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Experimental research on organic dye removal from polluted water using the oxidation method

Paliulis Dainius, Vaiškūnaitė Rasa

Ecological Chemistry and Engineering. S

2025

Vol. 32, nr 4

471--483

Electrochemical, biological, adsorption, and oxidative methods can be applied for the treatment of synthetic wastewater containing methyl orange (MO). In this study, MO was catalytically oxidised using ferrous sulphate (FeSO4) and hydrogen peroxide (H2O2). The effects of reagent concentrations, initial dye concentration, contact time, and pH on treatment efficiency were investigated, and the optimal process conditions were identified. FeSO4 and H2O2 are cost-effective and environmentally benign reagents: excess hydrogen peroxide decomposes into water, while the small amount of iron introduced does not significantly impair the quality of the treated effluent. The results showed that increasing the FeSO4 concentration from 0.02 % to 2.00 % enhanced the removal efficiency of C-MO from 81.5 % to 98.7 %, as the higher availability of Fe2+ ions accelerates the formation of HO● radicals. Increasing the H2O2 concentration from 0.6 % to 24 % raised the efficiency from 81.1 % to 94.5 %, and the highest degradation efficiency was achieved at pH 2.00 - 3.00, confirming that optimal Fenton reaction performance occurs under mildly acidic conditions. Investigation of the initial dye concentration revealed that the efficiency ranged from 80.4 % to 89.1 % when the dye concentration increased from 50 mg/L to 750 mg/L, while the reduction at higher concentrations indicates an insufficient amount of HO● radicals. Contact time studies showed that the efficiency increased from 39.8 % to 97.1 %, with the optimal reaction time being 2 hours. Overall, the findings demonstrate that the Fenton process is a highly effective method for the degradation of azo dyes and holds strong potential for application in wastewater treatment systems.

Wpływ przygotowania próbek gruntów i metodyki oznaczania na zawartość części organicznych w gruncie

Nguyen Giang

Polish Journal of Materials and Environmental Engineering

2023

Vol. 6 (26)

57--65

Soil organic matter content (SOM) is used e.g. in soil classification and erosion evaluation. How-ever, its value depends on soil specimen preparation and test method so it is useful to deal with these issues. Totally 150 specimens of soils CI, MS (from Bielsko-Biała, Poland) and different 3 soils, all classified as GC (from Ujsoły, Poland) were tested. To obtain values of SOM, the oxidation method using 30% hydrogen peroxide solution (H2O2) and loss of weight on ignition method (LOI) at 800°C (LOI-800) according to Polish Standard PN-88/B-04481 and LOI at 440°C according to the ASTM D 2974-87 (LOI-440) were applied. The tests were carried out for parti-cles smaller than 0.5 mm. For every soil, 30 specimens (every with a mass about 10 g of dry soil) were prepared from 2400 g of dried soil for 3 methods, so for every method, 10 specimens, taken from various soil amount in frame of total 800 g were prepared. The results showed that values of SOM of tested soils varied from 0.33% to 6.09%. The largest relative difference in values of SOM, caused by soil specimen preparation, was 97.63% (H2O2, soil GC) and the smallest relative difference was 1.65% (LOI-800, soil CI). The largest relative difference in values of SOM, caused by test method was 1126.53% (LOI-800 and H2O2, soil GC) and the smallest relative difference was 15.17% (LOI-800 and H2O2, soil CI). The various values of SOM caused by dif-ferent test method differently classify soils from organic point of view by the ISO14688-2:2004.

Przeanalizowano wpływ przygotowania próbki gruntu i metody oznaczania na zawartość ma-terii organicznej (SOM). W sumie przebadano 150 próbek gruntów (przygotowanych z różnej ilości gruntu) z Bielska-Białej (CI, MS) oraz z Ujsół (GC). Aby uzyskać wartości SOM zastoso-wano metodę utleniania 30% roztworem nadtlenku wodoru (H2O2) oraz metodę straty masy przy prażeniu (LOI) w temperaturze 800°C (LOI-800) i 440°C (LOI-440). Badania przeprowa-dzono dla cząstek gruntu mniejszych niż 0,5 mm. Wartości SOM wahały się od 0,33 do 6,09%. Największa względna różnica wartości SOM spowodowana przygotowaniem próbek wyniosła 97,63% (H2O2, grunt GC), a najmniejsza 1,65% (LOI-800, grunt CI). Największa względna róż-nica wartości SOM spowodowana metodą badania wyniosła 1126,53% (LOI-800 i H2O2, grunt GC), a najmniejsza 15,17% (LOI-800 i H2O2, grunt CI). Uzyskiwane różne wartości SOM mogą skutkować odmiennym klasyfikowaniem gruntu pod kątem organicznym.