Thesis (MEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Peach and apricot shells are agricultural waste products. These waste products
accumulate around canneries and food-processing plants in South Africa. No effort is
being made to utilise these waste products. This study is the first part of the product
development from these products i.e. peach shell activated carbon and apricot shell
activated carbon. By producing activated carbon from peach and apricot shells the
solid waste problem is addressed, but most of all a profit can be made.
But why activated carbon? Activated carbons are unique and versatile adsorbent with
a vast amount of adsorption applications. It can be produced via a simple oxidation
reaction with steam and the nature of peach and apricot shells are such that it is
expected that activated carbons with good adsorption properties can be produced from
it. The single largest consumer of activated carbon in South Africa is the gold mining
industry that uses imported coconut shell activated carbon for gold adsorption in the
gold recovery process. Activated carbon is also used as water purification adsorbents.
During this study activated carbons were produced in a fluidized bed reactor at
various activation conditions: 700 - 900°C, 0.0425 - 0.0629 g steamlg char.min and
30 - 60 min. This was done in order to find the optimum activation conditions within
the activation parameter range. The optimal activated carbons were defined as peach
and apricot shell activated carbons that showed good microporous as well as
mesoporous character. The optimal activated carbons produced are: peach shell
activated at 875°C, 0.0533 g stearnlg char. min, 60 min and apricot shell activated
carbon at 850°C, 0.0533 g steamlg char.min, 60min.
The possible use of these optimal activated carbons and two other activated carbons
produced (Peach shell activated carbon 900°C, 0.0425 g steamlg char. min, 60 min
and apricot shell activated carbon 900°C, 0.0425 g steamlg char.min, 60min) were
tested in gold recovery and water purification. The gold adsorption properties of
peach and apricot shell activated carbons were found to be better than two
commercial coconut shell activated carbons (Chemquest 650 and GRC 22). No
definite conclusions could, however, be drawn about the replacement of coconut shell activated carbon with peach or apricot shell activated carbon, because abrasion test
work and thermal regeneration of the experimental carbons still have to be performed.
The experimental activated carbons displayed good phenol adsorption characteristic,
although further test work is required. / AFRIKAANSE OPSOMMING: Perske- en appelkoospitte is landbouafvalprodukte. Hierdie afvalprodukte versamel
rondom inmaakfabrieke en voedselververkingsaanlegte. Tans word daar geen poging
in Suid-Afrika aangewend om hierdie afvalprodukte te benut nie. Hierdie studie is die
eerste deel van die ontwikkeling van die produkte: Perskepitdop-geaktiveerde
koolstof en appelkoospitdop-geaktiveerde koolstof. Deur geaktiveerde koolstof van
die perske- en appelkoospitdoppe te maak, word nie net 'n antwoord op die
vastestofafvalsprobleem gevind nie, maar daar kan ook geld gemaak word.
Hoekom geaktiveerde koolstof? Aktiveerde koolstowwe is veelsydige en unieke
adsorbente met 'n groot verskeidenheid adsorpsie toepassings. Dit kan vervaardig
word via 'n eenvoudige oksidasie reaksie met stoom en die aard van die perske- en
appelkoospitdoppe is sodanig, dat verwag kan word om geaktiveerde koolstowwe met
goeie adsorpsie eienskappe daarvan te kry. Die grootste enkelverbruiker van
geaktiveerde koolstof in Suid-Afrika is die goudmynbedryf, wat kokosneutdop
geaktiveerde koolstof invoer om goud te herwin. Geaktiveerde koolstof word ook
gebruik vir watersuiwering.
Tydens hierdie studie IS geaktiveerde koolstowwe by verskillende
aktiveeringskondisies in 'n gevloeïdiseerde bed vervaardig: 700 - 900oe, 0.0425 -
0.0629g stoornlg gepiroliseerde pitdoppe.min en 30 - 60 mm. Die
aktiveringskondisies is gevarieer om sodoende die optimale aktiveringskondisies
binne die aktiveringsparameterreeks te kry. 'n Geaktiveerde koolstof is as optimaal
geklassifiseer as dit 'n goeie mikro- sowel as mesostruktuur getoon het. Die optimaal
geaktiveerde koolstowwe is: geaktiveerde koolstof vervaardig van perskepitdoppe by
875°e, 0.0533 g stoornlg gepiroliseerde pitdoppe.min, 60 mm en geaktiveerde
koolstof vervaardig van appelkoospitdoppe by 850oe, 0.0533 g stoornlg
gepiroliseerde pitdoppe.min, 60min.
Die gebruik van die twee optimale geaktiveerde koolstowwe sowel as twee ander
geaktiveerde koolstowwe (perskepitdop-geaktiveerde koolstof, 900oe, 0.0425 g
stoornlg gepiroliseerde pitdoppe.min, 60 min en appelkoospitdop-geaktiveerde koolstof, 850°C, 0.0533 g stoom/g gepiroliseerde pitdoppe.min, 60min) is VIr
goudadsorpsie en watersuiwering ondersoek. Die goudadsorpsie eienskappe van die
perske-en appelkoospitdop-geaktiveerde koolstowwe was beter as die van twee
kommersiële kokosneutdop-geaktiveerde koolstowwe (Chemquest 650 and GRC 22).
Daar kan egter geen definitiewe gevolgtrekkings gemaak word oor die vervanging
van kokosneutdop geaktiveerde koolstowwe met dié van perske of appelkoospitdoppe
nie, aangesien daar nog toetsresultate oor die slytweerstand en reaktiverings
eienskappe van die eksperimentele geaktiveerde koolstowwe uitstaande is.
Die eksperimentele geaktiveerde koolstowwe toon goeie adsorpie ten opsigte van
fenol, maar verdere toetswerk is egter nodig.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52003 |
| Date | 12 1900 |
| Creators | Van Dyk, Lizelle Doreen |
| Contributors | Nieuwoudt, I., Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 168 p. : ill. |
| Rights | Stellenbosch University |
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