http://hdl.handle.net/10204/458 Thu, 23 May 2013 03:05:40 GMT 2013-05-23T03:05:40Z 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. The trandisciplinary methodology and approach to water supply and sanitation involves stakeholder engagement and community workshops in order to jointly frame the “problem”. The three case studies are: the Bulungula Incubator project at Nqileni in the Eastern Cape; Giyani local district municipality, Limpopo and the Kamiesberg Municipality in Northern Cape. Assessments of water quality using portable field hydrogen sulphide test kits were carried out at the sites. Water collected from springs and rivers was found to be generally unacceptable for drinking, whereas borehole water was usually not contaminated. Workshops were held with different community groups in the study areas and key issues emerged from the discussions. Ethical clearance was obtained to conduct household surveys and interviews took place with community members, In the E.Cape study area most people rely on natural sources of water such as the river or springs and they are concerned about water quality as pollution from animals is visible at these sources. Community members believe they sometimes get sick from their drinking water. Rainwater harvesting and boreholes with pumps have been introduced in the Eastern Cape site and generally people prefer the quality of this water but when pumps or gutters break there are no resources or skills to fix it and people revert to natural sources of water. Women and children are walking 200 m to 2 km per day to fetch water. There is not sufficient access to water infrastructure to irrigate crops, which is a problem as unemployment is high in the Limpopo case study site, with a high reliance on social grants and subsistence agriculture. Researchers observed that lack of reliable, acceptable quality water is contributing to stalled rural economic development. Other significant contributing factors are low skills, low levels of connection to supporting resources; poor access and distance to markets; and weak local governance evidenced by slow service delivery. The Northern Cape site has a history of CSIR involvement and European donor funded projects involving artificial groundwater research and currently reverse osmosis is taking place to purify the groundwater for drinking purposes. The Kamiesberg study site has a complicated history of water supply projects and provides a good case study of why and how water supply projects succeed or fail in an arid environment. 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/10204/6740 Title: Mitigating health problems associated with AMD in South Africa Authors: Schachtschneider, K Abstract: Acid mine drainage (AMD) is a serious threat to water quality in South Africa. Questions are being asked to South African government leaders as to what they are doing to mitigate the effects that South Africa’s mining industry is having on communities’ water supply and the water table. The CSIR has developed a novel process to reclaim high-quality precipitated calcium carbonate (PCC) from calcium-rich industrial solid waste. Calcium carbonate can be used to prevent AMD from becoming too acidic, as it has the effect of lowering water's pH level. Description: Copyright: 2012 Malnor Publications. This is an ABSTRACT ONLY. The definitive version is published in Government Digest, Vol. 31 (9,)pp 28-29 Thu, 01 Mar 2012 00:00:00 GMT http://hdl.handle.net/10204/6740 2012-03-01T00:00:00Z