Anam Asghar

A Comparison of Central Composite Design and Taguchi Method for Optimizing Fenton Process

In the present study, a comparison of central composite design (CCD) and Taguchi method was established for Fenton oxidation. [Dye]ini, Dye : Fe+2, H2O2 : Fe+2, and pH were identified control variables while COD and decolorization efficiency were selected responses. L 9 orthogonal array and face-centered CCD were used for the experimental design. Maximum 99% decolorization and 80% COD removal efficiency were obtained under optimum conditions. R squared values of 0.97 and 0.95 for CCD and Taguchi method, respectively, indicate that both models are statistically significant and are in well agreement with each other. Furthermore, Prob > F less than 0.0500 and ANOVA results indicate the good fitting of selected model with experimental results. Nevertheless, possibility of ranking of input variables in terms of percent contribution to the response value has made Taguchi method a suitable approach for scrutinizing the operating parameters. For present case, pH with percent contribution of 87.62% and 66.2% was ranked as the most contributing and significant factor. This finding of Taguchi method was also verified by 3D contour plots of CCD. Therefore, from this comparative study, it is concluded that Taguchi method with 9 experimental runs and simple interaction plots is a suitable alternative to CCD for several chemical engineering applications.

A review of the applications of organo-functionalized magnetic graphene oxide nanocomposites for heavy metal adsorption

Graphene-based adsorbents have attracted wide interests as effective adsorbents for heavy metals removal from the environment. Due to their excellent electrical, mechanical, optical and transport properties, graphene and its derivatives such as graphene oxide (GO) have found various applications. However, in many applications, surface modification is necessary as pristine graphene/GO may be ineffective in some specific applications such as adsorption of heavy metal ions. Consequently, the modification of graphene/GO using various metals and non-metals is an ongoing research effort in the carbon-material realm. The use of organic materials represents an economical and environmentally friendly approach in modifying GO for environmental applications such as heavy metal adsorption. This review discusses the applications of organo-functionalized GO composites for the adsorption of heavy metals. The aspects reviewed include the commonly used organic materials for modifying GO, the performance of the modified composites in heavy metals adsorption, effects of operational parameters, adsorption mechanisms and kinetic, as well as the stability of the adsorbents. Despite the significant research efforts on GO modification, many aspects such as the interaction between the functional groups and the heavy metal ions, and the quantitative effect of the functional groups are yet to be fully understood. The review, therefore, offers some perspectives on the future research needs.

Challenges and recommendations for using membranes in wastewater-based microbial fuel cells for in situ Fenton oxidation for textile wastewater treatment

Abstract Wastewater-based microbial fuel cell is a promising green technology that can potentially be used to treat recalcitrant wastewater such as textile wastewater through in situ Fenton oxidation while generating net positive energy. One of the main features of this technology is the use of membranes for isolating the cathode chamber for in situ H2O2 production (thus in situ Fenton oxidation). The challenges in this technology include membrane fouling and resistance, pH splitting, oxygen diffusion, substrate crossovers, effect of Fenton’s reagents and high cost of commercially available membranes. Therefore, this paper critically analyzes each challenge in detail to access their direct or indirect effects on the overall performance. Exploration of new materials and modifications of existing materials has produced cost-efficient and reliable membranes. However, their application in in situ Fenton oxidation has not been demonstrated. It is concluded that the use of membranes with high hydrophilicity, small pore size and materials enriched with sulfonated groups is suitable for in situ H2O2 production in the cathode chamber. Moreover, use of cleaning agents such as H2O2 or H2SO4 recovers the membrane performance for in situ H2O2 production. Thus, it offers a green technology because in situ H2O2 can be used for membrane cleaning and energy produced can be used for aeration of the cathode chamber.

Enhancement of Treatment Efficiency of Recalcitrant Wastewater Containing Textile Dyes Using a Newly Developed Iron Zeolite Socony Mobil-5 Heterogeneous Catalyst

Fenton oxidation, an advanced oxidation process, is an efficient method for the treatment of recalcitrant wastewaters. Unfortunately, it utilizes H2O2 and iron-based homogeneous catalysts, which lead to the formation of high volumes of sludge and secondary pollutants. To overcome these problems, an alternate option is the usage of heterogeneous catalyst. In this study, a heterogeneous catalyst was developed to provide an alternative solution for homogeneous Fenton oxidation. Iron Zeolite Socony Mobile-5 (Fe-ZSM-5) was synthesized using a new two-step process. Next, the catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis and tested against a model wastewater containing the azo dye Acid Blue 113. Results showed that the loading of iron particles reduced the surface area of the catalyst from 293.59 to 243.93 m2/g; meanwhile, the average particle size of the loaded material was 12.29 nm. Furthermore, efficiency of the developed catalyst was evaluated by performing heterogeneous Fenton oxidation. Taguchi method was coupled with principal component analysis in order to assess and optimize mineralization efficiency. Experimental results showed that under optimized conditions, over 99.7% degradation and 77% mineralization was obtained, with a 90% reduction in the consumption of the developed catalyst. Furthermore, the developed catalyst was stable and reusable, with less than 2% leaching observed under optimized conditions. Thus, the present study proved that newly developed catalyst has enhanced the oxidation process and reduced the chemicals consumption.

Sequential Optimization for Minimizing Material Cost and Treatment Time of Fenton Oxidation for Textile Wastewater Treatment

This paper examines the technical and economic feasibilities of the sequential optimization technique, i.e., Taguchi coupled with principal component analysis (PCA). Fenton oxidation with four operating parameters, such as [Dye]ini, Dye/Fe+2 (wt/wt), H2O2/Fe+2 (wt/wt), and pH, was selected as a case study. COD (%), TOC (%), and color removal efficiency were chosen as responses. Total principal component index (TPCI) values, obtained as an output of sequential optimization, were used to determine the optimized conditions for Fenton oxidation. [Dye]: 100 mg/L, Dye/Fe+2(wt/wt): 50, H2O2/Fe+2(wt/wt): 25 and pH: 3 were obtained as the optimized values. In addition, ANOVA and the interaction of factors showed that pH was the most significant factor with the percent contribution of 90.86%. Economic evaluation with simultaneous comparison with Taguchi and central composite design (CCD) showed that Taguchi coupled with PCA is the most economic and time-efficient optimization technique. In this study, experimental cost was reduced to

WITHDRAWN: A review on approaches for addressing the limitations of Fenton oxidation for recalcitrant wastewater treatment

54/m3, which showed 95% reduction relative to CCD. Moreover, chemical consumption and experimental time were also reduced by approximately 95–97% and 68%, respectively. Thus, it can be concluded that Taguchi coupled with PCA is the most cost-effective and less-laborious way of optimizing multi-response processes such as Fenton oxidation.

Textile wastewater treatment efficiency by Fenton oxidation with integration of membrane separation system

Abstract Fenton oxidation is an effective technology for the degradation of recalcitrant organic pollutants. However, conventional Fenton oxidation possesses some drawbacks such as the requirement of acidic pH condition, production of iron sludge and requirement of high chemical inputs. Strategies such as heterogeneous Fenton, fluidized bed Fenton, use of chelating agents and in-situ production of Fenton’s reagent have been studied as possible solutions to these limitations. Although there have been reviews on the fundamentals and applications of Fenton oxidation, a review with focus on the limitations of Fenton oxidation and their possible solutions is lacking. Here, we review the limitations of Fenton oxidation and the recent strategies toward addressing them. For each approach, fundamentals and applications in the removal of recalcitrant pollutants are reviewed. Heterogeneous Fenton process is the most widely investigated due to the progress in catalysis. Fluidized bed Fenton process could lower sludge generation and enhance process performance. Chelating agents are used to conduct homogeneous Fenton at circumneutral pH, though the potential detrimental effect of some chelating agents remains a source of concern. In situ production of Fenton’s reagent through bioelectrochemical technology (bioelectro-Fenton) is emerging as a possible strategy to reduce the cost associated with Fenton’s reagent.

Treatment of Recalcitrant Waste

Abstract This work investigates the performance of an integrated Fenton-Ultrafiltration treatment scheme to treat textile wastewater. The treated effluent is particle-free at a quality higher than that obtained by any novel membrane based process or Fenton oxidation in singularity. The study is divided into three parts: part one, Fenton process was optimized for COD: H2O2 (wt/wt), H2O2: Fe+2 (wt/wt) and pH to attain highest degradation removal and lowest sludge generation. The process efficiency was analyzed by considering COD, TOC and color removal as key parameters. Part two, the process was scaled up to 5 L and efficiency of integrated system was investigated under optimized conditions by using two different types of membranes at different operating pressures. Part three, the performance of membrane process was studied in terms of flux behavior and its recovery. The treated effluent has COD, TOC and color removal values of 48.0 mg/L, 1.2 mg/L and >99% respectively. These values are compliant to typical discharge environmental standards.

Advanced oxidation processes for in-situ production of hydrogen peroxide/hydroxyl radical for textile wastewater treatment: a review.

Abstract With the continuous increase in the worlds population and rapid industrialization, the world is witnessing an acute problem of controlling wastes generated from industrial processes. The situation is getting worse because of the intense consumption of chemicals, water, and energy. With global increases in energy consumption, the poor wastewater management strategies and treatment methods have prompted researchers and industrialists to look for treatment methods that are sustainable and energy efficient. Considering these aspects, an extensive approach of analyzing wastewater streams, production sources, and their characterization was adopted. For this purpose, landfill leachates and textile, pharmaceutical, and petroleum industries were analyzed and characterized in detail. Later, this idea was extended to analyzing various treatment processes with the potential of resource recovery. For this purpose, anaerobic treatment with the potential of methane production is a suitable option. Therefore, various anaerobic treatment technologies were analyzed and compared in detail in terms of treatment efficiency, methane production, and process durability. And it was concluded that anaerobic treatment is a sustainable, energy-neutral, and green technology for treatment of recalcitrant wastewaters. Furthermore, characterization of wastewater is necessary because the success of a specific anaerobic technology largely depends on the type and composition of the wastewater.