Oxidation of printed circuit board wastes in supercritical water

Preparation of nano-Cu2O/TiO2 photocatalyst from waste printed circuit boards by electrokinetic process

“…Experimental conditions were 713 K, 25 MPa and 1 h, respectively. Most of the BFR in the waste PCBs could be removed and Cu could be oxidized completely at such conditions according to previous reports [9,12].…”

“…The SCWO treatment experiments were conducted according to a previous literature [9]. In a typical experiment, 1 g of the sample and 20 ml of distilled water were introduced into a 200-ml high-pressure reactor made of 316 alloy, while 10 ml of hydrogen peroxide (H 2 O 2 , 30 wt.%) was used as oxygen source.…”

“…In a typical experiment, 1 g of the sample and 20 ml of distilled water were introduced into a 200-ml high-pressure reactor made of 316 alloy, while 10 ml of hydrogen peroxide (H 2 O 2 , 30 wt.%) was used as oxygen source. 1 g of NaOH was used as catch agent of Br species for removing the BFR [9]. Experimental conditions were 713 K, 25 MPa and 1 h, respectively.…”

“…In recent years, to obtain high purity Cu products from waste PCBs, many researchers [6][7][8] proposed some new process such as leaching-electrowinning [6], mechanical-electrometallurgy [7] and vacuum metallurgy technology [8]. Recently, Chien et al [9] reported that supercritical water oxidation (SCWO) method can be used for simultaneously effectively removing BFR and oxidize metals in waste PCBs. On the other hand, electrokinetic processes (EK) have been widely used for metals recovery from soil and solid wastes [10,11].…”

Recovery of metals from waste printed circuit boards by supercritical water pre-treatment combined with acid leaching process

“…At supercritical conditions (T > 374°C, P > 22.1 MPa), organic compounds and water form a single and homogeneous phase, which allows reaction to proceed rapidly by an elimination of the potential interface mass transport limitations (Modell, 1989;Shaw et al, 1991). At present, there are two main SCW processes used for the treatment of waste PCBs (Chien et al, 2000;Goto et al, 2003;Xiu and Zhang, 2009;Onwudili and Williams, 2009;Yin et al, 2011;Wang and Zhang, 2012). One is supercritical water oxidation (SCWO) process in the presence of oxygen, and the other is supercritical water depolymerization (SCWD) process under reducing atmosphere.…”