Eglal R. Souaya

A comparative study among different photochemical oxidation processes to enhance the biodegradability of paper mill wastewater

Advanced oxidation processes including UV, UV/H(2)O(2), Fenton reaction (Fe(II)/H(2)O(2)) and photo-Fenton process (Fe(II)/H(2)O(2)/UV) for the treatment of paper mill wastewater will be investigated. A comparison among these techniques is undertaken with respect to the decrease of chemical oxygen demand (COD) and total suspended solids (TSS) and the evolution of chloride ions. Optimum operating conditions for each process under study revealed the effect of the initial amounts of Fe(II) and hydrogen peroxide. Of the tested processes, photo-Fenton process was found to be the fastest one with respect to COD and TSS reduction of the wastewater within 45 min reaction time under low amounts of Fe(II) and hydrogen peroxide of 0.5 and 1.5mg/L, respectively, and amounted to 79.6% and 96.6% COD and TSS removal. The initial biodegradability of the organic matter present in the effluent, estimated as the BOD(5)/COD, was low 0.21. When the effluent was submitted to the different types of AOPs used in this study, the biodegradability increases significantly. Within 45 min of reaction time, the photo-Fenton process appears as the most efficient process in the enhancement of the biodegradability of the organic matter in the effluent and the BOD(5)/COD ratio increased from 0.21 to 0.7.

Stable plasmonic Ag/AgCl–polyaniline photoactive composite for degradation of organic contaminants under solar light

A series of novel plasmonic photocatalysts of Ag/AgCl–polyaniline (Ag/AgCl–PANI) were successfully synthesized by deposition–precipitation reaction followed by a photo-reduction method. The prepared photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, photoluminescence emission spectroscopy, and thermogravimetric analysis. Ag/AgCl–PANI was used to degrade methylene blue (MB) under simulated solar light. The effects of different parameters such as PANI content, initial pH and concentration of the MB solution, and catalyst dosage on the photo-degradation efficiency were assessed. Ag/AgCl–PANI plasmonic photocatalyst displayed much higher photocatalytic efficiency than the pure PANI or Ag/AgCl. The improved photocatalytic performances of the prepared photocatalysts were attributed to the high absorbance in the visible-light region, high surface areas of catalysts and the effective synergism of hetero-junction structure formed at the interface between Ag/AgCl and PANI, leading to improved separation of the photo-generated electron–hole pairs. A possible mechanism for the photo-degradation of MB molecules under simulated solar irradiation was suggested based on trapping experiments.

NiO-Al2O3 catalysts prepared at high pH variation of structure and texture upon thermal treatment

A series of five catalysts of NiO-Al2O3 of varying content (IA-VA) were prepared at pH ∼ 10 and dried at 80°C using neutral mesoporous alumina composed of μ-Al2O3 and poorly crystalline boehmite. Structural changes produced upon heat treatment up to 700° C were followed using XRD, TG and DTA techniques. The surface texture of the samples was investigated by nitrogen adsorption at 77 K. The effect of soaking period on the resulting preparation and on its thermally treated products was also investigated (III Aa).The presence of nickel in the form of the amine complex had a marked effect on the crystalunity of the support changing the boehmite to the well crystalline form-an effect which was not observed in the absence of the nickel amine complex. The presence of NH3 alone in the medium resulted in the appearance of two broad bands covering d distance ranges of 0.545 to 0.521 nm and 0.432 to 0.386 nm that also appeared in the XRD patterns of the catalyst samples. The ammonia penetrates between the layer structure of the support thus changing its interlayer distance.Soaking for 7 days was found to represent non-equilibrium conditions compared to soaking for 15 days.NiAl2O3was characterized in the catalyst samples and NiO appeared in samples heated at 225° C and increased at 325° C resulting from the decomposition of the physically adsorbed surface species [Ni (NH3)6](NO3)2 and [Ni (NH3)6](OH)2, respectively. The latter became pronounced for higher nickel concentrations as observed from DTA and DTG. The former decomposes exothermally at around 260° C and the latter endothermally at 325° C after losing the NH3 ligand in the temperature range 245 to 265° C.At nickel contents greater than 4.6% and at temperatures greater than 225° C a surface compound appeared with characteristic d distances in the ranges 0.202 to 0.2034 nm and 0.2363 to 0.2348 nm depending on treatment temperature. It results from the attack of the nickel amine complex on two adjacent hydroxyl groups.An increase in the surface parameters of Al2O3 was observed upon soaking in NH4OH solution alone and from pore analysis is found to contain two groups of mesopore sizes. The presence of the least amount of nickel content (1.5%) produced a marked increase in both specific area and total pore volume accompanied by a decrease in average pore radius. These changes reflect the structural changes of the support observed upon impregnation in the nickel-amine complex. Variations of the surface parameters of the catalyst samples with further increase in nickel content depend on the nickel species formed. However, at a nickel content of 9.6% more pores are being exposed that result from the penetration of more nickel ions between the support particulates. At still higher nickel contents blocking of the narrower pores and narrowing of the wider pores occurs as their VI−t plots indicate. Despite this narrowing the catalyst samples are still predominantly mesoporous retaining, in most cases the existence of two groups of pore sizes.Variations in soaking period seems to affect the texture of the low temperature samples but for samples treated at temperatures above 500° C the surface parameters are comparable irrespective of the period of soaking.

Utility of Activated Glassy Carbon and Pencil Graphite Electrodes for Voltammetric Determination of Nalbuphine Hydrochloride in Pharmaceutical and Biological Fluids

This work compares voltammetric response of nalbuphine hydrochloride (NP·HCl) at both activated glassy carbon and pencil graphite electrodes. The electrochemical oxidation of the drug was studied using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) techniques. For analytical purpose a well-resolved irreversible diffusion controlled voltammetric peak was established in Britton-Robinson (B-R) buffer solution of pH 6.00 using pencil graphite electrode (PGE). Using activated glassy carbon electrode (GCE) a well-resolved irreversible diffusion controlled voltammetric peak was obtained at pH 7.00 using the same buffer solution. According to the linear relationship between the peak current and NP·HCl concentration, DPV and SWV methods were developed for their quantitative determination in pharmaceutical and human biological fluids. The linear response was obtained in the range from to mol L−1 using PGE and from to mol L−1 using a GC electrode, respectively. Precision and accuracy of the developed method were checked by recovery studies.

Influence of the polyacrylonitrile proportion on the fabricated UF blend membranes’ performance for humic acid removal

Abstract Asymmetric blend membranes of polyethersulfone (PES)/polyacrylonitrile (PAN) were prepared and developed for ultrafiltration applications. The membranes were prepared by dissolving two polymers in N-methyl-2-pyrrolidone (NMP) as a solvent with diethylene glycol (DEG) and polyvinylpyrrolidone (PVP) as non-solvent and pore former, respectively. The produced membranes were characterized by scanning electron microscopy (SEM) and fourier transform infrared (FTIR) spectroscopy, and the hydrophilicity of membranes was tested by contact angle measurements. The performance of prepared membranes was carried out by an ultrafiltration testing unit, where the efficiency of membranes was determined according to the humic acid separation and treated water permeate flux. The results indicated that using 1 wt.% of PAN in polymer mixture provided a blending membrane with high mechanical properties and high performance; the humic acid rejection reached 92.47% with treated water permeate flux 70 l/m2·h at feed pressure 6 bar.

New eco-friendly anticorrosive core-shell pigments

Purpose – The purpose of this paper is to present the preparation of core-shell ferrites/kaolin pigments and comparing their efficiency in protecting metal substrates to original ferrites which were also prepared. Core-shell structured particles are recently gaining lots of importance due to their exciting applications in different fields; these particles are constructed from cores and shells of different chemical compositions which show ultimately distinctive properties of varied materials different from their counterparts. The new core-shell pigment is based on shell of different ferrites that comprises only 10-20 per cent of the whole pigment on kaolin (cores) which is a cheap and abundant ore that comprises 80-90 per cent of the prepared pigment. The new pigments do not only comprise two different components, but they also contain pigment and extender in the same compound; their loadings in the paint formulations ranges from 50 and 75 per cent of the whole pigment. The work showed that these eco-frien...

Preparation and Identification of a New [Cr2(NTA)2(μ-OH2)]·2H2O Complex

[Cr2(NTA)2(μ-OH2)]·2H2O is prepared by heating nitrilotriacetic acid (H3NTA) with an aqueous suspension of freshly precipitated Cr2O3·nH2O. Elemental analysis, IR spectra, UV/vis spectra, X-ray diffraction, thermogravimetric analysis, mass spectra and magnetic susceptibility measurements suggest the existence of a Cr-Cr bond. One of the three water molecules acts as a bridging ligand (μ-H2O) while the other two are waters of crystallization.

Study on the corrosion protection performance of new ferrite/kaolin core-shell pigments in epoxy-based paints

Purpose – The purpose of this study is to prepare core-shell ferrites/kaolin pigments and compare their efficiency in protecting metal substrates to original ferrites. The new pigments are based on precipitating a shell of different ferrites that comprise only 10-20 per cent of the whole pigment on kaolin (core), which is a cheap and abundant ore comprising 80-90 per cent of the prepared pigment. These new pigments combine the properties of both its core and shell counter-parts, exhibiting improved corrosion protection properties. Furthermore, the pigments are represented as efficient, economically feasible and eco-friendly with comparable efficiency to that of original ferrites in protecting steel substrates. Design/methodology/approach – The new pigments were characterized using different analytical and spectrophotometric techniques, e.g. transmission electron microscopy, energy-dispersive X-ray analysis and X-ray fluorescence. The pigments were then incorporated in epoxy-based paint formulations. The p...

Preparation, characterization and determination of acid dissociation and stability constants of some acid divalent-metal 1 : 2 nitrilotriacetate complexes

H2[MII(HNTA)2]·xH2O complexes of eleven divalent metals were prepared. These complexes were characterized via elemental analysis, IR spectra, TGA, DTA and 1H NMR. pKa1 and pKa2 of these acids were determined together with their log β 1 and log β 2 as metal complexes.

Structural thermal and textural studies on cobalt oxide/alumina supported catalysts

CoO/Al2O3 catalysts containing amounts of cobalt ranging form 2 to 20% were prepared atpH 11 from neutral mesoporous alumina composed of γ-Al2O3 and poorly crystalline boehmite, and were then dried at 80‡C. X-ray diffraction, DTA and TG techniques were used to study the structural changes produced upon thermal treatment up to 700‡C.Soaking of the alumina in cobalt ammine complex solutions for a period of 10 days (the time required for equilibrium) resulted in a series of catalyst samples (I–V). Another sample (III-a) was soaked for a period of 5 days only in order to study the effect of the soaking time upon the equilibrium conditions.Cobalt aluminate (CoAl2O4) bands were characterized in all catalyst samples except III-a. They increased in intensity with increasing cobalt content. Surface species appeared in samples heated to 80‡C, and others persisted at 150‡C. Heating to temperatures above 200‡C resulted in the formation of cobalt oxides, due to decomposition of the surface compounds. DTA and TG studies showed that this was more pronounced at higher concentrations of cobalt. Samples heated at 500‡C and above did not undergo any further structural changes, except that the boehmite in the support was converted to γ-Al2O3.The variations in the surface parameters followed the same pattern as found previously [1], demonstrating that the catalyst samples are mesoporous, with retention of two ranges of pore size in most cases.