Patent ID: 12195372

DETAILED DESCRIPTION OF EMBODIMENTS

The following description exemplifies how processes of this disclosure may be used to recover a water-soluble form of benzalkonium (BNZ) from water insoluble benzalkonium-perchlorate (BNZ-ClO4) complex. The recovery process is based on the different in solubility of BNZ-ClO4complex exhibits in water compared to ethanol (Table 1).

TABLE 1ClO4equilibrium concentration and solubility in different solventsComplex/ClO4equilibriumSolubilityprecipitantMatrixconc. [mM]product [Ks]BNZ-ClO4Salt water0.816.56 × 10−7BNZ-ClO4Deionized water0.204.04 × 10−8BNZ-ClO4Ethanol2315.35 × 10−2KClO4Ethanol0.277.36 × 10−8

As clearly evident from Table 1, BNZ-ClO4solubility product is larger in six orders of magnitude in ethanol compared to the solubility product in deionized water, and five orders of magnitude larger than the solubility in salt water.

Thus, BNZ-ClO4complex that is a product of water treatment for perchlorate removal by precipitation of BNZ-ClO4can be treated by dissolving the complex in ethanol, precipitation ClO4in the ethanol and then evaporating of the ethanol.

An exemplary schematic diagram of a process according to this disclosure is shown inFIG.1. Into reaction vessel106, a slurry of organocation-perchlorate salt (e.g. BNZ-ClO4) and a solution of a first salt (e.g. KOH dissolved in ethanol) are fed via feeding lines102and104, respectively. The organocation-perchlorate salt and first salt are brought into contact in reaction vessel106, permitting formation of organic solvent (e.g. ethanol) soluble second salt (e.g. BNZ-OH), and precipitation of metal-perchlorate (e.g. KClO4) in solid form due to its negligible dissolution in ethanol. A stream108of second salt dissolved in the organic solvent (e.g. BNZ-OH ethanolic solution) mixed with the solid metal-perchlorate (e.g. KClO4) is fed into a separation unit110, from which a stream112of the solution of the second salt (e.g. BNZ-OH ethanolic solution) is fed into a distillation column116, separating the solution of the second salt into solvent (e.g. ethanol)120and water soluble second salt (which may be in the form of a solid or an aqueous slurry). The second salt (e.g. BNZ-OH) can then be utilized to treat waste water contaminated with perchlorate ions.

From separator110, a stream114of metal-perchlorate in solvent (e.g. KClO4in ethanol) slurry is transferred into drier122, in which the solvent and the metal-perchlorate streams (124and126, respectively) are separated, to result in metal-perchlorate and solvent products.

FIG.2shows another variation of the process of this disclosure, in which, for the sake of brevity, functionally similar elements to those ofFIG.1were given like numbers, however shifted by 100. For example, reactor206inFIG.2has the same functionality as reactor106inFIG.1.

InFIG.2, the organic solvent vapor stream220from the distillation unit216is passed through condenser232to obtain organic solvent condensate. Similarly, organic solvent vapors stream224from drier222is passed through condenser230. The condensate streams are unified into feed line234, which feeds organic solvent into mixer203, to which a feed of first salt236is also fed. A solution of the first salt in the solvent (e.g. KOH in ethanol) is formed in mixer203, and then fed as feed stream204into reactor206. In this manner, the organic solvent may be recycled in the process.

An example of a process according to the present disclosure includes first mixing a slurry of water-insoluble organocation-perchlorate salt BNZ-ClO4with an organic solvent, such as ethanol, to dissolve the BNZ-ClO4in the ethanol. The low solubility of KClO4in ethanol (i.e. Ks=7.35×10−8) allows to separate most of the BNZ from the ClO4by adding KOH (as the first salt) and precipitating the ClO4as KClO4(which is ethanol insoluble). After the precipitation of the KClO4and separation of the BNZ-OH (being the second salt) solution in ethanol, the ethanol is evaporated and BNZ-OH is recovered, and can be re-used for treating high perchlorate concentration in fresh water brackish water or even brine (e.g. as described in WO 2014/128702).

Results of recovery of BNZ-OH from BNZ-KCLO4 by treating with KOH in ethanol are shown in Tables 2-1 to 2-3.

TABLE 2-1Step 1: Dissolving BNZ-ClO4in ethanolBNZClO4BNZ-ClO4inininincomplexcomplexethanolcomplexethanolrecovery (%)Test(g)(mg)(mg)(mg)(mg)BNZClO410.57269.8257.657.229.995.551.021.35490.4381.4104.019.877.819.030.55310.0293.265.727.294.641.3

As seen from Table 2-1, most of the BNZ is dissolved in the ethanol, with most of the tests showing BNZ recovery >90%. This precipitation was clearly evident as white precipitate that settled at the bottom of the tube after few minutes, in contrast to the BNZ-ClO4complex that floated in the source solution (due to the different densities of these solids—0.94 g/cm3and 2.2 g/cm3for BNZ-ClO4complex and KClO4, respectively).

The recovery of the ClO4was lower, as once the BNZ-ClO4complex is dissolved in the ethanol, some ClO4precipitates as KClO4in the presence of potassium ions that was attributed to drag out from the source solution (i.e. BNZ-ClO4slurry) that had K/ClO4ratio >50.

After dissolving the BNZ-ClO4in the ethanol, the ethanol contains BNZ, ClO4and any drag out from the source solution. At this point the goal is to remove as much ClO4from the ethanol in order to BNZ which is substantially ClO4-free. This is carried out by utilizing potassium ions, in order to precipitate KClO4out of the ethanol, as shown in Table 2-2.

TABLE 2-2step 2: Dosing KOH to the ethanol solutionBNZ (mg)ClO4KOH/ClO4BeforeAfterBeforeAfterEthanolmolarKOHKOHKOHKOHRecovery (%)Test(ml)ratioadditionadditionadditionadditionBNZClO4150.86128.8137.428.616.6106.658.1052.01190.7182.69.98.595.785.838.81.15252.1250.123.43.099.212.8

As seen from Table 2-2, the addition of KOH reduced the perchlorate concentration from >20 mg/l to <10 mg/l. During this stage no significant loss of BNZ was found as the BNZ recovery was >95%.

The last stage in the BNZ recovery process was evaporation of the ethanol and measurement of the BNZ that was left in the sample. No significant losses of BNZ during evaporation were found, as the recovery of BNZ was ≥95%, as seen from Table 2-3. Recovery that is >100% is attributed to experiment limitation.

TABLE 2-3step 3: ethanol evaporationEthanolBNZ inBNZ recovery afterBNZTest(ml)ethanol (mg)evaporation (mg)recovery (%)1382.494.2114.323109.5114.4104.430.411.410.895.0

The BNZ recovery percentage for each step of the process staged the recovery percentage was >92.9% , and the overall (steps 1+2+3) recovery was 94.4% (±19.9%). This results implies that it is possible to recover the BNZ with efficiency that is close to 100%.