Uklanjanje cijanida i rodanida iz voda

master's thesis

• Title (english): Removal of the cyanide and the rhodanide from waters
• Author: Vjeran Sunko
• Mentor: Lidija Furač (mentor)
• Committee member: Lidija Furač (predsjednik povjerenstva)
• Committee member: Matija Cvetnić (član povjerenstva)
• Committee member: Dajana Kučić Grgić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2023-06-30, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Cijanidi i rodanidi su toksični spojevi sa štetnim utjecajem na okoliš i ljudsko zdravlje. Cijanidi su poznati kao bitna sirovina kod proizvodnje farmaceutika, kozmetike, medicinskih i poljoprivrednih proizvoda te kod procesa obrade u metalurškoj industriji. Reakcijama cijanida sa sumporom nastaju rodanidi ili tiocijanati koji su karakterizirani kao spojevi manje toksičnosti, ali veće stabilnosti od cijanida. Razvojem industrije i povećavanjem proizvodnih kapaciteta raste i količina otpadnog cijanida točnije otpadnim vodama dospjevaju u okoliš. Stoga je potrebno provoditi obradu otpadnih voda prije ispuštanja iz postrojenja kako bi se smanjila njihova prisutnost u okolišu. Napredni oksidacijski procesi su vrsta procesa koji se koriste pri obradi takvih onečišćenih voda. Temelje se na korištenju oksidacijskih sredstava pomoću kojih dolazi do uspješne razgradnje i uklanjanja neželjenih organskih spojeva.
U ovom radu provedena su istraživanja uklanjanja cijanida (CN-) i tiocijanata (SCN-) iz modelnih otopina naprednim oksidacijskim procesima fotolizom, UV/H2O2 i UV/S2O82- pri pH vrijednostima 4, 7 i 10. Omjer onečišćivala (CN- i SCN-) prema oksidacijskom sredstvu (H2O2 i S2O82-) iznosio je 1:10 dok je valna duljina UV zračenja iznosila 254 nm. Rezultati su pokazali kako je najučinkovitija primjena UV/S2O82- za oba istraživana onečišćivala pri nižim pH. Metoda UV/S2O82- je najučinkovitija s 99,26% uklonjenog CN- i 80,26% uklonjenog SCN- pri pH = 4. Minimalne učinkovitosti pri uklanjanju oba onečišćivala zabilježene su kod čiste fotolize gdje je uklonjeno samo 40,90% CN- (pH = 7) i 21,49% SCN- (pH = 10). Najbrža je kinetika razgradnje CN- metodom UV/S2O82- (k = 0,0806 s^-1) pri pH=4 dok je najsporija tijekom čiste fotolize (k = 0,0076 s^-1) pri pH=7. Najbrža razgradnja SCN- je metodom UV/S2O82- (k =0,027 s^-1) pri pH=4 dok je najsporija tijekom čiste fotolize (k = 0,0041 s^-1) pri pH = 10. Navedene brzine uklanjanja CN- i SCN- su prvog reda odnosno kinetika se ipak smatra pseudo-prvog reda zbog velikog broj radikalskih reakcija.

Abstract (english)

Cyanides and rhodanides are toxic compounds with a negative influence on the environment and the human health. Cyanides are known as a important raw material in pharmaceutical, cosmetics, medical and agricultural product manufacture and in processing processes of the metallurgical industry. Reactions between cyanides and sulphur result with the formation of rhodanides or thiocyanites which are charaterized as compunds with lower toxicity but higher stability than cyanides. With the development of the industry and the increase in production capacity, the amount of cyanide and rhodanides that ends up in the environment within wastewaters increases. Because of that, it is necessary to carry out the wastewater treatment before the discharging to decrease their presence in the environment. Advanced oxidation processes are a type of processes which are used for treating that kind of polluted water. They are based on the usage of oxidizing agents which successfully result with the decomposition of unwanted organic compounds. This work deals with the removal od cyanides (CN-) and rhodanides (SCN-) from model solutions by the advanced oxidation processes using photolysis, UV/H2O2 and UV/S2O82- at pH values 4, 7 and 10. The ratio of pollutants (CN- and SCN-) to oxidizing agents (H2O2 and S2O82-) was 1:10, while the wavelength of the UV radiation was 254 nm The results showed that the usage of the UV/S2O82- method under lower pH values was the most effient for both pollutants. The UV/S2O82- method is the most efficient with 99.26% of CN- and 80.26% of SCN- removed at pH=4. Minimal efficiencies in the removal of both pollutants were recorded with pure photolysis, where only 40.90% of CN- (pH=7) and 21.49% of SCN- (pH=10) were removed. The fastest kinetics of the CN- degradation is by the UV/S2O82- method (k = 0.0806 s^-1) at pH=4, while the slowest is during pure photolysis (k = 0.0076 s^-1) at pH=7. The fastest degradation of SCN- is by the UV/S2O82- method (k = 0.027 s^-1) at pH=4, while the slowest is during pure photolysis (k = 0.0041 s^-1) at pH=10. The stated removal processes of CN- and SCN- contain first order reactions, that are actually considered to be pseudo-first order due to the large number of radical reactions.

• Keywords: cijanidi; rodanidi; napredni oksidacijski procesi; otpadne vode; razgradnja; uklanjanje; UV; UV/H2O2; UV/S2O82-
• Keywords (english): cyanides; rhodanides; advanced oxidation processes; waste waters; degradation; removal; UV; UV/H2O2; UV/S2O82-
• Language: croatian
• URN:NBN: urn:nbn:hr:149:422071
• Study programme: Title: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2033-01-01
• Created on: 2023-07-26 11:00:22