Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 28Citation - Scopus: 30Effect of Construction and Demolition Waste on the Long-Term Geo-Environmental Behaviour of Cemented Paste Backfill(Springer, 2021-05-05) Yilmaz, T.; Ercikdi, B.The construction and demolition waste (CDW) could be used as backfill material to fill the voids created during the ore production in underground mining. However, there is a need to clarify the impact of CDW on groundwater pollution when it is used as backfill material in cemented paste backfill (CPB) of sulphide-rich tailings (S-rT). This study presents the influence of CDW on the long-term geo-environmental behaviour of CPB samples (CPBs) when used as replacement (10 wt.%) to S-rT. For this reason, the dynamic-tank leaching test was conducted on CPBs and pH, conductivity (Ec), sulphate (SO42-) and heavy metals (HMs) analyses were executed for leachates over 30-360 days of leaching period. The effects of mineralogy and microstructure on the geo-environmental behaviour of CPBs were also analysed via X-ray fluorescence (XRD) and mercury intrusion porosimeter (MIP). The utilisation of CDW in CPB mixtures was found to reduce the SO42- release (up to 13.89%), neutralise the acid generated and lower the Ec (up to 22.16%). Furthermore, the HMs releases (except As, Cu and Zn) were prevented (Ni and Cr) or reduced up to 92%, which is compatible with the improved CPB microstructure. Only the release of arsenic (As) exceeded the limit value for groundwater in CPB of CDW leachate. These findings suggest that not only the cost, strength and stability but also the impact on groundwater pollution should be considered when disposing of CDW as CPB material in underground voids.Article Citation - WoS: 16Citation - Scopus: 16Arsenic Removal by the Micellar-Enhanced Ultrafiltration Using Response Surface Methodology(Iwa Publishing, 2019-12-27) Gokcek, Oznur Begum; Uzal, NigmetThe present research investigates the removal of arsenic (As) from aqueous solutions using micellar-enhanced ultrafiltration (MEUF) by utilizing two different surfactants: benzethonium chloride and dodecyl pyridinium chloride (BCl and DPCl). The impact of the operating variables and maximum removal efficiency were found under different conditions for BCl and DPCl surfactants. The maximum As rejection efficiency for MEUF with BCl and DPCl surfactants is 92.8% and 84.1%, respectively. In addition to this, a statistics-based experimental design with response surface methodology was used for the purpose of examining the impact of operating conditions, including initial pH, initial As concentration (ppb), and surfactant concentration (BCl, mM) in As-removal from aqueous solutions. In the analysis of the experimental data, a second-order polynomial model that was validated by statistical analysis for the BCl surfactant was used. On the basis of the response model created, the removal of As ions was acquired at optimum operating parameters, including the initial As concentration of 150 ppb, surfactant concentration of 5 mM and pH 10 for the BCl surfactant with 92.8% As-removal efficiency.