Determination of the potential gold electrowinning from an ammoniacal thiosulphate solution applied to recycling of printed circuit board scraps.

The use of electrochemical techniques in the selective recovery of gold from a solution containing thiosulphate, ammonia, and copper, obtained from the leaching of printed circuit boards from mobile phones using ammoniacal thiosulphate, are shown in this work. First, cyclic voltammetry tests were performed to determine the potential of electrodeposition of gold and copper, and then, electrowinning tests at different potentials for checking the rates of recovery of these metals were performed. The results of the cyclic voltammetry show that copper deposition occurs at potentials more negative than -600 mV (Ag/AgCl), whereas the gold deposition can be performed at potentials more positives than -600 mV (Ag/AgCl). The results of electrowinning show that 99% of the gold present in solutions containing thiosulphate and copper can be selectively recovered in a potential range between -400 mV (vs Ag/AgCl) and -500 mV (vs Ag/AgCl). Furthermore, 99% of copper can be recovered in potentials more negative than -700 mV (vs Ag/AgCl).

BDD anodic treatment of 6:2 fluorotelomer sulfonate (6:2 FTSA). Evaluation of operating variables and by-product formation.

The concerns about the undesired impacts on human health and the environment of long chain perfluorinated alkyl substances (PFASs) have driven industrial initiatives to replace PFASs by shorter chain fluorinated homologues. 6:2 fluorotelomer sulfonic acid (6:2 FTSA) is applied as alternative to PFOS in metal plating and fluoropolymer manufacture. This study reports the electrochemical treatment of aqueous 6:2 FTSA solutions on microcrystalline BDD anodes. Bench scale batch experiments were performed, focused on assessing the effect of the electrolyte and the applied current density (5-600 A m-2) on the removal of 6:2 FTSA, the reduction of total organic carbon (TOC) and the fluoride release. Results showed that at the low range of applied current density (J = 50 A m-2), using NaCl, Na2SO4 and NaClO4, the electrolyte exerted a minimal effect on removal rates. The formation of toxic inorganic chlorine species such as ClO4- was not observed. When using Na2SO4 electrolyte, increasing the applied current density to 350-600 A m-2 promoted a notable enhancement of the 6:2 FTSA removal and defluorination rates, pointing to the positive contribution of electrogenerated secondary oxidants to the overall removal rate. 6:2 FTSA was transformed into shorter-chain PFCAs, and eventually into CO2 and fluoride, as TOC reduction was >90%. Finally, it was demonstrated that diffusion in the liquid phase was controlling the overall kinetic rate, although with moderate improvements due to secondary oxidants at very high current densities.

Teaching basic life support to 12-16 year olds in Barcelona schools: views of head teachers.

AIM: To determine the opinion of head teachers on the educational and logistical characteristics required for a basic cardiopulmonary resuscitation (b-CPR) programme for secondary school teenagers to succeed. MATERIAL AND METHODS: The study was carried out in Barcelona which has 227 public and private secondary schools. Secondary school is started at 12 years old, and finished around 16 once teenagers pass grade 4. A hypothetical b-CPR program split into two parts (concepts and training) was introduced to all Barcelona secondary school head teachers, and a 23 question survey on the programme characteristics was mailed to them three times. RESULTS: One hundred out of 227 (44%) surveys were sent back: 63% from private and 37% from public secondary schools with 85% of head teachers being interested in incorporating a b-CPR programme in the school curriculum. Interested head teachers did not differ in age, sex, or kind of degree compared to their non-interested counterparts. Neither were differences found in secondary school characteristics (ownership, religious orientation, size, and neighborhood average income) of both groups of head teachers. Overall, it was considered that the programme could increase the students' self-esteem (86%), and be useful for saving lives (72%). It was also felt that both theoretical (77%) and practical classes (97%) should be given by healthcare providers. However, up to 69% thought that school teachers would be willing to give theoretical classes if trained previously. The school was identified as the best setting to perform the programme (83%), which should be given to grades 3 or 4 (97%), should last less than 5 h (83%), and should be completed within a time frame of less than 1 week (86%). The greatest programme barrier would be its cost if this was over 5-10 euro per student (55%). CONCLUSIONS: In Barcelona, most secondary schools surveyed were highly interested in a b-CPR programme for their teenagers in grades 3 or 4. Teachers would prefer healthcare providers to give the programme but would be willing to teach b-CPR theory if trained previously.