Reactive Red Research Articles

Bactericidal and biocatalytic temperature responsive microgel based self-cleaning membranes for water purification

The present study focuses on creating an antimicrobial and biocatalytic smart gating membrane by synthesizing unique core–shell microgels. The core–shell microgels are synthesized by grafting short chains of poly(ethylenimine) (PEI) onto a poly((N-isopropyl acrylamide)–co-glycidyl methacrylate)) (P(NIPAm-co-GMA)) core. Subsequently, the produced microgels are utilized as a substrate for synthesizing and stabilizing silver nanoparticles (Ag NPs) through an in-situ approach. These Ag NPs immobilized microgels are then suction filtered over a polyethylene terephthalate (PET) track-etched support to create cross-linked composite microgel membranes (CMMs). After structural and permeation characterization of the prepared CMMs, the laccase enzyme is then covalently grafted to the surface of the membrane and tested for its effectiveness in degrading Reactive red-120 dye. The laccase immobilized biocatalytic CMMs show effective degradation of the Reactive red-120 by 71%, 48%, and 34% at pH 3, 4, and 5, respectively. Furthermore, the immobilized laccase enzyme showed better activity and stability in terms of thermal, pH, and storage compared to the free laccase, leading to increased reusability. The unique combination of Ag NPs and laccase on a thermoresponsive microgel support resulted in a responsive self-cleaning membrane with excellent antimicrobial and dye degradation capabilities for environmentally friendly separation technology.

Adsorption of Reactive Red 120 Dye by Polyamide Nylon 6 Microplastics: Isotherm, Kinetic, and Thermodynamic Analysis

In this work, we investigated the effect of various adsorption parameters (solution pH, temperature, contact time, and the presence of phosphate and nitrate ions) on the adsorption of Reactive Red 120 (RR120) dye by Polyamide Nylon 6 (PN6) microplastics (MPs). Maximum uptake was achieved at pH 2.0, and the temperature rise from 295 to 313 K resulted in the decrease of the RR120 sorption by PN6. Equilibrium was achieved after 7 h, and the adsorption kinetic data obeyed the pseudo-second-order kinetic model. The experimental adsorption data were better fitted by the Langmuir isotherm model, and the qm was found to be 3.96 mg/g at pH 2.0 and 295 K. Thermodynamic studies pointed out that the adsorption was spontaneous and exothermic, with decreasing entropy at the solution/solid interface. Future work will focus on the effect of aging on the adsorptive properties of PN6 toward RR120 dye.

Identification of microfibers in drinking water with Nile Red. Limitations and strengths

Traditional drinking water treatment plants (DWTP) are not specifically designed for removing microplastics (MPs) from drinking water. Therefore, this emergent contaminant has been identified in water sources and final drinking water. Microfibers from plastic-based materials are a relevant category of MPs that has attracted attention in recent studies due to their significant presence in environmental samples. This study investigated the presence of microfibers (> 10 µm) in the raw water and the final drinking water of a DWTP located in Spain. It was observed that the DWTP studied was capable of removing 86% of microfibers from raw water. Even with this high removal rate, an amount of 613 microfibers/L (including natural, artificial, and synthetic materials) was counted in drinking water after disinfection. The reactive Nile Red was tested to investigate its use for staining microfibers from the mentioned DWTP and also from tap and bottled water samples in order to identify them. It was observed that microfibers from environmental samples can have different manifestations of fluorescence compared to pristine polymers, and it could be related to degrees of degradation and/or adsorption of organic and inorganic material on the microfibers’ surfaces. For this reason, the use of Nile Red could help understand the levels of degradation of these materials in the environment, and thus its use could go beyond the identification of MPs, which was initially proposed in previous studies.

Enhanced Adsorption of Two Reactive Dyes onto Al-Based Waterworks Sludge Modified by Calcination

Al-based waterworks sludge (ABWS) modified by calcination was reused as an adsorbent for the removal two reactive dyes, namely, reactive yellow 176 (RY-176) and reactive red 195 (RR-195) from aqueous solution. 800ºC was proved to be the optimal calcination temperature in the range of 200-900ºC. A series of static adsorption experiments were carried out using ABWS calcinated at 800ºC (ABWS-800) as adsorbent. The results indicated that the adsorption of both the two dyes by ABWS-800 was almost independent of initial solution pH, and the adsorption capacity of ABWS-800 for RR-195 was about 1.4 times higher than that for RY-176. The pseudo-second-order kinetic model was best among the three models to describe the adsorption of the two reactive dyes, and Freundlich isotherm model was better matched than the Langmuir isotherm model to describe the adsorption process. Na2SO4 inhibited the adsorption of the two dyes onto ABWS-800. This work provided the theoretical basis and technical support for the optimization of reaction conditions for the decontamination of dyes wastewater by “waste” ABWS.

Green and Facile Synthesis of Porous SiO2@C Adsorbents from Rice Husk: Preparation, Characterization, and Their Application in Removal of Reactive Red 120 in Aqueous Solution.

In this work, a green, novel, fast, and facile approach for synthesizing a SiO2/C nanocomposite series from rice husk (RH) through quenching and grinding techniques has been reported along with its application for the adsorptive removal of Reactive Red 120 (RR120) dye from an aqueous solution. The effect of carbonization temperature on the textural and interfacial features of RH was confirmed by scanning electron microscopy (SEM), while the structure and elemental composition of the as-synthesized RH were investigated via XRD, Brunauer-Emmett-Teller (BET), FT-IR, Raman, and X-ray photoelectron spectroscopy (XPS). The RH had a high surface area (521.35 m2 g-1), large micropores, mesopores, and total pore volumes of 0.5059, 3.9931, and 5.2196 cm3 g-1, while SiO2 and C were the two major components. In the batch adsorption test, the effects of pH, contact time, adsorbent mass, temperature, and initial RR120 concentration were investigated. The maximum adsorption capacity was fitted by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich (D-R), Hasley, Harkins-Jura, and BET isotherm models, and Langmuir was the best-fitted model. In addition, the pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich chemisorption models were used to explain the adsorption kinetics. Additionally, the values of Gibbs free energy, enthalpy, and entropy thermodynamics suggested that the RR120 adsorption phenomenon by RH8-3 was endothermic and spontaneous. The adsorption process was controlled by a physical mechanism, and the maximum adsorption capacity was found to be 151.52 mg g-1 at pH 2, with a contact time of 90 min, adsorbent amount of 0.03 g, and temperature of 313 K. The adopted technique may open up a new alternative route for the mass utilization of RH for the removal of dyes in water and wastewater and also for various practical applications.

Chitosan based radiation crosslinked and grafted matrix: An environment friendly adsorbent for dye uptake

The adsorption capacity of [2-(methacryloxy) ethyl] trimethylammonium chloride (MAETC) grafted-crosslinked chitosan (CRChitosan-g-MAETC) using ionizing radiation was evaluated for adsorption of anionic dyes namely Acid Blue-25 (AB25), Reactive Orange-16 (RO16) and Reactive Red-120 (RR120) from manufactured aqueous solutions. Effect of various experimental variables like dye concentration, pH, contact time duration, temperature and adsorption on adsorbent grafted to different extent on adsorption kinetics and on equilibrium adsorption was investigated. To understand the equilibrium adsorption of dyes on the adsorbent the data was fitted into Langmuir, Freundlich and Temkin adsorption isotherms while adsorption kinetics was examined using pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models. It was observed that the adsorption of all the three anionic dyes studied was better explained by the Freundlich model. Adsorption extent of dye varied with number of charge sites on the dye molecule. The adsorption of all the three anionic dyes followed pseudo-second order kinetics. Thermodynamic parameters such as standard enthalpy (ΔHo), standard entropy (ΔSo) and standard free energy (ΔGo) were estimated. The radiation grafted cationic adsorbent showed promising adsorbent properties for removal of anionic dyes.

Waste lignin-based cationic flocculants treating dyeing wastewater: Fabrication, performance, and mechanism

Lignin is often considered to be a complex polymeric structural material with excellent scalability. Reduced pressure distillation, a novel effective way, was proposed to recover reusable waste lignin from textile degumming black liquor. The structure of the recovered material was determined by Fourier Transform Infrared Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC) and Klason Component Analysis. Recycled lignin (RL) was used as the basis for the synthesis of a cationic recycled lignin-based polymers (CRLM) through graft polymerizing cationic monomer (DMC). The optimum synthesis conditions were obtained by conducting orthogonal experiments using the cationicity as the studied parameter, while selecting pH, DMC/RL, reaction temperature and time as independent variables. Recovery experiments showed that the maximum recovery concentration of RL in the black liquor was 5 g/L, with a purity of approximately 83 %. Orthogonal experiments showed that a low DMC/RL ratio was crucial for the synthesis of flocculants. When the molar ratio of DMC/RL was 3:1, the cationicity of the prepared CRLM was as high as 11.32 %. Zeta potential and decolorization experiments also confirmed the stable decolorization performance of CRLM in three kinds of anionic dye wastewater. The experimental results showed that charge neutralization, chemical bonding forces and auxiliary effects play great role to remove anionic dyes, resulting in 94 %, 89 % and 94.9 % removal against Reactive Red 195 (RR195), Acid Red 18 (AR18) and Direct 168 (DB168) respectively. Therefore, this study demonstrated the potential of using recycled waste lignin as synthesize lignin-based flocculants in the field of printing and dyeing wastewater by treating waste with waste.

Adsorption of Reactive Red 120 in Decamethyl-Cyclopentasiloxane Non-Aqueous Dyeing System

Traditional dyeing usually consumes a significant amount of water and salts, thus causing environmental pollution. Salt-free and low-water dyeing has become an important research direction in the cotton fabric dyeing industry. The non-aqueous media dyeing technology, using decamethylcyclopentasiloxane (D5) as the dyeing medium, has achieved energy saving and emission reduction in this industry. To investigate the influence of inorganic salts on the dyeing properties of reactive dyes in a non-aqueous medium dyeing system, the adsorption kinetics and level dyeing property of C.I. Reactive Red 120 were investigated at various concentrations of sodium sulfate. When no salts were included in the siloxane non-aqueous dyeing system, 80% of the reactive dye could diffuse onto the cotton fabric surface after 10 min. However, if 13% salts were added during dyeing, 87% of the reactive dye could diffuse to cotton fabric surface over the same amount of time. Moreover, the adsorption rate of dye was increased from 3.85 mg/g·min to 5.04 mg/g·min when the quantity of salts was increased from 0% to 13%. However, the concentration of sodium sulfate had minimal effect on the color depth of the dyed fabric and the final uptake of dye. But, when the concentration of sodium sulfate was significant, the level dyeing property of the dye became poor as the Sγ(λ) value was increased from 0.020 to 0.042. The adsorption kinetic of C.I. Reactive Red 120 in D5 dyeing solution may be best described by the pseudo-second-order kinetic model. As the sodium sulfate concentration increases, the half-dyeing time gradually decreases and the adsorption rate of dye increases. The repulsive force between the dye and the cotton fiber was lowered by the addition of sodium sulfate. Consequently, in the D5 dyeing system, the level dyeing property of reactive dye may be affected by the adsorption rate. Therefore, the formula of reactive dyes that do not contain salts can be applied successfully in non-aqueous dyeing systems.

Enhanced textile dye removal from wastewater using natural biosorbent and Shewanella algae B29: Application of Box Behnken design and genomic approach

In this study, Box-Behnken design combining seven factors at three levels were used to optimize the elimination of CI Reactive Red 66 in artificial seawater, by the combination of eco-friendly bio-sorbents and acclimated halotolerant microbial strain. Results showed that macro-algae and cuttlebone (2 %) were the best natural bio-sorbent. Additionally, the selected halotolerant strain able to rapidly remove dye was identified as Shewanella algae B29. The optimization process revealed that decolourization of CI Reactive Red 66 yields reached 91.04 % under the following variable values: dyes concentration (100 mg/l), salinity (30 g/l), peptone (2 %), pH (5), algae C (3 %), cuttlebone (1.5 %) and agitation (150 rpm). The whole genome analysis of S. algae B29 demonstrated the presence of several genes coding for valuable enzymes involved in textile dyes biotransformation, adaptation to stress as well as biofilm formation implying its potential use in biological textile wastewater treatment.

Pyrite Cinder as an Effective Fenton-like Catalyst for the Degradation of Reactive Azo Dye: Effects of Process Parameters and Complete Effluent Characterization

This research investigates the potential use of pyrite cinder (PC) as an efficient Fenton-like catalyst for the removal of the reactive azo dye Reactive Red 120 (RR120) from aqueous solutions. The characterization of its PC structure and composition confirmed its great potential to act as catalytic iron source in a heterogeneous Fenton system. Dye removal optimization was performed in terms of PC dosage (0.4–8 g/L), H2O2 concentration (2–25 mM), pH value (2–4.6), initial dye concentration (50–200 mg/L), and mixing time. The highest decolorization efficiency (92%) was achieved after a reaction time of 480 min under following conditions: RR120 = 50 mg/L, PC = 4 g/L, H2O2 = 10 mM, and pH = 3. After decolorization, an extensive analysis of the generated effluent was performed regarding metal leaching, mineralization, toxicity, and degradation product formation. The metal leaching indicated the necessity for a pH increase in order to remove the settled metal hydroxides. The mineralization efficiency was satisfactory, reaching 85% and 62% of the COD and TOC removal, respectively. The respirometry measurements and bioluminescence tests indicated the detoxification of the treated solution. The absorption spectra and GC/MS analysis confirmed the changes in the molecular structure in the form of the destruction of the azo bond, with a simpler aromatic and aliphatic intermediates formation. This study provides an effective method for removing azo dye in polluted water by employing waste tailings as alternative Fenton-like catalysts, while also using waste tailings as the secondary resource.

Rapid activation of peroxymonosulfate with iron(Ⅲ) complex for organic pollutants degradation via a non-radical pathway

Developing high-performance catalytic systems for eliminating contaminants effectively in water has received a lot of attention. However, the complexity of practical wastewater poses a challenge for degrading organic pollutants. Non-radical active species with strong resistance to interference have shown great advantages in degrading organic pollutants under complex aqueous conditions. Herein, a novel system was constructed by Fe(dpa)Cl2 (FeL, dpa = N, N'-(4-nitro-1,2-phenylene) dipicolinamide) activating peroxymonosulfate (PMS). The mechanism study verified that the FeL/PMS system had high efficiency in producing high-valent iron-oxo and singlet oxygen (1O2) to degrade various organic pollutants. In addition, the chemical bonding between PMS and FeL was elucidated by the density functional theory (DFT) calculations. The FeL/PMS system could remove 96% Reactive Red 195 (RR195) in 2 min, which was much higher than other systems involved in this study. More attractively, the FeL/PMS system demonstrated general resistance to interference from common anions (Cl−, HCO3−, NO3− and SO42−), humic acid (HA) and pH changes and were thus compatible with various natural waters. This work provides a new approach for producing non-radical active species, which is a promising catalytic system for water treatment.

Synergistic role of metal oxide loading cocatalysts on photocatalytic degradation of organic pollutants and inactive bacteria over template-free ZnFe2O4 nanocubes

For wastewater treatment, a highly reliable and ecologically friendly oxidation method is always preferred. This work described the production of a new extremely effective visible light-driven Ag2Ox loaded ZnFe2O4 nanocomposties photocatalyst using a wet impregnation technique. Under visible light irradiation, the produced Ag2Ox loaded ZnFe2O4 nanocomposties were used in the photodegradation of rhodamine B (RhB) and Reactive Red 120 (RR120) dyes. Analysis using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy revealed that Ag2Ox nanoparticles were well dispersed on the surface of ZnFe2O4 NPs and that the Ag2Ox loaded ZnFe2O4 NPs were created. When compared with bare ZnFe2O4 NPs, Ag2Ox-loaded ZnFe2O4 nanocomposites showed better photocatalytic activity for RhB and RR120 degradation under visible light (>420 nm) illumination. The reaction kinetics and degradation methodology, in addition to the photocatalytic degradation functions of Ag2Ox-loaded ZnFe2O4 nanocomposites, were thoroughly investigated. The 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites have a 99% removal efficiency for RhB and RR120, which is about 2.4 times greater than the ZnFe2O4 NPs and simple combination of 1 wt% and 2 wt% Ag2Ox loaded ZnFe2O4 nanocomposites. Furthermore, the 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites demonstrated consistent performance without decreasing activity throughout 3 consecutive cycles, indicating a potential approach for the photo-oxidative destruction of organic pollutants as well as outstanding antibacterial capabilities. According to the findings of the experiments, produced new nanoparticles are an environmentally friendly, cost-efficient option for removing dyes, and they were successful in suppressing the development of Gram-negative and Gram-positive bacteria.

Adsorption and photodegradation of reactive red 120 with nickel-iron-layered double hydroxide/biochar composites.

Layered double hydroxide (LDH) materials were widely applied for adsorption and photodegradation of pollutants for wastewater treatment. New efficient LDH materials with adsorption and photodegradation abilities will be promising candidates for pollutants removal. Hence, a series of NiFe-LDH/biochar (NiFe/BC) were fabricated by the coprecipitation method for synergistic adsorption and photodegradation anionic dyes of reactive red 120 (RR120). The removal experiment showed that the addition of an appropriate amount of biochar into NiFe-LDH enhanced the adsorption capacity and its photocatalytic ability. The optimized NiFe/BC2 composite can remove 88.5% of RR120 under visible light by adsorption and photocatalysis, which was much better than NiFe-LDH (63.3%) and biochar (2.6%). The photodegradation kinetic constant of the NiFe/BC2 composite was 3.1 and 104.8 times that of NiFe-LDH and BC. In addition, active species capture experiments and electron spin resonance (ESR) tests revealed the removal mechanisms of NiFe/BC composites for RR120 removal. This work affords a feasible strategy for preparing LDH-based photocatalyst with excellent adsorption and photocatalytic performance for wastewater treatment.

Construction of SnO2/CuO/rGO nanocomposites for photocatalytic degradation of organic pollutants and antibacterial applications

Water contamination by reactive dyes is a serious concern for human health and the environment. In this study, we prepared high efficient SnO2/CuO/rGO nanocomposites for reactive dye degradation. For structural analysis of SnO2/CuO/rGO nanocomposites, XRD, UV–Vis DRS, SEM, TEM-EDAX, and XPS analysis were used to characterize the physicochemical properties of the material. The characterization results confirmed great crystallinity, purity, and optical characteristics features. For both Rhodamine B (RhB) and Reactive Red 120 (RR120) degradation processes, SnO2/CuO/rGO nanocomposites were tested for their photocatalytic degradation performance. The SnO2/CuO/rGO nanocomposites have expressed the degradation rate exposed to 99.6% of both RhB and RR120 dyes. The main reason behind the photocatalytic degradation was due to the formation of OH radical's generation by the composite materials. Moreover, the antibacterial properties of synthesized SnO2/CuO/rGO nanocomposites were studied against E. coli, S. aureus, B. subtilis and P. aeroginosa and exhibited good antibacterial activity against the tested bacterial strains. Thus, the synthesized SnO2/CuO/rGO nanocomposites are a promising photocatalyst and antibacterial agent. Furthermore, mechanisms behind the antibacterial effects will be ruled out in near future.

Ultrasound-Assisted Synthesis of a ZnO/BiVO4 S-Scheme Heterojunction Photocatalyst for Degradation of the Reactive Red 141 Dye and Oxytetracycline Antibiotic.

The preparation of novel sunlight active photocatalysts for complete removal of pollutants from aqueous solutions is a vital research topic in environmental protection. The present work reports the synthesis of a ZnO/BiVO4 S-scheme heterojunction photocatalyst for degradation of the reactive red dye and oxytetracycline antibiotic in wastewater. ZnO and BiVO4 were first fabricated by a hydrothermal technique, and then, the ZnO/BiVO4 heterostructure was synthesized using an ultrasonic route. An increase of the surface area, compared to that of ZnO, was found in ZnO/BiVO4. The enhancement of charge separation efficiency at the interface was obtained so that a remarkable enhancement of the photocatalytic performance was detected in the prepared heterojunction photocatalyst. Complete detoxification of harmful pollutants was achieved by using the economical solar energy. The removal of the pollutants follows the first-order reaction with the highest rate constant of 0.107 min-1. The stability of the prepared photocatalyst was detected after five cycles of use. The ZnO/BiVO4 S-scheme heterostructure photocatalyst still provides high photoactivity even after five times of use. Hydroxyl radicals play an important role in the removal of the pollutant. This work demonstrates a new route to create the step-scheme heterojunction with high photoactivity for complete removal of the toxic dye and antibiotic in the environment.

Valorization of Solid Wastes from Textile Industry as an Adsorbent Through Activated Carbon Production

In this study, recycling of solid textile wastes into activated carbon and the potential use of these activated carbons in color removal were investigated. Cotton and cotton/polyester-blended fabric wastes and textile wastewater treatment sludge were selected as solid textile wastes. A two-stage method, low temperature carbonization, and chemical activation with ZnCl2 were applied to prepare large surface area and rich-pore structure activated carbon from fabric wastes and sludge in textile industry. The activated carbons were characterized by elemental analysis, Fourier-transform infrared spectroscopy, X-ray fluorescent, and Brunauer–Emmett–Teller analysis. The reactive dye (Reactive Red 141) adsorption capacity of the activated carbons was investigated by the batch adsorption method. Activated carbon yields were found in the range of 28–34%. Cotton textile waste-based activated carbons were found to have the highest surface area (~1380 m2/g), followed by cotton/polyester and wastewater treatment sludge-based activated carbons. Wastewater treatment sludge-based activated carbons showed the highest dye adsorption capacity (161.29 mg/g), possibly due to its higher mesoporosity. The obtained results showed that the adsorption of the reactive dye onto textile waste-based activated carbons produced by two-step process is favorable. The developed activated carbons fit the circular economy approach well, offering a promising potential for solid textile waste management, as well as for water remediation.

Decolorization of Reactive Red 120 by a novel bacterial consortium: Kinetics and heavy metal inhibition study

<abstract><p>Juru River is one of the most polluted rivers in Malaysia. A dye-degrading bacterial consortium has been isolated from the river's sediment. This consortium JR3 consists of <italic>Pseudomonas aeruginosa</italic> MM01, <italic>Enterobacter</italic> sp. MM05 and <italic>Serratia marcescens</italic> MM06, which were able to decolorize up to 700 ppm of the Reactive Red 120 (RR120) dye under optimal conditions with limited substrate available. Substrate inhibition kinetics were investigated, and, based on the best model, Aiba, the maximum growth rate was 0.795 h<sup>–1</sup>, while the saturation constant and inhibitory constant were 0.185% and 0.14%, respectively. In addition, the influence of various metal ions on the growth and decolorization rate of this bacterial consortium on RR120 was investigated. Chromium showed the weakest effect on the decolorization of 200 ppm RR120, with 73.5% removal and bacterial growth of 11.461 log CFU mL<sup>–1</sup>. Zinc yielded the second weakest effect, followed by silver and lead, with percentages of RR120 decolorization of 63.8%, 54.6% and 50.5%, respectively. Meanwhile, cadmium, arsenic and copper reduced the decolorization of RR120 in consortium JR3 by half. Mercury strongly inhibited decolorization by 32.5%. Based on the least inhibited heavy metal in RR120 decolorization activity of consortium JR3, the best inhibitory kinetic model was Levenspiel, with a maximum growth rate of 0.632 h<sup>–1</sup>, while the saturation constant and inhibitory constants were 15.08% and 0.5783%, respectively. The metal-tolerant azo dye-degrading bacterial consortium will be very useful in dye remediation in metal-laden polluted environments.</p></abstract>

Parametric studies of degradation of reactive red 120 by a novel approach of hydrodynamic cavitation

Hydrodynamic cavitation (HC) was used to study the degradation of reactive red 120 (RR120). The effect of several parameters such as RR120 concentration in liquid, operating pressure, system temperature, pH, and the effect of an oxidising agent (H 2 O 2 ) on RR120 % decolorization has been examined. Decolorization of RR120 via hydrodynamic cavitation appears to follow first-order kinetics. Using HC at 3.5 kg/cm 2 , 30 °C, pH = 2 and 10 mg l −1 dye concentration in aqueous solution, 74 % decolorization was achieved.

THE USE OF BACTERIAL LACCASE IMMOBILIZED ON AGROWASTE AS A POTENTIAL ECOFRIENDLY TECHNIQUE OF AZO DYE DE-COLORIZATION

In the modern world, the effluent of the textile industry contains azo dyes, which are considered an alarming threat to the environment. Crystal violet, malachite green, reactive red are the most common dyes which are wieldy used in textile industries. Due to the sophisticated structure of these dyes, they are mutagenic and carcinogenic to both humans and aquatic life. A viable alternative is an affordable and eco-friendly bioremediation technique using bacteria or their enzyme that can degrade the azo dyes. Azo dye contaminated samples were collected from the industrial area of Ahmedabad and Jetpur (Gujarat, India). Forty three isolates with various morphologies were employed in the dye de-colorization experiment. Among them four most promising isolates (E11, S32, S12 and J24) were selected which de-colorize the all three dyes. Agowaste materials with MBSS medium were used to produce laccase enzymes from S12. Laccase was partially purified with the help of pre-chilled acetone. Partially purified laccase was immobilized in sodium alginate beads with rice husks and check the de-colorization efficiency of our experimental dyes. From the results, immobilized laccase can degrade 55.29% crystal violet and 55.10% malachite green dye in 4hr of incubation. Because of its incredible de-colorization ability, immobilized laccase has quite the potential as a cost-effective, biologically beneficial strategy for treating the textile effluents.

Adsorption process of reactive red 2 using a low-cost activated charcoal: isotherm, kinetics and thermodynamics studies

Activated charcoal with an appropriate functional group was synthesized by carbonizing method, from the stem of Albizia Lebbeck. The average 75-125 µm mesh was utilized to separate particles. The charcoal parameters of bulk density, surface area, moisture content, pH, and pHzpc have been measured, which are concurrent with literature-reported values. Chemical functionality was studied by FT-IR spectroscopy and particle size was confirmed by scanning electron microscopy. The dye, Reactive Red 2(Red2), adsorbs on the surface of activated charcoal through microscopic holes. General parameter variations, namely exposure time, adsorbent dosage, initial dye concentration, temperature, and pH of the dye solution, were used to find out the best condition for dye removal. Compare to the reported adsorbents that require acidic conditions (pH<5), the prepared charcoal has been capable of absorbing Reactive Red 2 at an ambient pH of 5.5. The equilibrium adsorption data were found to match with the Langmuir and Freundlich isotherms, and thermodynamic tests indicated the endothermic adsorption process. Furthermore, it has been proven by Lagergren and models, that the monolayer coverage and first-order kinetics of adsorption indicate the scalability of the adsorptive process for large-scale dye removal from waste-water streams.