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Clinoptilolite-polypropylene composites for the remediation of water systems polluted with heavy metals and phenolic compounds

  • Authors: Motsa, Machawe M.
  • Date: 2012-06-07
  • Subjects: Clinoptilolite , Polypropylene , Heavy metals , Polluted water systems , Phenolic compounds , Reinforced composites
  • Type: Thesis
  • Identifier: uj:8725 , http://hdl.handle.net/10210/5076
  • Description: M.Sc. , In this study, natural and modified clinoptilolite (CLI) reinforced polypropylene (PP) composites possessing improved mechanical and adsorptive properties were prepared through melt-mixing. Determination of morphological, structural and thermal properties was achieved by means of different techniques (FTIR, TGA, DSC, electron microscopy and x-ray spectroscopy). Electron microscopy revealed that increasing filler loading beyond 20% leads to agglomeration of clinoptilolite particles reducing their dispersion within the matrix. Thermal studies showed that the reinforced composites had a lower thermal stability than the neat PP polymer, suggesting that the clinoptilolite interfered with polymer chain arrangement and bonding. It also showed that percentage crystallinity increased with increasing filler loading indicating that the filler particles acted as nucleating agents within the polymeric matrix during composite synthesis. Prior to the ion-exchange studies, water sorption behaviour of fabricated composites was evaluated because ion-exchange/adsorption studies were to be performed in aqueous media. It was therefore observed that the hydrophobic polymer, PP attained the property of water sorption mainly due to the porous structure of the composites created by mixing and extrusion and also by the addition of the hydrophilic filler material.
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Cu (II) removal from synthetic waste water by ion exchange process

  • Authors: Muzenda, Edison , Kabuba, John , Ntuli, Freeman , Mollagee, Mansoor , Mulaba-Bafubiandi, Antoine F.
  • Date: 2011
  • Subjects: Clinoptilolite , Ion exchange , Synthetic waste water , Waste water treatment , Heavy metals - Removal
  • Type: Article
  • Identifier: uj:4708 , ISSN 2078-0966 , http://hdl.handle.net/10210/10953
  • Description: The objective of this study was to investigate the potential of acid activated South Africa clinoptilolite as an adsorbent in the ion-exchange process for the removal of cations from aqueous solutions. The kinetic parameters affecting the adsorption of Cu (II) ions were studied. The adsorption of Cu (II) from synthetic waste water was found to be dependent on pH, temperature, contact time and initial adsorbate concentration. The pH was varied from 2.5 to 6 and the optimum pH for Cu (II) removal was found to be 4.0. The removal of Cu (II) ions increased with time and attained saturation in about 60-70 min. The equilibrium data showed that the adsorption was endothermic nature. Kinetics data showed that at higher temperatures, the rate of adsorption is higher for the clinoptilolite natural zeolite and that Langmuir equation successfully described the adsorption process.
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Kinetics study of ammonia removal from synthetic waste water

  • Authors: Muzenda, Edison , Kabuba, John , Ntuli, Freeman , Mollagee, Mansoor
  • Date: 2011
  • Subjects: Ammonium exchange , Langmuir isotherm , Clinoptilolite , Synthetic waste water
  • Type: Article
  • Identifier: uj:4698 , http://hdl.handle.net/10210/10933
  • Description: The aim of this study was to investigate ammonium exchange capacity of natural and activated clinoptilolite from Kwazulu-Natal Province, South Africa. X-ray fluorescence (XRF) analysis showed that the clinoptilolite contained exchangeable ions of sodium, potassium, calcium and magnesium. This analysis also confirmed that the zeolite sample had a high silicon composition compared to aluminium. Batch equilibrium studies were performed in an orbital shaker and the data fitted the Langmuir isotherm very well. The ammonium exchange capacity was found to increase with pH and temperature. Clinoptilolite functionalization with hydrochloric acid increased its ammonia uptake ability.
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Methanol amination using natural clinoptilolite

  • Authors: Levin, Lance Robin
  • Date: 2012-09-10
  • Subjects: Catalysis , Methanol , Clinoptilolite
  • Type: Thesis
  • Identifier: uj:9846 , http://hdl.handle.net/10210/7249
  • Description: M.Tech. , Clinoptilolite possesses acid and base properties, and is hydrothermally stable at high temperatures. It can be reactivated by simple oxidation, and is highly selective due to its unique-shape selectivity. It is also not harmful to the environment and it has shown benefits to soil as well (Mumpton,1977). An initial study of the reactions of methanol amination was done using both natural local and synthetic clinoptilolites. Characterization of each was done before and after modification using XRD, TPD and BET analysis. The BET analysis showed an increase in the surface area and pore diameter of both the natural and synthetic types after acid treatment and calcination. Most interesting of all was the large increase in surface area, where the natural type increased from 16 to 36.7 m 2/g after acid treatment and the synthetic type increased almost 13 times, from 2 to 27.7 m2/g after acid treatment. This effect had a strong influence on the selectivity of methylamines by allowing a larger surface area to be in contact with the feed reagents. The XRD of the treated and untreated natural and synthetic clinoptilolite were compared and discussed. The catalytic properties of zeolites depend on the treatment of clinoptilolite, and the characteristic peaks of natural and the acid treated form can be identified in the XRD plots.The TPD analyses showed that there were two acid sites associated with the clinoptilolite; one weak and one strong. The synthetic clinoptilolite weak acid site also showed a much lower ammonia uptake, than the natural clinoptilolite weak acid site. Clinoptilolite was shown to be successful as a catalyst for the production of dimethylamine with high selectivity. This was attributed to a transition state shape selectivity associated with the clinoptilolite channels. The natural clinoptilolite displayed good selectivities at 400°C and a 5:1 ratio of methanol to ammonia, and gave a high conversion of > 90% ammonia to amines. The synthetic clinoptilolite gave better conversions and lower TMA selectivity than the natural clinoptilolite over a large range of feed ratios and temperatures. This included conversions of over 90% for most ratios (at 400 and 450°C). The natural clinoptilolite gave better results than those obtained using the amorphous clinoptilolite, which is currently used in industry. For example, low TMA selectivity was observed when a ratio of 5:1 or greater (methanol to ammonia) was used. The TMA selectivity is still far lower than the thermodynamic equilibrium selectivities obtained without a catalyst (62%). The catalyst lifetime has been shown to deteriorate with time.
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Modeling of Co-Cu elution from clinoptilolite using neural network

Natural clinoptilolite for the removal of cobalt and copper from aqueous solutions

  • Authors: Nyembe, Dumsile W.
  • Date: 2011-03-02T10:12:23Z
  • Subjects: Water purification , Copper absorption and adsorption , Cobalt , Clinoptilolite
  • Type: Thesis
  • Identifier: uj:7054 , http://hdl.handle.net/10210/3593
  • Description: M.Sc. , The metallurgical industrial losses of base metals with waste solutions are an environmental threat to water sources, hence these metal ions must be removed prior to discharge into receiving bodies. In this study, Southern African clinoptilolite’s capability as an ion-exchanger with respect to Cu2+ and Co2+ was investigated in order to consider its application in metal cation removal from aqueous solutions. The clinoptilolite was characterised with X-ray powder diffraction (XRD), X-ray fluorescence (XRF), FTIR, thermogravimetric analyser (TGA) and SEM-EDS. The clinoptilolite was found to be a thermally stable alumino-silicate with calcite, dolomite and quartz as the main minerals. Investigations of Co2+ and Cu2+ uptake were first performed on non-mixed solutions of these cations. It was found that Cu2+ was removed faster than Co2+ with removal efficiencies of 79% and 63% respectively. The column method was used in the cation-exchange processes with synthetic solutions of 0.0020 M, 0.0698 M and 0.2000 M of Co2+ and Cu2+ concentrations which were measured using atomic absorption spectroscopy (AAS). The effects of Co2+ and Cu2+ ions on one another’s removal efficiency were investigated on Co/Cu mixed synthetic solutions by varying their concentration ratios in solution. The Cu2+ was generally found to be removed at lower rates than the Co2+. Investigations on added impurities in the form of Si4+ and Fe2+ in the mixed Co/Cu synthetic solutions were carried out to determine their effect on the removal efficiencies of the targeted metals. It was found that both Si4+ and Fe2+ greatly reduced the removal efficiency of Cu2+, especially with increased amounts of Si4+ in the Co/Cu solution.
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Thermodynamics of Cu (II) adsorption onto South African clinoptilolite from synthetic solution by ion exchange process.

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