WO2018235106A1 - Appareil d'élimination de métaux des eaux usées et procédé associé - Google Patents

Appareil d'élimination de métaux des eaux usées et procédé associé Download PDF

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Publication number
WO2018235106A1
WO2018235106A1 PCT/IN2018/050412 IN2018050412W WO2018235106A1 WO 2018235106 A1 WO2018235106 A1 WO 2018235106A1 IN 2018050412 W IN2018050412 W IN 2018050412W WO 2018235106 A1 WO2018235106 A1 WO 2018235106A1
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WO
WIPO (PCT)
Prior art keywords
chamber
cathode
anode
anolyte
metal
Prior art date
Application number
PCT/IN2018/050412
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English (en)
Inventor
Prof.Raghuram CHETTY
Prof.Indumathi M NAMBI
Saranya SRIRAM
Original Assignee
INDIAN INSTITUTE OF TECHNOLOGY MADRAS (IIT Madras)
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Publication of WO2018235106A1 publication Critical patent/WO2018235106A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4676—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction
    • C02F1/4678—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction of metals
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46133—Electrodes characterised by the material
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C02F2101/22—Chromium or chromium compounds, e.g. chromates
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/14—Paint wastes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/22—Nature of the water, waste water, sewage or sludge to be treated from the processing of animals, e.g. poultry, fish, or parts thereof
    • C02F2103/24—Nature of the water, waste water, sewage or sludge to be treated from the processing of animals, e.g. poultry, fish, or parts thereof from tanneries
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/30—Nature of the water, waste water, sewage or sludge to be treated from the textile industry
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C02F2103/346—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from semiconductor processing, e.g. waste water from polishing of wafers

Definitions

  • the present invention relates to wastewater treatment, particularly to wastewater treatment methods and apparatus based on electrochemical cell. More specifically, to a self- sustaining electrochemical cell to reduce chromium to lower nontoxic form using urea as anolyte.
  • the electrochemical method offers advantages of no chemical requirement and ease of operation with no residual contamination.
  • the limitations to scale up the existing technique are that they are either energy intensive or the process involves only phase transfer of pollutants rather than the complete metal ion destruction, thus attributing them unsustainable for real scale applications .
  • Ojedokun et al, 2016 investigated the adsorption of heavy metals such has Pb, Cr using cow dung as a bio sorbent.
  • the effect of pH, sorption contact time, adsorbate concentration, adsorbent dosage and temperature is studied.
  • Adsorption may not be a sustainable method of treating metals as it involves only phase transfer of the pollutant rather than complete metal ion reduction. Treating the cow dung with the metal is again challenging as the heavy metals would now be adsorbed onto the cow dung from wastewater.
  • Cr (VI) is not reduced or degraded as adsorption involves only mass transfer of pollutant from one other.
  • Xu et al, 2016 investigated the reduction of Cr (VI) with human urine as oxidant along with power generation.
  • the authors have developed a three chambered cell such as AEM - KCl - CEM.
  • AEM anion exchange membrane
  • CEM cation exchange membrane
  • the anode and cathode compartments are separated by KCl solution.
  • Their intention to place CEM close to the cathode is to prevent the migration of Cr (VI) from the cathode.
  • the AEM is placed near anode to prevent any NH 4 + ion from the anode chamber and the KCl completes the circuit.
  • Ni nano catalyst coated over the carbon cloth was their anode and bare carbon cloth was their cathode.
  • human urine as the anolyte fuel and 300 ppm of Cr (VI) at cathode and an external resistance of 200 ohm, the reduction experiments were performed. The authors have reported a reduction of 93 % after 71 hours.
  • Cow urine is employed as a source of nitrogen for the bacterial growth.
  • the authors have reported that the use of cow urine has significantly increased the growth response than urea or ammonium chloride or ammonium nitrate.
  • a Cr (VI) reduction of 74.5 % was observed with the isolated native bacterial strain.
  • the reported study involves "microorganisms” as the key player involved in the metal ion reduction, whereas in our system "electrons” are the key components.
  • the authors have employed cow urine as a source of nitrogen to enhance the growth of bacterial cells.
  • Electrodialytic buffer generator i.e., such as desalination system and (b) electrodialytically generating buffer i.e., generation of buffer through electrolysis.
  • the Electrodialytic buffer generator is a 3 electrode buffer system operated in a flow through mode, with an Anode (+), cathode (-) and a third electrode in the central buffer chamber.
  • the outlet of the chamber 1 is connected to the inlet of chamber 2 and the outlet of chamber 2 is connected to inlet of chamber 3 respectively.
  • the central buffer unit is separated from the anode and cathode chambers with ion exchange membranes namely CEM and AEM respectively.
  • aqueous electrolyte 0.5 M NaH 2 P0 4 or NaHPC ⁇
  • anode and cathode chambers with pH between 5 and 8
  • the central buffer chamber is filled with deionized water.
  • Bipolar plates have been employed as current collectors for the proper current flow between chambers 1 & 2 and chambers 1 & 3 respectively.
  • the ion exchange membranes and the electrodes are sandwiched to form a membrane electrode assembly
  • MEA typically an orientation of a fuel cell on continuous / flow through mode.
  • Gasket screens are selectively placed between the electrode and the membrane in order to prevent any further leaking and also to aid in preventing any detrimental effect to the MEA.
  • a load of 2 x 10 ohm is applied across the electrodes and the current flowing between the anode and central electrode is termed as CEM current
  • AEM current i.e. current flowing across AEM
  • the authors have not mentioned the potential that is applied to buffer generator cell, the chief principal of the present study is that, on the application of potential between the electrodes (which are either connected to the positive, negative or the grounded terminal), the ions in the respective electrolytic chamber drift towards to either anode or cathode based on their charge. This evidently demonstrates that electrolysis happens at all the three electrodes.
  • the CEM current generated is controlled to either be ⁇ to AEM current.
  • the primary mechanism is that, depending on the current generated by the CEM or AEM, determines the amount of OH ⁇ and H + ions in the systems are formed. As the potential is continually applied, these ions tend to transfer to their respective electrodes with the associated electrolysis of water. Upon this, the O 2 and H 2 gas is liberated with water oxidation and reduction. This causes an effective pH gradient in the system with prolonged electrolysis. Additionally, the anionic and cationic electrolyte split as Na + and 3 ⁇ 4 ⁇ 4 ⁇ or ⁇ 0 4 ⁇ . The selective transportation of these ions relies on the ion selective membrane to pass through.
  • Ion selective membranes such as AEM & CEM are employed.
  • the AEM passes anions and blocks the cations; CEM passes the cations and blocks the anion.
  • An aqueous cationic electrolyte is filled between chamber 1 and the central buffer chamber.
  • An aqueous anionic electrolyte is filled between central chamber and 3 rd chamber.
  • the potency of the designed cell relies on either generation of buffer or to deionize the electrolyte.
  • a degassing unit to remove the gases formed to reconfirm on the claimed hypothesis with the generation of H + or OH ⁇ and / generation of 3 ⁇ 4 or O 2 .
  • an apparatus for removal of metals from waste water comprising of: an electrochemical cell for reduction of a metal in waste water comprising of:
  • OCV open circuit voltage
  • anode chamber having an anode adapted to be in contact with an anolyte ;
  • a cathode chamber having a cathode adapted to be in contact with hexavalent containing waste water;
  • an open circuit voltage (OCV) developed between the electrodes and electrolytes drives the spontaneous oxidation of anolyte at anode and metal reduction at cathode; and extracting the reduced metal
  • Fig.l (a) is the schematic representation of three chambered cell with electrodes, electrolytes and membranes
  • Fig.l (b) is the graphical representation of removal efficiency of 400 ppm Cr(VI) dissolved in 0.5M H 2 S0 4 at a constant load of 1000 ohm at room temperature.
  • Fig.2 is the schematic representation the 3 chambered cell with ion separators, anolyte fuel and catholyte at a constant load.
  • Fig.3 (a) is the graphical representations of the comparison of cathodic efficiencies for different membrane configurations and 3 (b) the reduction at different initial concentrations of Cr with urea as anolyte fuel
  • Fig.3(c) is the graphical representations of comparison between influence of Milli Q water and 0.5 M phosphate buffer solution (PBS) for Cr (VI ) reduction at cathode and 3 (d) reduction kinetics at different concentrations with cow urine as anolyte fuel in anode-CEM-PBS-AEM-cathode system and a constant load of 1000 ⁇ .
  • PBS phosphate buffer solution
  • FIG.l and FIG 2 it is disclosed here a three- chambered cell namely anode chamber (A) , middle (buffer) (B) and a cathode chamber (C) .
  • Urea and cow urine has been employed as anolyte to reduce Cr(VI) to Cr(III) .
  • the buffer channel separates the anode and cathode compartments maintaining the overall ionic balance in the system.
  • the major highlight of the present invention includes the fundamental understanding for the need of membrane designs to primarily curtail the fuel crossover between the anode and cathode chamber which enhances the carcinogenic metal ion reduction.
  • a CEM placed next to anode and an AEM placed next to anode have effectively shown to improve the efficiency of Cr reduction.
  • Ni foam as anode and catalyst free carbon felt as cathode was used. The technology can thus be established in actuality as a self-driven alternate method to simultaneously oxidize the animal excretion on the anode and to reduce the Cr (VI) at the cathode to its lower nontoxic form.
  • the electrodes Ni foam and carbon felt were procured from Sigma Aldrich and AVCARD respectively.
  • the AEM and CEM were procured from FuMa-Tech, Germany and DuPont, USA.
  • the fresh electrodes were rinsed with MilliQ water, oven dried at 80°C and used.
  • the anolyte used for study was 0.1 M urea dissolved in 1 M KOH and the pH of the anode chamber was maintained between 10 and 12.
  • the phosphate buffer solution was prepared with K2HPO4 and KH2 PO4 in distilled water with pH 7 and 8.
  • the Cr (VI) as the catholyte was prepared using K 2 Cr 2 0 7 (oven dried for 2 h at 110 °C) in 0.5 M H 2 S0 4 with pH maintained between 1 and 2. Standard Cr solution of desired concentrations was prepared from the stock solution.
  • fresh cow urine was also employed as the anolyte fuel and experiments were performed with different initial concentrations of Cr (VI) . All the experiments were carried out connecting a 1000 ohm resistance as a constant load with copper wire used as current collector at ambient temperature and pressure in triplicates and the mean values are reported. All the chemicals used were of analytical grade .
  • the major highlight of the sandwiched membrane is that, the appropriate positioning of the CEM and AEM have served the purpose not to allow the H + and OH ions primarily which has aided in faster reduction.
  • the membranes functions to separate the ionic interference from the individual chambers and thereby maintain pH throughout the reduction period.
  • the anode and cathode chambers entail two extreme pH conditions to independently perform their oxidation and reduction.
  • an ideal separator is required to simultaneously utilize a waste to decontaminate a toxic pollutant.
  • a novel three chambered cell was configured with a phosphate buffer as separating channels between the anode and cathode compartments was designed.
  • Cow urine is an immoderate resource which is scarcely attempted for enhancing the reduction of carcinogenic pollutants.
  • the electro oxidation of urea / cow urine on Ni foam is the key player for the metal ion reduction at the cathode.
  • Ni +3 in the alkaline medium marks the spontaneous oxidation of urea (electron donor) to render electron flow from the anode compartment (Daramola et al, 2010) .
  • the electron generated at the anode compartment is readily consumed up by the Cr (VI) as electron acceptor at the cathode and is reduced ( Figure 2 ) .
  • the invention has attempted to simultaneously handle the dual wastes which are disposed into the environment.
  • the present invention has strived to reduce carcinogenic metal pollutant on one hand and as well oxidize a nitrogenous waste resource on the other in principal by electrochemical technique understanding the contribution of membranes and their orientation.
  • the present invention is sustainable in nature, which can definitely be commercialized as prototype and is absolutely eco- friendly .

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Molecular Biology (AREA)
  • Health & Medical Sciences (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)

Abstract

L'invention concerne une configuration de cellule électrochimique qui permet de simultanément traiter un déchet d'animal azoté d'une part et de réduire un ion métallique carcinogène d'autre part. L'invention concerne un appareil et des procédés pour réduire le chrome hexavalent (Cr+6) à un état non toxique inférieur, c'est-à-dire Cr+3, avec de l'urine de vache qui est une ressource facilement disponible en tant que combustible anolyte.
PCT/IN2018/050412 2017-06-23 2018-06-23 Appareil d'élimination de métaux des eaux usées et procédé associé WO2018235106A1 (fr)

Applications Claiming Priority (2)

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IN201741022070 2017-06-23
IN201741022070 2017-06-23

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110330155A (zh) * 2019-08-13 2019-10-15 东北大学 一种电解-络合硫酸酸洗废液萃取回收铬的方法
CN114561652A (zh) * 2022-03-04 2022-05-31 安徽理工大学 一种无膜法电解水制氢-还原性废水降解耦合装置及工艺

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130048498A1 (en) * 2011-08-23 2013-02-28 Dionex Corporation Three-electrode buffer generator and method
US20140083933A1 (en) * 2011-05-04 2014-03-27 Mike Young Shin Method for heavy metal elimination or precious metal recovery using microbial fuel cell

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140083933A1 (en) * 2011-05-04 2014-03-27 Mike Young Shin Method for heavy metal elimination or precious metal recovery using microbial fuel cell
US20130048498A1 (en) * 2011-08-23 2013-02-28 Dionex Corporation Three-electrode buffer generator and method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
W. XU ET AL.: "A urine/Cr(VI) fuel cell - Electrical power from processing heavy metal and human urine", JOURNAL OF ELECTROANALYTICAL CHEMISTRY, vol. 764, March 2016 (2016-03-01), pages 38 - 44, XP055554545 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110330155A (zh) * 2019-08-13 2019-10-15 东北大学 一种电解-络合硫酸酸洗废液萃取回收铬的方法
CN114561652A (zh) * 2022-03-04 2022-05-31 安徽理工大学 一种无膜法电解水制氢-还原性废水降解耦合装置及工艺

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