Evaluation of phase transfer kinetics and thermodynamic equilibria of Reactive Orange 16 sorption onto chemically improved Arachis hypogaea pod powder

Removal of fluoroquinolone antibiotic and sulfonated dye by functionalized Persea americana seed powder: Appraisal on phase transfer kinetics, equilibrium, economics, and applications in rural settings

The study focuses on reactive orange 16 (RO16), a sulfonated dye, and ciprofloxacin (CiP), a fluoroquinolone antibiotic treatment from aquatic surface by adsorption. The functionalized Persea americana seed powder (PASP) was developed by acid hydrolysis technique and investigated for RO16 and CiP removal in batch scale at different concentrations for CiP and RO16, pH (2-8), contact duration and temperature (303-318K). Utilizing a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDAX), the generated native PASP were assessed for their morphological characteristics. Fourier transform infrared (FTIR) spectroscopy was applied to examine the performing characteristics of PASP. Experimental findings with four kinetic mathematical models allowed the estimation of the process involved in the biosorption. The most effective agreement was explained by the pseudo-second-order model and Sips isotherm (Cip = 34.603 mg/g and RO16 = 30.357 mg/g) at 303K temperature. For Cip Process economics of the biosorbent was done, and it was observed that it was less than the readily market-available activated carbon.

A mechanochemically synthesized Schiff-base engineered 2D mixed-linker MOF for CO2 capture and cationic dye removal

Developing synthetic strategies for smart materials for the adsorption and separation of toxic chemicals is of great importance. Metal-organic frameworks (MOFs) have been proven to be outstanding adsorbent materials that possess excellent pollutant removal performances in wastewater treatment, including dye recycling. In this work, a neutral Cd(II) based 2D framework with a dual ligand strategy involving -OH functionalized 5-hydroxyisophthalic acid (5-OH-H2IPA) and the amide decorated Schiff base ligand (E)-N'-(pyridin-4-ylmethylene)isonicotinohydrazide (L) has been synthesized by different synthetic routes and characterized by various analytical methods. Thus, crystals of {[Cd(5-OH-IPA)(L)]·CH3OH}n synthesized via diffusion (ADES-7D) and the phase pure bulk product synthesized by conventional reflux (ADES-7C) and the mechanochemical grinding method (ADES-7M) have been established using PXRD data of the respective product showing identical simulated SXRD data to those of ADES-7D. The mechanochemically synthesized ADES-7M possesses a better surface area and CO2 adsorption capability compared to ADES-7C, which is also supported by electron microscopy and particle size measurements. Furthermore, ADES-7 can be used as an efficient adsorbent material for the reversible, selective adsorption (42-99%) and separation of the cationic dyes malachite green (MG), methyl violet (MV), methylene blue (MB), and rhodamine B (RhB) from the mixture of cationic/anionic dyes (methyl orange (MO) and bromocresol green (BCG)) in the aqueous phase. Specifically, ADES-7M possesses better dye capture capability compared to ADES-7C, even in the case of the bigger dye RhB with adsorption differences of 2.38 to 1.01 mg g-1, respectively. The dye adsorption kinetics follows pseudo-second-order kinetics, and the dye adsorption isotherm fits well with the Langmuir/Freundlich adsorption isotherm models. The probable mechanism of adsorption involving the supramolecular interaction between the host MOF and the guest dye has also been proposed.

An eco-friendly chitosan-genipin/SiO2 composite for reactive orange 16 dye removal: Insights into adsorption statistical modeling and mechanism

The present work develops an effective bioadsorbent of cross-linked chitosan-genipin/SiO2 adsorbent (CHI-GNP/SiO2). The developed CHI-GNP/SiO2 was employed for the removal of organic dye (reactive orange 16, RO16) from simulated wastewater. The optimization of the fundamental adsorption variables (CHI-GNP/SiO2 dose, time, and pH) via the Box-Behnken design (BBD) was attained for achieving maximal adsorption capacity and high removal efficiency. The good agreement between the Freundlich isotherms and empirical data of RO16 adsorption by CHI-GNP/SiO2 indicates that the adsorption process follows a multilayer adsorption mechanism. The reasonable agreement between the pseudo-second-order model and the kinetic data of RO16 adsorption by CHI-GNP/SiO2 was obtained. The maximum RO16 adsorption capacity (qmax) of CHI-GNP/SiO2 was identified to be 57.1 mg/g. The adsorption capacity of CHI-GNP/SiO2 is attributed to its unique surface properties, including its highly porous structure and the presence of functional groups such as amino and hydroxyl groups. According to the results of this investigation, CHI-GNP/SiO2 has the potential to be an adsorbent for the removal of acidic dyes from wastewater.

Novel Chitosan-ZnO nanocomposites derived from Nymphaeaceae fronds for highly efficient removal of Reactive Blue 19, Reactive Orange 16, and Congo Red dyes

The primary aim of this investigation was to synthesise novel adsorbent by incorporating greenly synthesized zinc oxide nanoparticles into chitosan matrix (G-ZnO-Cs). The production of ZnO Nanoparticles via a green approach involved the utilization of extracts derived from Nymphaeaceae fronds. This assertion was substantiated by the application of Field Emission Scanning Electron Microscopy (FESEM) and X-ray Diffraction (XRD) analytical techniques. Several Analytical methods such as Fourier Transform Infrared spectroscopy (FT-IR), Energy Dispersive X-ray Analysis (EDAX), FESEM, Thermogravimetric Analysis (TGA), XRD, Brunauer-Emmett-Teller (BET) analysis, and point-of-zero charge determination were used to characterize G-ZnO-Cs. Further study investigates the impact of five key processing parameters, namely pH, interaction duration, G-ZnO-Cs dosage, temperature, and initial concentration of dyes, on the removal of three organic dyes Reactive Blue 19 (RB 19), Reactive Orange 16 (RO 16), and Congo Red (CR) The adsorption process of Reactive Blue 19 (RB 19), Reactive Orange 16 (RO 16), and Congo Red (CR) dyes on G-ZnO-Cs were determined to comply to the pseudo-second-order (PSO) and Langmuir models, as determined through equilibrium and kinetic experiments. The highest adsorption capabilities for RB 19, RO 16 and CR dye were revealed to be 219.6 mg/g, 129.6 mg/g, and 118.8 mg/g, respectively. The elimination success rate of the fixed-bed column approach for treating huge volumes was highlighted in the conducted research. Moreover, the G-ZnO-Cs composite exhibited significant reusability due to its ability to undergo elution and simultaneous regeneration processes.

Bisphenol-A-diglycidyl ether modified chitosan/nano-SiO2 via hydrothermal process: A statistical modeling and adsorption mechanism for reactive orange 16 dye removal

In this study, chitosan/nano SiO2 (CTS/NS) was chemically modified with bisphenol A diglycidyl ether (BADGE) cross-linker-assisted hydrothermal process to create an effective adsorbent, CTS-BADGE/NS, for the removal of reactive orange 16 (RO16) dye from aquatic systems. Box-Behnken design (BBD) was used to optimize the adsorption process by varying the adsorbent dose (0.02-0.1 g/100 mL), pH (4-10), and time (20-360 min). The adsorption isotherm results indicated that the Langmuir model fits the experimental data well, suggesting that the adsorption process involves a monolayer formation of RO16 on the surface of CTS-BADGE/NS. The kinetic modeling of RO16 adsorption by CTS-BADGE/NS demonstrated that the pseudo-first-order model fits the adsorption data. CTS-BADGE/NS achieved an adsorption capacity of 97.8 mg/g for RO16 dye at optimum desirability functions of dosage 0.099 g/100 mL, solution pH of 4.44, and temperature of 25 °C. Overall, the π-π electron donor-acceptor system significantly improved the adsorption performance of the CTS-BADGE/NS. The results of the regeneration investigation demonstrate that the CTS-BADGE/NS exhibits effective adsorption of RO16, even after undergoing five consecutive cycles. The results of this study suggest that the developed CTS-BADGE/NS composite can be a promising adsorbent for water purification applications.

Effective utilization of discarded reverse osmosis post-carbon for adsorption of dyes from wastewater

In this study, the deployment of post Reverse Osmosis (RO)-carbon as a adsorbent for dye removal from water has been investigated. The post RO-carbon was thermally activated (RO900), and the material thus obtained exhibited high surface area viz. 753 m2/g. In the batch system, the efficient Methylene Blue (MB) and Methyl Orange (MO) removal was obtained by using 0.08 g and 0.13 g/50 mL adsorbent dosage respectively. Moreover, 420 min was the optimized equilibration time for both the dyes. The maximum adsorption capacities of RO900 for MB and MO dyes were 223.29 and 158.14 mg/g, respectively. The comparatively higher MB adsorption was attributed to the electrostatic attraction between adsorbent and MB. The thermodynamic findings revealed the process as spontaneous, endothermic, and accompanied by entropy increment. Additionally, simulated effluent was treated, and >99% dye removal efficiency was achieved. To mimic an industrial perspective, MB adsorption onto RO900 was also carried out in continuous mode. The initial dye concentration and effluent flow rate were among the process parameters that were optimized using the continuous mode of operation. Further, the experimental data of continuous mode was fitted with Clark, Yan, and Yoon-Nelson models. Py-GC/MS investigation revealed that dye-loaded adsorbents could be pyrolyzed to produce valuable chemicals. The cost and low toxicity associated benefits of discarded RO-carbon over other adsorbents reveal the significance of the present study.

Preparation of sisal fiber/polyaniline/bio-surfactant rhamnolipid-layered double hydroxide nanocomposite for water decolorization: kinetic, equilibrium, and thermodynamic studies

Sisal fiber is a potent economical biomaterial for designing composites because of its low density, high specific strength, no toxic effects, and renewability. The present study utilized sisal fiber as a starting material and subjected it to modification to produce a sisal fiber/polyaniline/bio-surfactant rhamnolipid-layered double hydroxide nanocomposite material denoted as SF@PANI@LDH@RL. The composite was evaluated for its efficacy in removing reactive orange 16 (RO16) and methylene blue (MB) from aqueous solutions. The synthesized adsorbent was characterized by FTIR, XRD, and SEM-EDS techniques; these analyses indicated the successful modification of the sisal fiber. The primary factors, including contact time, adsorbent dosage, dye concentration, temperature, and pH, were optimized for achieving the most excellent adsorption efficiency. On the one hand, methylene blue removal is enhanced in the basic solution (pH = 10). On the other hand, reactive orange 16 adsorption was favored in the acidic solution (pH = 3). The highest adsorption capacities for methylene blue and reactive orange 16 were 24.813 and 23.981 mg/g at 318 K, respectively. The Temkin isotherm model, which proves the adsorption procedure of methylene blue and reactive orange 16 could be regarded as a chemisorption procedure, supplies the most suitable explanation for the adsorption of methylene blue (R² = 0.983) and reactive orange 16 (R² = 0.996). Furthermore, Elovich is the best-fitting kinetic model for both dyes (R² = 0.986 for MB and R² = 0.987 for RO16). The recommended SF@PANI@LDH@RL adsorbent was reused six consecutive times and showed stable adsorption performance. The results demonstrate that SF@PANI@LDH@RL is a perfect adsorbent for eliminating cationic and anionic organic dyes from aqueous media.

Remediation of phthalate acid esters from contaminated environment—Insights on the bioremedial approaches and future perspectives

Phthalates are well-known emerging pollutants that are toxic to the environment and human health. Phthalates are lipophilic chemicals used as plasticizers in many of the items for improving their material properties. These compounds are not chemically bound and are released to the surroundings directly. Phthalate acid esters (PAEs) are endocrine disruptors and can interfere with hormones, which can cause issues with development and reproduction, thus there is a huge concern over their existence in various ecological surroundings. The purpose of this review is to explore the occurrence, fate, and concentration of phthalates in various environmental matrices. This article also covers the phthalate degradation process, mechanism, and outcomes. Besides the conventional treatment technology, the paper also aims at the recent advancements in various physical, chemical, and biological approaches developed for phthalate degradation. In this paper, a special focus has been given on the diverse microbial entities and their bioremedial mechanisms executes the PAEs removal. Critically, the analyses method for determining intermediate products generated during phthalate biotransformation have been discussed. Concluisvely, the challenges, limitations, knowledge gaps and future opportunities of bioremediation and their significant role in ecology have also been highlighted.

Recent advances in assessment methods and mechanism of microbe-mediated chlorpyrifos remediation

Chlorpyrifos (CP) is one of the Organophosphorus pesticides (OPs) primarily used in agriculture to safeguard crops from pests and diseases. The pervasive use of chlorpyrifos is hazardous to humans and the environment as it inhibits the receptor for acetylcholinesterase activity, leading to abnormalities linked to the central nervous system. Hence, there is an ardent need to develop an effective and sustainable approach to the on-site degradation of chlorpyrifos. The role of microbes in the remediation of pesticides is considered the most effective and eco-friendly approach, as they have strong degradative potential due to their gene and enzymes naturally adapted to these sites. Several reports have previously been published on exploring the role of microbes in the degradation of CP. However, detection of CP as an environmental contaminant is an essential prerequisite for developing an efficient microbial-mediated biodegradation method with less harmful intermediates. Most of the articles published to date discuss the fate and impact of CP in the environment along with its degradation mechanism but still fail to discuss the analytical portion. This review is focused on the latest developments in the field of bioremediation of CP along with its physicochemical properties, toxicity, fate, and conventional (UV-Visible spectrophotometer, FTIR, NMR, GC-MS, etc) and advanced detection methods (Biosensors and immunochromatography-based methods) from different environmental samples. Apart from it, this review explores the role of metagenomics, system biology, in-silico tools, and genetic engineering in facilitating the bioremediation of CP. One of the objectives of this review is to educate policymakers with scientific data that will enable the development of appropriate strategies to reduce pesticide exposure and the harmful health impacts on both Human and other environmental components. Moreover, this review provides up-to-date developments related to the sustainable remediation of CP.

Recent advances in the removal of dyes from wastewater using low-cost adsorbents

The presence of hazardous dyes in wastewater cause disastrous effects on living organisms and the environment. The conventional technologies for the remediation of dyes from water have several bottlenecks such as high cost and complex operation. This review aims to present a comprehensive outlook of various bio-sorbents that are identified and successfully employed for the removal of dyes from aqueous environments. The effect of physicochemical characteristics of adsorbents such as surface functional groups, pore size distribution and surface areas are critically evaluated. The adsorption potential at different experimental conditions of diverse bio-sorbents has been also explored and the influence of certain key parameters like solution pH, temperature, concentration of dyes, dosage of bio-sorbent and agitation speed is carefully evaluated. The mechanism of dyes adsorption, regeneration potential of the employed bio-sorbents and their comparison with other commercial adsorbents are discussed. The cost comparison of different adsorbents and key technological challenges are highlighted followed by the recommendations for future research.

Remedial strategies for abating 1,4-dioxane pollution-special emphasis on diverse biotechnological interventions

1,4-dioxane is a heterocyclic ether used as a polar industrial solvent and are released as waste discharges. 1,4-dioxane deteriorates health and quality, thereby attracts concern by the environment technologists. The need of attaining sustainable development goals have resulted in search of an eco-friendly and technically viable treatment strategy. This extensive review is aimed to emphasis on the (a) characteristics of 1,4-dioxane and their occurrence in the environment as well as their toxicity, (b) remedial strategies, such as physico-chemical treatment and advanced oxidation techniques. Special reference to bioremediation that involves diverse microbial strains and their mechanism are highlighted in this review. The role of macronutrients, stimulants and other abiotic cofactors in the biodegradation of 1,4-dioxane is discussed lucidly. We have critically discussed the inducible enzymes, enzyme-based remediation, distinct instrumental method of analyses to know the fate of intermediates produced from 1,4-dioxane biotransformation. This comprehensive survey also tries to put forth the different toxicity assessment tools used in evaluating the extent of detoxification of 1,4-dioxane achieved through biotransforming mechanism. Conclusively, the challenges, opportunities, techno-economic feasibility and future prospects of implementing 1,4-dioxane through biotechnological interventions are also discussed.

Low-cost treated lignocellulosic biomass waste supported with FeCl3/Zn(NO3)2 for water decolorization

Dye pollution has always been a serious concern globally, threatening the lives of humans and the ecosystem. In the current study, treated lignocellulosic biomass waste supported with FeCl₃/Zn(NO₃)₂ was utilized as an effective composite for removing Reactive Orange 16 (RO16). SEM/EDAX, FTIR, and XRD analyses exhibited that the prepared material was successfully synthesized. The removal efficiency of 99.1% was found at an equilibrium time of 110 min and dye concentration of 5 mg L^-1 Adsorbent mass of 30 mg resulted in the maximum dye elimination, and the efficiency of the process decreased by increasing the temperature from 25 to 40 °C. The effect of pH revealed that optimum pH was occurred at acidic media, having the maximum dye removal of greater than 90%. The kinetic and isotherm models revealed that RO16 elimination followed pseudo-second-order (R² = 0.9982) and Freundlich (R² = 0.9758) assumptions. Surprisingly, the performance of modified sawdust was 15.5 times better than the raw sawdust for the dye removal. In conclusion, lignocellulosic sawdust-Fe/Zn composite is promising for dye removal.

Adsorption behavior of rhamnolipid modified magnetic Co/Al layered double hydroxide for the removal of cationic and anionic dyes

In the present research, magnetic rhamnolipid-Co/Al layered double hydroxide (MR-LDH) was synthesized to uptake methylene blue (MB) and reactive orange 16 (RO16) from aqueous solution. The main parameters, including pH, adsorbent dosage, contact time, and initial analyte concentration, were optimized to achieve the best adsorption efficiency. Accordingly, the elimination of MB on MR-LDH is improved in the basic medium due to the electrostatic interactions between the negative charge of MR-LDH and the positive charge of MB dye. In contrast, the acidic medium (pH = 3) was favored for RO16 adsorption because of hydrogen bonding between the protonated form of azo dye and protonated hydroxyl groups at the surface of MR-LDH. The calculated maximum adsorption capacities for MB and RO16 were 54.01 and 53.04 mg/g at 313 K, respectively. The Langmuir model, which assumes monolayer adsorption on the adsorbent surface, provides the best explanation for the adsorption of both dyes (R² = 0.9991 for MB and R² = 0.9969 for RO16). Moreover, the pseudo-second-order kinetic model best described the adsorption process for MB (R² = 0.9970) and RO16 (R² = 0.9941). The proposed adsorbent maintains stable adsorption performance for four consecutive cycles. After each adsorption process, MR-LDH is easily separated by an external magnet. The findings show that MR-LDH was found to be an excellent adsorbent for the removal of both cationic and anionic organic dyes from aqueous solutions.

Preparation and characterization of lignin-derived hard templated carbon(s): Statistical optimization and methyl orange adsorption isotherm studies

In this study, lignin-derived zeolite templated carbon materials were fabricated to remove the organic contaminant, methyl orange. Response surface methodology with Box-Behnken design was used to optimize the adsorption parameters. Based on Box-Behnken design, a quadratic model was developed to correlate the adsorption variables with the response, removal efficiency. Analysis of variance revealed the adsorbent dosage as the most influential adsorption variable. Lignin derived ZSM-5 (PZ) and mordenite (PM) templated carbon materials exhibited high surface area; 476.0 and 716.0 m²/g respectively. The maximum theoretical adsorption capacity of PZ and PM for methyl orange was 514.0 and 225.0 mg/g, respectively. The experimental kinetic data best fitted to pseudo-second-order model for both the adsorbents. PZ adsorbent was also utilized to treat real wastewater containing dyes and achieved 40 % methyl orange removal efficiency. Adsorption thermodynamic study revealed the process as spontaneous, exothermic and also indicated the increment in entropy after adsorption.

Kinetics, equilibrium and thermodynamic investigations of methylene blue dye removal using Casuarina equisetifolia pines

Casuarina equisetifolia pines are degradable biopolymeric substance with dye-sequestering property was utilized as biosorbent to expel a cationic dye; methylene blue dye from simulated wastewater. The prepared adsorbent material was characterized for their structural, morphological and elemental features to understand their suitability in augmenting in dye-wastewater remediation. The results infer that 0.5 g/L biosorbent was proficient in removing 100 mg/L methylene blue (pH 7.0 ± 0.2) when agitated at 150 rpm for 120 min. Isothermal behavior were evaluated using non-linear isotherm models like Temkin, Langmuir and Freundlich models while the rate-limiting steps were found using kinetic models. Temkin isotherm and pseudo-first order model explained the removal mechanism among the models evaluated, which infers that the biosorption followed physisorption with the maximum adsorption capacity of 41.35 mg/g. Thermodynamic behavior of methylene blue removal by C. equisetifolia pines powder described the feasibility of biosorption as well as the type of heat involved. Equilibrium sorption capacities, rate constants and correlation coefficients explains that MB dye removal by C. equisetifolia pines is presumably physisorption, spontaneous and endothermic in nature.

A review on the microbial degradation of chlorpyrifos and its metabolite TCP

Chlorpyrifos (CPF) falls under the category of organophosphorus pesticides which are in huge demand in the agricultural sector. Overuse of this pesticide has led to the degradation of the quality of terrestrial and aquatic life. The chemical is moderately persistent in the environment but its primary metabolite 3,5,6-trichloro-2-pyridinol (TCP) is comparatively highly persistent. Thus, it is important to degrade the chemical and there are many proposed techniques of degradation. Out of which bioremediation is considered to be highly cost-effective and efficient. Many previous studies have attempted to isolate appropriate microbial strains to degrade CPF which established the fact that chlorine atoms released while mineralising TCP inhibits further proliferation of microorganisms. Thus, it has been increasingly important to experiment with strains that can simultaneously degrade both CPF and TCP. In this review paper, the need for degrading CPF specifically the problems related to it has been discussed elaborately. Alongside these, the metabolism pathways undertaken by different kinds of microorganisms have been included. This paper also gives a detailed insight into the potential strains of microorganisms which has been confirmed through experiments conducted previously. It can be concluded that a wide range of microorganisms has to be studied to understand the possibility of applying bioremediation in wastewater treatment to remove pesticide residues. In addition to this, in the case of recalcitrant pesticides, options of treating it with hybrid techniques like bioremediation clubbed with photocatalytic biodegradation can be attempted.

Fly ash modified magnetic chitosan-polyvinyl alcohol blend for reactive orange 16 dye removal: Adsorption parametric optimization

A magnetic biocomposite blend of chitosan-polyvinyl alcohol/fly ash (m-Cs-PVA/FA) was developed by adding fly ash (FA) microparticles into the polymeric matrix of magnetic chitosan-polyvinyl alcohol (m-Cs-PVA). The effectiveness of m-Cs-PVA/FA as an adsorbent to remove textile dye (reactive orange 16, RO16) from aquatic environment was evaluated. The optimum adsorption key parameters and their significant interactions were determined by Box-Behnken Design (BBD). The analysis of variance (ANOVA) indicates the significant interactions can be observed between m-Cs-PVA/FA dose with solution pH, and m-Cs-PVA/FA dose with working temperature. Considering these significant interactions, the highest removal of RO16 (%) was found 90.3% at m-Cs-PVA/FA dose (0.06 g), solution pH (4), working temperature (30 °C), and contact time (17.5 min). The results of adsorption kinetics revealed that the RO16 adsorption was better described by the pseudo-second-order model. The results of adsorption isotherm indicated a multilayer adsorption process as well described by Freundlich model with maximum adsorption capacity of 123.8 mg/g at 30 °C. An external magnetic field can be easily applied to recover the adsorbent (m-Cs-PVA/FA). The results supported that the synthesized m-Cs-PVA/FA presents itself as an effective and promising adsorbent for textile dye with preferable adsorption capacity and separation ability during and after the adsorption process.

Emerging novel polymeric adsorbents for removing dyes from wastewater: A comprehensive review and comparison with other adsorbents

Dye molecules are one of the most hazardous compounds for human and animal health and the excess intake of these materials can create toxic impacts. Several studies show the practicality of the adsorption process for dye uptake from wastewaters. In recent years, various adsorbents were used to be efficient in this process. Among all, polymeric adsorbents demonstrate great applicability in different environmental conditions and attract many researchers to work on them, although there is not enough reliable and precise information regarding these adsorbents. This study aims to investigate some influential parameters such as their type, physical properties, experimental conditions, their capacity, and further modeling along with a comparison with non-polymeric adsorbents. The influence of the main factors of adsorption capacity was studied and the dominant mechanism is explained extensively.