Conference Publications
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PublicationDetection of emerging pollutants Oxytetracycline and Paracetamol and the potential aquatic ecological risk associated with their presence in surface waters of the Arges-Vedea, Buzau-Ialomita, Dobrogea-Litoral River Basins in Romania(IOP Publishing Ltd., 2020)Pharmaceuticals are a major group of emerging pollutants frequently identified in surface waters. The occurrence of pharmaceuticals as environmental pollutants is a problem involving multiple aspects and continue to cause new and serious challenges to ecosystems and human health. For example, antibiotics exert a selective pressure on bacterial communities in aquatic environments, leading to the selection and increase in the prevalence of antibiotic-resistant bacteria, which is a major problem in the effective treatment of bacterial infections, while for analgesics, a number of adverse effects such as accumulation in tissues and behavioral changes were observed in aquatic organisms. In this paper, the detection by UHPLC-MS/MS of two widely used pharmaceuticals was performed, oxytetracycline (antibiotic) and paracetamol (analgesic) respectively, in surface water matrix from the Arges-Vedea, Buzau-Ialomita and Dobrogea-Litoral river basins in Romania. The potential aquatic ecological risk (RQ) was also estimated by the ratio between Measured Environmental Concentration (MEC) and Predicted No-Effect Concentration (PNEC).
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PublicationHeat evolution of class C fly ash geopolymers with different molarity of Sodium Hydroxide: nucleation growth and morphology properties towards early strength evaluation(IOP Publishing Ltd., 2020)The heat evolved during setting of class C fly ash geopolymers with different molarity of sodium hydroxide are discussed. The reaction kinetics and microstructure properties of geopolymers are studied towards the early strength development. Differential Scanning Calorimeter was applied to determine the heat evolved and Johnson-Mehl-Avrami-Kolmogrov Model was used to analyse the reaction kinetics during setting of the geopolymers. Morphology and strength development were monitored. The results revealed that the heat evolved increased proportionally with increasing molarity of sodium hydroxide. This indicated rapid reaction of geopolymerization due to the increasing of hydroxide ion content thus mainly affect dissolution process. It was also found that the geopolymerization during setting was governed by one-dimensional growth with instantaneous heterogeneous nucleation and this was supported by the morphology of the geopolymers observed. Among the activator molarities, the molarity of 12 (12M) was observed to be most influential based on its highest compressive strength (up to 46MPa at 7-days) and supported by the morphology properties results.
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PublicationA review of PM₁₀ concentrations modelling in Malaysia(IOP Publishing Ltd., 2020)The purpose of predictive modelling is to predict the variable of interest with reasonable precision, and often to assess the contribution of the independent variables to the dependent variable. In this paper, all of the works examined are aimed at predicting concentrations of outdoor PM₁₀ concentrations. The vast majority of the works reported used almost exclusively predictors of the meteorological and source emissions. However, the use of the Hybrid model in predicting PM₁₀ concentrations is still not widely used in Malaysia.
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PublicationThe influence of Sodium Hydroxide concentration on physical properties and strength development of high calcium fly ash based geopolymer as pavement base materials(IOP Publishing Ltd., 2020)This paper deals with the development of high calcium fly ash based geopolymers. Geopolymer paste was prepared from fly ash alkaline activator solutions using various mix design including molarity of sodium hydroxide used (6-14M) with solid-to-liquid ratio (1.0-3.0) and the sample were curing at ambient temperature. In this paper, flow value, setting time and unconfined compressive strength of high calcium fly ash based geopolymer paste was carried out using flow table equipment, Vicat’s apparatus and compression testing machine to measure the properties caused by high calcium fly ash. It was found that solid to liquid ratio of 2.0 and NaOH molarity of 12M was the best mix design to be applied due to its maximum unconfined compressive strength achieved (up to 19MPa at 28 days) as well as its flow ability of the fresh paste which shown better result compared to other mix designs. High calcium was also found to result in higher strength.
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PublicationCoagulation and flocculation treatment of biodiesel wastewater using Ferric Chloride(IOP Publishing, 2020)Attempts were made this study to examine of coagulation and flocculation process using ferric chloride and polyelectrolyte (cationic) for the treatment biodiesel wastewater. Removal of SS (suspended solid), color, COD (Chemical Oxygen Demand) and Oil and Grease (O&G) using ferric chloride and organic polyelectrolyte during coagulation/flocculation process were investigated. Also the optimum condition for coagulation/flocculation process, such as pH, coagulant dosage and polyelectrolyte dosage of solution were investigated using jar test experiment. The effect of different dosage of polyelectrolyte in combination with coagulant was also studied. The result revealed that in the range of pH tested, the optimal pH is 6. Percentage removal of 95%, 93%, 63%, 97% for SS, color, COD and O&G respectively, were achieved at optimum dosage value; 350 mg/L. While, 86.3%, 86.7%, 57.2, 81% removal of SS, color, COD, O&G respectively, were achieved with the addition 10 mg/L cationic to 125 mg/L ferric chloride. It can be conclude from this study that coagulation/flocculation may be a useful as a pre-treatment process for biodiesel wastewater.
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