Prediction of burning rate of coal in fluidized-bed combustion

A theory has been proposed to evaluate the burning rate of a single carbon particle in a continuously operated coal-fired fluidized bed. Experimental verification was carried out in a laboratory scale 200 mm × 200 mm combustor. The burning rate increases with the increase of the fluidization velocity and the size of the bed material. The predicted data on burning rate agree fairly well with the experimental values. The gas concentration in the bed and freeboard has also been measured and it is seen that the consumption of oxygen mostly takes place in the bed.     

Synthesis of poly(vinyl propionate) from poly(vinyl alcohol) in nonaqueous medium using ethyl nitrate dimethyl sulfoxide as a catalyst

Poly(vinyl alcohol) (PVA) can be dissolved in a nonaqueous medium in the presence of catalytic concentration of ethyl nitrate dimethyl sulfoxide, C₂H₅ONO₂·DMSO. From the PVA solution, poly(vinyl propionate), PVPR was prepared by the homogeneous esterification of PVA with propionic acid. The ester thus formed contained some unconverted hydroxyl group. The formation of the ester was confirmed by the IR and ¹H‐NMR spectra. The molecular weight of the ester was determined by GPC and intrinsic viscosity (η) was determined by viscometric method. Glass transition temperature, T_g, was obtained from differential scanning calorimetric (DSC) analysis. Thermal stabilities of the ester were checked by thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) analysis. The efficiency of the ester as a flow improver of crude oil was also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5675–5679, 2006     

First-principles studies of the superconductivity and vibrational properties of transition-metal nitrides TMN (TM = Ti,V, and Cr)

The present paper reports the structural, electronic, phonon and thermodynamical properties of some transition-metal nitrides (TMN: TiN, VN and CrN) by means of first-principles calculations. The computed equilibrium lattice constant and bulk modulus agree well with the available experimental and theoretical data. The electronic band structure and density of states calculations show metallic nature. The phonon frequencies are positive throughout the Brillouin zone for these compounds in rocksalt structure indicating dynamical stability. The calculated electron–phonon coupling constant λ and superconducting transition temperature agree reasonably well with the available experimental data. These compounds behave as a conventional phonon-mediated superconductor. Within the GGA and quasi-harmonic approximation, thermodynamical properties are also investigated.     

Recovery of metals and other beneficial products from coal fly ash: a sustainable approach for fly ash management

International Journal of Coal Science & Technology - Increasing production and disposal of coal fly ash (CFA) is a matter of serious environment concern. However, CFA contains various...     

Acetamide‐modified hyper‐cross‐linked resin: Synthesis,characterization, and adsorption performance to phenol from aqueous solution

Acetamide‐modified hyper‐cross‐linked resin, HCP‐HMTA‐AA, was prepared and its adsorption performance was evaluated using phenol as the adsorbate. The prepared HCP–HMTA–AA owned predominant micro/mesopores and medium polarity, making it possess a superior adsorption to phenol as compared with polystyrene (PS), chloromethylated polystyrene (CMPS), hyper‐cross‐linked polymer (HCP) and amino‐modified hyper‐cross‐linked resin (HCP–HMTA). The adsorption enthalpy was ?99.56 kJ/mol at zero fractional loading, multiple hydrogen bonding contributed to such a great adsorption enthalpy and an approximately planar hexahydric ring was formed between acetamide of HCP–HMTA–AA and phenol. The dynamic capacity of phenol on HCP–HMTA–AA was 291.3 mg/g at a feed concentration of 946.2 mg/L and a flow rate of 48 mL/h and the resin column was almost regenerated by a mixed solvent including 50% of ethanol (v/v) and 0.01 mol/L of sodium hydroxide (w/v). HCP–HMTA–AA was repeatedly used for five times and the equilibrium adsorption capacity for the five time reached 94.2% of the equilibrium adsorption capacity for the first time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41597.     

Hydrogen evolution reaction: The role of arsenene nanosheet and dopant

The state-of-the-art density functional theory (DFT) is employed to study the catalytic activity of arsenene for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). We have included dispersion correction to get accurate adsorption energy on the individual catalytic surface (top site). Using binding energy calculation, arsenene is shown to be a potential candidate for HER. Here we investigate the stability and electronic properties of the honeycomb structure of the arsenene system using first-principles calculation to find the effect of different dopants on the fundamental band gap, which is one of the primary parameters in the photocatalytic water splitting. Further, we sieved the dopant for better HER catalytic activity by substituting one of the arsenene (As) atoms by B, N, O, Ge, Ga and Se atoms to make arsenene a better candidate for HER. Our studies depict that HER activity is increased by 82% for O-doped arsenene and OER activity by 87% for B-doped arsenene as compared to pristine arsenene.     

Comparative delivery of Diltiazem hydrochloride through synthesized polymer: Hydrogel and hydrogel microspheres

In this study, interpenetrating polymer network (IPN) hydrogel based on polyvinyl alcohol (PVA) networking with polyacrylic acid (PAA) were prepared by a non‐conventional emulsion method without any added crosslinker, using benzoyl peroxide as initiator and sodium chloride (NaCl) as additive. The IPN hydrogel was characterized by using Fourier transformed infrared (FTIR) spectrophotometry, Thermo gravimetric analysis (TGA), and Scanning electron microscopy (SEM). (PVA‐co‐PAA)/NaCl normal IPN hydrogel (H) were fabricated into hydrogel microspheres (HM) by modified emulsion crosslinking method using glutaraldehyde‐saturated toluene as crosslinker and were loaded with Diltiazem hydrochloride (DL). The IPN hydrogel showed more swelling in simulated intestinal fluid (SIF). (PVA‐co‐PAA)/NaCl HM formulation A1 showed comparatively higher DL entrapment (79%) and better control over DL release up to 24 h. By comparing antihypertensive activity of DL loaded two formulations in normotensive rats, HM formulation A1 found more effective in reducing blood pressure to 40.1%. The experimental results demonstrated that (PVA‐co‐PAA)/NaCl HM had the greater potential than normal hydrogel to be used as a drug carrier. A single use of the prepared hydrogel microsphere system of DL can effectively control hypertension in rats. The system holds promise for clinical studies. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A Robust Extended Complex Kalman Filter and Sliding-mode Control Based Shunt Active Power Filter

Abstract—This article presents the design of a new shunt active power filter that employs a modified robust extended complex Kalman filter approach with an exponential robust term embedded for reference current estimation together with a current controller based on the sliding-mode control concept. The robust extended complex Kalman filter exploits a new weighted exponential function to handle these grid perturbations to estimate the reference signal in shunt active power filter system. The current controller in the proposed shunt active power filter has been designed using a sliding-mode control strategy because of its ability to handle parameter uncertainties and ease in implementation. To test the effectiveness of the proposed shunt active power filter, extensive simulations were performed using MATLAB/Simulink (The MathWorks, Natick, Massachusetts, USA), and real-time studies were made using OPAL-RT (Montreal, Quebec, Canada). Results obtained from the above studies using the proposed shunt active power filter together with the different variants of Kalman filter (Kalman filter, extended Kalman filter, extended complex Kalman filter) are analyzed, and it is observed that the proposed robust extended complex Kalman filter-sliding-mode control based shunt active power filter provides accurate and improved harmonics mitigation and reactive power compensation.     

Structural,electronic, and optical properties of orthorhombic and triclinic BiNbO4 determined via DFT calculations

We performed ab initio calculations using the FPLAW method with the local density approximation (LDA) implemented in the WIEN2 k code for the orthorhombic (α) and triclinic (β) phases of BiNbO₄. The modified Becke–Johnson exchange potential (mBJ)-LDA approach was also used to improve the electronic properties. The lattice constants calculated for both structures using the LDA are in good agreement with the experimental values. For the band structure calculations, the mBJ-LDA approach provides reasonable agreement for the band gap value compared with the LDA. The estimated (mBJ)-LDA band gap values are 2.89 eV (3.73 eV) and 2.62 eV (3.15 eV) for the α and β phases of BiNbO₄, respectively. Significant optical anisotropy is clearly observed in the visible-light region. We also calculated and evaluated the electron energy loss spectrum for BiNbO₄. This work provides the first quantitative theoretical prediction of optical properties and electron energy loss spectra for both the orthorhombic and triclinic phases of BiNbO₄.     

Preparation and characterization of biodegradable waterabsorbent PAN/SS nanocomposite

Polyacrylonitrile (PAN)/sodium silicate (SS) nanocomposite was prepared via nonconventional emulsion method using an in situ developed transition metal complex Cu(II)/glycine taking ammonium persulfate (APS) as initiator, with a novel motive of converting hydrophobic homopolymer PAN into hydrophilic nano material via nanotechnology by the inclusion of SS to the homopolymer. UV–visible spectral analysis was carried out which revealed various interactions between the in situ developed complex with other reaction components. The formation of the PAN/SS nanocomposite was confirmed by infrared spectra (IR). Furthermore, as evidenced by transmission electron microscopy (TEM), the composite so obtained was found to have nano scale structure. X‐ray diffraction (XRD) was carried out suggesting that the silicate layers were exfoliated during the polymerization process. An increase in the thermal stability for the developed nanocomposite was recorded by thermogravimetric analysis (TGA). Surprisingly, it was also found that the PAN/SS nanocomposite showed considerable amount of waterabsorbency and was biodegradable as tested by activated sludge and cultured media and further confirmed by scanning electron microscopy (SEM). POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers