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Process for removal of pentavalent arsenic from water

A pentavalent arsenic removal technology, applied in chemical instruments and methods, water pollutants, water/sewage treatment, etc., can solve the problem of poor arsenic removal efficiency, low processing capacity, leaching into the same or different water sources To wait for the problem, to achieve the effect of good efficiency and high processing capacity

Inactive Publication Date: 2000-08-09
AFFINITI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The remaining problems with this process are the mechanical problems of filtering the iron oxide / arsenic co-precipitate from the water, and ultimately the disposal of the arsenic-containing sludge which may then be leached to the same or a different water source
[0012] The classical ion exchange method using anion resins suffers from poor arsenic removal efficiency (90%), low throughput (1500 bed volumes), and severely reduced throughput and binding efficiency when the amount of competing ions such as sulfate is 50 ppm or higher these shortcomings
Classic ion exchange media has the disadvantage of poor service life when used in many types of hard well water

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0068] Example 1: Removal of pentavalent arsenic from an aqueous stream

[0069] Reillex HPQ resin from the manufacturer (Reilly Industries, Indianapolis, IN) contains approximately 3.4 meq / g of N-picoline functional groups and approximately 1.2 meq / g of pyridine functional groups; these two groups are bound to the resin The incorporation is facilitated by copolymerization of vinylpyridine monomers and subsequent N-alkylation with an alkyl halide in the backbone of . Crosslinking of the Reillex HPQ resin with divinylbenzene produced rigid porous pellets of 18-50 mesh size. Resin (1 volume) and deionized water (2-3 volumes) were slurried by stirring in an appropriately sized vessel, such as a beaker, prior to use in this example. Stop stirring and allow the resin to settle to the bottom of the vessel. Finer particles (particulates) are undesirable during column operation because they impede flow. Since fines do not settle as quickly as 18-50 mesh particles, the supernatant w...

example 2

[0075] Example 2: Stripping back bound pentavalent arsenic and regenerating PERFIX for reuse TM (N-Methylpyridinium) Resin

[0076] For the arsenic-saturated column described in Example 1, 100 mL (1 column volume) of a stripping solution consisting of 2N NaOH and 2N NaCl was flowed into and through the column at a rate of approximately 10 mL / min. Drops were collected and saved as stripping effluent for analysis. A second column volume (CV) of stripping solution was added in the same manner and collected. During the addition of the stripping solution, the color of the resin changed from light tan to dark brown. Each stripping effluent was serially diluted until Gutzeit's assay for arsenic fell within the analytical working range (0.100-3.0 ppm) for that assay, thereby determining more than 95-99% of the originally bound pentavalent arsenic (1200 mg ) was eluted by 2 column volumes of stripping solution.

[0077] The resin was then washed with 2 column volumes of water, foll...

example 3

[0083] Example 3: Reuse of stripped and reconditioned PERFIX TM (N-Methylpyridinium) Resin

[0084] Prepare pentavalent arsenic standard solution (100ppm) according to example 1, and add it to the N-picoline resin column (100mL PERFIX TM resin). Checking of the column for pentavalent arsenic (100 ppm) continued until arsenic (>0.100 ppm) was detected in the effluent from the column. The capacity of the stripped and reconditioned column for pentavalent arsenic is 150 column volumes or 15g arsenic / L resin. This result is slightly higher than the treatment capacity shown in Example 1 (12 g arsenic / L resin). It is believed that the resin bed settled to a higher degree in this example, resulting in enhanced chromatographic performance. This example illustrates PERFIX TM (N-Methylpyridinium) resins can be stripped, reconditioned and reused many times without loss of performance.

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Abstract

A process for the separation of pentavalent arsenic from an aqueous solution using an N-alkyl pyridinium-containing adsorption medium is disclosed. An oxidizing medium and process for the oxidation of trivalent arsenic to pentavalent arsenic with removal of the pentavalent arsenic so formed is also disclosed.

Description

field of invention [0001] The present invention relates to a method for removing an environmentally hazardous pollutant from an aqueous solution. More particularly, the present invention relates to an attractive process for the selective removal of arsenic from aqueous solutions containing pentavalent arsenic. The present invention also relates to a method of converting trivalent arsenic into pentavalent arsenic before separating pentavalent arsenic to facilitate the removal of arsenic. Background of the invention [0002] Arsenic is identified as a primary contaminant in US drinking water under the Safe Drinking Water Act of 1986 and its amendments. The 50 parts per billion (50 ppb) maximum contaminant concentration (MCL) for arsenic in the United States has been in effect since 1974. The US Environmental Protection Agency (EPA) has proposed lowering the MCL for arsenic from 50 ppb to 2 ppb based on recent findings related to health hazards for residents using drinking wa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J41/04B01J45/00C02F1/28C02F1/56C02F1/76
CPCC02F1/285B01J45/00B01J41/043Y10S210/911C02F1/766C02F2101/103C02F1/56B01J41/05
Inventor P·K·史密斯E·P·伯格曼
Owner AFFINITI
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