Alginate Adsorbent Research Articles

Selective adsorption of tetracycline and copper(II) on ion-imprinted porous alginate microspheres: performance and potential mechanisms.

A novel epichlorohydrin and thiourea grafted porous alginate adsorbent (UA-Ca/IIP) was synthesized using ion-imprinting and direct templating to remove copper ions (Cu(II)) and tetracycline (TC) in aqueous solution. UA-Ca/IIP demonstrated great selectivity for Cu(II) and TC among different coexisting anions (CO32-, PO43- and SO42-), cations (Ca2+, Mg2+ and NH4+), and antibiotics (oxytetracycline and sulfamethoxazole). The adsorption of TC and Cu(II) by UA-Ca/IIP was significantly affected by the pH of the solution, and the quantity of TC and Cu(II) adsorbed reached a maximum at pH 5. A pseudo-second-order model better fitted the kinetic data; the Langmuir model predicted the maximum adsorption quantities 3.527 mmol TC g-1 and 4.478 mmol Cu(II) g-1 at 298 K. Thermodynamic studies indicated that the TC and Cu(II) adsorption was more rapid at a higher temperature. Antagonistic and synergistic adsorption experiments showed that the adsorption capacity of TC would increase significantly with the increase of Cu(II) concentration. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that along with the influence of pH, electrostatic interaction and complexation were the main mechanisms of TC and Cu(II) adsorption. Regeneration experiments revealed that TC and Cu(II) were removed efficiently and that UA-Ca/IIP was recyclable over the long term. These results show that the modified porous alginate microsphere is a green and recyclable adsorbent, which has good selectivity and high adsorption performance for the removal of TC and Cu(II).

Manganese Removal Using Functionalised Thiosalicylate-Based Ionic Liquid: Water Filtration System Application.

Aiming at the generation of new functionalised thiosalicylate-based ionic liquids, a polymeric hydrogel consisting of 1-hexylimidazole propionitrile thiosalicylate [HIMP][TS], with a solid biomaterial support based on polyvinyl alcohol (PVA)-alginate beads, was produced. This study aimed to develop a treatment method for removing manganese (Mn) heavy metal from industrial wastewater, which is known to be toxic and harmful towards the environment and human health. The method utilised an adsorption-based approach with an alginate adsorbent that incorporated a functionalised thiosalicylate-based ionic liquid. The synthesised smooth round beads of PVA-alginate-[HIMP][TS] adsorbent were structurally characterised using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The Mn concentration and removal efficiency were evaluated using atomic absorption spectroscopy (AAS). Three important parameters were evaluated: pH, adsorbent dosage, and contact time. During optimisation using the interactive factor design of experiments through the Box-Behnken model, the results showed that the system achieved a maximum Mn removal efficiency of 98.91% at an initial pH of 7.15, with a contact time of 60 min, using a bead dosage of 38.26 g/L. The beads were also tested in an available water filtration prototype system to illustrate their industrial application, and the performance showed a removal efficiency of 99.14% with 0 NTU total suspended solid (TSS) and 0.13 mg/L turbidity analysis. The recyclability of PVA-alginate-[HIMP][TS] beads using 0.5 M HCl resulted in four cycles with constant 99% Mn removal. The adsorption capacity of Mn was also determined in optimum conditions with 56 mg/g. Therefore, the alginate-thiosalicylate-based ionic liquid system is considered an effective and environmentally friendly method for removing Mn heavy metal due to the high removal efficiency achieved.

Facile Synthesis of Sustainable Tannin/Sodium Alginate Composite Hydrogel Beads for Efficient Removal of Methylene Blue.

To meet the requirement of sustainable development, bio-based adsorbents were developed for the removal of dye contaminant. To improve the adsorption capacity of pure sodium alginate (SA) adsorbent for the removal of methylene blue (MB), aromatic bio-based tannin (Tan) was incorporated through the cross-linking with calcium ion. The obtained Tan/SA composite hydrogel beads were characterized with SEM, FTIR and TG, demonstrating that millimeter-sized beads were obtained through calcium cross-linking with enhanced thermal stability. The maximum capacity (247.2 mg/g) at optimal condition (pH = 12, T = 45 °C) was obtained for the 40%Tan/SA adsorbents, with a removal efficiency of 82.4%. This can be ascribed to the electrostatic attraction between SA and MB, as well as the formation of π–π stacking between Tan and MB. The adsorption process for MB is endothermic, and chemical adsorption, the removal efficiency was exceeded 90% after five cycles.

Production of Cellulose Nanocrystalline Additive Alginate Adsorbent for the Removal of Organic Dyes from Aqueous Solutions and Investigation of Dye Removal Efficiency

Hızlı nüfus artışı ve endüstriyelleşme ile her geçen gün artan su ihtiyacı ve atıksuların su kaynaklarına verdiği zararlar göz önüne alındığında, özellikle endüstriyel atıksuların deşarj öncesi arıtılması büyük önem taşımaktadır. Bu endüstriyel atıksuların başında yüksek su tüketimi ve boyar madde konsantrasyonu ile tekstil endüstrisi gelmektedir. Boyar maddelerin atıksulardan uzaklaştırılması için çeşitli fiziksel, kimyasal ve biyolojik arıtma yöntemleri kullanılmaktadır. Bu yöntemler arasında hem işletme hem performans açısından en kolay ve verimli yöntem adsorpsiyon olarak bilinmektedir. Ancak adsorbanın üretilmesi ve rejenerasyonu, yüksek maliyet ve enerji gerektirdiğinden, adsorpsiyon prosesinde sürdürülebilir malzemeye dayalı alternatif düşük maliyetli adsorbanların geliştirilmesi büyük önem taşımaktadır. Bu çalışmada yenilikçi ve çevre dostu selüloz nanokristal (SNK) katkılı aljinat adsorbanının üretilmesi ve metilen mavisi gideriminde kullanılması araştırılmıştır. Bu amaçla SNK katkılı aljinat bilyelerin metilen mavisi giderim performansının belirlenmesi için farklı adsorban konsantrasyonu ve farklı boyar madde konsantrasyonlarında kesikli adsorpsiyon deneyleri gerçekleştirilmiştir. En yüksek metilen mavisi giderim verimi, 100 mg/L boyar madde konsantrasyonu ve 0,5 g adsorban/50 mL boyar madde çözeltisi şartlarında gerçekleştirilen çalışma ile %35 olarak bulunmuştur. Ayrıca üretilen adsorbanın yeniden kullanılabilirliğinin araştırılması için bir seri adsorpsiyon-desorpsiyon çalışması gerçekleştirilmiş ve adsorbanın rejenerasyonu incelenmiştir.

Synthesis of high-porosity hybrid geopolymer/alginate adsorbent for effective removal of methylene blue and optimization of parameters using RSM

In this work, high-porosity geopolymer/sodium alginate (GSA) adsorbent was successfully prepared by entrapping fly ash-based geopolymer into sodium alginate (SA) using a simple method. The geopolymer slurry was firstly prepared which involved the utilization of sodium hydroxide (NaOH) as the alkaline activator followed by the addition of SA and albumen into the slurry. Natural albumen was used as the foaming agent. The effect of mass ratio of geopolymer to SA, albumen content (wt%), NaOH concentration and curing temperature (°C) on the removal of methylene blue (MB) was investigated using one factor at time (OFAT) method and optimized by response surface methodology (RSM), which achieved by 30 run of experiments using central composite design (CCD). A quadratic model was employed to correlate all the independent variables for maximizing the MB removal through the analysis of variances (ANOVA). The model suggested that the optimum condition for the preparation of GSA adsorbent for the efficient MB removal of 84.94% was achieved with mass ratio of geopolymer to SA was 1:0.13, albumen content of 25 wt%, NaOH concentration of 7 M and curing temperature of 60 °C. The albumen content was the most effective factor in the preparation of GSA adsorbent that increased the MB removal, followed by the curing temperature and mass ratio of geopolymer to SA.

Mechanistic study of selective adsorption and reduction of Au (III) to gold nanoparticles by ion-imprinted porous alginate microspheres

In this paper, a novel technique combining ion-imprinting and direct templating was applied to synthesize Au (III) imprinted epicholorohydrin/thiourea modified porous alginate adsorbent. The adsorbent has demonstrated outstanding selectivity towards Au (III) from multi-metallic solutions, and the porous structure generated from urea hydrolysis has provided fast adsorption kinetics. The maximum uptake capacity of Au (III) is 184.82 mg/g at 323 K, which is outstanding as a recyclable polysaccharide-based adsorbent. Photo-reduction of Au (III) to gold particles was observed in the adsorption process under UV light exposure, while visible light is not capable of stimulating electrons from the synthesized adsorbent. FT-IR, XPS, and DFT calculation have proved that hydroxyl, carboxyl, and NCS functional groups were involved in the adsorption-photoreduction of Au (III).

Development of doubly porous composite adsorbent for the extraction of fluoroquinolones from food samples

A doubly porous microcomposite polyaniline/graphene oxide/octadecyl-bonded silica magnetite (PANI/GOx/C18-SiO2-Fe3O4) alginate adsorbent was developed and employed to extract fluoroquinolones. The Fe3O4 facilitated rapid and convenient for the separation of the adsorbent from sample solutions. The double porosity of the alginate hydrogel enhanced the surface area of the polyaniline coating. The developed method exhibited good linearity of 0.0010–50 μg L−1 for danofloxacin; 0.0050–50 μg L−1 for norfloxacin, ciprofloxacin and enrofloxacin; and 0.010–50 μg L−1 for sarafloxacin and difloxacin. The limits of detection were between 0.001 and 0.010 μg L−1 with RSD below 9.0%. The PANI/GOx/C18-SiO2-Fe3O4 adsorbent was utilized to extract fluoroquinolones from honey, milk and egg samples and satisfactory extraction recoveries were achieved ranged from 80 to 98%. The developed adsorbent has good stability which can be reused up to 7 times, is simple to prepare and convenient to use for the extraction fluoroquinolones.

Mechanistic study of selective adsorption of Hg2+ ion by porous alginate beads

Porous alginate beads prepared by template-assisted emulsion polymerization were investigated as selective adsorbents for Hg2+ ions from tri-metallic solutions containing the same molar concentration of Hg2+, Cd2+ and Pb2+. We observed experimentally that mechanisms of selective adsorption of Hg2+ ion by the porous alginate beads are complicated and highly dependent on solution pH. Interactions between metal cations and the porous adsorbent at different pH values were further characterized by IR and XPS analyses. Results indicated that metal uptake at low solution pH is regulated predominantly by cation exchange, making the adsorbent extremely selective to Hg2+. Nonetheless, metal binding by electrostatic attraction and complexation become important with the increase of solution pH. To validate the sorption mechanisms, density functional theory (DFT) was employed to study the binding properties of metal cations with the porous alginate adsorbent. Our computational results are completely consistent with our experimental findings, providing the theoretical basis and explanations for selective adsorption of Hg2+ by porous alginate beads.

Synthesis of a novel graphene–kaolin–alginate adsorbent for dye removal, and optimization of the adsorption by response surface methodology

In this study, a novel sodium alginate, kaolin, and graphene nanoplate based bio-adsorbent was synthesized and used for cationic dye removal from synthetic wastewater. Central composite design of response surface methodology was applied for the optimization of dye adsorption onto the bio-adsorbent. Effects of dye concentration (from 2.5 to 7.5 ppm), pH (from 5 to 9), and adsorption dosage (from 5 to 15 g/L) were investigated to determine the optimum design points. According to the experimental design, the lowest dye removal was found as 64.80% when the adsorbent dosage was 5 g/L, dye concentration was 7.5 ppm and the pH value was 5. According to the design response, 63.16% of dye removal was achieved at the same conditions. The highest dye removal of 95.42% was obtained when the pH was 5, dye concentration was 2.5 ppm and the adsorbent dosage was 15 g/L. The experimental study gave the removal result of 94.94% at the same operating conditions. The model fitted with the experimental values with R2 = 0.97. The regeneration efficiency and reusability of graphene–kaolin–alginate beads were investigated by using desorption experiment. Adsorbents showed a removal efficiency of 97% after the regeneration.

Regeneration and reuse of bio-surfactant to produce colloidal gas aphrons for heavy metal ions removal using single and multistage cascade flotation

Bio-surfactants are commonly used in the treatment of wastewaters due to their favorable characteristics such as biodegradability and low toxicity. In this work, the bio-surfactants are extracted from low cost substrates like Ziziphus spina-christi (ZSC) plant leaves to reduce the cost of production. Thereafter, the bio-surfactant extracts were used for the preparation of colloidal gas aphrons (CGAs) to remove heavy metal ions (Cu2+, Pb2+) from aqueous solutions.The molecules extracted from the leaves induced the foaming and detergent properties of the solution. Surface tension and electric conductivity techniques confirmed the formation of critical micelle at 5 wt% surfactant concentration. CGA bubbles were generated using the bio-surfactant extracts and employed in single stage and multistage cascaded flotation units to remove Cu2+ and Pb2+ from aqueous solutions. In the single stage flotation, the removal of Pb2+ and Cu2+ from the single and equimolar mixed solution were low. However, in the multistage cascade flotation, the removal efficiency of Pb2+ and Cu2+ increased significantly to 90.7% and 88.2%, respectively. Interestingly, the collected foamate from the flotation columns was regenerated using calcium alginate adsorbent and reused further to prepare the CGAs. Bio-surfactant solution obtained from the leaves of ZSC proved to be useful in the preparation of CGAs and the treatment of heavy metal containing wastewater.

Preparation and characterization of polyacrylamide / sodium alginate microspheres and its adsorption of MB dye

A novel polyacrylamide (PAM) / sodium alginate (SA) adsorbent with double network structure was prepared by emulsion polymerization of acrylamide (AM) and SA. The chemical structure, thermal stability, crystallinity, pore size and distribution, surface area, surface morphology and energy dispersive spectrum of PAM/SA microspheres were determined by FTIR, TGA, XRD, BET, SEM and EDS. In addition, the effects of pH, temperature and adsorbent dosage on the adsorption capacity of Methylene blue (MB) were evaluated. The adsorption isotherms and kinetics as well as the thermodynamics of adsorption process were also studied. The results show that due to the entanglements between PAM and SA molecular chains. A double network structure is formed. The introduction of SA leads to the decrease of thermal stability and crystallization ability of PAM. The pore size is in the range of 0–200 nm, and the mesoporous structure is uniform. The particle size of is in the range of 1–10 u m. The surface of PAM/SA composite microspheres is smooth, and the ion crosslinking point is uniformly distributed. The results show that when pH=6, temperature is 25℃ and adsorbent dosage is 0.1g, the maximum adsorption capacity of PAM/SA composite microspheres is 75 mg/g. Langmuir isothermal model has better correlation with MB adsorption, and the maximum capacity obtained by simulation is 1070.54 mg/g. The pseudo-first-order kinetics and adsorption thermodynamics are better. The adsorption process is a physical adsorption rather than the chemical interation. The adsorption force decreases with the increase of temperature. The obtained PAM / SA composite microspheres have excellent adsorption capacity for dye removal from wastewater.

Study on adsorption of tetracycline by Cu-immobilized alginate adsorbent from water environment

Widespread concern had been given raise to the pollution of antibiotics including tetracyclines in water environment in recent years. A novel Cu-immobilized alginate adsorbent had been synthesized successfully through a facile fabrication way called sol-gel method, and its adsorption performance had been investigated for the tetracycline removal at various conditions, including the pH, temperature, the dosage of adsorbent, concentration and contact time. The adsorbent was characterized with SEM, EDX, FT-IR and XPS analyses to confirm its properties before and after adsorption. The equilibrium data was fitted well with the Freundlich isotherm model and the maximum adsorption capacity for tetracycline was 53.26 mg·g−1 at pH 3, 318.15 K, and 90 mg·L−1 tetracycline solution. The pseudo-second-order kinetic and Freundlich isotherm models combining with the correlative analysis implied that the tetracycline adsorption onto the Cu-immobilized alginate adsorbent was administrated by the n-π electron-donor-acceptor interaction (n-π EDA interaction), hydrogen bond and the cation bonding bridge. Moreover, thermodynamic study demonstrated that the nature of tetracycline adsorption was endothermic, feasible and spontaneous. Compared with the other adsorbents, the as-prepared adsorbent had an excellent tetracycline adsorption capacity, and was expected to be widely applied in the adsorption treatment of tetracycline wastewater.

Zinc oxide templating of porous alginate beads for the recovery of gold ions

In this study, a novel porous alginate adsorbent was prepared by zinc oxide templating to selectively adsorb Au (III) ions from multi-metallic solutions under acidic condition. Due to the porous structure of the prepared sorbent, high uptake capacity and fast adsorption kinetics of Au (ІІІ) were achieved, which renders the prepared adsorbent great potential for practical applications in fixed-bed columns for large-scale applications. The adsorption of Au (III) by the prepared adsorbent led to the reduction of Au (III) to metallic gold. Adsorption and reduction of Au (III) in the process are mediated by the ionic and covalent interaction between Au (III) ions and the protonated functional groups on the modified alginate.

New magnetic/Biosilica/Sodium Alginate Composites for removal of Pb (II) ions from aqueous solutions: Kinetic and isotherm studies

Lead is one of the heavy metals that have harmful effects on the human health and environment. In this study, a new magnetic/biosilica/sodium alginate adsorbent (MBSA) made by the coprecipitation method was used to remove lead from aqueous solutions. It was an experimental study conducted at laboratory scale. The properties of MBSA were analyzed by scanning electron microscope (SEM), XRD, and FTIR analyses. The influences of various parameters such as contact time (0–80 min), pH (3–11), initial lead concentration (10–80 mg/L), temperature (298–318 oK), and adsorbent dosage (0.5–4 g/L) on the sorption process were investigated. The equilibrium isotherm and kinetic models were used to evaluate the fitness of the experimental data. The results showed that lead removal using MBSA was obtained at an optimum pH of 11, contact time of 80 minutes, adsorbent dosage of 4 g/L, lead concentration of 10 mg/L (46.29 g/g), and temperature of 318 oK. Investigating the isotherm and kinetic equations showed that the experimental data of the lead adsorption process correlate with the Langmuir model (R2 = 973) and intraparticle diffusion kinetic model, respectively. The values of the thermodynamic parameters (ΔΗ°, ΔG°, ΔS°) indicated that the sorption of Pb (II) ions on MBSA was spontaneous and endothermic in nature. Due to the good removal efficiency, low cost of the process, and lack of production of harmful substances for the environment, this adsorbent can be used to remove lead from the industrial wastewater.

Alginate Adsorbent Immobilization Technique Promotes Biobutanol Production by Clostridium acetobutylicum Under Extreme Condition of High Concentration of Organic Solvent

In Acetone-Butanol-Ethanol fermentation, bacteria should tolerate high concentrations of solvent products, which inhibit bacteria growth and limit further increase of solvents to more than 20 g/L. Moreover, this limited solvent concentration significantly increases the cost of solvent separation through traditional approaches. In this study, alginate adsorbent immobilization technique was successfully developed to assist in situ extraction using octanol which is effective in extracting butanol but presents strong toxic effect to bacteria. The adsorbent improved solvent tolerance of Clostridium acetobutylicum under extreme condition of high concentration of organic solvent. Using the developed technique, more than 42% of added bacteria can be adsorbed to the adsorbent. Surface area of the adsorbent was more than 10 times greater than sodium alginate. Scanning electron microscope image shows that an abundant amount of pore structure was successfully developed on adsorbents, promoting bacteria adsorption. In adsorbent assisted ABE fermentation, there was 21.64 g/L butanol in extracting layer compared to negligible butanol produced with only the extractant but without the adsorbent, for the reason that adsorbent can reduce damaging exposure of C. acetobutylicum to octanol. The strategy can improve total butanol production with respect to traditional culture approach by more than 2.5 fold and save energy for subsequent butanol recovery, which effects can potentially make the biobutanol production more economically practical.

Biosorption and reduction of Au (III) to gold nanoparticles by thiourea modified alginate

In this study, modified alginate biosorbent has shown a remarkably selective adsorption of Au (III) ions from multi-metallic solutions containing equal moles of Au (III), Pd (II), Pt (IV), Co (II), Ni (II) and Cu (II) ions under acidic conditions. The maximum uptake capacity of Au (III) was found to be 8.47mmolg−1 at 323.15K. Adsorption of Au (III) by modified alginate biosorbent was accompanied by chemical reduction of Au (III), leading to the formation of gold nanocrystals and microcrystals. Biosorption and reduction of Au (III) in acidic media are mediated by the electrostatic and covalent interactions between Au (III) and hydroxyl, carboxyl, amino and CS functional groups of modified alginate adsorbent.

Kinetic and equilibrium investigation of Cu(II) removal by Co(II)-doped iron oxide nanoparticle-immobilized in PVA–alginate recyclable adsorbent under dark and photo condition

Magnetic nanoparticles of cobalt(II)-doped iron oxide (Co-Fe2O3) were synthesized by co-precipitation method using stable ferric and cobalt salts coated with different surfactants (citrate, acetate and polyetheylene glycol (PEG)) and water as the carrier. X-ray diffraction (XRD) and transmission electron microscope (TEM) confirmed the formation of single phase cobalt iron oxide nanoparticles while Fourier transform infrared (FTIR) was performed so as to ensure successful coating process. The nanoparticles were then immobilized in polyvinyl alcohol (PVA)-alginate gel matrix for the removal of Cu(II). X-ray photoelectron spectroscopy (XPS) was then used to validate the Cu(II) removal mechanism under photo condition. Langmuir equation was used to simulate the adsorption isotherms while Weber–Morris model and Langmuir–Hinshelwood model were then used to describe diffusion and adsorption kinetics. Adsorption–desorption results depicted that the PEG coated Co-Fe2O3 PVA–alginate adsorbent experienced only a 2.7% drop in removal efficiency after 5 cycles which made it a potential photoadsorbent to be used for Cu(II) removal.

Ceramic-Supported Alginate Adsorbent for the Removal of Heavy Metal Ions

Hybrid alginate/ceramic support sorbents have been developed by the physical imbibing of an alginic acid solution into silica pores and γ-alumina microspheres. The metal ion-binding capacity of the prepared hybrids was examined by means of batch Cd2+ ion adsorption experiments. In addition, since the porous γ-alumina microspheres proved capable of retaining higher quantities of alginic acid than silica, they were chosen as a more appropriate substrate for the application of a chemical modification procedure. In this context, the aim was to develop hybrid sorbents with an enhanced stability and adsorption capacity obtained by grafting the bio-molecule onto the substrate. Such chemical modification included grafting two different types of silanes onto the external surface and pores of γ-alumina, followed by chemical bonding of the alginate with the characteristic groups of the silane molecules involved. Such chemically-prepared sorbents exhibited almost twice the Cd2+ ion adsorption capacity of sorbents pre...

Activated carbon-containing alginate adsorbent for the simultaneous removal of heavy metals and toxic organics

By combining two functions of alginate gel and activated carbon, an activated carbon-containing alginate bead (AC-AB) adsorbent was developed and successfully used to simultaneously remove heavy metal ions and toxic organics. Quantitative analysis showed that almost all of the adsorption of toxic organics, such as p-toluic acid, is caused by the activated carbon in the AC-AB adsorbent, whereas the alginate component has a major role in the removal of heavy metals. A 50-L solution containing eight heavy metals (Pb 2+, Mn 2+, Cd 2+, Cu 2+, Zn 2+, Fe 2+, Al 3+ and Hg 2+) and four mineral ions was run continuously through a filter cartridge packed with 160 g of the AC-AB adsorbent. The adsorbent showed a high capacity to remove heavy metals completely from the water, while allowing essential minerals, such as K +, Na +, Mg 2+ and Ca 2+, to pass through the filter. The adsorbent could be regenerated using eluents, such as HNO 3, and reused repeatedly without considerable loss of its metal uptake capacity through 10 subsequent cycles of adsorption and desorption. With its high capacity and high selectivity for toxic heavy metals, the AC-AB adsorbent has enormous potential for application in drinking water treatment technologies.