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In this work, filamentous algae-based activated carbon was composited with Fe3O4 nanoparticles and applied as a potential adsorbent to remove Basic Blue 41. AAC/Fe3O4 nanocomposite was synthesised by the impregnation method and characterised by several techniques including, FTIR, FESEM, EDX, TGA, XRD, VSM, and BET. The characterisation results confirmed the existence of Fe3O4 in the nanocomposite structure, which had uniformly dispersed over AAC with mesoporous texture. The effects of various operational parameters on removal efficiency were investigated. The maximum AAC/Fe3O4 nanocomposite adsorption capacity (141 mg g−1) and removal rate (96.76%) were determined under optimum conditions (initial concentration of 100 mg L−1, solution pH of 9, nanocomposite dose = 1 g L−1 at 25°C for 90 min). The obtained adsorption data fitted well with the pseudo-second-order Langmuir isotherm model. The reusability assessment of AAC/Fe3O4 nanocomposite (with acidic solution) revealed about 11% decreases in the removal efficiency after five consecutive runs. Finally, bioassay studies using D. Magna confirmed AAC/Fe3O4 nanocomposite could create low toxicity and acceptable quality effluents. These attractive features make it a potential adsorbent for practical application in actual textile wastewater treatment. [ABSTRACT FROM AUTHOR]

The most important effect of humic acid (HA) as a natural organic matter in water is the reaction with disinfectants and the generation of toxic and carcinogenic byproducts. The aim of this study was to investigate the applicability of the sono-persulphate process for the removal of HA from aqueous media by box-Behnken design (BBD) using response surface methodology (RSM). This study was experimental and was performed in a laboratory-scale pilot. The effect of important operational parameters such as solution pH, persulphate concentration, and reaction time at three levels (+α, 0, and -α) was studied using a constant intensity of ultrasonic (US) waves (37 kHz) and the initial HA concentration of 25 mg/L. Optimisation and analysis of the results were performed by Design Expert 10 and the residual-HA was measured using a spectrophotometer. The results showed that the quadratic model was suitable for the data (Pvalue>0.0001) and the proposed model was confirmed with a high correlation coefficient ((R2 = 0.9966) and (R2Adj = 0.9932)). Under the optimal conditions for the process (pH of 3, optimal persulphate concentration of 0.514 mg/L and reaction time of 39.29 min), the observed removal efficiency was 87.59%. The synergetic degradation of the sono-persulphate process and removal of COD under optimal conditions were 42.63% and 81.2%, respectively. According to the results, the sono-persulphate process was found to be an appropriate process in the degradation of HA, and the BBD was found as a suitable tool for optimising the process conditions in the removal of HA. [ABSTRACT FROM AUTHOR]

This experimental study investigated the performance of Catechol degradation by US/TiO2/H2O2 process as an integrated advance oxidation process. In this experimental study, initial pH, dose of TiO2, initial concentration of Catechol, H2O2 concentration and reaction time parameters optimised BBD. The results suggest that US/TiO2/H2O2 process has a high efficiency in Catechol degradation. Optimum condition of US/TiO2/H2O2 process is pH = 3.43, H2O2 concentration = 130 mg/l, TiO2 dose = 0.34 g/l, Catechol concentration = 12.52 mg/l and reaction time = 70.64 min. According to predicate point, the percentage of Catechol removal in this condition was 96.2 and 92.34 as a predicated and experimental percentage of Catechol removal by this process. The kinetics of reaction follows pseudo-first-order kinetic. The synergist effect of sonolysis, TiO2 and H2O2 is 2.09 fold. 70 and 63% of initial COD and TOC were removed. Presence of radical scavenger has an adverse impact on the performance of US/TiO2/H2O2 process. [ABSTRACT FROM AUTHOR]

The coloured wastewater from the textile industries may show toxic or carcinogenic effects on the organism, when discharged into the rivers and lakes, which are changing their biological life. Therefore, in this study, the removal of basic violet 16 was investigated by a magnetite graphene oxide nanocomposites (Fe3O4@GO) optimising by the response surface methodology based on Box–Behnken method. Fe3O4@GO nanocomposite was prepared by a facile in situ co-precipitation method, resulting in a suitable composite for the adsorption of dye. The structure and morphology of the Fe3O4@GO adsorbent were investigated using XRD, FT-IR, SEM, BET and VSM techniques. Base on the SEM images, the Fe3O4 NPs were distributed between the GO sheets and empty spaces with visible large pores between GO sheets. Also, the results of the FT-IR analysis showed that the dominant group was carboxyl group. The various parameters were evaluated in the process such as pH, reaction time, adsorbent dose and initial concentration of dye. The proposed model (quadratic) was approved with a high correlation coefficient (R2 = 0.98) and (R2adj = 0.97). Desirable removal of dye (efficiency: 95.03%.) was obtained under following conditions: the dye concentration of 62.5 mg L−1, the absorbance of 0.2 g L−1, the reaction time of 60 min and solution pH of 7.5. The results of isotherms and kinetics adsorption study showed that the adsorption process follows the Langmuir isotherm (R2: 0.98) and the pseudo-second-order kinetic (R2: 0.99) models. The present study showed that the Fe3O4 @GO adsorbent has a high efficiency in the removal of violet 16. [ABSTRACT FROM AUTHOR]