Abstract:
Chromium recovery allows chromium to be reused in the chrome tanning
process, is very useful for decreasing environmental problems, the process is also cost
effective for leather industry. A solvent extraction process for chromium recovery, using
D2EHPA (di-2-ethylhexyl phosphoric acid) as an extracting agent, was investigated in this
research.
The experiment was divided into 2 stages: the extraction and recovery stage.
The first stage investigated three levels of three variables: NH3 dosage (4%, 8%, 12% v/v
of D2EHPA), D2EHPA dosage (10%, 20%, 30% v/v of organic phase), and extraction
time (1, 3, 6 minute[s]). In addition, three levels of two variables: HCl concentration
(3.6N, 4.8N, 6.0N) and recovery time (10, 30, 60 minutes), were investigated in the
recovery stage.
Results from the extraction stage showed that NH3 dosage, D2EHPA dosage
and extraction time had positive effects on chromium extraction efficiency. Statistical
analysis showed the best level in the extraction stage was achieved at a NH3 dosage of
12%, D2EHPA dosage of 30%, and extraction time of 6 minutes, which yielded an
average chromium extraction efficiency of 85.88% (SD = 2.20%).
The results from the recovery stage showed that HCl concentration and
recovery time had positive effects on chromium recovery efficiency. The best level in the
recovery stage was achieved at 6.0N HCl and a recovery time of 30 minutes which yielded
an average chromium recovery efficiency of 67.76% (SD = 1.66%).