Adsorbent For Water Treatment Research Articles

One-step green construction of granular composite hydrogels for ammonia nitrogen recovery from wastewater for crop growth promotion

The great application potential of hydrogel adsorbent in water treatment has been widely reported in recent years. However, practical application is severely restricted due to the tedious preparation procedures, high energy consumption, and potential environmental threat of spent adsorbent after adsorption. To address these challenges, a new method was proposed in this study to prepare granular hydrogel composites through one-step polymerization induced phase separation (PIPS), initiated via a redox reaction consisting with calcined oil shale semi-coke (COSSC) and active ingredients of in green tea (GT) at 40 °C. Then granular hydrogel was applied to remove NH4-N in wastewater, and the spent adsorbent after adsorbing was used as the medium for plant growth. The granular hydrogel exhibited a favorable swelling capacity of 205 g/g and excellent adsorption capacity of 40.2 mg/g for NH4-N. Remarkably, the adsorption process achieved equilibrium only within 30 min. To avoid the influence of soil and other factors, we conducted a soilless cultivation experiment, and the results showed that the total seed biomass of mung bean increased by 33.69% with adding 1% of spent hydrogels into the culture medium. Based on above excellent performance, this study presented a feasible idea for the green preparation granular hydrogel composites and offered a promising strategy for the sustainable utilization of spent adsorbent.

Occurrence, quantification and removal of triclosan in wastewater of Umbogintwini Industrial Complex in KwaMakhutha, South Africa

We report on the detection of an organic pollutant mostly found in local streams and wastewater treatment plants, specifically on triclosan detected in the Umbogintwini Industrial Complex (UIC), located on the south coast of Durban, KwaZulu-Natal in South Africa. Triclosan was successfully extracted from effluent samples using molecularly imprinted membrane adsorbents (MIMs) before quantification and removal using high-performance liquid chromatography (HPLC). This was done through fabrication of a polyvinylidene fluoride polymer using selective microparticles and molecularly imprinted polymers by means of phase inversion and an immersion precipitation method which results in enhanced hydrophilicity and membrane performance. The optimisation of experimental parameters – i.e. contact time and sample size – was performed through different stages of analysis. The synthesised MIMs exhibited an outstanding adsorption efficiency of 97% for triclosan in relation to those of non-imprinted membranes (NIMs) and pristine membranes at 92% and 88%, respectively. The analytical method employed had limits of detection and quantification of 0.21 and 0.69 parts per billion (ppb or μg/L) in wastewater effluent, respectively. The obtained efficiency results show great potential for future use of membrane and molecular imprinting technology, and that MIMs can be adopted as adsorbents for water treatment. The fast and highly selective methodology presented in this work could also be employed for the examination of persistent organic pollutants in the future to combat water scarcity in South Africa. Significance: The key finding of this work is the incorporation of molecularly imprinted polymers with a membrane adsorbent to improve the performance of the membrane. An unexpected finding was the existence of pollutants like triclosan in water within the boundaries of the KwaMakhutha community, near the human settlement. Among the MIMs, NIMs and bare membranes, higher removal efficiencies were displayed by the synthesised MIMs against the discovered pollutants. This work could open doors for advanced research in the community.

Highly stable hybrid porous polymers containing polyhedral oligomeric silsesquioxane (POSS)/Dibenzo[g,p]chrysene and Dibenzo[b,d]thiophene units for efficient Rhodamine B dye removal

In this study, we employed the Heck reaction method to synthesize three types of hybrid porous organic/inorganic polymers (HPPs) incorporating octavinylsilsesquioxane (OVS) units. Specifically, we synthesized OVS-TBN-DBTH, OVS-TBN-THS, and OVS-TBN-THSO2 HPPs by reacting OVS with different brominated organic compounds, namely, 2,7,10,15-tetrabromodibenzo[g,p]chrysene (TBN-Br4)/2,8-dibromodibenzo[b,d]thiophene (DBTH-Br2), TBN-Br4/2,3,7,8-tetrabromothianthrene (THS-Br4), and TBN-Br4/2,3,7,8-tetrabromothianthrene-5,5,10,10-tetraoxide (THSO2-Br4). Based on thermal analysis (TGA), the onset decomposition temperatures (Td10) for these HPPs were as follows: OVS-TBN-DBTH at 575 °C, OVS-TBN-THS at 313 °C, and OVS-TBN-THSO2 at 490 °C. Additionally, these HPPs exhibited high char yields, with values of 83, 53, and 67 wt% for OVS-TBN-DBTH, OVS-TBN-THS, and OVS-TBN-THSO2 HPPs, respectively. Furthermore, when analyzed using nitrogen adsorption–desorption measurements, both OVS-TBN-DBTH and OVS-TBN-THSO2 HPPs demonstrated impressive specific surface areas (SBET) of up to 380 m2/g. In addition, the OVS-TBN-DBTH and OVS-TBN-THSO2 HPPs provide an adsorption capacity of 70.62 and 77.1 mg g−1 (qmax from Langmuir isothermal Mode) toward RhB dyestuff at room temperature. In this adsorption system, after calculation, the OVS-TBN-THS HPP could be inferred that the adsorption is a pseudo-first order adsorption model. The OVS-TBN-THS HPP and OVS-TBN-THSO2 HPP in the pseudo-secondary order model have a better representation of the adsorption system for rhodamine B. This study introduces an innovative method for developing HPPs as adsorbents for water treatment and purification.

Integration of hierarchical magnesium silicate with polypyrrole-coated hollow Fe3O4 hybrids as a synergistic adsorbent toward efficient water treatment

Here we demonstrate the rational design and synthesis of hierarchical Fe3O4@PPy/Mgsilicate composites for applications in water treatments. Through a facile step-by-step strategy, ultrathin Mgsilicate nanosheets (NSs) are grown on polypyrrole (PPy) coated Fe3O4 NPs to achieve the hollow structured Fe3O4@PPy/Mgsilicate composites. This smart design can effectively shorten the mass transfer of molecules, increase the specific surface area, and provide more active sites for adsorption of organic pollutants. Owing to its large specific surface area, hierarchical hollow structures, and the synergistic adsorption effect between the PPy interlayer and magnesium silicate outlayer, the resulting composites exhibited excellent adsorption on Congo Red (CR) with high adsorption capacity of 540.5 mg·g-1. The separation of the composites after sorption can be easily performed with an external magnet because of the multiple Fe3O4 cores. These results indicate that the Fe3O4@PPy/Mgsilicate composites can be employed as a highly promising adsorbent in water treatment.

Polycaprolactone Composites/Blends and Their Applications Especially in Water Treatment

Biodegradable poly(ɛ-caprolactone) (PCL) and its composites or blends have received a lot of attention in the last decade because of their potential applications in human life and environmental remediation. Greater efforts have been made to develop biodegradable chemical materials as adsorbents that do not pollute the environment in order to replace traditional materials. Among the numerous types of degradable materials, PCL is currently the most promising, the most popular, and the best material to be developed, and it is referred to as a “green” eco-friendly material. Membranes and adsorbents for water treatment, packaging and compost bags, controlled drug carriers, and biomaterials for tissues such as bone, cartilage, ligament, skeletal muscle, skin, cardiovascular and nerve tissues are just some of the applications of this biodegradable polymer (PCL). The goal of this review is to present a brief overview of PCL, syntheses of PCL, its properties, PCL composites, and PCL blends and to provide a detailed investigation into the utility of PCL/PCL-based adsorbing agents in the removal of dyes/heavy metal ions. Overall, it can be confirmed that PCL blends and composites were found to be significant competitors to other well-known adsorbents in the treatment of wastewaters, necessitating a thorough investigation of their manufacture.

Preparation of mussel-inspired polydopamine-functionalized TEMPO-oxidized cellulose nanofiber-based composite aerogel as reusable adsorbent for water treatment

Water pollution is an ongoing trouble that is of significant urgency to resolve worldwide. However, traditional materials used in the process of water purification are costly and energy intensive. The preparation of low-cost, green and sustainable aerogels with low density, high porosity and high specific surface area (SSA) is a great challenge. In this paper, a mussel-inspired, low-cost, polydopamine (PDA)-functionalized TEMPO-oxidized cellulose nanofiber (TOCNF) PDA/TOCNF composite aerogel has been rationally designed and fabricated with low-density, high porosity and high SSA. The PDA/TOCNF composite aerogel shows low density (18.2 mg/cm3), high porosity (98.7 %), and large surface areas (41.3 m2/g). The resulting PDA/TOCNF composite aerogel could adsorb a maximum of 314.6 mg/g of methylene blue (MB). The recycle experiment for reusing of adsorbent showed that after five consecutive cycles, the removal ability of MB by the PDA/TOCNF composite aerogel still maintained higher than 90 %. In addition, the PDA/TOCNF composite aerogel also had a high adsorption capacity of heavy metal ions, for example, it adsorbs 446.0 mg/g of Cu2+, 222.0 mg/g of Pb2+, 267.0 mg/g of Cd2+, and 600.0 mg/g of Fe3+, respectively. The possible adsorption mechanisms imply that the PDA/TOCNF composite aerogel adsorbs MB due to the synergistic binding interactions, such as electrostatic attraction, π-π stacking interaction, Vander waals force, and hydrogen bonding. Similarly, the PDA/TOCNF composite aerogel adsorbs metal ions due to the electrostatic attraction and chelation of metal ions with the PDA/TOCNF aerogel. Therefore, PDA/TOCNF composite aerogels may have potential applications in wastewater treatment because of their sustainability and low energy consumption.

Synthesis of Sulfur-Doped Magnetic Iron Oxides for Efficient Removal of Lead from Aqueous Solutions

Heavy metal pollution poses an environmental risk, and its efficient removal and facile separation from water remains a challenge. Magnetic iron oxide, an eco-friendly, relatively stable, and easy-separation material, has been regarded as one of the most applicable adsorbents for water treatment. However, the limited adsorption capacity has restricted its applications. Herein, sulfur-doped magnetic Fe3O4 (Sx–Fe3O4) adsorbent was fabricated using a calcination method for the efficient removal of Pb(II) from water. In contrast to undoped Fe3O4, the introduction of doped sulfur greatly enhanced the adsorption performance of S–Fe3O4 over four times, with a maximum capacity of 333.33 mg g−1, which was synthesized at 300 °C with a raw molar ratio of S–Fe of 5. Based on the structure and morphology analysis, it was demonstrated that sulfur was successfully doped into the Fe3O4 structures, which resulted in Fe3O4 with active sulfur sites accordingly contributing to the adsorption enhancement through the combination of strong soft–soft interactions between soft base sulfur and soft acid Pb(II) along with surface adsorption. Sx–Fe3O4 could maintain the adsorption performance in the presence of competing ions. Furthermore, although the sulfur doping process exhibited slight side effects on the magnetic property, magnetic Sx–Fe3O4 maintained the high separation potential. This study presented a promising strategy to enhance the adsorption performance of Fe3O4 through sulfur doping for Pb(II) removal from water.

One-Step Fabrication of Recyclable Konjac Glucomannan-Based Magnetic Nanoparticles for Highly Efficient Cr(VI) Adsorption.

Recently, the natural polymer polysaccharide konjac glucomannan (KGM) has received attention as a promising adsorbent in water treatment due to its low toxicity, cost-effectiveness and biocompatibility. However, the high-level water absorbency of KGM makes it difficult to recover in water treatment. In this study, by combining KGM with magnetic nanoparticles, KGM-based magnetic nanoparticles (KGM-Fe3O4 NPs) with excellent adsorption properties and recyclability for heavy metals were prepared using an one-step precipitation method. The as-prepared KGM-Fe3O4 NPs have a spherical morphology of superparamagnetism with a small particle size (ca. 7.0 nm) and a large specific surface area (160.1 m2·g-1). Taking Cr(VI) as the target heavy metal ion, the above nanoparticles have a high adsorption capacity and fast adsorption rate for Cr(VI). The pseudo-second order kinetic model is more suitable to describe the adsorption process of Cr(VI) by KGM-Fe3O4 NPs, and the maximum adsorption capacity of Cr(VI) onto KGM-Fe3O4 NPs was calculated to be 41.67 mg·g-1 using the Langmuir isotherm model. In addition, KGM-Fe3O4 NPs with adsorbed heavy metal ions can be quickly recovered from a solution, regenerated, and reused in the next cycle. KGM-based Fe3O4 nanoparticles are promising adsorbents that show significant reusability for the removal of metal ions in water and wastewater treatment.

Application of 2D MoS2 Nanoflower for the Removal of Emerging Pollutants from Water.

Two-dimensional (2D) nanomaterial-MoS2 (molybdenum disulfide) has gained interest among researchers, owing to its exceptional mechanical, biological, and physiochemical properties. This paper reports on the removal of organic dyes and an emerging contaminant, Ciprofloxacin, by a 2D MoS2 nanoflower as an adsorbent. The material was prepared by a green hydrothermal technique, and its high Brunauer-Emmett-Teller-specific area of 185.541m2/g contributed to the removal of 96% rhodamine-B dye and 85% Ciprofloxacin. Various characterizations, such as X-ray diffraction, scanning electron microscopy linked with energy-dispersive spectroscopy, and transmission electron microscopy, revealed the nanoflower structure with good crystallinity. The feasibility and efficacy of 2D MoS2 nanoflower as a promising adsorbent candidate for the removal of emerging pollutants was confirmed in-depth in batch investigations, such as the effects of adsorption time, MoS2 dosages, solution pH, and temperature. The adsorption mechanism was further investigated based on thermodynamic calculations, adsorption kinetics, and isotherm modeling. The results confirmed the exothermic nature of the enthalpy-driven adsorption as well as the fast kinetics and physisorption-controlled adsorption process. The recyclability potential of 2D MoS2 exceeds four regeneration recycles. MoS2 nanoflower has been shown to be an effective organic pollutant removal adsorbent in water treatment.

Photo-modulated regeneration of hypercrosslinked polymer adsorbents for water treatment

Hypercrosslinked polymers (HCPs) are highly effective adsorbents for removing dyes from water. However, the regeneration of such adsorbents is typically achieved with energy-intensive thermal methods or with solvents that generate chemical waste. Here in this proof of concept study, we used HCPs loaded with azobenzene molecules (HCPs@Azo) that were developed in our previous work, and four types of dyes – Methyl Orange (MO), Methylene Blue (MB), Rhodamine B (RB), Uniblue A (UA), at concentrations ranging from 10 to 500 mg L−1, to demonstrate the feasibility of photo-modulated regeneration of HCP-based adsorbents. Azobenzene in HCP pores reduced dye adsorption by 4–31 %, but upon photo-isomerisation from trans to cis states, led to the desorption of 1.7–20 % dyes that were previously adsorbed. These desorption capacities were 71–209 % higher than using water for regeneration. Compared to the traditional method using organic solvents such as methanol to regenerate HCP-based adsorbents, our approach of photo-modulated regeneration led to the desorption of 50 % more MO and MB dyes. HCPs@Azo also demonstrated good reusability, showing comparable photo-modulated adsorption and desorption capacities after four cycles of UV–visible light irradiation. Results from this work can potentially pave the way for solvent-less regeneration of adsorbents, creating a waste-less adsorbent regeneration process.

Porous pillararene-based polymer as adsorbent and solid disinfectant for water treatment

Pillararene polymers have been widely used as excellent adsorbents for water treatment, but pillararene polymers with ultra-high specific surface area and versatility are still rarely reported. Herein, a quaternary ammonium salt modified pillar [5] arene polymer, QPBP [5], with specific surface area of 1844 m2 g−1 was successfully synthesized. Since QPBP [5] has abundant different adsorption sites, it exhibits excellent performance for the simultaneously removal of organic pollutants with different charges from water. The selected three model pollutants, Rhodamine B (RhB, positively charged), Sulfamethazine (SMT, electrically neutral) and Fulvic acid (FA, negatively charged), could be rapidly and efficiently removed from water by QPBP [5] within 10 min, which are much faster than them by most of the reported adsorbents. RhB and SMT are mainly adsorbed through hydrophobic interactions with the QPBP [5] surface, while FA is mainly removed through ion exchange. In addition, QPBP [5] also showed excellent reusability and adsorption performance for the environmentally relevant concentration of pollutants. Furthermore, the quaternary ammonium groups on QPBP [5] makes it a solid disinfectant with excellent antibacterial properties. In conclusion, QPBP [5] is a promising multifunctional adsorbent for the treatment of complex pollutants in water.

Study on adsorption performance and mechanism of peanut hull-derived magnetic biochar for removal of malachite green from water

Magnetic biochar (MBC) has the advantages including wide source of raw materials and low cost, and has become a potential adsorbent for water treatment, overcoming the shortcomings of biochar (BC) with the hard separation of solid and liquid. Peanut hull-derived magnetic biochar loaded with Fe3O4 (Fe3O4/BC) was prepared by co-precipitation method. By means of material characterization and batch processing experiments, material properties and environmental factors affecting adsorption performance were investigated. The adsorption mechanism of Fe3O4/BC on malachite green (MG) was revealed using adsorption isotherms, adsorption kinetics and thermodynamics. The results showed that Fe3O4 particles were uniformly loaded, the total pore volume was increased, surface oxygen-containing functional groups were formed, and the maximum adsorption capacity of the biochar reached 175.4 mg g−1, 1.6 times of that before modification. In a wide PH range, Fe3O4/BC showed high adsorption performance for MG, and significant influence from ionic strength wasn’t found. Chemical adsorption was the main adsorption mechanism, including electrostatic interaction, cation exchange, hydrogen bonding and π-π interaction. The study of adsorption mechanism will promote the application of MBC in the removal of organic pollutants from water.

Polysaccharides as Economic and Sustainable Raw Materials for the Preparation of Adsorbents for Water Treatment

Adsorption processes, due to their technical simplicity and cost-effectiveness, have arisen as one of the most well-known, straightforward solutions to water pollution. In this context, polysaccharides, due to their abundance, biodegradability, and biocompatibility, are appealing raw materials for the design of adsorbents. Moreover, some of them, such as chitosan, can be obtained from organic waste products, and their use additionally contributes to solving another concerning problem: organic waste accumulation. Unfortunately, due to their low adsorption capacities and/or physicochemical properties, native polysaccharides are not suitable for this purpose. However, there are alternatives that can overcome these physical or chemical limitations, often taking advantage of the versatility of their polyhydroxylated structure. In this context, this review aims to present an overview of the advances from 2019 onwards in the design of new adsorbents for water treatment from cellulose, alginate, chitosan, and starch, addressing the two main strategies reported in the literature: the preparation of either polysaccharide-based composites or polysaccharide derivatives. It is important to point out that, herein, special emphasis is placed on the relationship between the chemical structure and the efficiency as adsorbents of the analyzed materials, in an attempt to contribute to the rational design of adsorbents obtained from polysaccharides.

Novel Floating Adsorbent for Water Treatment: Organically Modified Layered Alkali Silicate by Facile Mechanochemical Reaction.

Adsorption serves as an effective way to collect (remove) contaminants from aqueous solution. In the present study, a novel floating adsorbent was designed through surface modification of a layered alkali silicate (octosilicate) using a silane coupling reagent (chlorodimethyl[3-(2,3,4,5,6-pentafluorophenyl)propyl]silane) to collect metal ions from water. By conducting the grafting by solvent-free mechanochemical reaction at room temperature, the external surface of octosilicate was modified to be hydrophobic while preserving the ion exchange capability in the interlayer space. Characterizations of XRD, IR, SEM, TGA, 29Si MAS NMR, and 19F MAS NMR confirmed the successful grafting at the external surface of octosilicate particles. The modified silicate demonstrated buoyancy at the air-water interface, facilitating the concentration of methylene blue, Ni2+, and Pb2+ from aqueous solutions. The adsorbed amounts of metal ions on the floating adsorbent were greater than those reported for the common nonfloating adsorbents (zeolites, clays, and clay minerals).

Fe3O4-chitosan nanocomposite as a magnetic biosorbent for removal of nickel and cobalt heavy metals from polluted water

Recently, natural polymers like chitosan have gained attention as promising adsorbents for water treatment. By combining chitosan with magnetic nanoparticles, their adsorption capabilities can be enhanced. In this study, chitosan-magnetite nanocomposite (CMNC) was synthesized via coprecipitation method to remove nickel and cobalt from aqueous solutions. The physicochemical properties of the synthesized CMNC were investigated by various techniques, including FESEM, TEM, XPS, FTIR, XRD, and VSM. The electron microscopy results confirmed the uniform dispersion of magnetite nanoparticles within CMNC nanocomposites, while VSM confirmed their significant magnetic properties. The adsorption experiments showed that at optimal conditions (pH = 6, contact time = 2 h, adsorbent dosage = 2 g/l), CMNC has high adsorption capacities of 30.03 mg/g for Ni2+ and 53.19 mg/g for Co2+. Furthermore, the adsorption data fitted best with the Langmuir isotherm, show that the active sites on CMNC are energetically homogenous. According to kinetic analysis, the experimental data were in good agreement with both pseudo-second-order and intra-particle diffusion models, which suggest that chemical sorption, along with mass transfer steps, influence the overall adsorption process. Finally, investigating the thermodynamic parameters (∆Gads, ∆Hads, ∆Sads) showed that the adsorption process on CMNC was endothermic and spontaneous, with stronger interactions observed between CMNC and Co2+ compared to Ni2+.

Simultaneous adsorption of methylene blue and amoxicillin by starch-impregnated MgAl layered double hydroxide: Parametric optimization, isothermal studies and thermo-kinetic analysis

Textile and pharmaceutical effluents contain significant amounts of dyes and antibiotics, which pose a serious threat to the ecosystem when discharged directly. Therefore, they should be treated by facile treatment techniques using low-cost materials. Layered double hydroxide (LDH) and its hybrids have emerged as robust and economic adsorbents for water treatment. Herein, magnesium/aluminum LDH and its starch-based composite were synthesized by a co-precipitation technique. The physicochemical features of the developed adsorbents were thoroughly characterized using various analytical tools. The developed materials were tested for the eradication of methylene blue (MB) and amoxicillin (AMX) in batch mode adsorption by varying operating conditions. Adsorption performance depends on the solution's pH. Under optimum adsorption conditions of pH 11, adsorbent dosage of 50 mg/L, and treatment time of 120 min, starch-impregnated MgAl-LDH exhibited maximum MB and AMX adsorption capacities of 114.94 and 48.08 mg/g, respectively. The adsorption mechanism states that hydrogen bonds and weak van der Waals forces are responsible for the removal of pollutants by the developed materials. Moreover, equilibrium and kinetic studies revealed that the removal of dye and antibiotic followed the Freundlich and Langmuir models with the pseudo-second-order reaction kinetics, respectively. The spent adsorbents were regenerated using 0.1 M HCl (for MB) and methanol (for AMX) eluent, and reusability studies ensured that the developed adsorbents retained their performance for up to four consecutive adsorption/desorption cycles. MgAl-LDH and its starch-based hybrid could thus be used to effectively remove organic contaminants from wastewater streams on a commercial scale.

Bioinspired High-Magnesium Calcite for Efficiently Reducing Chemical Oxygen Demand in Lake Water.

Organic matter accumulation in water can cause serious problems such as oxygen depletion and quality deterioration of waters. While calcium carbonate has been used as green and low-cost adsorbent for water treatment, its efficiency in reducing the chemical oxygen demand (COD) of water, which is a measure of organic pollution, is restrained by the limited specific surface area and chemical activity. Herein, inspired by the high-magnesium calcite (HMC) found in biological materials, a feasible method to synthesize fluffy dumbbell-like HMC with large specific surface area is reported. The magnesium inserting increases the chemical activity of the HMC moderately but without lowering its stability too much. Therefore, the crystalline HMC can retain its phase and morphology in aqueous environment for hours, which allows the establishment of adsorption equilibrium between the solution and the adsorbent that retains its initial large specific surface area and improved chemical activity. Consequently, the HMC exhibits notably enhanced capability in reducing the COD of lake water polluted by organics. This work provides a synergistic strategy to rationally design high-performance adsorbents by simultaneously optimizing the surface area and steering the chemical activity.

Nigella sativa-Manganese Ferrite-Reduced Graphene Oxide-Based Nanomaterial: A Novel Adsorbent for Water Treatment.

In this study, a novel nanohybrid composite was fabricated via the incorporation of manganese ferrite (MnFe2O4) nanoparticles into the integrated surface of reduced graphene oxide (rGO) and black cumin seeds (BC). The nanohybrid composite was prepared by a simple co-precipitation method and characterized by several spectroscopic and microscopic techniques. The characterization analysis revealed that the rGO-BC surface was decorated with the MnFe2O4. The strong chemical interaction (via electrostatic and H-bonding) between the integrated surface of rGO-BC and MnFe2O4 nanoparticles has been reported. The prepared composite was highly porous with a heterogeneous surface. The average size of the prepared composite was reported in the ranges of 2.6-7.0 nm. The specific surface area of the prepared composite was calculated to be 50.3 m2/g with a pore volume of 0.061 cc/g and a half pore width of 8.4 Å. As well, many functional sites on the nanohybrid composite surface were also found. This results in the excellent adsorption properties of nanohybrid composite and the effectual elimination of methylene blue dye from water. The nanohybrid was tested for various linear isotherms, such as Langmuir and Freundlich, for the adsorption of methylene blue dye. The Freundlich isotherm was the well-fitted model, proving the adsorption is multilayer. The maximum Langmuir adsorption capacity of nanohybrid composite for methylene blue was reported to be 74.627 mg/g at 27 °C. The adsorption kinetics followed the pseudo-second-order recommended surface interaction between the dye and nanohybrid composite. The interaction between methylene blue and the nanohybrid composite was also confirmed from the FTIR spectrum of the methylene blue-loaded adsorbent. The rate-determining step for the present study was intraparticle diffusion. Temperature-dependent studies of methylene blue adsorption were also carried out to estimate adsorption's free energy, enthalpy, and entropy. The methylene blue adsorption was feasible, spontaneous, and endothermic. A comparison study revealed that the present materials could be successfully prepared and used for wastewater treatment.

Removal of Reactive Red 195 and Methylene Blue dyes by adsorption on the surface of cobalt hydroxide-supported polystyrene waste particles

Waste-derived polystyrene microparticles loaded with cobalt hydroxide were prepared and tested as adsorbents for water treatment. The structure of the obtained adsorbent was analyzed by FT-IR, SEM-EDX and XRD techniques. Two dyes, namely, Reactive Red 195 and Methylene Blue were used to evaluate the adsorption behavior of the adsorbent toward anionic and cationic dyes, respectively. The effects of solution pH, contact time, temperature and adsorbent dose on the adsorption process were investigated. The adsorption data were analyzed using the Langmuir and Freundlich isotherms and the pseudo-first and pseudo-second order kinetic models. The thermodynamic parameters of the adsorption process (changes in enthalpy, entropy, and Gibbs free energy) were estimated. The maximum adsorption capacities estimated using the Langmuir model were 37.20 and 32.06 mg g−1 for Reactive Red 195 and Methylene Blue, respectively. The pseudo-first-order equation provided the best description for the adsorption kinetics. The evaluated thermodynamic parameters for adsorption indicated that the process was endothermic, random, and spontaneous. These results suggest that the cobalt hydroxide-loaded polystyrene waste could serve as an effective adsorbent for the removal of dyes from water.

Synthesis, Characterization of Titanium Dioxide Nanotubes, and their Application as an Adsorbent for Removing of Heavy Elements

The nanotubes were prepared by anodizing method. The anodization process was carried out using 60 volts between two titanium plates as electrodes, leaving a distance between the two electrodes 6.5 cm. The electrolyte contains (0.5 w/w NH4F, 2 w/w H2O, 5 w/w ethylene glycol). A scanning electron microscope (SEM) was used to examine the surface morphology of titanium dioxide nanotubes (TiO2). The SEM image shows that the prepared tubes are in the range (80-90 nm) in diameter. titanium dioxide nanotubes (TiO2) are used as effective adsorbents for water treatment. Titanium dioxide nanotubes (TiO2) have been used in the adsorption of heavy metals polluting water such as lead and cadmium. The study showed that the longer nanotubes had higher adsorption rates, as the lead adsorption rate reached 94.11% and the cadmium adsorption rate reached 29.81%. Estimate the concentration of the elements before and after adsorption was examined by using a flame atomic absorption device.