• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 421
  • 67
  • 61
  • 27
  • 18
  • 15
  • 12
  • 12
  • 12
  • 12
  • 12
  • 11
  • 3
  • 2
  • 1
  • Tagged with
  • 792
  • 792
  • 166
  • 100
  • 99
  • 99
  • 93
  • 93
  • 91
  • 88
  • 83
  • 82
  • 77
  • 71
  • 68
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

The effectiveness of vitis vinifera (grape) leaf litter to remove U.S. EPA priority phenols from simulated and industrial wastewaters

Afolabi, Wasiu Olalekan January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Chemistry in the Faculty of Applied Sciences at the Cape Peninsula University of Technology / This study sought to prepare and characterise activated carbons from Vitis vinifera (grape) leaf litter, and assess the efficiency and potential application of the adsorbent for the removal of four phenolic compounds (phenol (P), 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2-chlorophenol (2-CP)) from synthetic and industrial wastewaters. Vitis vinifera (grape) leaf litter (GL) was obtained locally, and washed, dried and pulvirized. Chemically activated carbons were prepared using H3PO4 (GLA) and NaOH (GLB). The adsorbents were characterized with SEM, FTIR, EDX and proximate analysis was also carried out. Phenols were extracted from water samples with SPE and analysed with HPLC. The prepared adsorbents were used in sorption of phenols from simulated phenolic wastewaters for optimization of adsorption. Optimal adsorption conditions were then applied for removal of phenols from wastewater samples collected from influents of treatment plants. Column and desorption studies were also carried out. The surface texture and morphology micrographs (using SEM) of the prepared materials/adsorbents showed that the prepared activated carbons possess improved pore structure, cavities and heterogeneous irregular surfaces capable of providing enhanced adsorption. EDX spectroscopy was used for elemental microanalysis and showed that the major constituent of the adsorbent is carbon. FTIR analysis revealed changes and absorption waveband drifts of surface functional groups after activation and adsorption. The proximate analysis of the prepared precursors demonstrated good quality of the active carbons. They had low moisture content (< 12%) and their inorganic matter content (ash) was less than 9% for the three sorbents. Iodine number value of the adsorbents was 342, 1065, and 571 mg/g for GL, GLA and GLB respectively. Excellent recoveries (92.60 – 102.85%) were obtained for the phenolic compounds (P, 2-NP, 4-NP and 2-CP) using polymeric SPE cartridges. Phosphoric acid activation yielded the most efficient activated carbon material relative to the non-treated biomass and those chemically activated with NaOH. Percentage removal was 92.70%, 99.92%, 99.98% and 99.90% for P, 2-NP, 4-NP and 2-CP respectively using GLA. Optimal pH for adsorption was 8, 4 and 7 for GLA, GLB and GL respectively at an equilibration time of 240 min. The evaluation of adsorption kinetics showed the adsorption process of GLA and GLB followed a pseudo-second order kinetic model while adsorption using GL was best described by intraparticle diffusion model. Adsorption equilibrium data were well fitted with Freundlich isotherm model for all three adsorbents. Adsorption capacity of GLA (for removal of phenols) was found to decrease with increase in temperature. In contrast, the sorption efficiency of GL and GLB increased when temperature was increased. Thermodynamic parameters of adsorption (ΔGo, ΔHo & ΔSo) were evaluated. Results revealed favourability and exothermic nature of adsorption of the phenols using GLA. Adsorption processes using GLB and GL were spontaneous and endothermic. Vitis vinifera leaf litter yielded good activated carbons and was effective in remediation of P, 2-NP, 4-NP and 2-CP from contaminated wastewaters.

Parametric study on the fabrication and modification of TiO2 nanotube arrays for photoeletrocatalytic degradation of organic pollutants

Tsai, Hei-lok., 蔡希樂. January 2010 (has links)
published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Cometabolism of trihalomethanes by nitrifying biofilters under drinking water treatment plant conditions

Wahman, David Gerard 28 August 2008 (has links)
Not available / text

The utilisation of maize tassel as an adsorbent for the removal of heavy metals from aqueous solutions

Zvinowanda, Caliphs M. January 2009 (has links)
Thesis (DTech. degree in Environmental, Water & Earth Sciences)--Tshwane University of Technology, 2009. / The potential of tassel from R52 maize cultivar for the removal of heavy metals from simulated and environmental aqueous samples as well as the physicochemical characteristics of tassel were investigated. Milled tassel powder was employed in metal removal from simulated aqueous sample and thereafter, the developed method was applied to environmental samples. This research has demonstrated the potential of maize tassel to adsorb metal ions from both simulated and environmental samples. Furthermore, metals adsorbed on tassel were easily desorbed suggesting that tassel can be employed in metal recycling.

Determination of endocrine-disrupting compounds in water and sediments from the Jukskei river catchment area.

Sibali, Linda Lunga. January 2008 (has links)
Thesis (DTech. degree in Environmental, Water and Earth Sciences)--Tshwane University of Technology, 2008.

Hydrodynamic behaviour of biological aggregates: settling and coagulation with small particles

Yuan, Yuan, 袁媛 January 2000 (has links)
published_or_final_version / Civil Engineering / Master / Master of Philosophy

Soil filtration of activated sludge effluent

Adams, William Pearson, 1945- January 1971 (has links)
No description available.

Water purification by forced-flow electrophoresis

Cooper, Frederick Christian, 1940- January 1964 (has links)
No description available.

Biological removal of phosphates from aquatic media

Greer, Douglas Edwin, 1941- January 1971 (has links)
No description available.

Effect of molecular weight on polymer filter aids

Burr, John Gregory, 1946- January 1972 (has links)
No description available.

Page generated in 0.1031 seconds