Surface characteristics of the iron-oxyhydroxide layer formed during brick coatings by ESEM/EDS, ²³Na and ¹H MAS NMR, and ToF-SIMS

Brick made locally by craftsmen in Bangui (Central African Republic) was modified first by HCl activation and second by iron-oxyhydroxide impregnation through the precipitation of ferric ions by NaOH at various fixed pH values (ranging from 3 to 13). The elemental analyses of synthesized compounds were performed using ICP-AES, and their surface chemistry/properties were investigated by environmental scanning electron microscopy (ESEM/EDS), 1H and 23Na MAS NMR spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The evidence of different 23Na chemical environments and the coexistence of Si and Al bound to ferrihydrite were made. The surface properties of this material which was found to be dependent upon synthesis pH, contributed to enhance metal uptake from water

MAS NMR investigations on a metakaolinite-rich brick after zeolitization by alkaline treatments

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Performance of FeOOH-brick based composite for Fe(II) removal from water in fixed bed column and mechanistic aspects

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Effects Of Chemical Activation on Surface Sites of The Brick: pH-Dependence on Metal Adsorption

Brick was coated with ferrihydrite under variable experimental (pH) conditions. Pore ndash size distributions were determined and basic functions formed at brick surfaces were differentiated and quantified using pHmetry and conductimetry. Lead(II) and iron(II) adsorption capacities of synthesized compounds were tested by conducting fixed ndash bed column experiments. Both a higher pH used for Fe(III) precipitation into ferrihydrite and a higher level of deposited iron contributed to improve the adsorption performance of this material. The number of generated XiAlO-, XiSiO- and XiFeO- sites was found to be the key factor controlling the adsorption capacity level, and not physical and textural parameters

Adsorption capacity of iron oxyhydroxide-coated brick for cationic metals and nature of ion-surface interactions

The adsorption of six metal ions (Cd2+, Cu2+, Fe2+, Ni2+, Pb2+ and Zn2+) from an aqueous solution by a new composite – iron oxyhydroxide (ferrihydrite) deposited onto pre-activated brick grains – was investigated under dynamic experimental conditions. Breakthrough curves were obtained under specified fixed-bed-column conditions, and the determined adsorption capacity (molar basis), Q, followed the order of QPb(II) > QCd(II) ≈ QZn(II) > QFe(II) > QNi(II) > QCu(II). An attempt was made to correlate the ionic characteristics of these cationic metals with adsorption performance, and data revealed how strongly metal cations were attracted to negatively charged brick sites via electrostatic interactions. In addition to electrostatic attractions, a process implicating outer-sphere complexes, ≡ S−Na(H2O)6+ and inner-sphere complexes, (≡ S−)2Me2 + (Me = metal), was suggested. ESEM/EDS analysis showed that cations were preferentially sorbed by ferrihydrite, rather than other hydroxyl groups in brick clays. A correlation also was found between the hydration free energy of Me2+ ions and hydrated radius, raising the possibility of water molecules being implicated in this adsorption mechanism. To confirm this hypothesis, 23Na and 1H MAS NMR were applied to our samples in order to examine the bonding states of sodium and water molecules and their dynamics at the material surface

Synergistic effect of light, pH and Artemisia annua extract on Enterococcus faecalis in aquatic microcosms

International audienceSynergistic effect of abiotic and biotic factors is not completely established in the process of disinfecting water by plant extracts. The present study aims to evaluate the synergistic effect of different pH values (4, 5, 6, 7, 8 and 9) and different infusion concentrations (10, 20 and 30%) of Artemisia annua on Enterococcus faecalis growth in aquatic microcosm under dark and lighting conditions. The results showed that under dark condition, there was a relative increase in abundance of E. faecalis cells in the presence of A. annua extract. Under lighting, there is a decrease in the abundance of E. faecalis at different infusion concentrations of A. annua. Extract of A. annua seems to favour the growth of E. faecalis cells in the dark, especially at slightly acidic pH. This growth was relatively significant at pH 6. In the presence of light, A. annua extract inhibited the growth of E. faecalis cells and this varied from one extract sample to another; and was significant at slightly basic pH. Under the lighting, different pH values do not appear to have significant influence on the inhibition of bacterial growth except for pH 8. Monoterpenes, sesquiterpenes and triterpenes molecules present in infusions could be involved in chemical reactions responsible for cellular inhibition under light condition. Research on photosensitizing compounds and a comparative study with conventional photosensitizers might attest for the involvement of photosensitivity reaction with the A. annua extracts

Sugarcane bagasse fly ash as an attractive agro-industry source for VOC removal on porous carbon

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