2-iminothiazolidin-4-ones by the reaction of aromatic/aliphatic amines, aryl isothiocyanates, and ethyl bromoacetate, catalysed by guanine-functionalized SBA-16, [SBA-16@G], as an efficient and recyclable heterogeneous solid base catalyst. The methodology is simple and offers a broad-substrate scope under mild reaction conditions. (c) 2021 Elsevier Ltd. All rights reserved.

A new graphene oxide (GO) supported Cu(II) Schiff base complex (GO-SB-Cu) has been synthesized by utilizing Schiff base functionalized GO (GO-SB) and copper acetate in ethanol under reflux. The synthesized complex was characterized using several techniques such as Fourier Transform Infrared spectroscopy (FTIR), Powdered X-ray Diffraction (PXRD), Fourier Transform (FT-Raman), Thermo Gravimetric Analysis (TGA), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transition Electron Microscopy (HRTEM), Elemental Dispersive X-ray analysis (EDX), Elemental mapping, X-ray Photo electron Spectroscopy (XPS) and Atomic Absorption Spectroscopy (AAS) analysis. The complex was found to be highly efficient in the click reaction for synthesis of 1,4-disubstituted 1,2,3-triazoles at room temperature and an operationally simple and efficient one-pot synthesis of 2H-indazoles from commercially accessible reactants at ambient temperature, without using any base, additive or co-catalyst. A variety of electron donating/withdrawing groups were employed to explore the scope of the reactions. Interestingly, aliphatic and heterocyclic amines were also tested and found active in the synthesis of 2H-indazoles. Our results demonstrated that the reaction could be scaled up conveniently and the catalyst could be easily recycled upto successive four times without any noteworthy loss in the catalytic action. High yield of the products, easy workup, environmentally benign, high stability of the catalyst and mild reaction conditions are the key points of this catalyst. All the synthesized organic products were identified by 1H and 13C NMR spectroscopy.

A simple non-hydrothermal method for the synthesis of maltodextrin functionalized SBA-16 (SBA-16@MD) is reported for selective adsorption of heavy metal ions (HMIs) including Cd2+, Zn2+, and Cu2+ from aqueous solution. The as-synthesized SBA-16@MD is fully characterized by FESEM, EDX, HRTEM, PXRD, solid-state 13C NMR spectrum, TGA, and BET surface area measurement. The HMIs adsorption was investigated for several parameters, for example, HMIs concentration, adsorbent dose, temperature, pH, contact time, and stirring speed. The SBA-16@MD shows high values of adsorption capacity for Cd2+ (575.53 mg/g), Zn2+ (564.67 mg/g), and Cu2+ (509.73 mg/g) respectively, at pH 6. The calculated adsorption data are best fitted with the Langmuir isotherm inferring homogeneous HMIs adsorption on the surface of SBA-16@MD. The kinetic data are consistent with the pseudo-second-order and intraparticle diffusion models. The calculated thermodynamic data reveals that the nature of adsorption is endothermic and spontaneous. The high values of adsorption capacity, SBA16@MD for Cd2+, Zn2+, and Cu2+ can be explained based on electrostatic interactions and ion exchange taking place between the SBA-16@MD surface and HMIs.

Due to the supply gap towards increasing demand as well as loss of precious metals by illegal recycling, present research reports application-oriented processes developed at CSIR-NML, India to recover precious metals from small components of e-waste containing ~0.1–0.8% Ag, ~0.03–0.9% Au, ~0.01–0.02% Pd, ~0.0003–0.0005% Pt, and related effluent. Firstly, ~99.99% Au was recovered from plated e-waste using the process of selective leaching followed by charcoal adsorption and heat treatment, whereas the second process consists of dismantling, physical/ chemical pre-treatment of e-waste followed by hydrometallurgical processing to recover 99% Ag, 99.9% Au, 95% Pd, and 90% Pt. Apart from the above, leaching and selective precipitation were used to recover ~95% Ag from waste computer keyboards. The effluent generated during the e-waste processing was found to contain ~8–10 mg/L Au, which was also recovered using ion-exchange technique. All processes presented are scientifically validated and commercially viable after scale-up studies.

Novel route has been developed to selectively extract lithium (Li), cobalt (Co) and manganese (Mn) from the leach liquor of discarded lithium ion batteries (LIBs) containing 1.4 g/L Cu, 1.1 g/L Ni, 11.9 g/L Co, 6.9 g/L Mn and 1.2 g/L Li. Initially, Cu and Ni were extracted by solvent extraction techniques using 10% LIX 84-IC at equilibrium (Eq.) pH 3 and 4.6, respectively. Subsequently, precipitation studies were carried out at different conditions such as pH, reaction time, precipitant concentration etc., to optimize the parameters for selective precipitation of Co from the leach liquor. Result showed that 99.2% Co was precipitated from the leach liquor (11.9 g/L Co, 6.9 g/L Mn and 1.2 g/L Li) after extraction of Cu and Ni in a range of pH 2.9 to 3.1 using un-diluted ammonium sulfide solution (10% v/v) as a precipitant at 30 degrees C, while only 0.89% Mn and 0.62% Li were co-precipitated. After Co precipitation, 98.9% Mn was extracted from the filtrate using 10% D2EHPA at equilibrium pH 4.5, and Li remained in raffinate. From the obtained purified solution, metals could be recovered either in a form of salt/metals by precipitation/evaporation/ electrolysis method. (C) 2020 Elsevier Ltd. All rights reserved.

A cocatalyst plays an essential role in photoassisted hydrogen generation, and it is an almost inevitable component of a photocatalyst. Costly noble metal (e.g., Pt) cocatalysts exhibit almost irreplaceable efficiencies, and finding a suitable replacement is a challenging proposition. Controlled synthesis of a nanoparticle cocatalyst on semiconductors at the nanoscale level is one of the most promising approaches to accomplish the Pt equivalent activity. Herein, a photodeposited metallic Ni-based cocatalyst containing a small amount of Pt (<2 atom % with respect to Ni) on reduced/black TiO2-x is introduced. The developed cocatalyst (2.21 wt % Ni and 0.094 wt % Pt with respect to TiO2-x) exhibits better charge separation efficiency and photoassisted hydrogen generation rate than an only-Pt (0.91 wt %) cocatalyst from methanol-water. The rates are 69 and 3.1 mmol g(-1) h(-1) for a Ni-based cocatalyst, while 65 and 2.5 mmol g(-1) h(-1) for a Pt cocatalyst, respectively, under ultraviolet-visible and visible light. A small amount of Pt ensures the photodeposition of Ni nanoparticles adjacent to Pt nanoparticles, enhancing the charge migration from the reduced TiO2-x surface for hydrogen evolution. It is found that in the absence of Pt, the photodeposited Ni(OH)(2) is obtained instead of metallic Ni nanoparticles, which exhibits a comparatively low hydrogen generation rate. The present study opens an alternative way to cocatalyst design and fabrication by the controlled synthesis of nanoparticles for a wide range of photocatalytic conversions facilitated by enhanced charge separation.