Ff. Peng et Pk. Di, REMOVAL OF ARSENIC FROM AQUEOUS-SOLUTION BY ADSORBING COLLOID FLOTATION, Industrial & engineering chemistry research, 33(4), 1994, pp. 922-928
Adsorbing colloid flotation (ACF) with ferric hydroxide as the copreci
pitant, anionic surfactant sodium dodecyl sulfate (SDS) as the collect
or, and nitrogen microbubbles has been shown to be effective in removi
ng arsenic from low concentration of arsenic aqueous solution (approxi
mately 10 mg/dM3). Experiments were conducted to assess the effects of
pH, dosages of SDS and Fe(III), gas flow rate, foreign anions includi
ng NO3-, SO42-, and PO43-, and Al(III) addition on the efficiency of t
he arsenic removal by ACF. When pH is at the range of 4-5,99.5 % arsen
ic removal efficiency can be achieved. The optimal operating condition
s are 35 ppm SDS, 80 ppm Fe(III), 40 cm3/min gas flow rate, 500 rpm ro
tary speed of stirrer, and 5 min ferric hydroxide floc formation time.
The analysis results indicate that foreign anions SO42- and PO43- hav
e an inhibiting effect on the removal of arsenic, while AI(III) additi
ons can compensate for the effect. An actual mine wastewater sample co
ntaining 10.4 ppm arsenic(V), 0.76 ppm chromium(VI), and 0.55 ppm lead
was tested by adsorbing colloid flotation at the optimal operation co
nditions. The residual arsenic, chromium, and lead are 0.07, 0.06, and
0.04 ppm, respectively. The interaction mechanisms between Fe(OH)3-be
aring arsenic floc and SDS were analyzed and interpreted by means of z
eta-potential, infrared spectra analysis, and molecular orbital theory
. The adsorption of SDS can occur physically and chemically on Fe(OH)3
at the pH range of 4-5.