Metallic anion recovery from aqueous streams and removal agent recycle in the polymer–surfactant aggregate process

Abstract

In a previous contribution, a new application of the polymersurfactant aggregate (PSA) process was developed; the removal of metallic anions from dilute aqueous solutions. A subsequent pH adjustment method has been developed to recover the metallic anions from the flocculated PSAs into a concentrated solution and then to recover the polymer (PAA) and surfactant (MTAB) for recycling. A base solution is firstly added to the flocs to leach out the bound metallic anions in 15 minutes, and then a coarse filter is used to separate out the basic solution containing 5-20 times more concentrated metallic anions than the original effluent. The flocs can then be completely dissolved in an acid solution for recycling. The results show that the recovery efficiency of CrO42-at an optimum pH of 12 is 94%, and the recovery efficiency of PAA-MTAB at its optimum pH of 1.4 is 94%. The removal efficiency of 0.2 mM CrO42solution remains at the same level using recovered PAA-MTAB. In short, the sequential pH adjustment method is able to recover and concentrate the metallic anions from the flocculated PSAs, and then recover the removal agent for recycling into the process with little deterioration of removal ability.

Inorganic anion removal using micellar enhanced ultrafiltration (MEUF), modeling anion distribution and suggested improvements of MEUF: A review

“…Further research found adjustment of pH can result in greater recover the metallic anions from the flocculated PSAs into a concentrated solution, essentially recovering the polymer and surfactant for re-use. Results on the overall recycle process have shown that up to 94% of both CrO 4 2− and the PAA-MTAB were recovered and were able to be reused, respectively, upon addition of NaOH and H 2 SO 4 at optimal dosages [125].…”

Interaction among branched polyethylenimine (PEI), sodium dodecyl sulfate (SDS) and metal cations during copper recovery from water using polymer-surfactant aggregates

“…In addition, using a cationic surfactant with a longer tail group facilitates the formation of PSAs and the removal of metallic anions [18]. Research results on the overall recycle process have shown that up to 94% of both CrO4 2− and the PAA-MTAB can be recovered and reused, respectively, via addition of NaOH and H2SO4 at the optimum dosage [19].…”