Simultaneous recovery of metals and degradation of organic species: Copper and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)

Abstract

In mixed wastewater streams, the presence of metal ions can retard the destruction of organic contaminants and the efficiency of recovery of the metal is reduced by the presence of organic species. The reduction in the efficiency of these methods is due to the formation of complexes between the organic species and the metal ions in solution. Results are presented for copper -2,4,5-T system in which both effects occur. A photolytic cell alone can achieve the complete degradation of 2,4,5-T, in the presence of TiO 2 or H 2 O 2 , at pH 3.5. The addition of Cu(II) ions, however, retard the degradation of 2,4,5-T and complete mineralization of 2,4,5-T was not achieved and the system also leaves Cu(II) ions in solution. An electrolytic cell alone can be used to recover copper in pH range 1.5 -4.5 but is not capable of achieving complete disappearance of 2,4,5-T by anodic oxidation. A combined photolytic -electrolytic system is capable of achieving simultaneous destruction of 2,4,5-T and recovery of copper from mixed wastewater streams at pH 3.5. The percentage destruction of 2,4,5-T and the recovery of copper can be increased further by using a combined photolytic and an activated carbon concentrator cell system. This system can achieve the simultaneous recovery of copper and the degradation of 2,4,5-T without the use of an additional oxidants or catalysts.

Efficient removal of herbicide 2,4-dichlorophenoxyacetic acid from water using Ag/reduced graphene oxide co-decorated TiO2 nanotube arrays

“…Chlorinated phenoxyacetic acid herbicides have been used worldwide on a large scale in agriculture to control the growth of broad-leaved weeds on rice, maize, wheat, and in post-emergence applications in most developing countries [1,2]. Among these herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) is very difficult to be decomposed due to its chemical and biological stability [3,4].…”

Electrochemical removal of CuII in the presence of humic acid

“…46% is obtained in both the absence and presence of Cu II . This is an interesting result considering that the presence of Cu II with other chelating agents like 2,4,5-trichlorophenoxyacetic acid 27 or ethylenediaminetetraacetic acid (EDTA), 28 decreases the rate of removal for both chelating agent and organic content. When a membrane is used to separate the cell there is a decrease in the amount of TOC, which varies with the type of membrane used.…”

“…To support these observations, the current efficiency values associated with the Cu II removal are presented in Table 2. This would appear to be unusual behavior, but it must be remembered that this phenomenon is probably due to the presence of HA in solution, which is free to interact at the anode or cathode and such an interaction would probably increase with increasing 27 demonstrates that the presence of chelating agents decreases the rate of Cu II removal and this is attributed to the formation of the chelate-metal complex, transport to the electrode surface and increase in activation energy required to deposit the complexed metal. In addition, at higher current densities hydrogen evolution will be more significant, competing with Cu deposition.…”

Recovery of critical metals from dilute leach solutions – Separation of indium from tin and lead

“…The cell was developed from one used in earlier work to achieve simultaneous recovery of metals and destruction of organic components from dilute solution [43][44][45][46]. It consists of a Pyrex vessel (with an outer diameter 16 cm and height 30 cm) containing…”

“…For example, indium deposition is about 10 5 times faster from solutions in which the basic ion [In(H2O)5OH] 2+ predominates than it is from acidic solutions in perchloric acid where the indium is present as In(H2O) [38]. In earlier work [39,40] the authors have described the development of electrochemical cells designed to monitor trace levels of metals, to recover metals from dilute solution [41], to separate cobalt and nickel [42], and to simultaneously remove metals and degrade organic contaminants in effluent streams [43][44][45].…”