Skip to main content
. 2021 May 7;75:105586. doi: 10.1016/j.ultsonch.2021.105586

Table 1.

Studies based on combined approaches of US in the treatment of dye effluent.

Sr. No. Simulated/ real industrial dye effluent Treatment scheme Operating Conditions Important Results Ref.
1 C. I. Acid Orange 7 US + O3, UV + O3, US + O3 + UV, US + UV Co = 19.967 mg/L, US frequency = 520 kHz based on piezoelectric transducer, UV lamps (max emission at 253.7 nm), US power density = 0.073 W/L, O3 = 40 mg/L, Flow ratio of Ar(argon):O2 = 1:0.5, pH of solution = 5.5, Temperature = 25 °C, T = 60 min. For US + O3, UV + O3, US + UV, US + O3 + UV, 27%, 33%, 6% and 40% of mineralization reported respectively, US + O3 + UV approach offered a biodegradable form of effluent (BOD5/TOC = 0.45) after treatment, Combined approach of US + O3 + UV as well as gas mixture (Ar/O2) presence improved degradation efficiency of dye. [11]
2 Dye industrial wastewater US (bath), EF, US + EF, EF + US C0 = 15360 mg/L, US bath frequency = 33 kHz, US power = 100 W, Voltage = 3 V, Electrode area = 30 cm2, Electrode distance = 4 cm, FeSO4 = 100 mg/L, pH of solution = 3, Temperature = 38–40 °C, Electrolysis time = 120 min. For US, EF, US followed by EF and EF followed by US, 10.4%, 79.2%, 81.3% and 85.4% of COD reduction obtained respectively, Sonication assisted electro-Fenton process was the best treatment process. [22]
3
  • i.

    Textile industrial effluent-I

  • ii.

    Textile industrial effluent-II

 US + H2O2, US + O3, US + Fenton + Lime, HC + Fenton + Lime, Only Fenton, HC + NaClO, HC + Fenton
  • i.

    C0 = 2500–3000 mg/L, H2O2 = 4800 mg/L, H2O2/Fe2+= 3, CaO (lime) = 2000 mg/L, O3 = 400 mg/h, pH of solution = 2,

  • ii.

    C0 = 230–250 mg/L, H2O2 = 350 mg/L, H2O2/Fe2+= 0.33, NaClO = 1000 mg/L, pH of solution = 7.
  • i.

    US + H2O2, US + O3, US + Fenton + Lime, HC + Fenton + Lime resulted in 12% (t = 120 min), 20% (t = 120 min), 92% (t = 240 min), and 86% (t = 240 min) of COD reduction respectively,

  • ii.

    Only Fenton, HC + NaClO, HC + Fenton resulted in 65.15%, 47.87% and 80.45% of COD reduction respectively.

Combined approach was most effective as compared to an individual approach, cavitation enhanced the efficiency of metal-catalysed Fenton oxidation		 [23]
4
  • i.

    Reactive Orange 107 (azo dye)

  • ii.

    Real industrial effluent
  • i.

    US + H2O2, US + MNPs, MNPs + H2O2, US + MNPs + H2O2

  • ii.

    US + MNPs + H2O2
  • i.

    C0 = 50 mg/L, MNPs dosage = 800 mg/L, H2O2 loading = 340.15 mg/L, US power = 300 W, pH of solution = 5, T = 30 min,

  • ii.

    C0 = 2360 mg/L, TOC = 733 mg/L, TDS = 1970 mg/L, MNPs dosage = 800 mg/L, H2O2 loading = 340.15 mg/L, US power = 300 W, pH of effluent = 5, T = 30 min.
  • i.

    For binary system of US + H2O2, US + MNPs and MNPs + H2O2, 12.1%, 33.3% and 54.6% of decolorisation was reported respectively; for tertiary system of US + MNPs + H2O2, 92% of decolorisation was obtained, US irradiation enhanced the catalytic activity by dispersion of the aggregated MNPs in aqueous solution.

  • ii.

    For US + MNPs + H2O2 process, 79.25% as COD removal and 66.54% as TOC removal was demonstrated

 [24]
5
  • i.

    direct red 31 (DR31)

  • ii.

    Real textile effluent
  • i.

    US + H2O2 + EC, US + EC, H2O2 + EC

  • ii.

    US + H2O2 + EC, (EC:Electro-coagulation)
  • i.

    C0 = 1500 mg/L, NaCl = 5844 mg/L, H2O2 = 1020.4 mg/L, pH of solution = 3, US frequency = 37 kHz, US power = 256 W, T = 20 min,

  • ii.

    C0 = 271 mg/L, TOC0 = 201 mg/L, NaCL = 5844 mg/L, H2O2 = 1020.4 mg/L, pH of solution = 11.4, US frequency = 37 kHz, US power = 256 W, T = 60 min.
  • i.

    For US + H2O2 + EC, US + EC, H2O2 + EC, 93.3%, 65.3% and 54.1% respectively of decolorisation was reported.

  • ii.

    For US + H2O2 + EC, 86.7% and 58.7% of COD removal and TOC removal respectively is obtained, US reduced mass transfer resistance by eliminating the passive layer formed on the electrode surface.

 [25]
6 Eosin B Sonocatalysis, US + ZnO C0 = 5.08 mg/L, ultrasonic power = 250 W, ZnO dosage = 2170 mg/L, volume = 100 ml, Ambient temperature, T = 72 min. For US + ZnO approach, 93.46% as dye degradation was obtained, US enhanced the catalytic performance of the ZnO nanoparticles in terms of the enhanced degradation of the dye [26]
7 Malachite dye US + MNPs C0 = 200 mg/L, US frequency = 40 kHz, Magnetic nanomaterial (Fe3O4/HA) dose = 200 mg, volume = 100 ml, T = 35 min. Almost complete degradation of malachite dye was obtained using US combined with nanomagnetic particles within 35 min of treatment, US enhanced the mineralization of the dye by enhancing the formation of OH• radicals [27]
8 Direct Blue 15 (azo dye) US + H2O2 + Fe0 C0 = 43.61 mg/L, Fe0 = 1000 mg/L, H2O2 = 175.18 mg/L, US power density = 120 W/L, US frequency = 60 kHz, pH of solution = 3, T = 10 min. For US + H2O2 + Fe0, almost 99% of decolorization of azo dye was obtained. US improved the synergetic mechanism by providing additional OH• radicals and also helped to produce more quantities of Fe2+ ions during the process. [28]
9 Azure B dye US, Fenton, Sono-electro-Fenton C0 = 40 mg/L, COD = 152.9 mg/L, US power = 91 W, US frequency = 23 kHz, Fe2+= 44.68 mg/L, H2O2 = 81.64 mg/L, Platinum gauze counter and saturated calomel reference electrode, pH of solution = 2.6 to 3, T = 60 min, US, Fenton, Sono-electro-Fenton resulted in 25%, 85% and 98% of dye removal and 21%, 68% and 85% of COD removal respectively, US enhanced the yield of hydroxyl radical in the process and hence the oxidation rates [29]
10 C.I. Reactive Black 5 US, O3, US + O3 Co = 19.836 mg/L, US frequency = 520 kHz, US irradiation intensity = 1.63 W/cm2, O3 concentration = 3360 mg/L, temperature = 20 ± 0.5 °C, T = 60 min. For US, O3 and US + O3, 2, 50, 76% of total mineralization was obtained respectively, US enhanced the mass transfer of O3 and also improved the rate of degradation in US + O3 as compared to that accomplished by O3 alone. [30]
11
  • i.

    Disperse blue 60

  • ii.

    Reactive red 241

 US, EC, US + EC
  • i.

    C0 = 100 mg/L, Fe-Al electrode, US frequency = 40 kHz, US Power = 180 W, current density = 50 A/m2, pH of solution = 6,

  • ii.

    C0 = 100 mg/L, Fe-Al electrode, US frequency = 40 kHz, US Power = 180 W, current density = 75 A/m2, pH of solution = 6.
  • i.

    For US + EC, complete color and COD reduction was obtained at current density of 50 A/m2,

  • ii.

    For US + EC, 99.9% and 99% of color and COD reduction was obtained respectively at current density of 75 A/m2

US decreased treatment time by enhancing the efficiency of the EC process.		 [31]
12 Acid Blue 113 US + Fenton, UV + Fenton C0 = 25 mg/L, H2O2 = 1.701 mg/L, FeVO4 = 1000 mg/L, US frequency = 37 kHz, UV intensity = 15 mW/cm2, US Power = 320 W, pH of solution = 6, T = 16 min. US + Fenton, UV + Fenton resulted in 99% and 97% of decolorisation, 80% and 70% of TOC removal respectively, US more efficiently worked for the dye removal as compared to UV + Fenton scheme. [32]
13 C.I. reactive yellow 145 US + Fenton, Fenton C0 = 50 mg/L, COD = 190 mg/L, temperature = 24 ± 2 0C, US type = US water bath (indirect irradiation), US bath frequency = 35 kHz, US bath power = 80 W, Fe2+= 20 mg/L, H2O2 = 20 mg/L (For Fenton process), H2O2 = 15 mg/L (For sono-Fenton process), pH of solution = 3, T = 60 min. 91% and 47% of color and COD removal were obtained in sono-Fenton process respectively, 95% and 51% of color and COD removal were obtained in only Fenton process respectively, US improved decolorization at lower chemical consumption. [33]
14 Acid green 50 textile dye US, UV, US + Fenton, UV + Fenton C0 = 23.064 mg/L, US frequency = 20 kHz, US amplitude = 60%, UV lamp power = 15 W, Fe2O3 = 100 mg/L, T = 30 min (for US + Fenton and UV + Fenton) and 40 min (US and UV). US, UV, US + Fenton, UV + Fenton resulted in 48%, 10, 94% and 85% of decoloration respectively, US enhanced the mass transfer, resulted in additional hydroxyl radical production and improved catalyst activity (by continuous cleaning) in the Fenton process. [34]
15 Azo dye Orange II US, UV, US + UV, US + UV + Fenton C0 = 49.04 mg/L, US power = 22.3 W, US frequency = 850 kHz, UV lamp (at 254 nm), H2O2 = 170.07 mg/L, Fe = 5.585 mg/L, Fe2+:H2O2 (molar ratio) = 1:50, pH of solution = Changed from 6.5 to 4 after treatment, T = 120 min. US, UV, US + UV, US + UV + Fenton resulted in 6.5%, 28.9%, 47.8% and 80.8% of decolorization respectively, US enhanced the degree of decolorization in the US + Fenton system [66]

*C0 = initial dye concentration, TOC0 = initial total organic carbon, MNPs = magnetic nanoparticles, EC = Electrocoagulation, EF = electro-Fenton, T = treatment time.