Decolorization of a textile dye, reactive red 198 (rr198), by Aspergillus parasiticus fungal biosorbent

A response surface model to examine the reactive red 239 sorption behaviors on Rhizoclonium hieroglyphicum: isotherms, kinetics, thermodynamics and toxicity analyses

The present study is an attempt to investigate the potentiality of Rhizoclonium hieroglyphicum in the removal of reactive red 239 (RR239) from aqueous solution and to assess the toxicity of the treated dye solution. Optimisation of the process variables namely dye and biosorbent concentrations, pH, temperature and incubation time for RR239 removal was performed using Response Surface Methodology (RSM) assisted Box Behnken Design (BBD) model. The recycling and regeneration efficiency of the dye adsorbed alga was evaluated using different eluents under optimized conditions. Further to understand the adsorption mechanism, isotherms, kinetics and thermodynamic studies were performed. UV-vis and FT-IR spectroscopy was employed to confirm the interaction between the adsorbate and biosorbent. The nature of the treated dye solution was assessed using phyto, microbial and brine shrimp toxicity studies. On the basis of quadratic polynomial equation and response surfaces given by RSM, 90% decolorization of RR239 was recorded at room temperature under specified optimal conditions (300 mg/L of dye, 500 mg/L of biosorbent, pH 8 and 72 h of contact time). Desorption experiments demonstrated 88% of RR239 recovery using 0.1 N acetic acid as an eluent and 81% of dye removal in regeneration studies. The data closely aligned with Freundlich isotherm (R2 - 0.98) and pseudo-second-order kinetic model (R2 - 0.9671). Thermodynamic analysis revealed that the process of adsorption was endothermic, spontaneous, and favorable. UV-Vis and FT-IR analyses provided evidence for adsorbate-biosorbent interaction, substantiating the process of decolorization. In addition, the results of phyto, microbial and brine shrimp toxicity assays consistently confirmed the non-toxic nature of the treated dye. Thus, the study demonstrated that R. hieroglyphicum can act as a potent bioremediation agent in alleviating the environmental repercussions of textile dyeing processes.

Fabrication of Fe3O4 core-TiO2/mesoSiO2 and Fe3O4 core-mesoSiO2/TiO2 Double Shell Nanoparticles for Methylene Blue Adsorption: Kinetic, Isotherms and Thermodynamic Characterization

Herein, Fe3O4 core-TiO2/mesoSiO2 and Fe3O4 core-mesoSiO2/TiO2 double shell nanoparticles were prepared by first (R1) and second (R2) routes and applied for the removal of methylene blue. The reported adsorption capacities for R1-0.2, R1-0.4 and R2 samples were 128, 118 and 133 mg.g-1, respectively, which were obtained after 80 min as equilibrium contact time, and pH of 6 using a methylene blue concentration of 200 ppm. The adsorption of methylene blue using the prepared Fe3O4 core-meso SiO2/TiO2 double shell was analyzed by kinetic and isotherms models. In addition, thermodynamic investigations were applied to assess the spontaneous nature of the process. The obtained results confirmed that the pseudo-second order model is well fitted with the adsorption data and the Freundlich-isotherm assumption suggested a multilayer adsorption mechanism. In addition, results of the thermodynamic investigation indicated that ΔG° was in the range of -2.3 to -6.8 kJ/mol for R1-0.2, -2.8 to -6.3 kJ/mol for R1-0.4 and -2.0 to -5.2 kJ/mol for R2. In addition, the ΔH° and ΔS° values were found in the range of 26.4 to 36.19 kJ.mol-1 and 94.9 to 126.3 Jmol-1 K-1, respectively. These results confirm that the surfaces of Fe3O4 core-mesoSiO2/TiO2 and Fe3O4 core-TiO2/mesoSiO2 double shell exhibit a spontaneous tendency to adsorb methylene blue from the aqueous solutions. The achieved performance of Fe3O4 core-meso SiO2/TiO2 and Fe3O4 core-TiO2/meso SiO2 double shell as adsorbent for methylene blue removal will encourage future research investigations on the removal of a broad range of contaminants from wastewater.

Design and modeling of the decolorization characteristics of a regenerable and eco-friendly geopolymer: Batch and dynamic flow mode treatment aspects

One of the most important environmental and health issues today is the elimination of the dye pollution from the contaminated water ecosystem. The use of geopolymers to eliminate such contaminants has recently emerged as a promising alternative. In this study, metakaolin based geopolymer (MKBG) was synthesized to be a promising adsorbent for Basic Blue 7 (BB7). To optimize the input parameters (solution pH, MKBG dose, mixing time, temperature, mixing speed, column diameter, and flow rate) towards BB7 removal by MKBG, a Box-Behnken design (BBD) was employed to develop the response model, followed by numerical optimization. The quadratic models correlating the adsorption variables to BB7 adsorption yield as responses were developed for batch and dynamic flow systems. The pseudo-second-order model accurately predicted the BB7 adsorption kinetics on MKBG. Decolorization yields of BB7 in batch and continuous systems reached 96 % and 56 %, respectively. The Langmuir model accurately described equilibrium data, thereby justifying monolayer and homogeneous adsorption. The MKBG demonstrated significant reusability up to 20 dynamic flow adsorption cycles. IR, SEM, and zeta potential measurements were used to describe the sorbent structure, and the mechanism of MKBG-BB7 interaction was assessed. Overall, MKBG offers a good application potential for the treatment of basic dye contaminated waters.

Application of ZnO-Nd Nano-Photocatalyst for the Reactive Red 198 Dye Decolorization in the Falling-Film Photocatalytic Reactor

A large amount of Reactive red 198 (RR198) is released yearly into the environment. RR198 is toxic for human and aquatic creatures; therefore, it should be removed from wastewater before releasing into the environment. In this study, the nano ZnO-Nd -photo-catalyst for the first time was synthesized by the combustion method. First, the physical characteristics of the generated nano photocatalyst were evaluated using FESEM, XRD, Bandgap calculation, and FTIR analysis. Then, the ZnO-Nd nano-photocatalyst was suspended into the contaminated water with RR198 dye in a falling-film photocatalytic reactor. The effects of parameters such as the amount of H2O2, catalyst dose, pH, and initial concentration of dye were investigated during the experiments. Finally, the decolorization process with the falling-film photocatalytic reactor was optimized using response surface methodology (RSM). The physical characteristics showed that the average particle size of the synthesized ZnO-Nd was 40 nm. Doping ZnO with Nd reduced the photocatalyst energy bandgap by 14%. The results indicated that the optimum amount of catalyst dose and pH level was 0.1 g/L and 5, respectively. The simultaneous usage of H2O2 and ZnO-Nd with an H2O2/dye ratio of two increased dye removal performance by 90%. The results demonstrated that the developed equations can be applied to predict the performance of the falling-film photoreactor. This study showed that using the nano ZnO-Nd photocatalyst in a falling-film photocatalytic reactor under optimum operating conditions is an appropriate way to remove RR198 from water.

Efficacy of green waste-derived biochar for lead removal from aqueous systems: Characterization, equilibrium, kinetic and application

The removal of toxic metals from the aquatic ecosystem is one of the most pressing environmental and public health concerns today. A strong potential has recently emerged for the removal of such metals using biochar sorbents. Biosorption technology could make a significant difference in the future. It is a viable and cost-effective alternative to the remediation of toxic pollutants utilizing various biomaterials. In the current study, batch and fixed-bed studies were performed to evaluate the performance of Capsicum annuum L. seeds biochar (CASB) as an alternative material in removing toxic Pb(II) from aqueous solutions. Removal characteristics were investigated by considering the equilibrium and kinetic aspects. Biosorption equilibrium was established within 40 min. The optimum dosage of CASB for Pb(II) removal was determined as 2.0 g L^-1. Biosorption data were well predicted by a non-linear Langmuir isotherm model. Monolayer biosorption occurred for CASB with a maximum capacity of 36.43 mg g^-1. Biosorption kinetics fitted well with a pseudo-first-order kinetic model. The external mass transfer may control Pb(II) transport mechanism. Dynamic flow mode biosorption and regeneration potential of CASB were also examined. The application of CASB exhibited a 100% removal yield in real apple juice samples spiked with low concentrations of Pb(II). Exhausted points for the CASB packed columns were recorded as 195 and 320 min for simulated wastewater (SW) and synthetic Pb(II) solution, respectively. FTIR, BET, SEM-EDX analysis, and zeta potential measurements were used for the characterization of biochar and assessment of the metal ion-biosorbent interaction mechanism. Finally, our study provides a practical approach for the uptake of Pb(II) ions from contaminated solutions.

Zeolite modification with cellulose nanofiber/magnetic nanoparticles for the elimination of reactive red 198

In this paper for the first time, a cost-effective reinforced zeolite with cellulose nanofibers and magnetic nanoparticles (MZeo/Cellulose nanofiber) was used for the elimination of reactive red 198 (RR198) dye. The fabricated sorbent was characterized by SEM, FTIR, and XRD. The effect of operational parameters, including pH, RR198 concentration, the mass ratios of zeolite to cellulose nanofiber and zeolite coated cellulose to Fe₃O₄ nanoparticles, contact time, agitation speed, sorbent dosage, and temperature were studied. The prepared sorbent exhibited the maximum removal efficiency of 99% for RR198 removal at 30 °C. The presence of other dyes along with the target dye did not negatively affect the adsorption process and RR198 removal efficiency from actual water samples seemed satisfactory and rational. Equilibrium studies confirmed that both Langmuir and Freundlich models described the RR198 adsorption on MZeo/Cellulose nanofiber indicating physical and chemical interactions between the sorbent and RR198 molecules. Kinetic studies demonstrated that pseudo-second-order fitted best with experimental data. Also, thermodynamic studies showed the endothermic nature of the adsorption process. Compared to zeolite, MZeo/Cellulose nanofiber represented a promising removal efficiency for the elimination of RR198 dye from contaminated water.

Myco-decontamination of azo dyes: nano-augmentation technologies

Effluents of textile, paper, and related industries contain significant amounts of synthetic dyes which has serious environmental and health implications. Remediation of dyes through physical and chemical techniques has specific limitations. Augmented biological decontamination strategies 'microbial remediation' may involve ring-opening of dye molecules besides the reduction of constituent metal ions. Both bacterial and fungal genera are known to exhibit metabolic versatility which can be harnessed for effective bio-removal of the toxic dye contaminants. Ascomycetous/basidiomycetes fungi can effectively decontaminate azo dyes through laccase/peroxidase enzyme-mediated catalysis. The extent, efficacy, and range of fungal dye decontamination can be enhanced by the conjugated application of nanomaterials, including nanoparticles (NPs) and their composites. Fungal cell-enabled NP synthesis- 'myco-farmed NPs', is a low-cost strategy for scaled-up fabrication of a variety of metal, metal oxide, non-metal oxide NPs through oxidation/reduction of dissolved ions/molecules by extracellular biomolecules. Augmented and rapid decontamination of azo dyes at high concentrations can be achieved by the use of myco-farmed NPs, NPs adsorbed fungal biomass, and nano-immobilized fungi-derived bio-catalytical agents. This manuscript will explore the opportunities and benefits of mycoremediation and application of fungus-NP bionanoconjugate to remediate dye pollutants in wastewaters and land contaminated with the effluent of textile industries.

A critical review on recent advancements of the removal of reactive dyes from dyehouse effluent by ion-exchange adsorbents

The effluent discharged by the textile dyehouses has a seriously detrimental effect on the aquatic environment. Some dyestuffs produce toxic decomposition products and the metal complex dyes release toxic heavy metals to watercourses. Of the dyes used in the textile industry, effluents containing reactive dyes are the most difficult to treat because of their high water-solubility and poor absorption into the fibers. A range of treatments has been investigated for the decolorization of textile effluent and the adsorption seems to be one of the cheapest, effective and convenient treatments. In this review, the adsorbents investigated in the last decade for the treatment of textile effluent containing reactive dyes including modified clays, biomasses, chitin and its derivatives, and magnetic ion-exchanging particles have been critically reviewed and their reactive dye binding capacities have been compiled and compared. Moreover, the dye binding mechanism, dye sorption isotherm models and also the merits/demerits of various adsorbents are discussed. This review also includes the current challenges and the future directions for the development of adsorbents that meet these challenges. The adsorption capacities of adsorbents depend on various factors, such as the chemical structures of dyes, the ionic property, surface area, porosity of the adsorbents, and the operating conditions. It is evident from the literature survey that decolorization by the adsorption shows a great promise for the removal of color from dyehouse effluent. If biomasses want to compete with the established ion-exchange resins and activated carbon, their dye binding capacity will need to be substantially improved.

Bio-bleaching of Remazol brilliant blue-19 by Stereum ostrea

Efficiency of white-rot fungi-Stereum ostrea (S. ostrea) as a test culture and Phanerochaete chrysosporium (P. chrysosporium) as a reference culture in colour removal from a textile dye, Remazol brilliant blue-19 (RBB-19) in medium was compared in this study. S. ostrea was more efficient than P. chrysosporium in decoloration process. Different parameters pH, temperature, sources of carbon and nitrogen, stationary and shaking conditions were optimized for bleaching of dye by the fungal cultures. Optimal growth conditions for decoloration of dye by both cultures were pH 5.0, temperature 35 °C, glucose and fructose as best carbon source at 1 % level, peptone and urea as best nitrogen source and shaking conditions (150 rpm). Culture broth free of colour (99 % of decoloration) was achieved with S. ostrea as against 70 % decoloration by P. chrysosporium on 6th day of incubation. Adsorption of dye to fungal biomass as reflected by colour coating on biomass and participation of lignolytic enzymes in colour removal appeared to be mechanisms involved in decoloration process. The ability of both fungal cultures in removal of colour in effluents with dyes collected from silk saree-weaving cottage unit was tested. S. ostrea was also found to be more effective in colour removal from effluent. S. ostrea appears to be a promising culture for application of bioremediation in decoloration of dyes.

A study of Reactive Red 198 adsorption on iron filings from aqueous solutions

In recent years, reactive dyes have been widely used in textile industries with particular efficiency. They dyes are often toxic, carcinogenic and mutagenic. Improper treatment and non-scientific disposal of dyed wastewater from these industries into water sources has created many environmental problems and concerns around the world. The purpose of the present study is to investigate the efficiency of iron filings in adsorption of Reactive Red 198 from aqueous solutions. This study was conducted using an experimental method at the laboratory scale. In this study, the effects of operating parameters such as pH (1-11), initial dye concentration (40-400 mg/L), contact time (5-120 min) and iron dose (0.1-1 g) with a mesh of<100 were studied. Dye concentration was determined using a spectrophotometer at a wavelength of 520 nm. The results indicated that maximum adsorption capacity of the dye in question was obtained at pH 3, contact time of 60 min and adsorbent dose of 1 g. At initial dye concentration of 100 and 200 mg/L, by increasing the dose of waste iron from 0.1 to 1 g, the removal percentage increased from approximately 76.89% to 97.28% and from 22.64% to 68.03%, respectively. At pH 3, contact time of 5 min and constant waste iron dose of 0.8 g, the dye removal efficiency was 85.34%. By increasing the contact time to 120 min, the removal efficiency increased to 99.2%. Welding iron waste as an inexpensive and available adsorbent has an optimum ability for adsorption of Reactive Red 198 from aqueous solutions.

Biosorption of reactive dye from aqueous media using Saccharomyces cerevisiae biomass. Equilibrium and kinetic study

The biosorption Brilliant Red HE-3B reactive dye by nonliving biomass, Saccharomyces cerevisiae, in batch procedure was investigated. Equilibrium experimental data were analyzed using Freundlich, Langmuir and Dubinin — Radushkevich isotherm models and obtained capacity about 104.167 mg g−1 at 20°C. The batch biosorption process followed the pseudo-second order kinetic model. The multi-linearity of the Weber-Morris plot suggests the presence of two main steps influencing the biosorption process: the intraparticle diffusion (pore diffusion), and the external mass transfer (film diffusion). The results obtained in batch experiments revealed that the biosorption of reactive dye by biomass is an endothermic physical-chemical process occurring mainly by electrostatic interaction between the positive charged surface of the biomass and the anionic dye molecules. The biosorption mechanism was confirmed by FT-IR spectroscopy and microscopy analysis