Doaa A. Ahmed

Synthesis, characterization, fluorescence and catalytic activity of some new complexes of unsymmetrical Schiff base of 2-pyridinecarboxaldehyde with 2,6-diaminopyridine.

The Schiff base, 2-[(pyridin-2-ylmethylidene)amino]-6-aminopyridine (L) was synthesized by 1:1 condensation of 2-pyridinecarboxaldehyde and 2,6-diaminopyridine. The ligand and its complexes were characterized by different physicochemical studies. The analytical and spectroscopic tools indicated that the synthesized complexes have the general formulae: [M(L)Cl2]·2H2O (M=Cu(II), Ni(II) and Co(II)), [La(L)3](NO3)3·3H2O and [Sm(L)(ClO4)3]·3H2O. Vibrational spectra indicated the coordination of L to metal ions through its pyridyl and azomethine nitrogen atoms. The presence of water molecules in all reported complexes has been supported by TG/DTA studies. Kinetic and thermodynamic parameters were computed using Coats and Redfern method. The prepared ligand and its complexes exhibited intraligand (π-π∗) fluorescence and can potentially serve as photoactive materials. The catalytic activity of the complexes toward the decomposition of hydrogen peroxide was investigated. Both the ligand and its complexes have been screened for antibacterial activities.

Effect of demolition/construction wastes on the properties of alkali activated slag cement

Abstract The key point of this investigation is to study the effect of demolition and building wastes on the physico-chemical and mechanical properties of alkali activated slag (AAS). In this study, ground granulated blast-furnace slag (GGBFS) was activated by mixture of 3:3 wt.% sodium hydroxide:liquid sodium silicate (NaOH:Na2SiO3) ratio by weight of GGBFS. AAS was individually replaced by 10 wt.% ceramic, red clay brick and concrete wastes (CW, RCBW and CoW). The results showed that, significant shorter setting times were observed when AAS was replaced by CW, RCBW or CoW. The AAS-CoW showed the shortest setting times compared to other all mixes. The chemically combined water and pH decreased in the direction of AAS-CoW > AAS > AAS-RCBW > AAS-CW. CoW has a positive effect on the compressive strength development at one day of curing, while, CW and RCBW have a negative effect at the same time (1 day). At later ages of curing, the AAS-RCBW showed the highest compressive strength values as compared with AAS-CW, AAS-CoW and AAS. The crystallinity degree of hydration products enhanced when AAS was replaced by these wastes. Also, the Fe2O3 present in waste played an important role on the development of compressive strength. The hydration products were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) and the results were compared with the development in compressive strength.

Effect of Some Industrial Wastes onthe Physico-Chemical and Mechanical Properties of Hardened Cement Pastes

In this work, Portland cement (OPC) is replaced by different ratios of aBlast Furnace Slag, Silica Fume(SF) and Cement Kiln dust (CKD). Compressive strength, combined water and phase composition of cement are measured after 1,3,7,28,90,180,270 and 360 days immersion in tape water.The effect of5%magnesium sulfate solutionon curingofthe hardenedblendedcement pastes was also examined. Such replacement modified the strength, pore structure, and permeability of the hardened cement pastes. Sulphateattack on cement paste causes a serious deterioration. The aim of this investigation is to study the physico-chemical and mechanical properties of the prepared hardened blended cement pastes as well as study the effect of magnesium sulphate attack on these pastes. In addition, the effect of replacement of OPC by some additive was examined.

Removal of copper ions by Friedel´s salt

Friedels salt (3CaO.Al2O3.CaCl2.10H2O) or (Ca4Al2(OH)12Cl2(H2O)4), a layered double hydroxide (LDHs), is a calcium aluminate hydrate and used as an adsorbent for copper (Cu 2+ ) ions from aqueous solution .In our study,we carefully examined the adsorption behaviors of Friedels salt toward different concentrations of copper solutionat pH = 4. Both experimental and modeled data indicate that Friedels salt can adsorb all copper ions from solution at pH=4 for total [Cu/mg] in solution= 724.8 mg/l (3mM/l) with high efficiency ˃99.9 % of adsorbent FS.The FS, at different pHs,shows a higherstability at pH=6 thanat pH=4 andpH=8. Finallythis study suggests that Friedels salt is a potential cost – effective adsorbent for Cu [ІІ] removal.