http://hdl.handle.net/10204/683 Fri, 24 May 2013 22:01:17 GMT 2013-05-24T22:01:17Z http://hdl.handle.net/10204/6743 Title: Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite as a potential adsorbent for Cr (VI) removal Authors: Setshedi, KZ; Bhaumik, M; Songwane, S; nyango, MS; Maity, A Abstract: Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite (PPy OMMT NC), was prepared as a potential adsorbent, via in situ polymerization of pyrrole monomer for adsorption of toxic Cr(VI) from aqueous solution. The WAXD and SAXS results indicated that the clay sheets were exfoliated in the prepared nanocomposite. HR-TEM results showed good dispersion of the clay into the polymer matrix. The presence of the PPy polymer in the nanocomposite and adsorption of Cr(VI) onto the nanocomposite were confirmed using ATR-FTIR. Using the BET method, an improved surface area was observed for the PPy-OMMT NC compared to native clay. Batch adsorption studies whereby the pH, initial Cr(VI) concentration, sorbent dosage and temperature were varied, revealed that Cr(VI) adsorption process was rapid, spontaneous in nature and favoured with increased temperature at pH 2. The kinetic data fitted well to the pseudo second order kinetic model while the equilibrium data was satisfactorily described by the Langmuir isotherm. The Langmuir maximum adsorption capacity of Cr(VI) onto PPy-OMMT NC at pH 2.0 was found to be 112.3, 119.34, 176.2 and 209.6 mg/g at 292 K, 298 K, 308 K and 318 K, respectively. The selective adsorption of Cr(VI) was demonstrated in binary adsorption systems with co-existing ions. Moreover, desorption experiments revealed that the nanocomposite can be reused effectively for two consecutive adsorption–desorption cycles without any loss of its original capacity. Groundwater test results showed that the nanocomposite is a potential adsorbent for Cr(VI) ion removal from contaminated water sources. Description: Copyright: 2013 Elsevier. This is an ABSTRACT ONLY. The definite version is published in Chemical Engineering Journal, vol. 222, pp186-197 Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10204/6743 2013-01-01T00:00:00Z http://hdl.handle.net/10204/6742 Title: Environmental change in Bushbuckridge Authors: Erasmus, BFN; Coetzer, K; Mambo, J; Archer, E; Fisher, JT; Asner, GP Abstract: Bushbuck Ridge is a typical cultural landscape where the interdependency of people and the environment shape the savanna ecosystem goods and services upon which many people are dependent. The forced resettlement of people in the apartheid era, together with Mozambican refugees, have resulted in high human densities. The majority of people rely heavily on the rural rangelands for a variety of natural products, and the ability of these ecosystems to continue delivering these products under conditions of climate change and land cover change is in doubt. Historical trends show that settlements are expanding, with an increasing corresponding footprint around each village, where woodland resources are depleted. People can and do adapt to environmental change, but projecting current trends in the changes that we observe, combined with increased unpredictability of rainfall, threatens to decouple the age-old interdependencies in the this cultural landscape, and present inhabitants with conditions beyond their adaptation capacity. Description: Copyiright: Sun Media Publishing,Stellenbosch, South Africa Sun, 01 May 2011 00:00:00 GMT http://hdl.handle.net/10204/6742 2011-05-01T00:00:00Z http://hdl.handle.net/10204/6741 Title: Sustainable water for rural security - A transdisciplinary approach Authors: Maherry, A; Genthe, B; Steyn, M; Clarke, S; Beukman, E; Audouin, M; Van Wyk, I; Wall, K Abstract: This abstract presents the work conductive by the CSIR project entitled Sustainable Water for Rural Security with the following aims: to link research disciplines within the CSIR which together can provide an appropriate science base to enable the provision of clean water to rural communities; to bridge the knowing-doing gap by carrying out research on integrated implementation in partnership with communities and implementing Agencies; to ensure the sustained and expanded impact of this action-research through effective transfer of knowledge and technologies; and to identify the critical design criteria that ensure sustainability of rural water supply systems in South Africa. Description: WISA 2012 Biennial Conference and Exhibition. Conference Proceedings, Cape Town International Convention Centre, 6-10 May 2012 Tue, 01 May 2012 00:00:00 GMT http://hdl.handle.net/10204/6741 2012-05-01T00:00:00Z http://hdl.handle.net/10204/6738 Title: Development and uptake of scenarios to support water resources planning, development and management: examples from South Africa Authors: Funke, N; Claassen, M; Nienaber, S Abstract: The international agenda on water resources development reflects societal needs, political agendas, economic realities and the state of resources. The industrial revolution, which started in the 18th century, brought social and economic prosperity but also marked a major shift in humanity’s impact on the earth’s systems. This shift is now referred to as the Anthropocene, where humans have brought such vast and unprecedented changes to the planet that this era represents a new geological time interval. Societal needs have shifted since the 1940s from a need for modest food production to a need for increased agricultural productivity that has been met by high yield crops, the use of pesticides, the application of fertiliser and advanced agricultural techniques. This development has averted food shortages, but has also resulted in humanity having to pay a heavy price in terms of increased water use and energy consumption, as well as environmental degradation. Description: Copyright: Intech publishing, New York, USA Wed, 01 May 2013 00:00:00 GMT http://hdl.handle.net/10204/6738 2013-05-01T00:00:00Z