The technological development and application of waste-to-resource strategy is
significantly critical and crucial in both environmental and manufacturing industries, via
which we do not only provide practical treatments to toxic waste materials but also
translate them into usable products. It has been considered as a preferred method which
should be applied in future wastewater treatment strategies.
In this study, we investigated the process of incorporating cadmium oxide and nickel
oxide into ceramic-based materials with the phases of CdAl4O7, and CdFe2O4. Such
products are of less harmful effect to the natural environment and can also be of
beneficial use with their good mechanical properties identified by nano-indentation. We
proved the possibility and provided an opportunity to convert the waste from
wastewater treatment process to a new material resource.
XRD is preferred for characterizing solid mixtures to determine the relative
abundances of crystalline phases during the reaction process. As a result, we can obtain
the relative abundance information on the growth of the crystalline products, such as
CdAl4O7, and CdFe2O4 according to the change of fabrication temperatures. In that case,
the starting reaction temperature and the optimized temperature (at which the completed
reaction could be achieved) could be revealed. In Cd-Al system, the starting temperature
for CdAl4O7 formation is 900 °C, and the optimized formation temperature is around
1020 °C. On the other hand, for Cd-Fe system, such temperatures are of 700 °C and
850 °C correspondingly.
In our research, it is shown that the ceramic-process is an effective strategy to
stabilize the waste hazardous metals (cadmium and nickel) by materials such as
aluminate, ferrite, and kaolin commonly used in ceramic industry. Through this method,
the difficult-to-treat wasted metals would become reusable and applied in building and
infrastructure projects. Products containing CdAl4O7, CdFe2O4 and NiAl2O4 have
shown higher resistance to acidic leaching, comparing to CdO and NiO used as the
starting materials to simulate the waste metal forms discharged from the industrial
stream. Furthermore, similar measurements by alkaline attack on the sintered products
(NiAl2O4 containing samples) were also studied.
Besides the investigation to leaching behavior, the mechanical properties are also
measured by nano-indentation in our work. The incorporation of metal waste into the
fabrication of ceramic products is valuable due to the preferred stabilization
mechanisms of crystal structures and the large volume of ceramic products needed by
the construction industry. Furthermore, because the product safety and functionality
should not be compromised, a fundamental understanding of the surface properties of
metal containing phases should be further established, rather than relying solely on data
from regulatory tests on bulk samples. Therefore, the results of this study demonstrate
the superior mechanical properties of nickel spinel containing products, comparing to
the cristobalite silica matrix, under severe acid attack. / published_or_final_version / Civil Engineering / Master / Master of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174486 |
| Date | January 2011 |
| Creators | He, Yue, 贺悦 |
| Contributors | Shih, K |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47753067 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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