Adsorption Of MB Research Articles

Modelling studies of methylene blue dye removal using activated corn husk waste: Isotherm, kinetic and thermodynamic evaluation

Corn husk waste (CHW) was evaluated as an alternative simple treatment strategy to remove methylene blue dyes (MB). Various experimental factors, such as pH, concentration, contact time, and temperature, were studied during the adsorption process. Optimum conditions were obtained at pH 6, initial concentration of 800 mgL−1, contact time of 60 min, and temperature 298 K with an adsorption capacity of 41.06 mgg−1. The kinetics study was analyzed using pseudo-first-order, pseudo-second-order, intra-particle diffusion, and Elovich models. Moreover, the pseudo-second-order process model can characterize the MB chemisorption kinetics. The experimental results were fitted to the Langmuir isotherm model. The obtained thermodynamic parameters (ΔHo,ΔSo,ΔGo) revealed that MB adsorption was spontaneous and exothermic. The optimum conditions for removing MB on laboratory wastewater was 99.79 %, while for MB on batik industry water was 51.40 %. CHW had an excellent capability to be used for 4 times cycle.

Activation temperature dependence of Adonidia merrillii palm seed porous activated carbons textural properties. Adsorption of methylene blue in batch systems

From a char of Palm seed (CSP), activated carbon at 973, 1073, and 1173 K was obtained (CASPs). These temperatures developed textural properties to favor the adsorptive properties. The CASPs percentage of burning decreased with the increase of the activation temperature from 76 to 26%. These products were obtained with a CO2 flow (as activating gas) and a short time of activation. The CASPs were characterized by mercury porosimetry, adsorption of N2, CO2, and methylene blue at 77, 273, and 298 K, respectively. Wide supermicropores were obtained for CASP1173 and narrow mesoporosity was achieved for CASP973 and CASP11073 (1.4–2.0 nm and 2.0–5.0 nm, respectively). Mercury porosimetry determined that the activated carbons have mesopores with diameters smaller than 50 nm and macropores with diameters greater than 50 nm. The use of Dubinin and Langmuir models showed that the adsorption occurred in the larger diameter micropores and smaller diameter mesopores of the highest and shortest diameters (above 3.85 mmol/g). The activated carbon at 973 K showed a higher methylene blue adsorption capacity (181.03 mg/g). The MB adsorption was determined by the diameters of the adsorbent pores. For this reason, a batch adsorption system to remove this contaminant was proposed.

Optimization removal of methylene blue from aqueous solution by adsorption on Fe3O4@PVA/GT magnetic nanocomposite by Taguchi method

In this project, Fe3O4@PVA/GT magnetic nanoparticles were synthesized; then, its property was investigated in the adsorption of methylene blue from wastewater samples. Polyvinyl alcohol and Tragacanth gum are used as other components to improve the adsorption rate. Conditions such as the amount of adsorbent, the amount of MB, the pH of the environment, and the ambient temperature investigated the percentage of MB removal, and the Taguchi method was used to find the optimal results. XRD, FTIR, DLS, SEM, and VSM were used for sample analysis. The XRD pattern of Fe3O4@PVA/TG nanocomposite shows characteristic peaks related to the cubic phase of Fe3O4 while other phases are amorphous. The value of VSM for nanocomposite was 33.14(emu/g). The BET method shows that the values of SSA, total pore volume, and pore diameter are 25.58 m2g−1, 0.086 cm3g−1, and 13.55 nm respectively. The optimum conditions that achieved higher adsorption of MB are Fe3O4@PVA/TG (%w/v): 0.4, pH = 9, temperature (°C): 35, and MB concentration: 10 ppm which had 93 % adsorption after 4 h. It was revealed that this nanocomposite had high adsorption performance on MB, with a removal rate of over 93 %.

Biosynthesis of green CuO@C nanocomposite using Combretum indicum flower extract for organic dye removal: adsorption performance, modeling, and recyclability studies.

Water contamination becomes one of the most high-priority environmental concerns, calling for the efficient treatment techniques. Bionanocomposites can be robust adsorbents, but the synthesis requires toxic chemicals or energy consuming and cause the secondary pollution. Green nanocomposites can be biogenically synthesized using the plant extract to end up with a critically safe strategy. Herein, we used the flower extract of Combretum indicum plant as a bio-based reductant and carbonaceous source for the green CuO@C nanocomposite. This green nanoadsorbent obtained a specific surface area of 17.33 m2/g, good crystallinity, and functional group-containing surface, i.e., -OH and -CONH-. We also conducted the optimization of parameters, i.e., concentration, CuO@C dose, pH, time, and temperature, and reached removal efficiencies towards malachite green (MG, 83.23%), Congo red (CR, 84.60%), brilliant blue (BB, 71.39%), and methylene blue (MB, 23.67%). The maximum adsorption capacities were found as ordered, MG (46.387 mg/g) > MB (23.154 mg/g) > BB (22.8 mg/g) > CR dye (11.063 mg/g). Through the intra-particle diffusion kinetic model, MG and BB adsorption endured a three-step process, while CR and MB adsorption was a two-step process. The recyclability of the green CuO@C nanocomposite was three cycles with 67.54% for the final cycle of BB removal. Moreover, the nanoadsorbent displayed a high stability, checked by X-ray diffraction, FT-IR analysis, EDX spectra, and SEM images. It is recommended that the green CuO@C nanocomposite biosynthesized using the Combretum indicum flower extract can be a good alternative for the dye treatment from wastewater.

Zn-modified biochar preparation from solvent free in-situ pyrolysis and its removal of methylene blue

In this study, Zn-modified biochar obtained through of Jerusalem artichokes straw with zinc carbonate was used to explore its effect on the adsorption of methylene blue. The physical and chemical properties of Zn-modified biochar were investigated using a variety of characterization, including SEM, BET, FT-IR, Raman, XRD, and XPS. Compared with the original biochar, the specific surface area (1037.17 m2·g−1) of Zn-modified biochar pyrolysis at 800 °C (Zn-BC 800) increased approximately 22 times. The adsorption of methylene blue with Zn-BC 800 could be more accurately illustrated by the pseudo-second-order kinetic model. The fitting results of adsorption isotherms showed that the Langmuir model could better suit the adsorption process at three different temperatures. At 318 K, Zn-BC 800 had a maximum adsorption capacity for methylene blue of 477.13 mg·g−1. According to the thermodynamic analysis, the process was a spontaneous endothermic reaction, and increasing the reaction temperature was beneficial to the reaction. Hydrogen bond and π-π interaction were the main mechanism of adsorption of MB by Zn-BC 800, which was determined by FTIR and XPS analysis. Zn-BC 800 still had a high adsorption effect on methylene blue after 5 cycles, indicating that the composite was a highly efficient cationic dye adsorbent, which could effectively remove dyes from wastewater.

Green preparation of magnetic ferroferric oxide-polyvinyl alcohol-alginate coated UiO-67 nanospheres: Characterization, adsorption properties and adsorption mechanism of methylene blue

In this paper, a kind of magnetic ferric oxide/polyvinyl alcohol/calcium alginate/UiO-67 (Fe3O4/PVA/CA/UiO-67) nanospheres with homogeneous surface interconnecting structures was prepared by using macromolecular polymer polyvinyl alcohol and sodium alginate as carriers and zirconium organic skeleton as nanocrystals. The properties of magnetic nanospheres were studied by SEM, FT-IR, TGA, XRD, BET, VSM and Zeta potential. The impression of diverse temperatures, MB concentrations, interaction time, pH, and magnetic aerogel sphere dose on MB removal was studied. The optimum adsorption temperature and pH of magnetic nanospheres for MB were 298 K, and 10, respectively. Langmuir simulated that the maximum removal of MB by magnetic nanospheres at room temperature (298 K) was 1371.8 mg/g. The removal of MB by magnetic nanospheres complied with the pseudo-first-order kinetic model. The isotherm simulation can infer that the Langmuir model was more comply with MB adsorption on magnetic aerogel spheres. Thermodynamic studies have confirmed that the removal of MB by magnetic nanospheres was exothermic and spontaneous. The interaction mechanism of MB on magnetic nanospheres can be deduced by FT-IR and BET, including hydrogen bond, π-π bond, electrostatic interaction, and mesoporous pore flow. The removal rate of nanospheres for MB still reached 70.06 % after six cycles.

Biosorption of Methylene Blue dye by Ligustrum lucidum fruits biomass: Equilibrium, isotherm, kinetic and thermodynamic studies

<p>.In this work, biomass from Ligustrum lucidum fruits (LF) was used for the first time as a novel adsorbent to remove the Methylene Blue dye (MB) from aqueous solutions. The adsorption equilibrium was attained after 60 min, and the adsorption followed the pseudo-second-order kinetic model. The rise of temperature from 295 K to 313 K resulted in a decline in the adsorption capacity, suggesting an exothermic process. The Langmuir isotherm model was found to fit better the experimental adsorption data than the Freundlich isotherm model. The maximum monolayer adsorption capacity obtained from the Langmuir isotherm model at pH 5.6 was evaluated to be 95.4 mg/g and 91.8 mg/g at 295 K and 313 K, respectively. The thermodynamic studies indicated that the adsorption was a spontaneous and exothermic process with increasing randomness at the solid/solution interface. Based on FTIR and ionic strength studies, the adsorption of MB by LF mainly occurs via electrostatic interactions and the formation of outer-sphere complexes.</p>

Preparation of chitosan-based ternary nanocomposite hydrogel film by loading graphene oxide nanosheets as adsorbent for enhanced methylene blue dye removal

Our objective in this study is to fabricate a novel chitosan-based ternary nanocomposite hydrogel film by incorporating graphene oxide (GO) nanosheets into a chitosan/partially hydrolyzed polyacrylamide (PHPA) network to boost adsorption efficiency through one step self-assembly process in water. Basically, H-bonding interactions drive the formation of a crosslinking network structure. The Batch adsorption experiments evaluated the hydrogel nanocomposite's MB adsorption performance. By loading GO, surface roughness, swelling percentage (from 21,200 % to 35,800 %), elastic modulus of up to 73.7 Pa, and adsorption characteristics (from 282 mg/g to 468 mg/g) were enhanced. The nanocomposite displayed outstanding thermally/pH responsiveness properties. MB adsorption equilibrium was reached after 45 min and the adsorption capacity was 476.19 mg.g−1 when the initial concentration was 100 mg/L. The MB adsorption kinetics and isotherms by the nanocomposite were well correlated by the PSO and the Langmuir models (R2 > 0.99), respectively. The loaded nanocomposite was shown to be regenerative for five cycles through desorption studies. Thermodynamic analysis indicated that MB adsorption occurred spontaneously (ΔG°: −16.47 kJ/mol, 303 K) and exothermically (ΔH°: −79.49 kJ/mol). A plausible adsorption mechanism was proposed for the nanocomposite developed for MB removal. Our results can contribute to the design and fabrication of nanocomposite adsorbents to treat wastewater.

Preparation of Biomass Biochar with Components of Similar Proportions and Its Methylene Blue Adsorption.

Rapeseed straw, bagasse, and walnut peel have a large amount of resource reserves, but there are few technologies for high value-added utilization. In the research of biochar, walnut green husk is rarely used as raw material. In addition, the three main components of biomass (lignin, cellulose, and hemicellulose) are present in similar proportions, and the differences between the physical and chemical properties of biochar prepared with similar amounts of biomass raw materials are not clear. Using three kinds of biomass of the same quality as raw materials, biochar was prepared via pyrolysis at 400 °C, and activated carbon was prepared via CO2 activation at 800 °C. The results showed that the pore numbers of the three kinds of biochar increased after activation, resulting in the increase of the specific surface area. The resulting numbers were 352.99 m2/g for sugarcane bagasse biochar (SBB)-CO2, 215.04 m2/g for rapeseed straw biochar (RSB)-CO2, and 15.53 m2/g for walnut green husk biochar (WGB)-CO2. Ash increased the amount of carbon formation, but a large amount of ash caused biochar to form a perforated structure and decreased the specific surface area (e.g., WGB), which affected adsorption ability. When the three main components were present in similar proportions, a high content of cellulose and lignin was beneficial to the preparation of biochar. The adsorption value of MB by biochar decreased with the increase of biomass ash content. After activation, the maximum adsorption value of MB for bagasse biochar was 178.17 mg/g, rapeseed straw biochar was 119.25 mg/g, and walnut peel biochar was 85.92 mg/g when the concentration of methene blue solution was 300 mg/L and the biochar input was 0.1 g/100 mL at room temperature. The adsorption of MB by biochar in solution occurs simultaneously with physical adsorption and chemical adsorption, with chemical adsorption being dominant. The optimal MB adsorption by SBB-CO2 was dominated by multimolecular-layer adsorption. This experiment provides a theoretical basis for the preparation of biochar and research on its applications in the future.

Double network cross-linked hydrogel coating membrane with photocatalytic self-cleaning performance for efficient oil-water separation

Oil-water separation is one of the most attractive areas in the field of energy and the environment. However, the synthesis of oil-water separation membranes with high separation efficiency and anti-fouling via simple methods is still a challenge. In this work, a double network with tannic acid and g-C3N4 cross-linked gelatin hydrogel coating membrane was prepared via ultrasound and coating. The prepared hydrogel had excellent mechanical properties and swelling resistance and also endowed the membrane with underwater superoleophobicity. For stratified oil-water mixtures, the separation flux achieved 40,355 ± 1957 L·m−2·h−1 and separation efficiency higher than 99 %. Moreover, after 40 cycles, there was no decrease significantly in separation performance. For oil-in-water emulsions, the separation efficiency is >99.90 % under gravity. The adsorption of MB by the GE-CNTA-PP membrane conformed to a pseudo-first-order kinetic process (R2 = 0.99906), which was consistent with the Langmuir isothermal adsorption model (R2 = 0.99932). The contaminated membrane could self-clean via photocatalytic reaction, which mechanism was explained through theoretical investigation of the band structure of g-C3N4 by DFT. Due to these obvious advantages, the practical application of the gelatin-based hydrogel membrane in the purification of oily wastewater is promising.

Rapid and facile synthesis of micro-mesoporous ZIF-8 materials with enhanced adsorption of methylene blue

Zeolitic imidazolate frameworks (ZIFs) have been widely applied in many research fields, such as catalysts and adsorption. To meet the needs of scale applications, the development of simple, rapid and high-yield synthesis is a great necessity. In this work, a novel and facile strategy for the rapid synthesis of micro-mesoporous ZIF-8-H at room temperature within a very short time of 16 min using inexpensive quaternary ammonium base (tetramethylammonium hydroxide pentahydrate, TMAH) as a template was proposed. Results showed that in addition to significantly shortening crystallization time, the TMAH template also induced abundant mesopores for ZIF-8-H, which can improve the adsorption rate and fully use the adsorption active sites. More importantly, the ZIF-8-H yield of the proposed strategy is 3.6 times more than that of the conventional method, which is conducive to the realization of large-scale production. Among ZIF-8-H-x-t, ZIF-8-H-0.8-16 prepared with TMAH/Zn2+ molar ratio x of 0.8 and reaction time t of 16 min exhibited the highest MB removal effectiveness of 96.3 ± 0.8%, a remarkable increase of 127% compared to ZIF-8-M prepared by conventional method (42.5 ± 0.9%). Additionally, the MB adsorption onto ZIF-8-M and ZIF-8-H-0.8-16 fitted well with the pseudo-first-order kinetics model and Langmuir isothermal model, suggesting the monolayer adsorption behavior is dominant. The ZIF-8-H-0.8-16 showed a maximum adsorption capacity of 47.90 mg/g, which is higher than that of ZIF-8-M.

Hydrochar derived from Liquorice root pulp utilizing catalytic/non-catalytic hydrothermal carbonization: RSM optimization and cationic dye adsorption assessment

The present study targeted producing hydrochar from Liquorice root pulp employing the catalytic/non-catalytic hydrothermal carbonization (HTC) method and evaluating its performance in methylene blue adsorption from an aqueous solution. The response surface methodology (RSM) was utilized to assess the impact of operational variables such as temperature, time, and water/ solid ratio on the yield of hydrochar production and MB adsorption capacity. The maximum yield of hydrochar production and dye adsorption capacity was achieved at 168 °C, 2.016 h, and a water/solid ratio of 9.215. The assessment of the catalytic HTC process at different concentrations of ZnCl2 demonstrated the 0.25 M solution had the most positive effect on MB adsorption capacity. The physicochemical characteristics of hydrochars were evaluated utilizing techniques such as CHN, FTIR, BET, XRD, TGA, and SEM. Also, the peak fitting method presented a semi-quantitative assessment of the impact of the catalytic/ non-catalytic HTC process on the oxygenated functional groups of hydrochars. The methylene blue adsorption process was evaluated by conducting the experiments at different values of effective parameters such as pH, contact time, initial dye concentration, and dose of adsorbent as temperature. Furthermore, the kinetic and isotherm models were studied to describe the dominant mechanisms in the MB adsorption process. The maximum MB adsorption capacity was achieved at 290.65 and 314.62 mg/g for hydrochar and modified hydrochar at pH of 9, initial dye concentration of 400 mg/L, 45 min of contact time, 1 g/L of adsorbent dose, and temperature of 25 °C. Finally, studying the thermodynamic parameters of the adsorption process demonstrated MB adsorption's spontaneity and exothermic nature.

Adsorption of MB and Pb(II) before and after magnetic modification: Performance and mechanism

This study described the simple fabrication process of manganese dioxide decorated composites(Mn@RS) and magnetic-functional modified composites (MC-Mn@RS) that can effectively adsorb MB and Pb(II) in the aqueous medium. The structural and physicochemical characteristics of the as-prepared composites were evaluated by BET, XRD, SEM, FTIR, XPS, point of zero charge (pHPZC), TGA and VSM techniques. The effect of the contact time, pH value, and initial concentration on the adsorption capacity of MB and Pb(II) onto Mn@RS and MC-Mn@RS were investigated by using batch equilibrium experiments. The results exhibited that in single system, the adsorption capacity of Mn@RS against MB and Pb(II) were obtained 128.5 mg g−1 and 196.04 mg g−1, respectively. The adsorption capacity of MC-Mn@RS against MB and Pb(II) were obtained 325.8 mg g−1 and 98.07 mg g−1, respectively. Till now, the mutual effects and competitive adsorption of MB and Pb(II) onto biochars have never been reported. In the binary systems, the Pb (II) adsorption on Mn@RS was severely inhibited, while the uptake of MB was not affected significantly, clearly demonstrating the adsorption affinity was in the order of MB > Pb(II) in the coexisting solution. The electrostatic attraction, complexation, surface precipitation and physical adsorption were the main adsorption mechanism of Pb (II) on Mn@RS and MC-Mn@RS. The adsorption mechanism of MB on Mn@RS mainly contained electrostatic attraction, π-π interaction, n–π interaction and electrostatic attraction, while that on MC-Mn@RS mainly were determined by pore filling and n–π interactions. In addition, the MC-Mn@RS exhibited excellent reusability (retained 90.76% removal efficiency after five cycles) and solid–liquid separation efficiency due to strong magnetism(24.78 emu g−1). The gained results were powerful proof for removing MB and Pb(II) from wastewater, economically and effectively, and for paving the way to the preservation of cleaner fresh water resources and a greener society.

The production of activated carbon from Acacia erioloba seedpods via phosphoric acid activation method for the removal of methylene blue from water

Wastewater treatment requires a lot of granular activated carbon to absorb the dissolved organic components. This article describes a low-cost process for making highly active adsorption activated carbons from biomass, which could be used for wastewater treatment. A one-step carbonization and chemical activation with phosphoric acid at 500 °C produced low-cost acacia-derived porous activated carbons. The activated carbons' moisture, ash, volatile matter, and fixed carbon content were determined using proximate analysis. The activated carbon's adsorption qualities were also determined by studying its bulk density, surface morphology, power of hydrogen, iodine number, and methylene blue number index. To test the produced activated carbons for water treatment, batch adsorption dynamics were performed at room temperature for the removal of methylene blue from aqueous solution. Compared to activation using H2SO4, H3PO4 proves superior in generating well-developed pores, leading to a mesoporosity and microporosity structure with a larger surface area and high adsorption capacity. Brunauer–Emmett–Teller determined the sample's specific surface area, which was found to be 387 m2/g. The iodine number for 50, 100, and 200 μm activated carbon particles size was 620, 592, and 632 mg/g, respectively. The adsorption of MB on AC material better fits with Langmuir's adsorption isotherm; hence, particles are adsorbed on well-pronounced heterogeneous surfaces. The sips model is found to best represent the equilibrium data with R2 values of 0.994, suggesting the heterogeneous surface adsorption of MB on AC. Therefore, the adsorption of AC by MB involves physical and chemical processes. The produced AC hence appears to remove dissolved organic contaminants from raw water.

Sustainable remediation of dye-contaminated wastewater using novel cross-linked Hex-CCP-co-PPT microspheres

The presence of dyes in contaminated water poses substantial dangers to the health of both humans and aquatic life. A process called precipitation polymerization was used to create unique cross-linked hexa-chlorocyclotriphosphazene-co-phenolphthalein (Hex-CCP-co-PPT) microspheres for the purpose of this research. Advanced methods such as X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermogravimetry (DTG) were used to characterise these microspheres. In a simulated solution, the performance of Hex-CCP-co-PPTs as a sorbent for removing MB dye was investigated, and the results showed an unprecedentedly high removal rate of 88.4% for MB. Temperature of 25 °C, a Hex-CCP-co-PPTs dose of 40 mg, an MB concentration of 20 ppm, an MB solution volume of 20 mL, a contact time of 40 min, and a pH of 9 were found to be the optimal experimental conditions. According to the results of the kinetic and adsorption analyses, the PSO and Langmuir adsorption models are the best ones to use. These models favour the chemi-sorption nature and mono-layered adsorption of MB in comparison to Hex-CCP-co-PPTs. Importantly, the thermodynamic analysis demonstrated that the process of removing MB by utilizing Hex-CCP-co-PPTs was endothermic and occurred spontaneously. These findings highlight the potential application of Hex-CCP-co-PPT microspheres in Algal Membrane Bioreactors (AMBRs) for the efficient and sustainable removal of dye from wastewater. This would contribute to the protection of ecosystems as well as the public's health.

Novel nanofiltration membrane modified by metal oxide nanocomposite for dyes removal from wastewater

This study focuses on the development of a nanocomposite membrane using polyvinyl chloride and nanocellulose@titanium aluminate to effectively filter and adsorb dye from wastewater. Various analytical techniques were used such as FTIR, XRD, SEM, and TGA to characterize the synthesized adsorptive nanocomposite membrane. The thermal and electrical properties of the membrane were measured using a static system. The study investigated the effect of different adsorbent dosages, pH levels, and dye concentrations on the membrane’s adsorption ability. The PVC-NC@TALCM nanocomposite membrane was found to remove 98.6% of MB dye when loaded with 5% titanium aluminate at pH 10. Kinetic and isotherm studies revealed that the adsorption of MB onto the membrane followed pseudo-second-order kinetics and Freundlich isotherms, respectively. The researchers also highlighted the economic and eco-friendly nature of the PVC-NC@TALCM nanocomposite membrane as a viable option for the removal of MB from industrial wastewater.

Removing of cationic dyes using self-cleaning membranes-based PVC/nano-cellulose combined with titanium aluminate

This research used the phase inversion approach to construct polyvinyl chloride nanocellulose@titanium aluminate nanocomposite membranes (PVC/NC@TALCM) to adsorb and filter dye from wastewater. FTIR, XRD, and SEM were used to determine the adsorptive nanocomposite membrane that had been synthesized. The thermal and electrical properties measurements were carried out using a static system. The influence of several adsorbent dosages, pH, and dye concentrations on the nanocomposite membrane’s adsorption ability was investigated. Using a dead-end filtration system, the PVC-NC@TALCM was evaluated as a pressure filtration membrane system. It was found that 98.6% of MB dye was removed by PVC-NC@TALCM membrane, which was loaded with 5% titanium aluminate at pH 10. The kinetic adsorption studies indicated that the adsorption of MB onto the PVC-NC@TALCM nanocomposite membrane obeys pseudo-second-order that indicates the chemosorption process. The isotherm data were described using Freundlich and Langmuir models, and the Freundlich isotherms were shown to be more closely match the experimental data than the Langmuir model. Finally, the PVC-NC@TALCM nanocomposite membrane was economical, environmentally friendly, and self-cleaning.

A novel effective bio-originated methylene blue adsorbent: the porous biosilica from three marine diatom strains of Nanofrustulum spp. (Bacillariophyta)

In the present paper, for the first time the ability of the porous biosilica originated from three marine diatom strains of ‘Nanofrustulum spp.’ viz. N. wachnickianum (SZCZCH193), N. shiloi (SZCZM1342), N. cf. shiloi (SZCZP1809), to eliminate MB from aqueous solutions was investigated. The highest biomass was achieved under silicate enrichment for N. wachnickianum and N. shiloi (0.98 g L−1 DW and 0.93 g L−1 DW respectively), and under 15 °C for N. cf. shiloi (2.2 g L−1 DW). The siliceous skeletons of the strains were purified with hydrogen peroxide and characterized by SEM, EDS, the N2 adsorption/desorption, XRD, TGA, and ATR-FTIR. The porous biosilica (20 mg DW) obtained from the strains i.e. SZCZCH193, SZCZM1342, SZCZP1809, showed efficiency in 77.6%, 96.8%, and 98.1% of 14 mg L−1 MB removal under pH 7 for 180 min, and the maximum adsorption capacity was calculated as 8.39, 19.02, and 15.17 mg g−1, respectively. Additionally, it was possible to increase the MB removal efficiency in alkaline (pH = 11) conditions up to 99.08% for SZCZP1809 after 120 min. Modelling revealed that the adsorption of MB follows Pseudo-first order, Bangham’s pore diffusion and Sips isotherm models.

Polydopamine-modification of a magnetic composite constructed from citric acid-cross-linked cyclodextrin and graphene oxide for dye removal from waters.

The effect of polydopamine (PDA) modification on aminated Fe3O4 nanoparticles (Fe3O4-NH2)/graphite oxide (GO)/β-cyclodextrin polymer cross-linked by citric acid (CDP-CA) composites were studied for the removal of a cationic dye (methylene blue, MB) and an anionic dye (Congo red, CR) from waters. The micro-structural and magnetic characterizations confirmed the successful preparation of Fe3O4-NH2/GO/CDP-CA and PDA/Fe3O4-NH2/GO/CDP-CA composites. The maximum MB and CR adsorption capacities of Fe3O4-NH2/GO/CDP-CA were 75mg/g and 104mg/g, respectively, while the corresponding amounts for PDA/Fe3O4-NH2/GO/CDP-CA composite were 195mg/g and 64mg/g, respectively. The dye sorption behaviors of these two composites were explained by their corresponding surface-charged properties according to the measured zeta potential results. Moreover, the high saturation magnetizations and the stable dye removal rate in the adsorption-desorption cycles indicated the good recyclability and reusability of the fabricated composites.

Synthesis of Amino-Engineered Graphene Oxidize Nanocomposite (GO/SBA-15) for Potential Copper Ions and Dye Removal from Aqueous Solution

Air, water, and soil pollution are worldwide problems. Of these, heavy metals and organic dyes are the main targets for removal. Graphene oxide (GO), especially functionalized GO, has shown great application potential for the removal of contaminants from wastewater. This study used Santa Barbara Amorphous-15 (SBA-15) with amino acid to functionalize GO, not only to increase the adsorption sites, but also chelate with heavy metals to improve the adsorption efficiency. The optimal experimental conditions for Cu2+ adsorption were obtained by response surface methodology (RSM): pH=5.8, C0=38.38 mg/L, M=0.56 g/L, and T=35.68°C. The optimum experimental conditions for MB adsorption were pH=10.24, C0=82.70 mg/L, M=0.33 g/L, and T=35.27°C, and absorption rates all above 70%. Also, the adsorption mechanism, desorption, and reusability of the complexes are reviewed. Finally, the application potential of GO/SBA-15 as an adsorbent in the field of industrial wastewater treatment is summarized and its prospects are discussed.