Adsorbent For Wastewater Treatment Research Articles

Adsorption and Desorption Study of Reusable Magnetic Iron Oxide Nanoparticles Modified with Justicia adhatoda Leaf Extract for the Removal of Textile Dye and Antibiotic.

The release of tetracycline hydrochloride (TCH) and methylene blue (MB) dye into the aquatic system uncontrollably caused major environmental and health problems; hence, their prevention required serious attention. Adsorption process is now being researched in order to increase adsorption efficiency and reprocess to alleviate environmental issues. The use of magnetic nanoparticle as an adsorbent for wastewater treatment has a lot of prospective. A magnetic iron oxide nanoparticle surface modified by Vasaka (Justicia adhatoda) leaf extract (JA-MIONs) is used to give a fast removal approach for MB dye and TCH antibiotics. Dynamic light scattering, UV–Vis and band gap measurement, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy were operated to analyse the formation and size of these magnetic nanoparticles. The impacts of different factors such as contact time (30–150 min), adsorbate concentration (10–50 mg/L), pH (4–10), and adsorbent dose (2–10 mg) were explored. Adsorption kinetics and isotherms show that it follows the pseudo-first-order kinetic and the Freundlich isotherm, with maximum adsorption capacities of 76.92 mg/g for MB and 200 mg/g for TCH at 298 K. The reusability of the JA-MIONs eventually exhibited a decline in the adsorption percentage of MB and TCH after five and four times respectively. After the desorption-adsorption cycles, this adsorbent continued to exhibit significant adsorption capacity. This investigation furnished the significant reference data for the synthesis of JA-MIONs as a novel and auspicious adsorbent for the industrial clean-up of toxic dyes and heavily used antibiotics from water.

Biochar Derived from Palm Waste Supported Greenly Synthesized MnO2 Nanoparticles as a Novel Adsorbent for Wastewater Treatment

Water pollution with dye effluents from different industries is a broadly established environmental and health problem that needs serious attention. In this study, making use of Acacia nilotica seed extract, greenly synthesized MnO2 nanoparticles were loaded on the surface of biochar derived from palm waste (MnO2/PF), with specific surface areas of 70.97 m2/g. Batch experiments were adopted, aiming to evaluate the performance of palm fronds, biochar, and the MnO2/PF adsorbents in methyl orange (MO) removal from an aqueous solution. The feedstock and synthesized biochars were comprehensively characterized using XRD, SEM-EDX, FTIR, and BET surface area techniques. Moreover, the influences of the modification of palm fronds, initial dye concentrations, pH, and adsorbent dosage on MO uptake were examined. The results demonstrated that MnO2/PF biochar nanocomposite led to an increase in the removal efficiency by 6 and 1.5 times more than those of palm fronds and biochar, respectively. In addition, it was found that the second-order kinetic model presented the kinetic adsorption very well. This paper demonstrates that the depositing of greenly synthesized MnO2 nanoparticles on the date palm waste biochar forms a novel adsorbent (MnO2/PF) for the removal of MO from aqueous solutions. Furthermore, this adsorbent was easy to synthesize under moderate conditions without the need for chemical capping agents, and would thus be cost-effective and eco-friendly.

Simultaneous removal of As(V) and Pb(II) using highly-efficient modified dehydrated biochar made from banana peel via hydrothermal synthesis

Efficient removal of arsenic (As) and lead (Pb) from industrial wastewater has long been a critical environmental issue due to their serious risk to human health. Therefore, in this work, a modified banana peel biochar (MBPB) was prepared by mixing calcium nitrate, diammonium hydrogen phosphate, sulfuric acid, ferric nitrate with dehydrated banana peel biochar as adsorbent for As(V) and Pb(II) removal in wastewater, and their absorption mechanism was investigated. SEM-EDS, TEM, FTIR, XRD, XPS, BET, kinetic, and isothermal characteristics of MBPB and pristine banana peel biochar (PBPB) were conducted. The behavior of both metal ions on MBPB and PBPB was well explained by the pseudo-second-order kinetic with Langmuir and Freundlich models. We found that the two biochar’s behaviors were mixture processes of monolayer and multilayer adsorption, achieving maximum capacities as determined by the Langmuir model of 39.5 mg g−1 (MBPB-As), 33.2 mg g−1 (MBPB-Pb), 30.8 mg g−1 (PBPB-Pb), and 23.5 mg g−1 (PBPB-As), with maximum efficiencies of 98.7% (MBPB-As) and 90.3% (MBPB-Pb) under optimum conditions. Thermodynamic tests showed that As(V) and Pb(II) removal on MBPB was a spontaneous and endothermic physisorption process. MBPB showed great reusability in As(V) and Pb(II) removal, with removal rates as high as 71.4% and 66.5% after five cycles, respectively. Selective adsorption of As(V) and Pb(II) was also investigated on MBPB, and the removal rate was still high in the mixture of heavy metals. These findings provide a feasible method for the environmental-benign utilization of banana peel as a low-priced adsorbent in wastewater treatment.

Facile fabrication of a broad-spectrum starch/poly(α-l-lysine) hydrogel adsorbent with thermal/pH-sensitive IPN structure through simultaneous dual-click strategy

A thermal/pH-sensitive interpenetrating network (IPN) hydrogel was prepared facilely from starch and poly(α-l-lysine) through amino-anhydride and azide-alkyne double-click reactions in one pot. The synthesized polymers and hydrogels were systematically characterized using different analytical techniques such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and rheometer. The preparation conditions of the IPN hydrogel were optimized via one-factor experiments. Experimental results indicated the IPN hydrogel possessed pH and temperature sensitivity. Effect of different parameters (pH, contact time, adsorbent dosage, initial concentration, ionic strength, and temperature) on adsorption behavior were investigated in monocomponent system with cationic methylene blue (MB) and anionic Eosin Y (EY) as model pollutants. The results indicated that the adsorption process of the IPN hydrogel for MB and EY followed pseudo-second-order kinetics. The adsorption data for MB and EY fitted well with the Langmuir isotherm model, indicating monolayer chemisorption. The good adsorption performance was due to various active functional groups (–COOH, –OH, –NH2, etc.) in the IPN hydrogel. The strategy described here opens up a new way for preparing IPN hydrogel. The as-prepared hydrogel exhibits potential application and bright prospects as an adsorbent in wastewater treatment.

A novel terpolymer nanocomposite (carboxymethyl β-cyclodextrin-nano chitosan-glutaraldehyde) for the potential removal of a textile dye acid red 37 from water.

Carboxymethyl β-cyclodextrin-nanochitosan-glutaraldehyde (CM-βCD:nChi:Glu) terpolymer was prepared as a nano-adsorbent for the removal of the anionic textile dye, acid red 37. The terpolymer nanocomposite formation and characterization were clarified by FTIR, XRD, scanning electron microscopy, TEM, Brunauer-Emmett-Teller specific surface area (BET-SSA), and zeta potential. The removal of the textile dye was investigated by using the batch adsorption method, investigating the effect of pH, dye concentration, adsorbent dose, contact time, and temperature. The results revealed that the maximum removal efficiency of 102.2mg/L of the dye is about 99.67% under pH 6.0, the optimal contact time is 5min, and the adsorbent dosage is 0.5g/L. At 29°C; the adsorption capacity increased from 81.29 to 332.60mg/g when the initial concentration of the dye was increased from 40.97 to 212.20mg/L. Adsorption kinetics fitted well with the pseudo-second-order model with a good correlation (R 2 = 0.9998). The Langmuir isotherm model can best describe the adsorption isotherm model. Based on the experimental results, the CM-βCD:nChi:Glu terpolymer has a promising potential as an efficient novel adsorbent for the removal of textile dye acid red 37 from contaminated water. This study's preparation techniques and demonstrated mechanisms offer valuable insights into the adsorbent-adsorbate interactions mechanism, analysis, challenges, and future directions of beta-cyclodextrin/chitosan-based adsorbents in wastewater treatment.

Utilization of metal industry solid waste as an adsorbent for adsorption of anionic and cationic dyes from aqueous solution through the batch and continuous study.

Industrial waste, for instance, textile effluents when released into the ecological system without first being treated or with inappropriate levels of treatment, can lead to serious issues deteriorating the environment and human health. Moreover, solid waste from various industries has also become a major issue due to massive urbanization. For instance, the waste from the metal industry has been rapidly increasing such as Jarosite which has various metals, metal oxides, and silica in its composition. Therefore, Jarosite was utilized as an adsorbent for the adsorption of anionic Congo red (CR) and cationic Methylene blue (MB) dyes from aqueous solutions. The processed adsorbent sample was characterized by BET, XRD, SEM, EDS, FTIR, and XPS techniques. The effects of initial dye concentration, pH, adsorbent dose, temperature, and contact time were examined. The metal industry waste is used as a low-cost abundant adsorbent with great potential for adsorption ability to remove the CR (97.5%) and MB (68.5%) at pH 7, contact time 90min, adsorbent dose 0.1g, and initial dye concentration 50mg/L. The adsorption data followed the adsorption isotherm and Kinetics for both dyes. The removal of both dyes was a physical adsorption process, endothermic and spontaneous reaction. Column adsorption investigation was described by AB (Adams-Bohart) and YN (Yoon-Nelson) models. According to the economic view, the utilization of jarosite for dye removal is a cost-effective approach, because it is collected free of cost from industries. Henceforth, for the first time, toxic metal industry waste was successfully utilized as an adsorbent for wastewater treatment.

A Critical Review of Snail Shell Material Modification for Applications in Wastewater Treatment.

Sea material is becoming increasingly popular and widely used as an adsorbent in wastewater treatment. Snail shell, a low-cost and natural animal waste material, has been shown to have a high calcium content (>99%) and a large potential surface area for the development of sustainable adsorbents. This paper presents a novel synthesis of methods for using snail shell absorbent materials in the treatment of wastewater containing heavy metals, textile dyes, and other organic substances. Modified biochar made from snail shells has gained popularity in recent years due to its numerous benefits. This paper discusses and analyzes modification methods, including impregnating with supplements, combining other adsorbents, synthesis of hydroxyapatite, co-precipitation, and the sol-gel method. The analysis of factors influencing adsorption efficiency revealed that pH, contact time, temperature, initial concentration, and adsorbent dose all have a significant impact on the adsorption process. Future research directions are also discussed in this paper as a result of presenting challenges for current snail adsorbents.

Preparation of a novel CSM@ZIF-67 composite microsphere to facilitate Congo red adsorption from dyeing wastewater

ABSTRACT Chitosan (CS) is commonly used as an adsorbent for wastewater treatment because of its low cost, strong adsorption properties, and high availability of raw materials required for its production. However, CS exhibits limited adaptability to pH, poor mechanical properties, and high swelling in aqueous media; these limitations restrict its widespread use. To address these issues, herein, zeolitic imidazolate framework-67 (ZIF-67) is loaded onto crosslinked CS microspheres (CSM) to prepare CSM@ZIF-67, a composite adsorbent. Next, the CSM@ZIF-67 is applied to the treatment of Congo red (CR) dye, which is typically present in printing and dyeing wastewater. The results demonstrate that the in situ synthesis of metal-organic frameworks (MOFs) on CSM improve the dispersion of MOFs and preserve the morphology of the MOFs. The adsorption equilibrium of CSM@ZIF-67 is reached within 150 min, and its adsorption capacity is as high as 538.4 mg/g at a pH of 9 and temperature of 25 °C. The CR adsorption process is consistent with the pseudo-second-order kinetic and Langmuir isotherm models, thus revealing that chemisorption is the primary rate-limiting step, and the pollutants are adsorbed on the adsorbent surface in a monolayer. Experiments on material cycling and regeneration performance reveal that the removal efficiency of CSM@ZIF-67 remains above 90%, even after five rounds of adsorption. CSM@ZIF-67 has abundant functional groups and adsorption sites and can efficiently remove CR through mutual interactions between the metal coordination effect, π–π conjugation, hydrogen bonding, and electrostatic interactions.

Removal of Dye from Wastewater Using a Novel Composite Film Incorporating Nanocellulose

Research shows that the composite material is used as an adsorbent to remove pollutants from wastewater. This work is aimed at producing a novel composite film comprising chitosan, polyvinyl alcohol, and cornstarch incorporating nanocellulose (CPCN). The composite film was prepared by a blending method wherein nanocellulose was extracted using a chemical method from banana bract. The prepared CPCN was characterized using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) with EDX to understand their molecular interaction and surface morphology, respectively. The effect of parameters including pH, adsorbent dosage, initial dye concentration, and contact time on the adsorption of methylene blue (MB) dye was studied. The maximum adsorption was found to be up to 63.13 mg/g MB with a pH of 10, adsorbent dosage of 2 g, an initial concentration of 150 ppm, and contact time of 120 min at room temperature (25°C) indicating a moderate adsorption capacity of the CPCN. Comparing the Langmuir and Freundlich adsorption isotherm models, the former fitted well with MB dye adsorption data, implying that the models can be applied to uptake MB dye by CPCN. In the kinetic adsorption experiment, the adsorbed dye almost reached equilibrium at about 120 min for the CPCN and followed the pseudo-second-order kinetic model. Therefore, the CPCN can be used as a potential adsorbent in wastewater treatment.

Facile synthesis and characterization of magnesium and manganese mixed oxides for the efficient removal of tartrazine dye from aqueous media.

Nanomaterials are the most effective class of substances for use as adsorbents in wastewater treatment. Hence, the current study involves the facile and low-cost synthesis of MgMn2O4/Mn2O3 and MgMn2O4/Mn2O3/Mg6MnO8 as novel nanostructures from mixed solutions of Mg(ii) and Mn(ii) ions using the Pechini sol-gel method. After that, the remaining powder was calcined at 500, 700, and 900 °C for 3 h; the products were designated as G500, G700, and G900, respectively. The G500 sample consists of MgMn2O4 and Mn2O3, while the G700 and G900 samples consist of MgMn2O4, Mg6MnO8, and Mn2O3. The synthesized nanostructures were characterized using several tools, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and N2 adsorption/desorption analysis. The average crystallite size of the G500, G700, and G900 samples is 210.53, 95.27, and 83.43 nm, respectively. The SEM images showed that the G500 sample consists of square and rectangular bars with an average diameter of 3.18 μm. Also, the G700 and G900 samples consist of hexagonal, polyhedral, and irregular shapes with an average diameter of 1.12 and 0.54 μm, respectively. The synthesized nanostructures were further utilized as adsorbents for the efficient removal of tartrazine dye from aqueous media. The experimental data showed a good fit with the Langmuir isotherm and pseudo-first-order model. The maximum adsorption capacities of the G500, G700, and G900 adsorbents toward tartrazine dye are 328.95, 359.71, and 395.26 mg g-1, respectively.

The Prospect of Biochar by Oil Palm Empty Fruit Bunch (OPEFB) in the Removal of Contaminants Emerging Concern (CECs)

Although pharmaceuticals are detected at low levels, their continued release into the environment might result in significant long-term concentrations and lead to damaging consequences on humans, animals, and the environment. The findings have been analysed that various pharmaceutical components were found in sewage treatment plants, including naproxen sodium. Naproxen sodium has been found in various water sources, such as in groundwater and in drinking water. Utilizing OPEFB as adsorbent in wastewater treatment is a feasible alternative. This study focussed on the adsorption capacity of OPEFB biochar for naproxen removal water. The highest percentage removal (99.7%) of naproxen achieved at 100 ppm concentration with 2.5 g of OPEFB biochar. Meanwhile, the usage of 5.0g of OPEFB biochar showed the highest percentage of the removal of naproxen sodium at 100 ppm concentration after 24 hours was 99.27%. OPEFB is one of the most suitable and have the potential in removing almost all the pollutants in wastewater by undergoing the adsorption process.

MODELLING AND OPTIMIZATION OF CADMIUM REMOVAL FROM WASTEWATER ONTO SUGARCANE BAGASSE ACTIVATED CARBON

The presence of sugarcane bagasse as an agricultural waste in the environment is a cause for concern as it defaces the environment. It is bulky and difficult to manage. This prompt the need to research into the reuse of sugarcane bagasse in a more rewarding way, thereby saving the environment from its litters. In this study, Sugarcane bagasse was collected from Gaskiya Road in Zaria and converted to activated carbon using thermal and chemical methods. The Sugarcane bagasse was divided into three portions and carbonized at temperatures of 300, 325 and 350oC and then chemically modified with 1M H3PO4 acid at ratio of 1:2. Batch adsorption experiments were carried out using three input variables: adsorbent dosages of 0.2 - 1.0 g; initial cadmium concentrations of 5 - 25 mg/l and carbonization temperatures of 300 - 350 oC with the corresponding output variables of removal efficiency (X1) and adsorption capacity (X2). The experimental data were modeled, optimized and validated using Response Surface Methodology (RSM). The optimum operating conditions for adsorption of cadmium onto sugarcane bagasse activated carbon were: carbonization temperature of 300 oC, initial cadmium concentration of 25 mg/l and adsorbent dosage of 1.0 g with the corresponding optimized removal efficiency and adsorption capacity of 100% and 2.5mg/g, respectively. The optimized removal efficiency and adsorption capacity were validated and the errors of 0.000 and 0.009%, respectively were recorded. It was concluded that sugarcane bagasse was effective in the removal of cadmium from wastewater and hence its reuse as an adsorbent in wastewater treatment is a viable waste management option. Also the model developed had proven to be valid in predicting the output variables.

Advanced Treatment of Direct Dye Wastewater Using Novel Composites Produced from Hoshanar and Sunny Grey Waste

The present project is designed to investigate the potential of hoshanar and sunny grey marble wastes to remove direct violet 51 dye from wastewater using adsorption process. The effect of different parameters such as pH, adsorbent dose, initial dye concentration, and contact time were studied to optimize the results of adsorption process. Different isothermic models (Temkin, Langmuir isotherm, Freundlich isotherm, Harkin Jura, and Dubinin-Radushkevich models) and kinetic models (pseudo-first order and pseudo-second order) were employed to adsorption data to find out the best fit model, i.e., Langmuir isotherm and pseudo-second order model. Marble waste composites were also characterized by using different techniques such as scanning electron microscopy (SEM) for surface morphology and Fourier transform infrared spectroscopy (FTIR) to determine chemical arrangements, structure, and functional groups of adsorbents. Hoshanar treated with a mixture of potassium ferricyanide, and sodium meta silicate showed maximum adsorption capacity of 105.31 mg/g as compared to untreated hoshanar (67.19.45 mg/g). So, the conversion of HM into HMPS makes it an affordable, efficient, and available adsorbent for wastewater treatment.

Magnetic Fe3O4 embedded chitosan–crosslinked-polyacrylamide composites with enhanced removal of food dye: Characterization, adsorption and mechanism

The water solubility in acid solution, relative low adsorption capacities and unsatisfactory separation performance limit application of traditional chitosan-based adsorbents in wastewater treatment. To break the limitation, a hydrophilic magnetic Fe3O4 embedded chitosan–crosslinked-polyacrylamide composites (abbreviated as m–CS–c–PAM) were prepared by a two–step method. The m–CS–c–PAM composites were systematically characterized using SEM, XRD, FTIR, VSM, TGA and BET. Sunset yellow (SY) was selected as model food dye to investigate adsorption kinetics and thermodynamic parameters of food dye adsorption onto m–CS–c–PAM. Compared with magnetic Fe3O4/chitosan, m–CS–c–PAM can adapt to a wider range of pH (2–10) and resist the presence of inorganic salts. m–CS–c–PAM was proved to have high adsorption capacity (359.71 mg g−1) for SY dye at 298 K, much higher than magnetic Fe3O4/chitosan and many reported adsorbents. Moreover, m–CS–c–PAM could be rapidly and efficiently separated from treated solution within 15 s by an external magnet and regenerated by NaOH solution. With its excellent adsorption capacity, pH–independent adsorption capability for food dye, easy and convenient separation ability, satisfactory reusability, m–CS–c–PAM can be a promising material for food wastewater treatment.

Effect of material age on the adsorption capacity of low-, medium-, and high-calcium alkali-activated materials

Alkali-activated materials (AAMs) are actively studied as adsorbents in wastewater treatment. They are frequently classified as low-, medium-, or high-calcium content since the gel nanostructure of AAMs changes upon the introduction of network-modifying cations (e.g., Ca2+). Furthermore, AAMs undergo changes in the phase composition and pore structure upon aging. In the present study, these two aspects were assessed for the first time in the context of adsorption: three typical mix designs involving metakaolin, blast furnace slag, or their mixture were prepared and studied for ammonium (NH4+) uptake at 7-, 28-, or 90-day age. The adsorption capacity of the “zeolite-like” metakaolin-based geopolymer increased from 34 to 87 mg/g when material was cured up to 90 days at room temperature. However, the adsorption capacity increase appears to be also depending on the metakaolin structure as approx. 1-month and 8-year old samples prepared with another metakaolin grade indicated almost similar adsorption capacity. Adsorption was clearly hindered when blast furnace slag was introduced in the mix designs, which turns the gel into “tobermorite-like” chain structures. Thus, this study demonstrated that using the Ca-content of precursors and material age are significant parameters for the interpretation of the adsorption results and practical development of AAM-based adsorbents.

An investigation on adsorption of carbamazepine with adsorbents developed from flax shives: Kinetics, mechanisms, and desorption

In this work, adsorbents based on hydrochars and steam activated hydrochars developed from flax shives were used to adsorb carbamazepine (CBZ) from simulated contaminated water. The adsorption kinetics was investigated at various temperatures (293–313 K) and times (2–96 h). Four different kinetic models were used to analyze the experimental CBZ adsorption kinetic data. Among the tested various models, the pseudo-second-order kinetic model provided the best simulation to the kinetic data of both adsorbents with R2 of being 0.98 and above, and activation energy of 31.8 and 16.45 kJ/mol, respectively. The determined adsorption rate constant of the steam activated hydrochars ((5.88–9.09) × 10−5) was much higher than that of the hydrochars ((2.81–6.44) × 10−6). Further, X-ray photoelectron spectra and Near-Edge X-Ray Absorption Fine Structure (NEXAFS) Spectroscopy analysis were done before and after loading with CBZ. The results show π-π electron donor-acceptor interaction played an important role on the adsorption mechanism of CBZ on the above-mentioned adsorbents. Hydrophobic interaction also contributed while the roles of hydrogen bonding and electrostatic attraction between CBZ and adsorbents with opposite charges is insignificant. Pore filling may contribute. Desorption of CBZ from CBZ-loaded adsorbents was investigated with various organic solvents, and water at different pH (2, 6 and 10), among which ethanol was the most effective solvent to desorb CBZ. Overall, the results demonstrated that flax shives are promising feedstocks to be made into adsorbents for treatment of wastewater contaminated by antibiotics and additional pharmaceuticals.

Highly reactive adsorbent based on carboxymethyl xanthan gum‐g‐poly(4‐vinylpyridine) copolymer for the potential removal of Acid Orange 10 dye and Cr(VI) ions for water treatment

AbstractThe removal efficiency of an anionic acid dye, Acid Orange 10 dye (AO‐10), and hexavalent chromium metal Cr(VI) from an aqueous medium using carboxymethyl xanthan gum‐g‐poly(4‐vinyl pyridine), CMX‐g‐P(4VP), as a novel adsorbent was studied. The influences of pH, adsorbent dose, temperature, and equilibrium time on the adsorption process were evaluated to optimize the conditions for maximum removal of the adsorbate. Both AO‐10 and Cr(VI) removal were pH‐dependent, with the most excellent adsorption capacity occurring at pH 2.5. AO‐10 and Cr(VI) had maximum adsorption capacities of 1961 and 492 mg g−1, respectively, considerably high. The adsorbent may be efficiently reused for five cycles, according to the desorption studies. The experimental adsorption equilibrium data were described using the Langmuir, Freundlich and Dubinin‐Radushkevich isotherm models. The Langmuir is judged the closest to the description of the practical. In addition, the kinetics of the adsorption process is controlled using pseudo‐first‐order and intraparticle diffusion kinetic models, while the thermodynamic process proved the spontaneous and exothermic nature of removing AO‐10 and Cr(VI) ions. Overall, the results showed that CMX‐g‐P(4VP) might be a very efficient re‐usable adsorbent in wastewater treatment.

Comparative of alginate/graphene oxide and alginate/magnetite graphene oxide aerogel as adsorbents

Magnetite graphene oxide (MGO) has gained attention as a potential adsorbent in wastewater treatment. In this study, incorporation of MGO into biopolymer matrix and dried by supercritical CO2 to improve the adsorption efficiency is presented. Alginate/MGO aerogel was prepared by blending the MGO with alginate and formed hydrogel by ionic crosslinking through external gelation. The blend ratio of MGO and alginate studied are comprised of 2 and 3 wt%, respectively. The hydrogel was dried by supercritical CO2 at 110 ± 5 bar and 40 °C in 4h. The physical-chemical properties of alginate/MGO adsorbent and its adsorption efficiency via removal of methylene blue (MB) are studied. The sharp curve for 30% weight loss for both types of adsorbents has been shown around 200 °C in TGA correspond to the exothermic peak form in DSC analysis. Alginate/GO and alginate/MGO are stable over temperatures of 300 and 700 °C, respectively. Alginate/GO successfully adsorbed 90% of MB concentration meanwhile the alginate/MGO had removed up to 84% of MB. Another highlighted technique is supercritical CO2 drying which considered as one of the most promising techniques to preserve the structure of aerogel with minimal shrinkage as low as 15% in comparison to ambient drying (50%).

Preparation and adsorption properties of green cellulose-based composite aerogel with selective adsorption of methylene blue

Four green aerogels were prepared to remove the cationic dye methylene blue (MB), using the method of solution mixing and freeze-drying. Polyethylene glycol diglycidyl ether (PEGDE) was employed as a crosslinker. The structure and performance of the adsorbents were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), zeta potential measurement and mechanic testing. The results identified that PEGDE efficiently assisted in forming network structure of the porous aerogels, and the removal rates of four aerogels were all higher than 90%. The aerogel composed of sodium carboxymethyl cellulose (CMC) and carboxylated cellulose nanofibers (CNF–C) performed best with adsorbance of 579.50 mg/g, which had a strong electrostatic attraction with MB, exhibited selective adsorption, and did not collapse after ten cycles of underwater compression tests. The adsorption process of CMC/CNF–C aerogel was compatible with the pseudo-second-order kinetic model and Langmuir isothermal model, and the maximal adsorption capacity was 917.43 mg/g. According to the calculation of thermodynamic parameters, the adsorption process was spontaneous and benefited from temperature rise in 20–40 °C. After five regenerations, the adsorption capacity of CMC/CNF–C aerogel decreased from 579.5 mg/g to 513.2 mg/g, indicating a reusable adsorbent in wastewater treatment.

Nano Adsorbents in Wastewater Treatment: A New Paradigm in Wastewater Management

Increasing water pollution has urged the need to elucidate more potent techniques for removing contaminants from wastewater 1 and groundwater. Numerous techniques or processes have been explored and designed for water purification. Amongst all other water/wastewater remediation techniques, nanotechnology has gained wider attention in water remediation via numerous mechanisms, such as the adsorption of heavy metals and the removal of pathogens. Nanoadsorbent materials have emerged as a promising solution for solving this crucial environmental issue. Their unique chemical and physical properties, such as higher ranking, quality, and status, promote their application compared to traditional adsorbents. Recent research studies have reported their promising potential in water treatment, including polymeric, carbon, tubezeolites, and metal nanosorbents. Hence, this review mainly aims to provide summarized data presenting all the beneficial aspects of nanosorbents in wastewater/water remediation.