https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:52041 Wed 27 Sep 2023 10:00:50 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:44659 Wed 19 Oct 2022 10:03:48 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:22765 Wed 11 Apr 2018 12:10:12 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:33682 2+ and Cd²⁺ on defluoridation by calcite because Spent Pot Lining (SPL, a byproduct generated during the aluminum production) leachate is a complex chemical cocktail. To better understand defluoridation processes and replicate the situation in the field, column tests were conducted. Results indicate that presence of neither Ba²⁺ nor Cd²⁺ has significant impact on fluoride retention when compared with the blank (no metals) because the relative concentration values (F/F_o) as well as the transport parameters like retardation factor (R_c) and distribution coefficient (K_d) are almost the same. PHREEQC, a geochemical software, was then applied to simulate the column test processes (i.e., 1D reactive/transport processes) based on the mechanism of CaF₂ precipitation followed after calcium dissolution. As indicated in the batch reactor test, addition of Cd²⁺ may inhibit calcite dissolution; therefore, a new phase "CalciteSupp" (a phase representing the suppressed solubility of calcite) was defined. Modeling results exhibit good predictions of observed data, and the log_k solubility of the hypothetical "CalciteSupp" equilibrium phase implies the suppression of calcite dissolution in the metal samples. Moreover, saturation indices obtained by modeling indicate the precipitation of CdCO₃ and BaCO₃, revealing that addition of metals may influence fluoride removal at some point during the process, but has no big impact on overall defluoridation. The initial development of the PHREEQC geochemical model presented shows potential in being able to be used as a predictive tool for the design of fluoride remediation strategies, such as permeable reactive barriers, and transport parameters obtained on the basis of the column tests, and CXTFIT (a computer program for evaluating and estimating transport parameters) modeling can be applied in practical design.]]> Wed 05 Dec 2018 12:10:50 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:33681 −1. Fluoride removal half-life (t_0.5) values were found to increase in the order Ba ≈ stonedust (a 99% pure natural calcite) < Cd < Co < Mn. A barrier width of 0.97 ± 0.02 m was found to be required for the fluoride/calcite (stonedust) only system when using no factor of safety, whilst in the presence of Mn and Co, the width increased to 2.76 ± 0.28 and 19.83 ± 0.37 m respectively. In comparison, the PSO model predicted a required barrier thickness of ∼46.0, 62.6 & 50.3 m respectively for the fluoride/calcite, Mn and Co systems under the same conditions.]]> Wed 04 Dec 2019 12:54:35 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:53299 Tue 21 Nov 2023 11:54:38 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:44623 Tue 18 Oct 2022 10:29:47 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:54136 Tue 06 Feb 2024 11:50:12 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:33034 Thu 23 Aug 2018 15:48:49 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49477 Thu 18 May 2023 15:02:01 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40242 Thu 07 Jul 2022 11:20:41 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:39284 Thu 02 Jun 2022 15:26:29 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28144 2 +, Ba^{2 +} and Mn^{2 +}) on the kinetics of fluoride removal from solution by natural zeolite was investigated. In order to better understand the kinetics, the pseudo-second order (PSO), Hill (Hill 4 and Hill 5) and intra-particle diffusion (IPD) models were applied. Model fitting was compared using the Akaike Information Criterion (AIC) and the Schwarz Bayesian Information Criterion (BIC). The Hill models (Hill 4 and Hill 5) were found to be superior in describing the fluoride removal processes due to the sigmoidal nature of the kinetics. Results indicate that the presence of Mn (100 mg L^{- 1}) and Cd (100 mg L^{- 1}) respectively increases the rate of fluoride sorption by a factor of ~ 28.3 and ~ 10.9, the maximum sorption capacity is increased by ~ 2.2 and ~ 1.7. The presence of Ba (100 mg L^{- 1}) initially inhibited fluoride removal and very poor fits were obtained for all models. Fitting was best described with a biphasic sigmoidal model with the degree of inhibition decreasing with increasing temperature suggesting that at least two processes are involved with fluoride sorption onto natural zeolite in the presence of Ba.]]> Sat 24 Mar 2018 07:36:37 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:33118 Mon 27 Aug 2018 18:23:55 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:51805 Mon 20 Nov 2023 14:28:45 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49248 Mon 08 May 2023 10:42:20 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49245 Mon 08 May 2023 10:28:18 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:51499 Fri 08 Sep 2023 11:56:57 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:47884 Fri 03 Feb 2023 15:59:52 AEDT ]]>