Dye Removal Capacity Research Articles

Post-tanning wastewater treatment using electrocoagulation: Optimization, kinetics, and settlement analysis

Post-tanning process in the tannery industry generates complex wastewater. Continuous electrocoagulation (EC) with carbon-steel electrodes was used to treat synthetic/post-tanning wastewater. Research surface methodology, based on central composite design (RSM-CCD), was used for variables optimization and analysis of variance (ANOVA) to relate all parameters. Optimal variables were identified as initial pH 3.0, current density 6.4 mA m−2, initial dye concentration 125 mg L−1, NaCl concentration 1000 mg L−1, and inlet flow rate 176 mL min−1 to produce 71% dye removal, operational costs (OC) 0.05 US$ m−3, power consumption 1.3 kWh m−3, iron consumption 0.05 kg m−3, dye removal capacity per dissolved mg iron (qe) 4.3 mg Dye L−1 C−1 and total dissolved solids (TDS) removal 43.5%. Best process conditions were used to treat real post-tanning wastewater and resulted in carbon oxygen demand (COD) and TDS abatement (23% and 76%, respectively), as well as low OC (0.84 US$ m−3) and energy consumption (20.6 kWh m−3). Pseudo-first-order kinetic model was found fitting experimental results, having electrical energy per order (EEO) of 1 kW h m−1 order−1 with a higher k = 1.14 min−1. Scanning electron microscopy analysis suggested the presence of iron nanoparticles within the sludge. All input and output parameters resulted in statistically significant where TDS and qe were the most valued for effective pollutant removal optimization and prevention of TDS increase in treated water. The outcomes of this study suggest EC as a suitable treatment for post-tanning wastewater and further knowledge of steel-carbon EC reactor design and sludge reusing purposes.

Iron-biochar production from oily sludge pyrolysis and its application for organic dyes removal.

In this study, a single-step pyrolysis approach was developed to directly convert oily sludge (OS) with high iron content into a magnetic iron-char catalyst for organic dyes removal. Magnetic iron-char catalysts were employed to degrade crystal violet (CV), methylene blue (MB), and sunset yellow (SY). The OC800 iron-char catalyst prepared from OS was not only rich in iron (mainly stable Fe3O4), but also showed favorable pore structures. Effects of operation parameters like temperature, H2O2 dosage, and pH on dye removal based on Fenton degradation were examined. In OC800 Fenton system (0.5mL H2O2, 500mg/L dye concentration, and pH=2 in 50mL solution), the maximum dye removal capacities of SY, CV, and MB were 83.61, 639.19, and 414.25mg/g, respectively. In dyes degradation experiments, the prepared catalyst could be reused (more than 3 successive cycles) due to higher stability and less leaching of iron. One-step pyrolysis of OS with high iron content thereby represents a promising approach to transform sludge waste to functional biochar that removes hazardous dyes.

Facile and novel preparation of 2D-MoS2/carbon nanodots composite with high adsorption efficiency and capacity for dye removal

Here, hydrophobic bulk molybdenum disulfide (MoS2) was efficiently exfoliated into two dimensional (2D) nanosheets assisted with amphiphilic carbon nanodots (CNDs) in pure water. The optimized concentration of obtained 2D-MoS2 is as high as 0.41 mg/mL, which is higher than that of reported literatures. The average lateral size and layer number of 2D-MoS2 is 142.6 (±2.3) nm and 4, respectively. The characterizations and simulation demonstrated that CNDs can be instantly adsorbed on the surface of 2D-MoS2 and form 2D-MoS2/CNDs composite. Thus, after standing for 1000 h, the concentration of 2D-MoS2 still accounts for 90 % of the initial concentration with the help of CNDs. Further, this technique can also be used to prepare graphene and 2D-WS2 nanosheets. 2D-MoS2/CNDs composite as adsorbent showed excellent adsorption capacity (1136.9 mg/g) and ultrafast adsorption rate (1 min) for methylene blue removal, which benefits from abundant adsorption sites and high dispersion. This work not only develops a facile and universal technique for green preparation of 2D nanomaterials in one pot, but also provides a promising adsorbent for removing organic pollutants from aqueous solution.

Surface Modification of Biochar for Dye Removal from Wastewater

Nowadays, biochar is being studied to a great degree because of its potential for carbon sequestration, soil improvement, climate change mitigation, catalysis, wastewater treatment, energy storage, and waste management. The present review emphasizes on the utilization of biochar and biochar-based nanocomposites to play a key role in decontaminating dyes from wastewater. Numerous trials are underway to synthesize functionalized, surface engineered biochar-based nanocomposites that can sufficiently remove dye-contaminated wastewater. The removal of dyes from wastewater via natural and modified biochar follows numerous mechanisms such as precipitation, surface complexation, ion exchange, cation–π interactions, and electrostatic attraction. Further, biochar production and modification promote good adsorption capacity for dye removal owing to the properties tailored from the production stage and linked with specific adsorption mechanisms such as hydrophobic and electrostatic interactions. Meanwhile, a framework for artificial neural networking and machine learning to model the dye removal efficiency of biochar from wastewater is proposed even though such studies are still in their infancy stage. The present review article recommends that smart technologies for modelling and forecasting the potential of such modification of biochar should be included for their proper applications.

Indirect Additive Manufacturing: A Valid Approach to Modulate Sorption/Release Profile of Molecules from Chitosan Hydrogels.

This work studied the influence of hydrogel’s physical properties (geometry and hierarchical roughness) on the in vitro sorption/release profiles of molecules. To achieve this goal, chitosan (CS) solutions were cast in 3D-printed (3DP) molds presenting intricate shapes (cubic and half-spherical with/without macro surface roughness) and further immersed in alkaline solutions of NaOH and NaCl. The resulting physically crosslinked hydrogels were mechanically stable in aqueous environments and successfully presented the shapes and geometries imparted by the 3DP molds. Sorption and release profiles were evaluated using methyl orange (MO) and paracetamol (PMOL) as model molecules, respectively. Results revealed that distinct MO sorption/PMOL release profiles were obtained according to the sample’s shape and presence/absence of hierarchical roughness. MO sorption capacity of CS samples presented both dependencies of hierarchical surface and geometry parameters. Hence, cubic samples without a hierarchical surface presented the highest (up to 1.2 × greater) dye removal capacity. Moreover, PMOL release measurements were more dependent on the surface area of hydrogels, where semi-spherical samples with hierarchical roughness presented the fastest (~1.13 × faster) drug delivery profiles. This work demonstrates that indirect 3DP (via fused filament fabrication (FFF) technology) could be a simple strategy to obtain hydrogels with distinct sorption/release profiles.

Adsorption characteristics of methyl red dye by Na2CO3-treated jute fibre using multi-criteria decision making approach

This article reports the use of sodium carbonate-treated jute fibre (SCTJF), for the removal of an azo dye methyl red (MR). Face-centred CCD, based on RSM, experimental design has been used to acquire a definite number of experimental paths in order to ascertain improved experimentation towards reaching performance characteristics that are ideal in order to remove the dye (MR) dissolved in aqueous solution. Independent variable parameters used for dye removal and maximum adsorption capacity (Qmax) are: rotational speed (100 RPM, 150 RPM and 200 RPM), temperature (293 K, 303 K and 313 K), pH (3, 7 and 11) and adsorbent (SCTJF) dose (10 mg/L, 14 mg/L and 18 mg/L), where Qmax of the treated jute was considered to be the performance measure for dye removal. ANOVA was used in conjunction with a quadratic model of second order to explore the impact of operating variables and their elucidation. pH = 7.08, temperature = 299.57 K, SCTJF dose = 14.74 g/L, and stirring speed = 155 RPM were found to be the best process conditions. With a desirability of 0.98, the computed experimental Qmax (32.11 mg/g) and anticipated Qmax (31.7 mg/g) were in resonance within the domain threshold, indicating outstanding accuracy of the experimentation operations.

Characterization and dye removal capacity of green hydrothermal synthesized ZnO nanoparticles

In the present study, self-assembled ZnO nanoparticles were synthesized via a hydrothermal method utilizing an aqueous extract of mentha pepperita L (peppermint) leaves. The effect of parameters, including the amount of extract, reaction time, and pH was investigated on the structure and morphology of synthesized nanoparticles. X-ray diffraction (XRD) patterns confirmed the formation of pure well-crystallized ZnO nanoparticles using a zinc nitrate solution (50 mM) and peppermint extract in a volume ratio of 6:1 at pH of 8 and 12. However, the morphology and crystallite size of the particles were different in pH of 8 and 12. Fourier transform infrared (FTIR) spectra confirmed the modification of the ZnO surface with peppermint extract components. Analysis of N2 adsorption and desorption cycles showed the increment of surface area by about 5 times using peppermint extract. Scanning electron microscope (SEM) images revealed the formation of a self-assembled sphere structure using peppermint extract. Mechanism of dissolution-precipitation was proposed for green hydrothermal synthesis of ZnO nanoparticles, based on XRD and SEM results at various reaction times. The synthesized ZnO nanoparticles (reaction time of 24 h and pH of 8) were used to remove methylene blue (MB) dye from an aqueous solution, and adsorption and photocatalytic process were studied. The mass of the dye adsorbed per mass of the adsorbent, qt, grew up by increasing the initial dye concentration. Conversely, the photocatalytic degradation percent decreased. In addition, the final adsorption capacity in 50 mL of 30 ppm dye solution was almost the same in 0.01 and 0.05 g of ZnO, although it was smaller in 0.1 g of ZnO. The maximum degradation efficiency was derived by using 0.05 g ZnO. Self-assembled structure, high capacity of adsorption, and excellent photocatalytic properties were unique characteristics of the synthesized ZnO nanoparticles.

Removal of amaranth dye by modified Ngassa clay: Linear and non-linear equilibrium, kinetics and statistical study

This study aimed at the adsorption of an anionic dye (amaranth) in a batch aqueous medium onto a local clay material collected in Cameroon. The prepared adsorbents were tested towards various adsorption parameters and the characterization was performed using X-ray Fluorescence (XRF), X-ray Diffraction (XRD),Fourier transform Infrared Spectroscopy (FTIR).The surface morphology of clay was revealed using scanning electron microscopy (SEM). The Brunauer–Emmett–Teller(BET) surface area, pore volume and pore diameter of Row-Clay, Na-Clay and Al-Clay were determined. The surface ereas found were 57.50; 65.83 and 67.65 respectivily for Raw-Clay, Na-Clay and Al-Clay. Statistical errors analysis were used to show the best fitting isotherm or kinetic models of the adsorption data. The results revealed that, natural and modified clay materials are made up of various functional groups characteristics of the minerals present on the surface of clay as shown by FTIR, qnd XRD. The equilibrium kinetic was reached at contact time of 5 min, 15 min and 20 min at pH = 3. According to the error analysis, the best isotherms that fit adequately the adsorption data was Sips and Hills isotherms of three parameters, Langmuir and Freundlich two parameters. Therefore, it was concluded that the local clay material has a dye removal capacity and could be exploited by the local people in clothing and textile industry as dye removal agent.

Quick and enhanced separation of Eosin Yellow dye from aqueous solution by FeCl3 interaction: thermodynamic study and treatment cost analysis

ABSTRACT Dyes and their metabolites have noxious and carcinogenicity potential and are known to be hazardous for human beings and other living organisms. The discharge of untreated wastewater comprising wide varieties of synthetic dyes into the water resources is one of the vital environmental problems. Therefore, in this study, the efficacy of the chemical coagulation method was explored using ferric chloride as a coagulant to remove the toxic dye Eosin Yellow (EY) from aqueous solution. The interaction between FeCl3 and EY dye was quick and profound at a solution pH of 2.2, yielding the brownish precipitate with a dye removal efficiency of more than 98%. An extremely high dye removal capacity of 1263 mg/g is reported for 100 mg/L of EY dye concentration at optimum experimental conditions. The possible chemical interaction between FeCl3 and EY dye can be attributed to the formation of polymeric complex, as oxygen atoms of carbonyl, phenolate and carboxylate groups of EY dye molecule interact strongly with Fe3+ ions. The presence of various coexisting anions could reduce the EY dye removal efficiency by 2%–5%; however, the required FeCl3 dose has increased from 64 to 170 mg/L. Thermodynamic studies showed that the interaction of EY dye with FeCl3 was exothermic and spontaneous in nature. The investigation of real industrial wastewater samples has exhibited a 90%–215% increase in the required FeCl3 dose as compared to the control experiment for the initial EY dye concentration from 100 to 750 mg/L. Sludge volume index analysis indicates that FeCl3 generated highly dense sludge with good settling characteristics. X-ray diffraction and field emissionscanning electron microscopy characterisation of the generated sludge indicate the polycrystalline nature with a combination of spherical and irregular shape grains of the sludge. Treatment cost analysis revealed that the cost involved in dye removal is in the range of 0.99–3.60 USD ($)/kg of dye removed.

Controlled synthesis of graphene oxide/silica hybrid nanocomposites for removal of aromatic pollutants in water

The remarkable characteristics of graphene make it a model candidate for boosting the effectiveness of nano-adsorbents with high potential owing to its large surface area, π–π interaction, and accessible functional groups that interact with an adsorbate. However, the stacking of graphene reduces its influence adsorption characteristics and also its practical application. On the other hand, the widespread use of aromatic compounds in the industry has aggravated the contamination of the water environment, and how to effectively remove them has become a research hotspot. Herein, we develop the functionalization of silica nanoparticles on graphene oxide nanosheet (FGS) by a facile, cheap, and efficient synthesis protocol for adsorption of Trypan Blue (TB) and Bisphenol A (BPA). It was demonstrated that chemical activation with KOH at high autoclaving temperature successfully transformed rice husk ash (RHA) into FGS. The graphene oxide layered interlamination was kept open by using SiO2 to expose the interlayers' strong adsorption sites. XRD, EDX, FTIR, Raman spectroscopy, SEM, HR-TEM, and BET surface area are used to investigate the chemical composition, structure, morphology, and textural nature of the as-produced FGS hybrid nanocomposite. The various oxygen-containing functional groups of the hybrid nanocomposites resulted in a significantly increased adsorption capacity, according to experimental findings. In addition, FGS2, the best composite, has a specific surface area of 1768 m2g−1. Based on Langmuir isotherms, the maximal TB dye and BPA removal capacity attained after 30 min were 455 and 500 mg/g, respectively. The Langmuir isotherm model, a pseudo-second-order kinetic model, and an intraparticle diffusion model have all been used to provide mechanistic insights into the adsorption process. This suggests that BPA and TB adsorption on FGS2 is mostly chemically regulated monolayer adsorption. Due to its unique sp2-hybridized single-atom-layer structure, the exposed graphene oxide nanosheets' extremely hydrophobic effect, hydrogen bonding, and strong—electron donor–acceptor interaction contributed to their improved adsorption of BPA and TB. According to adsorption thermodynamics, FGS2 adsorption of TB and BPA is a spontaneous exothermic reaction that is aided by lowering the temperature. For adsorption-based wastewater cleanup, the produced nanocomposites with a regulated amount of carbon and silica in the form of graphene oxide and silica can be used. These findings suggest that functionalized GO/SiO2 hybrid nanocomposites could be a viable sorbent for the efficient and cost-effective removal of aromatic chemicals from wastewater.

Application of calcium alginate-PANI@sawdust wood hydrogel bio-beads for the removal of orange G dye from aqueous solution.

This work aims to investigate the adsorption performance of orange G (OG) dye from aqueous solutions employing PANI@sawdust biocomposite enrobed by calcium-alginate bio-beads (Alg-PANI@SD). The as-prepared adsorbent was characterized by scanning-electron-microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), and Fourier transforms infrared (FT-IR) spectroscopy and used to remove orange G dye from aqueous water. Batch tests were performed as a function of adsorbent dosage, pH, contact time, interfering ions, and initial OG dye concentration. Experimental results show that the kinetic model of pseudo-first-order (PFO) and Freundlich isotherm perfectly fit the entire experimental data. Additionally, the prepared composite exhibited an excellent regeneration capacity and reusability for OG dye removal. The results revealed that the as-prepared Alg-PANI@SDbio-beads have the potential to be applied as a low-cost adsorbent for the adsorption of OG dye from aqueous media.

Activated Bledug Kuwu’s Clay as Adsorbent Potential for Synthetic Dye Adsorption: Kinetic and Thermodynamic Studies

Bledug Kuwu is one of the geological phenomena as a mud volcano that occurs in Kuwu, Purwodadi, Grobogan, Central Java, Indonesia. The evaluation of Bledug Kuwu’s clay as one of the adsorbents for synthetic dyes has been carried out. The preparation of the adsorbent started with washing the clay with distilled water, followed by activation with a solution of hydrochloric acid (1 M) under mechanistic stirring for overnight. The C−H and O−H groups found on the clay adsorbent could attract methylene blue by dispersion forces and hydrogen bonding. Hydrocloric acid activation process for clay can increase surface area from 49 to 70 m2.g−1, meanwhile, reducing the average crystal size from 48.3 to 43.4 nm. The dye removal capacity increased from 34 to 40 mg.g−1 in corresponding to the increase of the temperature from 30 to 50 °C. The results showed that the equilibrium adsorption capacity of activated Bledug Kuwu’s clay reached 99% in an adsorption time of 20 min. The kinetic models of methylene blue adsorption onto BKC and ABKC adsorbents follow the pseudo-second order and the adsorption process is spontaneous with free energy (ΔG) as −23.519 kJ.mol−1. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Evaluation of Original and Enzyme-Modified Fique Fibers as an Azo Dye Biosorbent Material

As natural fibers, low-cost biosorbents have proven to be an effective and clean tool to remove textile dyes from wastewater. In this research, the Reactive Black 5 removal ability of original and enzyme-modified natural fibers were assessed. A fiber extracted from a Colombian fique plant (Furcraea sp.) was employed. The effects of fique fiber protonation with different solvents and dye solution pH on RB5 removal were evaluated. The biosorbent chemical composition was modified using the commercial enzymes pectinase, ligninase, and xylanase. The point of zero charge (PZC) of the original and modified material was measured, and the dye removal capacity of the three enzyme-modified fibers was determined. Fiber protonation with 0.1 M HCl and a dye solution with pH of 2.4 increased the RB5 elimination to 49.1%. The change in the fiber chemical composition led to a reduction in the PZC from 5.5 to a 4.7–4.9 range. Pectinase-pretreated fique fibers presented the highest dye removal of 66.29%, representing a 36% increase in RB5 dye removal. Although the original fique fiber showed RB5 dye removal ability, its enzymatic modification changed the charge distribution on the fiber surface, improving the capture of dye molecules. Enzyme modification can be applied to obtain new functionalities for plant fibers as biosorbent materials.

Nitrogenated Graphene Oxide-Decorated Metal Sulfides for Better Antifouling and Dye Removal.

Nitrogenated graphene oxide-decorated copper sulfide nanocomposites (CuxS-NrGO, where x = 1 and 2) are designed to be incorporated in polysulfone (PSF) membranes for effective fouling resistance of PSF membranes and their dye removal capacity. The developed membranes possess more hydrophilicity and an enhancement in pure water flux (PWF). Also, the highest bovine serum albumin (BSA) rejection of 89% was observed when compared to membranes with pristine PSF (5 L/m2 h PWF and 88% BSA rejection) and CuS-incorporated PSF membranes (14 L/m2 h PWF and 83% BSA rejection) because of N doping and enhanced permeability. It is also found that the CuxS-NrGO-incorporated PSF membranes exhibited a significantly higher fouling resistance, a larger permeate flux recovery ratio (FRR) of nearly 82%, and a congo red dye rejection of 93%. CuxS-NrGO nanoparticles thus demonstrate the potential efficacy of enhancing the hydrophilicity, leading to a better flux, dye removal capacity, and antifouling capacity with a very high FRR value of 82% because of a strong interaction between the N-active sites of the NrGO, CuxS, and polysulfone matrix, and negligible leaching of nanoparticles is observed.

Cellulose Nanofiber-Based Aerogels from Wheat Straw: Influence of Surface Load and Lignin Content on Their Properties and Dye Removal Capacity.

Water pollution is one of the most serious problems worldwide. Nanocellulose-based aerogels usually show excellent adsorption capacities due to their high aspect ratio, specific surface area and surface charge, making them ideal for water purification. In this work, (ligno)cellulose nanofibers (LCNFs/CNFs) from wheat straw residues were obtained using two types of pre-treatments: mechanical (Mec) and TEMPO-mediated oxidization (TO), to obtain different consistency (0.2, 0.4, 0.6 and 0.8) bioaerogels, and their adsorption capacities as dye removers were further studied. The materials were characterized in terms of density, porosity and mechanical properties. An inversely proportional relationship was observed between the consistencies of the aerogels and their achieved densities. Despite the increase in density, all samples showed porosities above 99%. In terms of mechanical properties, the best results were obtained for the 0.8% consistency LCNF and CNF-Mec aerogels, reaching 67.87 kPa and 64.6 kPa for tensile strength and Young’s modulus, respectively. In contrast, the adsorption capacity of the aerogels was better for TEMPO-oxidized aerogels, reaching removal rates of almost 100% for the CNF-TO5 samples. Furthermore, the residual lignin content in LCNF-Mec aerogels showed a great improvement in the removal capacity, reaching rates higher than 80%, further improving the cost efficiency of the samples due to the reduction in chemical treatments.

Multicomponent click polymerization for the synthesis of coumarin containing 1,4-polytriazoles and their application as dye adsorbent

The synthesis of heterocycle-based polymers have remained an important area of research in polymer chemistry. Herein we report a one-pot synthesis of a set of novel coumarin containing regioselective 1,4-polytriazols by multicomponent click polymerization using Cs2CO3 as a base and copper(I) acetate as a catalyst in DMF medium. In this one-pot process, O-alkylation followed by a three-component click reaction between the coumarin-linked dialkyne, sodium azide and alkyl/benzyl dibromides provide novel polymers having coumarin-triazole-linker (C-T-L) units. Ten novel polymers have been synthesized with high molecular weights (Mw = 20,080–46,340 g/mol) and very good yields (83–93%). All the polymers were well characterized by IR, NMR, and GPC. The dye removal capacities of these polymers were evaluated for methylene blue (MB), rhodamine B (RB), methyl orange (MO), and congo red (CR). Polymers P1, P2, and P3 showed very high affinity towards methylene blue dye and among them, P2 showed the highest dye removal efficiency (971 mg/g) for MB. The reusability of P2 was checked and found excellent removal efficiency (RE = 96%) up to the eighth cycle.

Use of Anionic Surfactant-Modified Activated Carbon for Efficient Adsorptive Removal of Crystal Violet Dye

Studies have been carried out to investigate the removal of crystal violet (CV) cationic dye by using rice husk which was used as a raw material to prepare activated carbon (AC) and it was treated with anionic surfactant. In this process, AC was treated with three different anionic surfactants, namely, lauryl sulfate ACMAS, ACSDS, and ACHTAB. Characterization and analysis of optimum ACMAS were done using different techniques which were used which proves the adsorption of the dye by ACMAS. Effects of various physical parameters like time of contact, additive salts, initial dye concentration, effect of pH, and effect of adsorbent dose were studied. Minute changes in the dye removal capacity were observed due to the presence of various cations. Cations like NO2- caused an increase in the capacity of adsorption but cations like Fe2+decreased the capacity of adsorption in the sample solution. The effectiveness of film diffusion and intraparticle has been shown by mass transfer parameters. The various kinetic studies have shown that pseudo second-order kinetic study best suited with the experimental data. Error analysis and studies of isotherms have shown that the adsorption equilibrium was controlled by Langmuir isotherm study with maximum CV dye adsorption capacity of 235.7 mg/g. Thermodynamics studies revealed endothermicity of the process with negative [Formula: see text] values and positive [Formula: see text] and [Formula: see text] values. Activation energy of 48.31 kJ/mol suggested chemisorption process of the system. Column studies were carried out by using different models to study the variation of bed depth, dye concentration, flow rate, etc. Regeneration experiments have given the ability of the adsorbent to be reused. In this present study, it has been noticed that the use of anionic surfactant-treated activated carbon significantly improved the adsorption of dye and this is a process of adsorption in which not much attention has been given for research till date.

In situ formation of tannic (TA)-aminopropyltriethoxysilane (APTES) nanospheres on inner and outer surface of polypropylene membrane toward enhanced dye removal capacity

Tannic acid (TA) − 3-aminopropyltriethoxysilane (APTES) coating (TA-APTES coating) composed of abundant nanospheres with secondary reaction sites has many distinct advantages for surface modification. Herein, an in-situ growth method is proposed to generate TA-APTES nanospheres on both the outer and inner surface of polypropylene (PP) membrane. Compared with previous reported TA-APTES nano spheres coating just on the outer surface of the membrane (named PP-Su-NPs), TA-APTES nano spheres on both outer and inner surfaces prepared with this method (named PP-En-NPs) exhibits much better functional performance after secondary reactions. As a proof of concept, the TA-APTES nanospheres is functionalized by tannic acid, polyethyleneimine (PEI) and Fe3+ to carry positive charges for absorbing anionic dyes, and the dye adsorption performance of the PP-En-NPs after the secondary reactions is 7–8 times higher than that of PP-Su-NPs. Interestingly, the functionalized coating can not only absorb anionic dyes, but also cationic dyes, and selective desorption is also realized for this functionalized coating. The possible mechanism is revealed in this study. This study will accelerate the development of the TA-APTES coating, and make it become a powerful tool for membrane modification.

Chemically modified sugarcane bagasse-based biocomposites for efficient removal of acid red 1 dye: Kinetics, isotherms, thermodynamics, and desorption studies

Novel eco-friendly and economically favourable chemically modified biosorbents and biosomposites from sugarcane bagasse (SB) has been investigated for the first time for efficient removal of Acid red 1 dye from wastewater. As fabricated biosorbents and biocomposites were characterized analytically. Batch adsorption experiments has been performed to optimize operating parameters and the determined optimum conditions are; pH: 2, dose: 0.05 g, contact time: between 60 and 75 min, initial dye concentration: 400 mg L−1, and temperature: 30 °C, at which maximum Acid red 1 dye removal capacities were found (within range of 143.4–205.1 mg g−1) by as-designed SB-derived chemically modified biosorbents and biocomposites. This high adsorption capacity was accompanied due to its large specific surface area (30.19 m2 g−1) and excessive functional active binding sites. In terms of the nature of adsorption process, kinetic and isothermal studies demonstrated that experimental data shows greater fitness with pseudo 2nd order and Langmuir model. Thermodynamics analysis revealed that the adsorption process is spontaneous, feasible, and exothermic in nature. Adsorption selective studies signifies that lower concentration of co-existing metallic ions were not interfered during the removal of Acid red 1 dye, which confirms that under optimized adsorption conditions the biosorbents and biocomposites exhibited greater affinity for dye molecules. The excessive quantity (82%) of loaded dye molecules within the adsorbents were extracted within the NaOH eluting media which predicts that as designed biocomposites could have capability of reusability. Hence, it is anticipated that this type of novel SB-derived biocomposites could be considered as greener potential candidate material for commercial scale dye removal applications from industrial wastewater.

Carbon nanotubes-reinforced preparation of flat MoS2 nanomaterials: Co-enhancement of acoustic exfoliation efficiency and dye removal capacity

A novel and effective preparation technology was developed to prepare ultrathin molybdenum disulfide (MoS2) crystals with a high yield of the top-down exfoliation. Multidimensional carbon nanotubes (MWCNTs) were selected to be an assistant to enhance the effect of the traditional ultrasonic exfoliation efficiency. The rough and messy tubes strengthened the shear force in some parts during the acoustic treatment, which helped to weaken the van der Waals force between the MoS2 layers. Excitingly, this high-efficiency strategy can increase the dispersion concentration of nanosheets by 15 times compared to the traditional acoustic production, which represented the preparation yield was improved greatly. It is found that the addition of MWCNTs not only facilitated the exfoliation efficiency of bulk material but also indirectly improved the adsorption of malachite green (MG) in wastewater. With a maximum removal capacity of 87.80 mg g−1, the adsorption ability of the nanotubes-reinforced layered adsorbent was effectively strengthened. In addition, the performance of reproducibility, stability, functioning free radical types, and the adsorption models were systematically studied.