Biosorption of hexavalent chromium based on modified Y zeolites obtained by alkali-treatment

The structural modification of external surface of NaY was investigated in order to enhance efficient biosorption systems consisting of a bacterial biofilm, Arthrobacter viscosus, supported on that zeolite, for removing hexavalent chromium from aqueous solutions. The supported bacterial biofilm reduces Cr(VI) to Cr(III) and this cation is then retained in the zeolite by ion exchange. NaY zeolite was modified by alkali-treatments using NaOH 2.0 M, with two different contact periods of time between the zeolite and the alkaline solutions, resulting in NaYA and in NaYB. The biosorbents supported on the modified NaY zeolite were tested in solutions with low concentration of chromium. The results showed that the modification of external surface of NaY zeolite allows an efficient Cr removal, and the maximum removal efficiency was observed for NaYA sample that was submitted to a smoother chemical treatment.The authors acknowledge to Dr. A.S. Azevedo for collecting the powder diffraction data and Dr. C Ribeiro, from Departamento de Ciencias da Terra of Universidade do Minho, for chemical analyses. This work was supported by Fundacao para a Ciencia e Tecnologia (FCT-Portugal), under program POCTI-SFA-3-686. H.F. and B.S. gratefully acknowledge FCT-Portugal for the PhD grants

Catalytic reutilization of chromium-loaded NaY oxidation of ethyl acetate

EUROPACAT IX - Catalysis for a Sustainable WorldThe aim of this study is the reutilization of new materials obtained by biorecovery of chromium from water, in catalytic oxidations of volatile organic compounds. A biosorption system consisting of a microorganism supported on a NaY zeolite was used to remove hexavalent chromium from contaminated water. After the biosorption process, the chromium-loaded zeolite was used as catalyst to be applied in catalytic oxidation of ethyl acetate. The results showed that a higher content of chromium enhanced the activity and the C0 2 selectivity of the catalystinfo:eu-repo/semantics/publishedVersio

Biorecovery of Cr(VI) from wastewater and its catalytic reutilization

The performance of two zeolites with different structures and acidity properties was evaluated on the biosorption of Cr(VI) and catalytic oxidation of ethyl acetate. The starting zeolites, HY and HZSM5, were modified by ion exchange treatments in order to obtain zeolites with different acidity and sodium content. Arthrobacter viscosus supported on the different zeolites was used for Cr(VI) recovery from solution. The best removal efficiencies and uptake of chromium were achieved for the Y zeolites due to their higher ion exchange capacity. The Y and ZSM5 zeolites were characterized by ICP-AES, SEM, NH3 chemisorption, XRD and N2 adsorption. Y and ZSM5 zeolites obtained after biosorption of chromium were successfully reused as catalysts in the oxidation of ethyl acetate. The chromium-loaded ZSM5 zeolites were considerably more active and selective towards CO2 than chromium-loaded Y zeolites, essentially due to its different framework structure, textural and acidity properties

Reutilization of Cr-Y zeolite obtained by biosorption in the catalytic oxidation of volatile organic compounds

This work aims at the reutilization of a Cr-loaded NaY zeolite obtained by biorecovery of chromium from water as catalyst in the oxidation of volatile organic compounds (VOC). Cr-NaY catalysts were obtained after biosorption of Cr(VI) using a bacterium, Arthrobacter viscosus, supported on the zeolite. The biosorption experiments were conducted at different pH values in the range 1–4. The catalysts were characterized by several techniques, namely ICP-AES, SEM-EDS, XRD, XPS, Raman, H2-TPR and N2 adsorption. The zeolite obtained at pH 4 has the highest content of chromium, 0.9%, and was selected as the best catalyst for the oxidation of different VOC, namely ethyl acetate, ethanol and toluene. For all VOC tested, the catalyst with chromium showed higher activity and selectivity to CO2, in comparison with the starting zeolite NaY. The presence of chromium shifted also the reaction pathways. In terms of selectivity to CO2, the following sequence was observed: ethyl acetate > toluene > ethanol.This work was partially funded by the Centre of Biological Engineering and Centre of Chemistry (University of Minho, Portugal) through a POCTI project (ref: POCTI-SFA-3-686), by the Spanish Ministry of Science and Innovation (CTQ2008-04261/PPQ) and by FCT and FEDER under Programs POCI 2010 and COMPETE, Project PTDC/AMB/69065/2006

Evaluation of ion exchange-modified Y and ZSM5 zeolites in Cr(VI) biosorption and catalytic oxidation of ethyl acetate

The aim of this work was the evaluation of the performance of two zeolites with different structures (FAU and MFI) and acidity properties in the biosorption of Cr(VI) and catalytic oxidation of ethyl acetate. The starting zeolites, Y (FAU) and ZSM5 (MFI), were modified by ion exchange treatments with NaNO3 in order to obtain zeolites with different acidity and sodium content. A biosorption system consisting of a bacterium, Arthrobacter viscosus, supported on the different zeolites was used for Cr(VI) reduction and removal from solution. The best removal efficiencies and uptake of chromium, above 90% and 14 mgCr/gzeolite respectively, were achieved for Y zeolites due to their higher ion exchange capacity in comparison with ZSM5 zeolites. The ion exchange treatment did not produce considerable changes on the uptake process performed by the modified zeolites. Y and ZSM5 zeolites were characterized by ICP-AES, SEM, NH3 chemisorption, XRD and N2 adsorption. Y and ZSM5 zeolites obtained after biosorption presented chromium loadings between 0.92 and 1.20%, and were successfully reused as catalysts in the oxidation of ethyl acetate. The chromium-loaded ZSM5 zeolites were considerably more active and selective towards CO2 than chromium-loaded Y zeolites, essentially due to their different framework structure, textural and acidity properties. The different sodium content of Y and ZSM5 zeolites did not produce marked changes in the catalytic behaviour of these catalysts.B. Silva, H. Figueiredo and O.S.G.P. Soares thank FCT-Portugal (Fundacao para a Ciencia e Tecnologia) for the concession of their PhD grants. A.E. Lewandowska thanks the Spanish Ministry of Science and Innovation for a "Juan de la Cierva" postdoctoral position. This work was partially funded by the Centre of Biological Engineering and Centre of Chemistry (University of Minho, Portugal) through a POCTI project (ref: POCTI-SFA-3-686), by the Spanish Ministry of Science and Innovation (CTQ2008-04261/PPQ) and by FCT and FEDER under Programs POCI 2010 and COMPETE, Project PTDC/AMB/69065/2006

The effect of foot massage on long-term care staff working with older people with dementia: a pilot, parallel group, randomized controlled trial

Background: Caring for a person with dementia can be physically and emotionally demanding, with many long-term care facility staff experiencing increased levels of stress and burnout. Massage has been shown to be one way in which nurses’ stress can be reduced. However, no research has been conducted to explore its effectiveness for care staff working with older people with dementia in long-term care facilities. Methods: This was a pilot, parallel group, randomized controlled trial aimed at exploring feasibility for a larger randomized controlled trial. Nineteen staff, providing direct care to residents with dementia and regularly working ≥ two day-shifts a week, from one long-term care facility in Queensland (Australia), were randomized into either a foot massage intervention (n=9) or a silent resting control (n=10). Each respective session lasted for 10-min, and participants could receive up to three sessions a week, during their allocated shift, over four-weeks. At pre- and post-intervention, participants were assessed on self-report outcome measures that rated mood state and experiences of working with people with dementia. Immediately before and after each intervention/control session, participants had their blood pressure and anxiety measured. An Intention To Treat framework was applied to the analyses. Individual qualitative interviews were also undertaken to explore participants’ perceptions of the intervention.Results: The results indicate the feasibility of undertaking such a study in terms of: recruitment; the intervention; timing of intervention; and completion rates. A change in the intervention indicated the importance of a quiet, restful environment when undertaking a relaxation intervention. For the psychological measures, although there were trends indicating improvement in mood there was no significant difference between groups when comparing their pre- and post- scores. There were significant differences between groups for diastolic blood pressure (p= 0.04, partial η2=0.22) and anxiety (p= 0.02, partial η2=0.31), with the foot massage group experiencing greatest decreases immediately after the session. The qualitative interviews suggest the foot massage was well tolerated and although taking staff away from their work resulted in some participants feeling guilty about taking time out, a 10-min foot massage was feasible during a working shift. Conclusions: This pilot trial provides data to support the feasibility of the study in terms of recruitment and consent, the intervention and completion rates. Although the outcome data should be treated with caution, the pilot demonstrated the foot massage intervention showed trends in improved mood, reduced anxiety and lower blood pressure in long-term care staff working with older people with dementia. A larger study is needed to build on these promising, but preliminary, findings