Additively manufactured nylon-12 adsorbent for gold recovery
Suerbaeva, Asiia (2020)
Diplomityö
2020
School of Engineering Science, Kemiantekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
http://urn.fi/URN:NBN:fi-fe202002034319
http://urn.fi/URN:NBN:fi-fe202002034319
Tiivistelmä
Gold is a non-renewable metal which is widely scattered in nature. Currently, gold mining is a major gold production route, however, this industry is very expensive and causes environmental issues. Methods applied for leaching and extraction of gold from the ores include the usage of toxic compounds such as mercury (Hg) and cyanides (CN). In addition, the recovery process of gold from cyanide solution is inefficient and therefore, precious metals may be wasted in tailings. Another waste stream containing a considerable amount of gold is a waste of electric and electronic equipment. Thus, effective technology for recovery of gold from secondary sources should be created.
Additive manufacturing (AM) is a rapidly developing process due to its major advantages over conventional subtractive techniques. It provides the ability to obtain complex shapes in a short time using a wide range of materials. Freedom in design and geometries together with high accuracy allows gaining efficiency in chemical process applications. In this research, the polymer-based adsorbent was fabricated by AM, more precisely powder bed fusion (PBF) of plastic with a system of EOSINT P 395, from commercially available nylon-12. A mesh-shaped object with a layer thickness of 0.12 mm allowed achieving high surface area to enhance the adsorption process. Variety in design optimization of the adsorbent provides the ability to fulfill the requirements in different processing factories.
Adsorption of Au(III) from synthetic solution onto AM nylon-12 adsorbent was performed. The maximum adsorption capacity was achieved at pH 0 after 24h. Adsorption isotherm showed a good fitting by Langmuir equation suggesting monolayer adsorption. Kinetic data were well described by the Elovich model. According to SEM images, gold nanoparticles were formed on the polymer surface after adsorption. However, based on XPS results, majority of gold adsorbed on the polymer in the form of Au(I). Therefore, the adsorption mechanism was proposed to be chelation of Au(I) complex with nitrogen active sites.
Additive manufacturing (AM) is a rapidly developing process due to its major advantages over conventional subtractive techniques. It provides the ability to obtain complex shapes in a short time using a wide range of materials. Freedom in design and geometries together with high accuracy allows gaining efficiency in chemical process applications. In this research, the polymer-based adsorbent was fabricated by AM, more precisely powder bed fusion (PBF) of plastic with a system of EOSINT P 395, from commercially available nylon-12. A mesh-shaped object with a layer thickness of 0.12 mm allowed achieving high surface area to enhance the adsorption process. Variety in design optimization of the adsorbent provides the ability to fulfill the requirements in different processing factories.
Adsorption of Au(III) from synthetic solution onto AM nylon-12 adsorbent was performed. The maximum adsorption capacity was achieved at pH 0 after 24h. Adsorption isotherm showed a good fitting by Langmuir equation suggesting monolayer adsorption. Kinetic data were well described by the Elovich model. According to SEM images, gold nanoparticles were formed on the polymer surface after adsorption. However, based on XPS results, majority of gold adsorbed on the polymer in the form of Au(I). Therefore, the adsorption mechanism was proposed to be chelation of Au(I) complex with nitrogen active sites.