https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:37099 Tue 18 Aug 2020 09:55:43 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:34057 in situ by embedding magnetite into the palygorskite structure through co-precipitation method. The physico-chemical characteristics of Pal-IO and their pristine components were examined through various spectroscopic and micro-analytical techniques. Batch adsorption experiments were conducted to evaluate the performance of Pal-IO in removing Pb(II) from aqueous solution. The surface morphology, magnetic recyclability and adsorption efficiency of regenerated Pal-IO using desorbing agents HCl (Pal-IO-HCl) and ethylenediaminetetraacetic acid disodium salt (EDTA-Na₂) (Pal-IO-EDTA) were compared. The nanocomposite showed a superparamagnetic property (magnetic susceptibility: 20.2 emu g^-1) with higher specific surface area (99.8 m² g^-1) than the pristine palygorskite (49.4 m² g^-1) and iron oxide (72.6 m² g^-1). Pal-IO showed a maximum Pb(II) adsorption capacity of 26.6 mg g^-1 (experimental condition: 5 g L^-1 adsorbent loading, 150 agitations min^-1, initial Pb(II) concentration from 20 to 500 mg L^-1, at 25 °C) with easy separation of the spent adsorbent. The adsorption data best fitted to the Langmuir isotherm model (R² = 0.9995) and pseudo-second order kinetic model (R² = 0.9945). Pb(II) desorption using EDTA as the complexing agent produced no disaggregation of Pal-IO crystal bundles, and was able to preserve the composite's magnetic recyclability. Pal-IO-EDTA exhibited almost 64% removal capacity after three cycles of regeneration and preserved the nanocomposite's structural integrity and magnetic properties (15.6 emu g^-1). The nanocomposite holds advantages as a sustainable material (easily separable and recyclable) for potential application in purifying heavy metal contaminated wastewaters.]]> Tue 05 Feb 2019 12:51:19 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49463 Thu 18 May 2023 13:01:04 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26339 Sat 24 Mar 2018 07:35:55 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30891 14C-tracing study showed that the mild acid/alkali-treated clay products increased the PAH biodegradation (5–8%) in the order of 0.5 M HCl ≥ unmodified > 3 M NaOH ≥ 0.5 M NaOH for smectite, and 0.5 M HCl > 0.5 M NaOH ≥ unmodified ≥ 3 M NaOH for palygorskite. The biodegradation was correlated (r = 0.81) with the bioavailable fraction of PAHs and microbial growth as affected particularly by the 0.5 M HCl and 0.5 M NaOH-treated clay minerals. These results could be pivotal in developing a clay-modulated bioremediation technology for cleaning up PAH-contaminated soils and sediments in the field.]]> Sat 24 Mar 2018 07:30:38 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26716 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy. The XRD patterns indicated preservation of the crystalline structure of palygorskite following all the treatments. These findings were supported by the Al (IV) and Al (VI) coordination peaks (chemical shift ~ 55 and 2.9 ppm, respectively) which were unaltered in the ²⁷Al MAS NMR spectra of the samples. The acid-thermal activated palygorskite exhibited the highest specific surface area (152.7 m² g^-1) and pore volume (0.2137 cm³ g^-1) which respectively were 3-fold and 69% greater than the raw palygorskite. The potentiometric titration analyses highlighted the possible role of Al derivatives towards development of the surface charge of the activated palygorskites. Electrokinetic studies described the stability of the activated products (zeta potential values ranging from - 5 mV to - 32 mV) at different electrolyte (NaNO₃) concentrations. Combined acid-thermal activated palygorskite displayed a stronger specific adsorption of multivalent cations, and held a direct relevance to environmental remediation. Findings of this study will assist in the development of palygorskite-based adsorbents for heavy metal contaminants remediation.]]> Sat 24 Mar 2018 07:26:22 AEDT ]]>