Dye Removal Efficiency Research Articles

Green and eco-friendly scalable synthesis of chitosan-carbon nanocomposite for efficient dye removal

The integration of activated carbon with chitosan (CS) for dye removal offers a multitude of benefits, making this hybrid material a promising and efficient solution for water purification. Activated carbon (C) was synthesized from fruit wastes and then mixed with CS for the preparation of chitosan‑carbon nanocomposite (CSCNC) using ball milling technique. XRD and ATR-FTIR techniques affirmed the preparation of CSCNC. Additionally, the findings obtained from TEM and SEM analyses signifying the deposition of activated carbon onto the surface of CS. The majority of particle size and polydispersity index (PdI) for CSCNC were found to be 162.8 nm and 0.483, respectively as displayed from DLS technique. The current research work was examined the adsorption and desorption behaviors of Methylene Blue (MB) using CSCNC. Adsorption experiments reveal a time-dependent process characterized by an initial rapid phase and gradual approach to equilibrium, with the pseudo-second-order kinetics model providing the best fit. The adsorption capacity exhibited a rising pattern as pH increased, reaching its peak value of 912.4 mg/g. Both Langmuir and Freundlich isotherm models explained the equilibrium relationship between MB and the nanocomposite, offering insights into maximum adsorption capacity and surface characteristics. Desorption studies explored the nanocomposite's regenerative potential under varying conditions. The findings contributed to the sustainable design of water treatment technologies, emphasizing the nanocomposite's efficiency, scalability, and regenerative capabilities.

Fast and Efficient Removal of Anionic Dyes from Water by Hierarchical Porous MIL-101(Cr)

Fast and Efficient Removal of Anionic Dyes from Water by Hierarchical Porous MIL-101(Cr)

Investigating the performance of CoFe2O4@TiO2 nanomaterial as multifunctional cathode catalyst for simultaneous dye degradation and oxygen reduction in microbial desalination cell

Microbial desalination cell (MDC) is an emerging technology in which water is desalinated and energy is generated by the breakdown of organic compounds and catalyzed by microorganisms using the potential gradient created in the reactor. MDC efficacy is substantially influenced by the oxygen reduction reaction (ORR) occurring at the cathode, albeit potential hindrances include sluggish reaction rates and biofouling development. The present study involved synthesizing and utilizing CoFe2O4@TiO2 nanocomposite as a multifunctional catalyst on a cathode surface for efficient ORR and dye removal. XPS, HRTEM, and XRD techniques were used to ascertain the NPs' morphology, surface properties, dimensions, and XRD patterns. Physicochemical investigation showed that the nanoparticles had a consistent distribution, a mean diameter of 18.11 nm, and a spherical shape. Researchers tested MDCs with nanoparticles (NPs). The highest power density was 4.56 W/m3, 50 % more than the MDC with a lower loading density. The desalination efficiency was found to be 60 % at 1.5 mg/cm2 CoFe2O4@TiO2, however, it was 80 and 81 % at 2.5 and 2.0 mg/cm2 catalyst concentrations, respectively. The dye degradation efficiency of as high as 88 % was observed with CoFe2O4@TiO2 nanocomposite cathode MDC. The findings show that CoFe2O4@TiO2 nanocomposite might be an economically feasible ORR catalyst, improving MDC efficiency and cost.

Activated carbon based TiO2 nanocomposites (TiO2@AC) used simultaneous adsorption and photocatalytic oxidation for the efficient removal of Rhodamine-B (Rh–B)

The availability of fresh water is limited compared to its huge consumption. Conversely, certain industries like dyes, textiles, paper, and tanning not only consume vast quantities of fresh water, but also generate significant amounts of wastewater that poses severe threats to living organisms. The present investigation focuses on the degradation of Rhodamine-B (Rh–B) as a model pollutant by using the nanocomposite based on waste scrap tire-derived activated carbon (AC) and titanium dioxide (TiO2). These nanostructures were fabricated using wet chemistry techniques. Analysis using scanning electron microscopy (SEM) revealed that the morphology of the structures remained largely unchanged even with a concentration of 6 mg of AC. X-ray diffraction (XRD) results confirmed the successful fabrication of rutile and anatase phases of TiO2@AC nanocomposite. The XPS results confirmed the presence of AC and TiO2 in the composite. Furthermore, the optical band gap of the nanocomposites decreased up to 17.17 % and 34.57 % through direct and indirect methods respectively, owing to the varying quantity of AC used. The narrowing of optical band gap and the increased surface oxygen vacancies were caused by the successive addition of AC during the synthesis of nanocomposites. This resulted in the efficient degradation of Rhodamine-B (Rh–B) using adsorption and photocatalytic oxidation. The findings demonstrate a significant influence of AC on the TiO2 catalyst in the removal of Rh–B dye. The maximum efficiency of dye removal, reaching up to 99.14 %, was achieved with the highest concentration of AC, thus demonstrating almost complete elimination of Rh–B dye. The findings suggest that the use of waste scrap tires can be effectively applied to design efficient photocatalysts for addressing the wastewater management issues.

A strategy for the efficient removal of acidic and basic dyes in wastewater by organophilic magadiite@alginate beads: Box-Behnken Design optimization

In this study, four adsorbents were developed: layered silicate magadiite material (mag), Hexadecyltrimethylammonium intercalated magadiite (HDTMA@mag), a cross-linked composite of sodium alginate and magadiite (ALG@mag) and a cross-linked composite of sodium alginate and HDTMA@magadiite (ALG@HDTMA@mag). The adsorbents were evaluated for their effectiveness in removing of Methylene Blue (MB) and Eriochrome Black T (EBT) dyes. The prepared adsorbents were characterized using SEM, XRD, FTIR, and zeta potential measurements. Kinetic modeling results indicated that both film diffusion and intraparticle diffusion are useful as rate-determining processes in adsorption for all adsorbents. For both dyes, the Langmuir isotherm model provided a good correlation with the adsorption equilibrium data. ANOVA analysis for the best adsorbent (ALG@HDTMA@mag beads) revealed that MB removal was significantly influenced by the positive individual effects of contact time and ALG@HDTMA@mag dose. However, the individual effect of MB concentration exhibited an antagonistic effect throughout the adsorption process. The optimal parameters for achieving an adsorption capacity of 118.54 mg/g were a dye concentration of 60 ppm, a contact period of 1800 min, and an ALG@HDTMA@mag dose of 50 mg.

Nano-catalytic behavior of CeO2 nanoparticles in dye adsorption: Synthesis through bio-combustion and assessment of UV-light-driven photo-adsorption of indigo carmine dye

This study explores the adsorption of indigo carmine dye using bio-combusted cerium oxide nanoparticles (CeO2 NPs). CeO2 NPs were synthesized using a bio-combustion method, and then subjected to structural, morphological, and optical characterization for thorough investigation. Structural investigation was carried out using X-ray diffraction (XRD), which revealed a cubic structure with evaluated average crystallite size of 11.55 nm. Later, the same was verified by employing W–H plot (13.57 nm). UV–Vis spectroscopy revealed an effective band gap of 3 eV suited for photocatalytic applications. The metal-oxygen phonon band at 986.32 cm−1 and 871.96 cm−1 is confirmed using Infrared Spectroscopy (FTIR). The morphological analysis was done using Transmission and Scanning Electron Microscopy (TEM and SEM), which revealed well-dispersed, aggregated structure enclosing spherical nanoparticles with an average size of ∼14 nm. The early precursors were validated using EDAX analysis and SEM. Optical characteristics were investigated using photoluminescence (PL), which revealed a large charge transfer band between 360 nm and 435 nm. The dye removal efficiency of CeO2 NPs was evaluated against Indigo Carmine dye using UV light. The results showed that the significantly adsorption, with more than 70 % removed after 150 min. Kinetic experiments revealed that the depreciation occurred via a pseudo-first-order reaction process. Furthermore, the impacts of certain factors such as dye dosage, pH, reusability, and scavenger on adsorption rate were explored and shown to be effective values for the adsorption process. This study emphasizes the potential of CeO2 NPs as excellent photocatalysts for environmental remediation, especially in dye removal applications.

Synthesis of iron loaded jackfruit peel biochar through microwave heating as a stable and active heterogenous Fenton catalyst for dye degradation

Iron-loaded biochar derived from jackfruit peels (Fe-JP) was synthesised by pyrolysis in a microwave furnace and iron was loaded onto the peels prior to pyrolysis, facilitated by sonication. The primary objective of the investigation was to examine the degradation process of methylene blue (MB) dye and Acid Red 1 (AR1) dye by the using Fe-JP biochar as a heterogeneous Fenton catalyst. The investigation encompassed an examination of the impact of different operating parameters, such as pH, catalyst dosage, and H2O2 concentration. The synthesised Fenton catalyst underwent characterization using Field Emission scanning electron microscopy (FESEM), Energy Dispersive X-ray (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques, Fourier transform infrared (FTIR) spectra analysis, Raman spectroscopy, Brunauer-Emmet-Teller (BET) analysis. At a pH of 3, using an initial MB dye concentration of 20 mg/L and initial AR1 dye concentration of 50 mg/L, an 8 mM H2O2 concentration, and a catalyst dose of 2 g/L, the maximum dye removal efficiency reached 96.5 % and 98 % respectively, while the total organic carbon (TOC) removal efficiency reached 68.5 % and 75 % respectively. The observed reaction time under the given experimental conditions was 120 min. The thermal stability of the biochar catalyst was found to be excellent based on the Thermogravimetric analysis (TGA) and Differential Scanning Calorimeter (DSC) studies. The catalysts that were developed demonstrated remarkable durability and negligible leaching of iron, hence enabling their repeated usage in subsequent cycles. The findings of the investigation suggest that the primary mechanism responsible for the degradation of the dye was the surface-based heterogeneous Fenton activity. Additionally, the effect of adsorption on the elimination of colour under varying pH conditions was examined, which had a very low influence in dye degradation (<30 %). The conducted scavenging investigations in the research have indicated the major involvement of hydroxyl radicals (OH) in the degradation process, followed by surface-bound hydroxyl radicals (OHsurface), superoxide radicals (O2−) and ultimately by singlet oxygen radicals (1O2). The study's economic analysis demonstrated that using microwave mode of heating for catalyst synthesis is both green and cost-effective. This observation suggests the possibility of practical implications in the domain of dye degradation.

PCN-222/H3PW12O40/graphene oxide@cotton cloth with improved photocatalytic/photothermal properties for water decontamination

In this study, a novel visible-light-driven PCN-222/H3PW12O40/graphene oxide@cotton cloth (PCN-222/HPW/GO@Cot) photocatalytic platform was developed for efficient water sterilization and purification. PCN-222/HPW/GO ternary photocatalyst was prepared via one-pot solvothermal method, and anchored onto cotton cloth though catechol-amine reaction. By introducing HPW as the quasi-semiconductor co-catalyst and efficient electron trap, the photocatalytic activity of PCN-222 was boosted. Besides, the addition of GO further enhanced electron transfer capability and photothermal properties. PCN-222/HPW/GO@Cot exhibited significantly improved organic dye photodegradation and sterilization efficiencies compared to PCN-222 and PCN-222/HPW coated cotton cloths. It also maintained consistent organic dye removal efficiency over reuse cycles and retained high sterilization activity after repeated washings, indicating its remarkable durability and coating stability. The band positions and the enhanced photocatalytic/photothermal mechanisms were investigated in depth. This research suggests the great potential of PCN-222/HPW/GO@Cot photocatalytic platform for practical water purification and sterilization applications, and the potential to become multifunctional textiles.

Efficient Adsorptive Removal of Cationic Dyes from Aqueous Solution by Magnetic Silica Core-Shell Nanoparticles

Efficient Adsorptive Removal of Cationic Dyes from Aqueous Solution by Magnetic Silica Core-Shell Nanoparticles

Efficient adsorption removal of anionic dyes by waste PET-derived MIL-101(Cr)

Adsorption can be used as a pollutant removal method to solve the increasingly serious problem of synthetic dye pollution and metal organic framework (MOF) is considered as a novel adsorbent for its unique structure. However, the high cost and high toxicity during the synthesis procedure of MOFs like MIL-101(Cr) limited their potential on the large-scale production and application. In this paper, waste PET plastic was depolymerized to prepare terephthalic acid (TPA) as an organic linker to synthesize MIL-101(Cr). Besides, Hydrofluoric acid (HF) was not added during the synthesis to avoid poisonous pollution. MIL-101(Cr) was applied to the adsorption of anionic dyes reactive red 2 (RR2) and reactive blue 19 (RB19). The batch experiments exhibited kinetic data best fitted the pseudo-first-order model (PFO) with the adsorption capacity of 662.87 (RR2) and 863.67 mg g-1 (RB19). The isotherm adsorption data fitted well with the Freundlich isotherm, indicating formation of multilayer coverage over the surface of MIL-101(Cr). The highest regeneration rate of MIL-101(Cr) at the fourth cycle was 91.18 and 91.44 % after RR2 and RB19 adsorption. X-ray photoelectron spectroscopy (XPS) technique and Fourier Transform Infrared (FTIR) spectroscopy both indicated the possible adsorption mechanism of MIL-101(Cr) toward RR2 and RB19 could be attributed to electrostatic interactions, hydrogen bonding, and the π-π stacking. This work proposed a novel method using waste plastics as raw materials to synthesize eco-friendly pollutant adsorbent, which had an enlightening effect on pollutant treatment.

Enhanced photocatalytic activity of Ag/ZnO nanocomposite immobilized on kanthal coils

Constructing hybrid semiconductor photocatalysts and increasing the charge-carrier density are effective strategies for enhancing the photocatalytic performance of ZnO. This study elucidates the synergistic effects of electron trapping and surface plasmon resonance (SPR) on the activity of ZnO photocatalysts. Ag/ZnO nanocomposites were synthesized on Kanthal coils using a two-step method involving the immobilization of ZnO on Kanthal coils and the coupling of Ag nanoparticles. XPS and RTPL analyses verified the synergistic effects of electron trapping and SPR on the activity of the Ag/ZnO nanocomposites. The photocatalytic performance of the composite was evaluated in the degradation of rhodamine B (RhB) dye. The Ag/ZnO nanocomposite exhibited significantly enhanced removal efficiency for RhB dye (38.2–70.5% depending on the deposition time). The Ohmic contact at the Ag/ZnO heterojunction extended the lifetime of the photoinduced charge carriers, whereas the SPR facilitated the generation of more electrons for the photocatalytic reaction. However, the excessive deposition of Ag nanoparticles compromised the photocatalytic performance of the Ag/ZnO nanocomposite. This study provides valuable insights for developing efficient ZnO-based photocatalytic materials for addressing environmental challenges.

Efficient removal of Methylene blue dye from aqueous medium utilizing eco-friendly chitosan adsorbents

ABSTARCT Dyes released through various industrial operations are a major threat to the environment. The recent study introduced an eco-friendly adsorbent based on the grafting of phenolic acids (caffeic and/or gallic acids) on chitosan to reduce the hazardous impact of color effluent pollution. The morphology and structure of synthesized adsorbents were confirmed by physical and chemical tools such as TGA, FTIR, SEM, EDX, point of zero charge, water regain, and resistance of adsorbents to dissociation in acidic media. The synthesized adsorbents’ removal efficiency toward MB dye, a model cationic organic pollutant, from aqueous medium was evaluated. The factors impacting dye adsorption were investigated, including pH, dye initial concentration, and temperature. The response surface methodology (RSM) was used to confirm the interaction effects of the process variables and optimize the ideal conditions of adsorption. The maximum adsorption capacity was 257.0 and 391.8 mg/g for AI and AII, respectively, at initial MB concentration of 550 ± 1 mg/L, pH 8, and 21 ± 1 °C. MB adsorption is an exothermic chemosorption process that takes place via electrostatic attraction in an alkaline medium. Both AI and AII demonstrated significant reuse ability when eluted with a 0.5 M HCl solution.

Green reduction of ZnO nanoparticles using cationic dialdehyde cellulose (cDAC) for efficient Congo red dye removal

More sustainable materials have been becoming an important concern of worldwide scientists, and cellulosic materials are one alternative in water decontamination. An efficient strategy to improve removal capacity is functionalizing or incorporating nanomaterials in cellulose-based materials. The new hybrid cDAC/ZnONPs was produced by green synthesis of zinc oxide nanoparticles (ZnONPs), promoting the in situ reduction and immobilization on the cationic dialdehyde cellulose microfibers (cDAC) surface to remove Congo red dye from water. cDAC/ZnONPs was characterized by scanning electron microscopy (SEM-EDS) and infrared spectroscopy (FTIR), which showed efficient nanoparticles reduction. Adsorption efficiency on cationic cellulose surface was investigated by pH, contact time, initial concentration, and dye selectivity tests. The material followed the H isotherm model, which resulted in a maximum adsorption capacity of 1091.16 mg/g. Herein, was developed an efficient and ecologically correct new adsorbent, highly effective in Congo red dye adsorption even at high concentrations, suitable for the remediation of contaminated industrial effluents.

Na-Kenyaite as Efficient Basic Blue-41 Dye Removal: Synthesis and Regeneration Studies

Na-kenyaite materials are available in nature and can easily be prepared in the laboratory. These materials exhibit interesting adsorption properties; therefore, they can be invested in the new wastewater treatment technologies. This study investigates the removal of basic blue-41 (BB-41) dye from artificially contaminated water using Na-kenyaite materials in batch mode. Firstly, Na-kenyaites were prepared by the hydrothermal process at a temperature of 150 to 170 °C for a period of 2 to 7 days using different silica sources and ratios of SiO2/NaOH/H2O. The prepared materials were characterized by different techniques such as XRD, FTIR, 29Si MAS NMR, TGA/DTA, SEM, and nitrogen adsorption isotherms. A pure Na-kenyaite phase was successfully obtained using a fumed silica source and 5SiO2/Na2O/122H2O ratio. The removal experiments of basic blue-41 estimated the effectiveness of Na-kenyaites in removing properties, investigating the influence of the solid dosage, initial basic blue-41 concentration, and solution pH or Na-kenyaite solid. Results showed optimal dye removal of around 99% at pH levels above 7. Furthermore, the estimated maximum removal capacity from the Langmuir isotherm was between 124 and 165 mg/g. The results demonstrated efficient removal by Na-kenyaites and its prominence for wastewater treatment. Finally, this study explored the regeneration and reuse of Na-kenyaites through seven cycles and reported a design of a batch adsorber system to reduce the initial concentration of 200 mg/L at different percentages.

Efficient Removal of Methylene Blue Dye from Aqueous Media Using Facilely Synthesized Magnesium Borate/Magnesium Oxide Nanostructures.

Methylene blue dye in water sources can pose health risks to humans, potentially causing methemoglobinemia, a condition that impairs the blood's ability to carry oxygen. Hence, the current study investigates the synthesis of novel magnesium borate/magnesium oxide (Mg3B2O6/MgO) nanostructures and their efficiency in removing methylene blue dye from aqueous media. The nanostructures were synthesized using the Pechini sol-gel method, which involves a reaction between magnesium nitrate hexahydrate and boric acid, with citric acid acting as a chelating agent and ethylene glycol as a crosslinker. This method helps in achieving a homogeneous mixture, which, upon calcination at 600 and 800 °C, yields Mg3B2O6/MgO novel nanostructures referred to as MB600 and MB800, respectively. The characterization of these nanostructures involved techniques like X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, N2 gas analyzer, and field-emission scanning electron microscope (FE-SEM). These analyses confirmed the formation of orthorhombic Mg3B2O6 and cubic MgO phases with distinct features, influenced by the calcination temperature. The mean crystal size of the MB600 and MB800 samples was 64.57 and 79.20 nm, respectively. In addition, the BET surface area of the MB600 and MB800 samples was 74.63 and 64.82 m2/g, respectively. The results indicated that the MB600 sample, with its higher surface area, generally demonstrated better methylene blue dye removal performance (505.05 mg/g) than the MB800 sample (483.09 mg/g). The adsorption process followed the pseudo-second-order model, indicating dependency on available adsorption sites. Also, the adsorption process matched well with the Langmuir isotherm, confirming a homogeneous adsorbent surface. The thermodynamic parameters revealed that the adsorption process was physical, exothermic, and spontaneous. The MB600 and MB800 nanostructures could be effectively regenerated using 6 M HCl and reused across multiple cycles. These findings underscore the potential of these nanostructures as cost-effective and sustainable adsorbents for methylene blue dye removal.

A statistical optimization for almost-complete methylene blue biosorption by Gracilariabursa-pastoris

In this study, the dried biomass of four marine algae, namely Porphyra sp., Gracilaria bursa-pastoris, Undaria pinnatifida and Laminaria sp., were screened for their ability to remove methylene blue (MB) dye from aqueous solutions. Statistical approaches of the Plackett-Burman Design (PBD) and Box-Behnken Design (BBD) were applied to optimize different environmental conditions in order to achieve the maximum MB removal percentage by Gracilaria bursa-pastoris. The biosorbent was characterized before and after adsorption process using FTIR, XRD and SEM analysis. Additionally, isotherms, kinetics and thermodynamics studies were conducted to investigate the adsorption behavior of the adsorbent. The results showed that Gracilaria bursa-pastoris achieved the highest dye removal efficiency (98.5 %) compared to 96.5 %, 93.5 % and 93.9 % for Undaria pinnatifida, Porphyra sp. and Laminaria sp., respectively. PBD analysis revealed that the agitation speed, pH, and biomass dose were found to be the significant parameters affecting MB removal onto Gracilaria dried biomass. According to the BBD results, the maximum dye removal percentage (99.68 %) was obtained at agitation speed of 132 rpm, pH 7 and biomass dose of 7.5 g/L. FTIR, XRD and SEM analysis demonstrated the participation of several functional groups in the adsorption process and changes in the cell surface morphology of the adsorbent following the dye adsorption. The adsorption isotherms showed better fit to Freundlich model (R2 = 0.9891) than the Langmuir, Temkin, and Dubinin-Radushkevich models. The adsorption kinetics were best described by the pseudo-second-order model (R2 = 0.9999), suggesting the chemical interactions between dye ions and the algal biomass. The thermodynamic parameters indicated that the adsorption of MB onto Gracilaria dried biomass was spontaneous, feasible, endothermic and random. These results indicate that dried biomass of Gracilaria bursa-pastoris is an attractive, environmentally friendly, cheap and effective agent for MB dye removal from environmental discharges.

Design and evaluation of a polyaniline-Azadirachta indica composite for efficient dye removal: Insights from experimental and theoretical simulations

In this study, a novel composite of polyaniline and Azadirachta indica sawdust (PAIS) was synthesized to explore its potential in the adsorptive removal of methylene blue (MB) and crystal violet (CV) dyes from aqueous solution. PAIS was characterized using various instrumental techniques, including FTIR, SEM/EDXS, XRD, TEM/SAED, BET, and TGA-DTG/DTA analyses. Batch adsorption tests revealed that pH, medium temperature, initial adsorbate concentration, adsorbent dose, and contact duration significantly influence adsorption efficiency. Adsorption equilibrium was reached at 30 min for MB and 90 min for CV in an acidic medium (up to pH 7), with minimal changes observed beyond these times. The Langmuir isotherm provided the best validation, with a maximum monolayer adsorption capacity of 454.54 mg/g for MB and 370.37 mg/g for CV, showcasing superior performance compared to most reported materials. The adsorption process adhered to a pseudo-second-order approach for both dyes, with a high coefficient of determination value. The adsorption of MB and CV by this innovative adsorbent was spontaneous, endothermic, and accompanied by entropy enhancement. The adsorbent loaded with dyes was subjected to different desorbing agents (HCl, NaOH, NaCl, CH3COOH, and H2O), and HCl was the most effective. Computational studies using Density Functional Theory supported the experimental results, confirming the higher efficiency of PAIS for MB removal over CV. It is submitted that PAIS uniquely exhibits highly adaptable, recyclable, and potent low-cost adsorbent properties for eliminating both dyes from aqueous systems, representing a significant advancement in the field of dye removal.

Efficient removal of Eosin Yellow dye using solvothermal synthesised Ni/Al layered double hydroxide and layered double oxide: insights into adsorption kinetics and thermodynamics

ABSTRACT The accumulation of organic pollutants in the environment is swelling steadily and raising the alarm for their redressal. Layered double hydroxides (LDH) and layered double oxides (LDO) are gaining prominence for their potential to address this challenge. This work includes an eco-friendly facile solvothermal synthesis of Ni/Al LDH and their calcination to Ni/Al LDO. The prepared nanomaterials were characterised by XRD, FE-SEM, HR-TEM, FT-IR, BET and TGA techniques, which confirm the highly porous structure of synthesised nanomaterials with a high specific area of 109.94 m2g−1 and 188.94 m2g−1 for Ni/Al LDH and Ni/Al LDO, respectively. A systematic study was conducted to explore the adsorptive potential of these materials towards the removal of organic dye Eosin Yellow (EY). The adsorptive efficiency was found to be 95% and 99% for Ni/Al LDH and Ni/Al LDO, respectively, under the optimised conditions of pH, adsorbent dose, contact time, dye concentration and temperature on adsorptive removal of EY dye, which was analysed by BBD-RSM (Box-Behnken Design Response surface methodology). The adsorption data fits best with the Freundlich isotherm model and pseudo-second-order kinetics. The thermodynamic study confirms the exothermic adsorptive process. The durability and reusability of the synthesised adsorbents were ascertained by their retention of the adsorptive efficiency even after five adsorption-desorption cycles which were as high as 91% and 85% for Ni/Al LDH and Ni/Al LDO, respectively. The mechanism of adsorption involves electrostatic interaction and hydrogen bonding between the surface of adsorbent and adsorbate as well as intercalation of dye molecules.

Boronate-modified electro-spun Fe doped carbon nanofibrous membrane for selective dye adsorption, catalytic degradation, and bacterial inhibition in treatment of water

Recently, dye and microorganism have become the main sources of water pollution due to the rapid development of modern industries and wantonly draining of living sewage. Therefore, the efficient removal of dye and microorganism from the wastewater have attracted considerable attentions of the scientists and engineers around the world. In this regard, a novel phenyl boronic acid (PBA) modified electro-spun Fe doped carbon nanofibrous membrane, C/Fe@PBA, was fabricated in this study for simultaneously selective removal of dye and efficient inhibition of bacteria in water. Firstly, the C/Fe@PBA displayed selective adsorption towards Congo Red (CR) among other dyes by the adsorption order of CR>Methyl Orange (MO) > Neutral Red (NR) > Methylene Blue (MB) > Malachite Green (MG) > Rhodamine B (RhB) with adsorption ability at 25.75, 8.41, 7.11, 7.02, 5.41, and 3.13 mg·g−1. The pseudo first order kinetics and Langmuir isotherm model is calculated to better match the adsorption process of the as prepared membrane towards CR. After 7 rounds of adsorption desorption or 5 degradation cycles, the carbon membrane showed a removal efficiency of 62.2 % or 57.4 %, respectively. Furthermore, the C/Fe@PBA can be employed as effective catalyst to degrade CR in presence of H2O2 under 808 nm near-infrared (NIR) irradiation by the photothermal effect, and the possible catalytic mechanisms and degradation pathway were proposed. Moreover, the as prepared membrane exhibited high bactericidal rate of 99.94 % and 97.44 % against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. In conclusion, the as prepared carbon membrane with ability of selective adsorption, catalytic degradation, and bacterial inhiation is a promising candidate of filtration membrane in practical sewage management.

Nano clinoptilolite zeolite as a sustainable adsorbent for dyes removal: Adsorption and computational mechanistic studies

Clinoptilolite, a naturally occurring zeolite with unique adsorption properties, is investigated in its nanoscale form as a sustainable adsorbent for effectively removing contaminant dyes, rhodamine B (RhB), malachite green (MG), and methyl green (MeG), from aqueous solutions. The nano clinoptilolite was prepared by ball milling and characterized using various techniques including XRD, FTIR, SEM, TGA, BET, and zeta potential to confirm its structure, functional groups, porous morphology, thermal stability, surface area and pore size distribution, and surface charge, respectively. The nano clinoptilolite has a crystalline size of 19.5 nm, determined by XRD. Its average hydrodynamic size in water is 285 nm, measured by dynamic light scattering. Adsorption experiments were carried out to evaluate the dye removal efficiency under various conditions such as pH, zeolite dose, dye concentrations, and contact time. The equilibrium adsorption data were fitted with different isotherm models such as Freundlich, Langmuir, Langmuir-Freundlich, and Sips; and the kinetics adsorption data were fitted with pseudo-first-order, pseudo-second-order, mixed-order, and Avrami models. Nanosized clinoptilolite exhibited a high maximum adsorption capacity for MG (191.36 mg MG/g at pH 5.0), exceeding a previous report by 336 % (43.86 mg MG/g). RhB adsorption capacity on zeolite was 58.02, 24.28 mg/g at pH 3.0, 7.0, and MeG was 162.94 mg/g at pH 7.0. Finally, Monte Carlo and molecular dynamics simulations were used to elucidate the specific binding sites, adsorption energies, and mechanisms involved in the removal process.