Sodium Alginate Beads Research Articles

Encapsulation of biogenic manganese oxide and Pseudomonas putida MnB1 for removing 17 α-ethinylestradiol from aquatic environments

In this study, we fabricated BMO-MnB1 beads by encapsulating biogenic manganese oxide (BMO) and Pseudomonas putida MnB1 into a calcium alginate hydrogel matrix and evaluated its possible use as a novel material for removing 17α-ethinylestradiol (EE2) from aqueous environments. A response surface methodology (RSM) was used to investigate the individual and interaction effects of the four independent encapsulation conditions (i.e., sodium alginate concentration, CaCl2 concentration, curing time, and bead size) on the removal efficiency of EE2 to obtain optimal encapsulation products. The effects of different experimental conditions (i.e., pH, temperature, initial EE2 concentration, and BMO-MnB1 bead concentration) on the removal of EE2 were also examined. The reusability of BMO-MnB1 beads was also studied in comparison with free BMO and P. putida MnB1 and purified BMO. The results suggested that the optimal conditions for the preparation of BMO-MnB1 beads were the sodium alginate concentration of 3%, the CaCl2 concentration of 0.2 M, the curing time of 3 h, and the bead size of 2.5 mm. Successful fabrication of BMO-MnB1 beads was confirmed via optical microscopy and field emission scanning electron microscopy analysis. Initial pH, initial EE2 concentration, bead concentration, and temperature markedly affected the EE2 removal rates by the BMO-MnB1 beads. The BMO-MnB1 beads exhibited good separation and satisfactory reusability; they could be recycled up to 14 times without obvious changes in the bead structure. This study demonstrates that encapsulation of BMO and P. putida MnB1 into alginate beads can be an excellent strategy with great efficiency and reusability, and high potential for industrial applications for EE2 removal.

Quorum Quenching Cell Entrapping Bead by Polyvinyl Alcohol Method for Biofouling Mitigation in Lab-scale MBR

Quorum Quenching (QQ) bacteria such as Rhodococcus sp. BH4 and Pseudomonas putida have excellent anti-biofouling potential as they disrupt Quorum Sensing (QS) system and inhibit biofilm formation on membranes. Cell Entrapping Beads (CEBs) in which the QQ bacteria are immobilized is one of the most effective methods to mitigate membrane biofouling in MBR. The CEBs are very crucial as they mainly protect QQ bacteria from harsh environment of the sludge for better QQ effect and help in physical cleaning of membranes in a submerged MBR. Previously simple sodium alginate (SA) beads were used but it was found that their durability was very low in real wastewater. Polyvinyl Alcohol (PVA) is a better alternative due to its higher durability, chemical stability and low cost. Several brands of PVAs with different polymerization degrees were used here and small amount of SA was added to avoid agglomeration of PVA beads. Concentrations of SA/PVA were varied and different temperature of cross-linking solution also was examined. Then quality of the beads was evaluated on physical and biological aspect. It was found that a PVA of 2,270 polymerization degree with 8% mixed in 1% SA makes the most stable CEBs. A certain brand of SA didn’t prevent agglomeration of CEBs while a specific brand of SA did even at lower concentrations. Temperature of cross-linking solution also was found to have significant effect on internal structure of beads. The quality of CEBs made by the best method found in this research was confirmed through series of tests, i.e. freeze drying, scanning electron microscopy, activity test after immobilization of QQ bacteria in the beads.

Formulation and Evaluation of Pseudoephedrine Hydrochloride Loaded Alginate Microbeads

Multiple unit dosage forms such as microbeads have increased acceptance because of added even spreading of the drug in the gastrointestinal tract, unvarying drug absorption, abridged local irritation and removal of undesirable intestinal retaining of polymeric material, when compared to non-disintegrating single unit dosage form. The purpose of the presented research is to develop microbeads of pseudoephedrine hydrochloride utilizing sodium alginate as the hydrophilic carrier in combination with HPMC as drug release modifier to lessen the dosing frequency and thereby advance the patient compliance. The microbeads were formulated by varying concentrations of HPMC and calcium chloride. The optimum formulation was chosen based upon in vitro drug release studies and further evaluated. The compatibility of drug-polymer was studied using FTIR analysis. The prepared formulation underwent evaluation for various parameters like drug entrapment, microbeads size, swelling index, mucoadhesive property and stability. No significant drug-polymer interactions were observed in compatibility studies and the formulation was found to be stable on 45 days storage. The formulations exhibited an extended drug release pattern which was the ultimate aim of the study. The microbeads represented good yield, high drug entrapment, low microbeads size and appropriate swelling property. The in vitro wash-off test indicated that the sodium alginate microbeads represent decent mucoadhesive properties. Henceforth, the formulated HPMC coated sodium alginate beads can be utilized as a substitute and cost-effective carrier for the oral controlled delivery of pseudoephedrine hydrochloride.
 Keywords: microbeads, pseudoephedrine hydrochloride, sodium alginate, drug release

Synchronous degradation of phenol and aniline by Rhodococcus sp.strain PB-1entrapped in sodium alginate-bamboo charcoal-chitosan beads

ABSTRACT The biodegradation of benzene series compounds is a difficult problem in environment pollution control, which is attributed to the deficiency of high efficiency bacteria and suitable embedding materials. In this study, the immobilized cells Rhodococcussp. strain PB-1 was used to synchronously biodegrade phenol and aniline by entrapped in sodium alginate (SA)-bamboo charcoal (BC)-chitosan acetate (CA) beads. The free cells of the strain PB-1 could completely degrade 1500 mg/L phenol or 800 mg/L aniline within 48 h, while the degradation rate of 2000 mg/L phenol and 1500 mg/L aniline was 35.76% and 68.06% at 72 h, respectively. The ortho-cleavage pathway was used to degrade phenol and aniline by strain PB-1. However, after entrapped with SA-BC-CA beads,the removal rate of 2000 mg/L phenol was 100% at 108 h, 1500 mg/L aniline was 100% at 62 h and 2000–3000 mg/L total toxic compounds was over 95% at 120 h. These beads could be used four times and were more effective than SA or SA-BC beads. The SA-BC-CA beads could remarkably improve the stability and degradation efficiency of strain PB-1, and thus provide a potential application in the removal of phenol and aniline in wastewater.

Properties of sustainable cellular concrete prepared with environment-friendly capsule aggregates

This study introduced novel environment-friendly capsule aggregates (CAs) with core-shell structures by encapsulating sodium alginate beads (SABs) with a fly ash shell. Two types of CAs with different particle sizes were synthesized by adjusting the SAB size. Cellular concretes with different densities were further fabricated by these lightweight aggregates. The effects of CAs on the density, flow value, setting time, compressive strength, and modulus of elasticity of the concrete were studied. The microstructure and evolution mechanism of CAs in the cementitious matrix were also discussed. The results demonstrated that the CAs shell has the capacity to protect the SAB in the core from damage during the mixing process. The alginate core can achieve a density reduction of 25% for cellular concrete from fresh to dry condition. The function of CAs not only effectively lightens the weight of concrete with the alginate dehydration, but also provides internal curing for the cementitious matrix to reduce its autogenous shrinkage. The results indicated that it is feasible to use CAs for the production of the lightweight concrete to achieve goal densities of 1200, 1400 and 1600 kg/m3, with corresponding compressive strengths and modulus of elastic ranging from 11.5 to 28.3 MPa and 9.5–18.3 GPa, respectively.

Using Zeolite/Polyvinyl alcohol/sodium alginate nanocomposite beads for removal of some heavy metals from wastewater

Functionalized Polyvinyl alcohol/sodium alginate (PVA/SA) beads were synthesized via blending Polyvinyl alcohol (PVA) with sodium alginate (SA) and the glutaraldehyde was used as a cross-linking agent. The zeolite nanoparticles (Zeo NPs) incorporated PVA/SA resulting Zeo/PVA/SA nanocomposite (NC) beads were synthesized for removal of some heavy metal from wastewater. The synthesizes beads were characterized via Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), particle size analyzer (PSA), and scanning electron microscope (SEM). The adsorption kinetics of the selected metal ions onto Zeo/PVA/SA NC beads followed the pseudo-first-order model (PFO) and the adsorption isotherm model was well fitted by the Langmuir model. Moreover, the thermodynamic studies were also examined; the outcomes showed that the adsorption mechanisms of the selective metal ions were endothermic, the chemical in nature, spontaneous adsorption on the surface of the Zeo/PVA/SA NC beads. The removal efficiency using Zeo/PVA/SA NC modified beads reached maximum at the pH value of 6.0 for Pb2+, Cd2+, Sr2+, Cu2+, Zn2+, Ni2+, Mn2+ and Li2+ with 99.5, 99.2, 98.8, 97.2, 95.6, 93.1, 92.4 and 74.5%, respectively, while the highest removal are achieved at pH = 5 for Fe3+ and Al3+ with 96.5 and 94.9%, respectively and decreased at lower or higher pH values. The survival count (%) of the E. coli cells were 34% on the SA beads, 11% on the PVA/SA, and 1% on the Zeo/PVA/SA NC modified beads, after 120 min exposure at 25 °C. Reusability experimental displays that the synthesized beads preserved a significant decrease in the sorption capacity after 10 repeating cycles. The Zeo/PVA/SA NC beads were able to eliminate 60–99.8% of Al3+, Fe3+, Cr3+, Co2+, Cd2+, Zn2+, Mn2+, Ni2+, Cu2+, Li2+, Sr2+, Si2+, V2+, and Pb2+ ions from the natural wastewater samples collected from 10th Ramadan City, Cairo, Egypt.

Development and evaluation of sodium alginate-basil seeds mucilage beads as a suitable carrier for controlled release of metformin

Sodium alginate (SA) is a natural biopolymer that is used as biodegradable and non-toxic material in medical and pharmaceutical fields. Although crosslinked SA with calcium ions in the presence of monovalent salts are unstable. The aim of this work is to employe plant mucilage in combination of SA beads to improve the properties of SA beads. SA beads containing metformin drug (MET) were modified using basil seed mucilage (BSM) to achieve controlled release was investigated. The presence of BSM in the SA structure results in more stability, less swelling, and consequently lower release. The effect of pH 1.2 and pH 7.4 on its release and swelling of the beads was studied, and the results showed that the lowest swelling and release was from the acidic environment. Sodium Tripolyphosphate (TPP) as a cross-linker in the bead structure caused a lower release and swelling. The chemical structure of beads was confirmed by FTIR, SEM indicated the porous structure of SA bead and continuous structure of SA/BSM bead and DSC indicated that the presence of BSM in the bead structure decreased the chain motility. Also, cytotoxicity of BSM was investigated by MTT method, and the mucilage toxicity was not confirmed until 3 ml.

Removal of Ciprofloxacin with Aluminum-Pillared Kaolin Sodium Alginate Beads (CA-Al-KABs): Kinetics, Isotherms, and BBD Model

In recent years, the problem of water pollution caused by antibiotics has attracted wide attention. The common use of antibiotics represents a threat to both human health and environmental safety. The modification of kaolin clay is promising due to its high efficiency, easy operation, and low cost. In this study, a novel material, aluminum-pillared kaolin sodium alginate beads (CA-Al-KABs), was synthesized by gelling and solidification processes. The structure and chemical properties were characterized by various analytical methods. The influencing factors (such as adsorbent dosage, contacting time, pH, ion strength, temperature, and initial concentration) and adsorption mechanism of ciprofloxacin (CIP) were studied. Furthermore, adsorption kinetics, adsorption isotherms, and a Box–Behnken design (BBD) model were conducted. Moreover, CA-Al-KABs’ adsorption efficiency towards other antibiotics were also evaluated. The adsorption experiments showed that the acidic environment (pH = 4) was more favorable for the adsorption of ciprofloxacin. The adsorption kinetics of ciprofloxacin by CA-Al-KABs microspheres were confirmed to be more suitable with the pseudo-first-order kinetics model. The Langmuir isotherm model showed that the maximum adsorption capacity of CA-Al-KABs microspheres to ciprofloxacin was 68.36 mg/g at 308.15 K. The adsorption driving force of CIP near CA-Al-KABs may be the electrostatic attraction. Further, CIP could also form complexes with Ca2+ and Al—Al—OH on CA-Al-KABs, and thus CIP was attracted to the adsorbent. Adsorption thermodynamics showed that the adsorption process was exothermic, feasible, and spontaneous. In addition, the adsorption performance on other antibiotics indicated CA-Al-KABs’ broad application in the treatment of antibiotic wastewater.

Modelling release mechanisms of cinnamon (Cinnamomum zeylanicum) essential oil encapsulated in alginate beads during vapor-phase application

Encapsulation efficiency of Cinnamomum zeylanicum essential oil (EO, at 5% v/v) in sodium alginate beads and its controlled release was determined. Composition of vapors generated by the beads was assessed by solid-phase microextraction. Water and EO released from the beads in the vapor phase were determined at 59% or 88% relative humidity at 4 °C or 25 °C. First and second order dynamic models appropriately described release mechanisms of water and EO, demonstrating Fickian behavior in both cases, in which diffusion mainly depends on EO concentration gradients. Encapsulation efficiency was 85.43% ± 4.97%, volatile components (cinnamaldehyde, caryophyllene, and α-caryophyllene) were detected in the vapor phase. Water and EO release rates were higher at the higher temperature, while a higher relative humidity led to lower water release but greater EO diffusion. Furthermore, enhanced antifungal (against Botrytis cinerea, Penicillium expansum, Alternaria alternata, or Colletotrichum gloeosporioides) activity of encapsulated EO was observed in vapor phase.

Evaluation of sodium alginate for encapsulation-vitrification of testicular Leydig cells

This study reports encapsulation-vitrification of Leydig cells. The Leydig cells were encapsulated in sodium alginate beads of different sizes and cryopreserved by vitrification or slow freezing. Physico-chemical characterization of beads was done by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Fluorescence Recovery after Photobleaching (FRAP) and in vitro biodegradation study. Surface morphology of cryopreserved cell-encapsulated beads was evaluated by Environmental Scanning Electron Microscopy (E-SEM), encapsulation efficiency and viability of cells were assessed by Trypan blue assay, mitochondrial activity (MTT assay) and cytoplasmic esterase enzyme activity (FDA assay), respectively. Results showed that vitrification gives better results than slow freezing with respect to surface morphology as well as cell viability of the cell-encapsulated beads (86.94 ± 2.20% vs. 67.94 ± 2.30%; p < 0.05). Encapsulation of cells in small diameter beads (1.8 mm) gave a better cell proliferation rate than large (2.1 mm and 2.7 mm). There was a significant difference in the population doubling time (47.9 ± 1.7 h vs. 67.1 ± 2.5 h) and cell proliferation rate (0.50 ± 0.24 vs. 0.36 ± 0.24 per day) of vitrified-warmed cell encapsulated beads with different diameter (p < 0.05). Encapsualtion in sodium alginate beads is a promising method for cryopreservation of Leydig cells by slow freezing as well as vitrification.

A mechanistic insight into defluoridation of simulated wastewater applying bio-inspired sodium alginate bead

The experiment successfully investigated fluoride (F−) uptake capacity of bio-inspired sodium alginate bead (BISAB) using ZSM-5 as an adsorbent through a series of batch studies. The study conducted to observe impact of individual parameter on F− adsorption reveals pH and adsorbent dose to have dominant effect in BISAB uptake as compared to time and temperature. Adsorbent prepared from ZSM-5 with high surface area and micropore volume can adsorb 92% of fluoride at optimized condition. Langmuir, Freundlich, D–R and Tempkin isotherms have been studied for fluoride adsorption. Among all models, Langmuir isotherm fitted exceptionally well over other models; this can be concluded from the regression coefficient obtained for Langmuir model which was very close to 1. The kinetic study suggests F− adsorption onto prepared BISAB to follow pseudo-second-order kinetics of average rate constant 6.5475×10−4 g/fluoride per min. Thermodynamic parameters ΔH°, ΔS° and ΔG° were found to be 10.167 kJ/mol, 29.35 J/mol and − 4.71 to − 13.4444 kJ/mol, respectively. The fluoride adsorption onto BISAB was endothermic reaction.

Growth and Production of Lipids in Raphidocelis subcapitata Immobilized in Sodium Alginate Beads

The growth and production of lipids in the green microalga Raphidocelis subcapitata immobilized in alginate gel are studied. The beads are made from alginate (2% w/v) and CaCl2 (1% w/v). The dry weight, the concentration of cells, and the lipid content are determined after dissolution of the beads in a sodium phosphate buffer. The results show that variations in biomass do not reflect variations in the number of cells in R. subcapitata. Cells divide more rapidly (Gc = 3.45 ± 0.3 days) than biomass is produced (Gm = 4.1 ± 0.4 days) during the exponential growth phase. Therefore, the average mass of the immobilized cells decreases until it reaches its minimum at the end of the exponential phase. Thus, during the stationary phase, cell division ceases while biomass production continues, and the average mass of the immobilized cells increases. In the present study, it is shown that this increase is due to the accumulation of lipids following the depletion of nitrates and phosphates in the culture medium. A lipid content of 24.7 ± 2.5% (dcw) and a lipid productivity of LP = 29.8 ± 3.0 mg/L/day are recorded at the end of culture. These results suggest that immobilized R. subcapitata has promising potential for biodiesel production.

Mechanism study on manganese(II) removal from acid mine wastewater using red mud and its application to a lab-scale column

Red mud, a by-product produced in the alumina industry, has been considered as a serious environmental burden. In this study red mud and three modified samples were used as adsorbents to remove Mn(II) from acid wastewater, and the removal ability of raw red mud were investigated in a lab-scale column after prepared as immobilized beads. Compared with the unmodified red mud, Mn(II) removal rate of the Fe(III)-modified, heat-treated and acid-activated red mud decreased by 34.26%, 65.34%, and 54.93%, respectively. Characterization of the adsorbents before and after reaction indicated that BET surface area of red mud did not play the main role in Mn(II) sorption, whereas O–C–O, Si–O–Al and Fe–O groups were significant for Mn(II) chemisorption process. However, minerals containing these active groups were decomposed and transformed partly in the modified samples. The maximum adsorption capacity of unmodified red mud in batch experiment was calculated to be 56.81 mg·g−1 at initial Mn(II) concentration of 95 mg·L−1 and pH of 6.0. Freundlich model gave a better fit to the adsorption data, and the whole adsorption behavior was closer demonstrated by pseudo-second-order kinetic model. Column experiments demonstrated that Mn(II) removal ability of immobilized red mud was at least 1.81–3.19 times larger than that in batch experiment, probably due to the generation of active manganese oxide and use of sodium alginate beads.

Self‐Healing of Cracks in Concrete Using Bacillus Strains Encapsulated in Sodium Alginate Beads

AbstractThis research focused on the self‐healing of micro‐cracks in concrete by using different Bacillus strains. The encapsulation of strains in sodium alginate was protected with the bacterial mass, which prevented them from leaching. A viability test was performed to check the viability of bacteria in the highly alkaline environment. The encapsulated bacterial mix having 2–3% of total volume of concrete cubes was effective without compromising compressive strength. The calcium carbonate (CaCO3) precipitation was observed under urease activity. The SEM (Scanning Electron Microscope) revealed the direct involvement of ureolytic bacteria in CaCO3 precipitation. A 16% increase in compressive strength in concrete and significant healing was achieved with Bacillus Subtilis. However, with Bacillus Anthracis, only 6% increase in the concrete strength was achieved. Moreover, the Bacillus Pasteurii did not give effective results. Bacillus Subtilis provided better results than the other strains. The bacterial culture in sodium alginate beads within 2–3% was optimum for compressive strength and self‐healing of cracks.

Effect of Rheological Properties of Sodium Alginate-pectin Composite Solution on the Formation and Texture of Core-shell Capsules

Based on the synergistic gel formation mechanism between sodium alginate and pectin in presence of calcium ion,the sodium alginate-pectin hydrogel beads with shell-core structure,i.e. core-shell capsule,were prepared using reverse spherification technique,by adding the calcium-containing core solution into the sodium alginate-pectin complex solution. The rheological properties of both sodium alginate-pectin complex and the core solution were tested with the texture analyzer and rheometer and their effects on the texture properties of the core-shell capsules were studied. Results indicated that the viscosity of the complex solution gradually decreased gradually with the increase of the proportion of pectin in the complex system. The sodium alginate and pectin hydrogel beads prepared with sodium alginate-pectin ratio of 7:3 (w/w)and the concentration was 0.6%,showed the highest value of maximum force((430.1±24.4) g·cm-2)and chewability of the outer shell((1054.9±23.4) g).The optimized spherification(standard rate was 100%)and texture properties(the highest value of maximum force was(376.3±18.2) g·cm-2 the chewability was(1104.0±43.3) g)were obtained with xanthan gum concentration of 0.4% and the calcium lactate concentration of 1.5% in core liquid.

Enrichment and immobilization of oil-degrading microbial consortium on different sorbents for bioremediation testing under simulated aquatic and soil conditions

Microorganisms with high oil-degrading ability are essential for bioremediation of oil-contaminated environments and oil spills. In the present study, a microbial consortium was enriched from a long-term oil-contaminated soil by acclimatization with crude oil, and was cultured with sucrose as a carbon source. Immobilization of the microbial consortium cells was prepared onto sodium alginate (SA) beads. To enhance the mass transfer of the immobilized microspheres, activated carbon, biochar, corn stalk and sawdust were used, respectively, to accelerate the degradation of petroleum hydrocarbons. The immobilized beads and the distribution of microbial cells inside the immobilized beads were examined using scanning electron microscopy (SEM). The degradation efficiency of total petroleum hydrocarbon (TPH) by different immobilized beads in aquatic systems (mineral salt medium, artificial seawater) was evaluated by gravimetric method after 7 d of incubation. Results showed that TPH degradation efficiency of the immobilized beads was higher than that of the microbial culture, and that of the immobilized beads containing adsorbent carriers was higher than the SA immobilized beads. The highest TPH degradation efficiencies of SA-CS immobilized beads in mineral salt and artificial seawater were up to 54.2% and 50.5%, respectively, and the highest TPH degradation efficiency of biostimulation + SA-AC immobilized beads treatment in oil-contaminated soil was up to 63.7% after 10 weeks of incubation. Our results suggest that the immobilized microorganism is a promising approach for a wide range of bioremediation applications in different petroleum-contaminated environments.

Ibuprofen sorptive efficacy of zirconium caged date seed derived steam activated alginate beads in a static bed column.

The sorption capability of zirconium coupled sodium alginate beads of steam activated biochar derived from date seed (Zr(DSPB)Al) was explored towards Ibuprofen (IBP) removal from simulated water solution in a static bed column. The impact of governing variables viz. column bed height (5–25 cm), influent (IBP) concentration (10–30 mg L−1) and inflow rate (2–6 mL min−1) was investigated in the present study. The column experimentation reflected that with an increase in column bed length, the breakthrough curve height was increased. The maximum sorbent uptake was found to be 23.33 mg g−1 from an optimal column bed height of 20 cm, influent (IBP) concentration of 30 mg L−1 and inflow rate of 2 mL min−1 with the achievement of 94.86% of IBP removal. The bed depth service model (BDST) was studied to examine the sorbent's efficacy and it was observed that column bed height was one of the effective factors towards effective IBP sorption. The Yoon–Nelson model and Thomas model corroborated extremely well with the experimental findings. The desorption study presented a sorbent efficiency up to 5 cycles for IBP exclusion with 37.59% regeneration of the column. The investigation indicated that the novel sorbent Zr(DSPB)Al with proficient performance could be successfully applied for IBP elimination from aqueous solutions.

Cucumber peel bead biosorbent for multi-ion decontamination of drinking water collected from a mine region in New Zealand

ABSTRACT Cucumber peel as a bead was examined for its ability to remove heavy metals from drinking water. Deionised laboratory water was spiked with seven toxic ions namely, arsenic, cadmium, chromium, copper, mercury, lead and nickel at 0.1 mg L−1 and kinetic studies were performed over 72 h. Kinetic data were modelled using film diffusion, pore diffusion, Weber-Morris, pseudo-first-order, pseudo-second-order and Elovich equation. The bead surface was imaged before and after biosorption using scanning electron microscopy coupled with energy dispersive spectroscopy (EDS). Results indicated that different ions contained in a multi-ion solution were biosorbed by different mechanisms and at different rates. Equilibrium biosorption for Cd, Hg and Ni was ∼91, 90 and 67%, respectively, at 24 h. These ions diffused through the pores of the bead, as they were not identified by EDS, and their biosorption increased with an increase in temperature. The least biosorbed ions were As and Cr with ∼21 and 17% equilibrium biosorption, respectively. The removal of only Cu, Hg, Pb and Ni was pH-dependent. Cucumber peel beads removed all spiked ions from real drinking water collected near the Macraes gold mine in New Zealand, but the biosorption percentage was lower for Cd, Cu, Pb and Ni compared to spiked deionised laboratory water. The results of this study suggest that cucumber peel when immobilised on a sodium alginate bead can be used as a potential biosorbent for the removal of multiple toxic ions from drinking water and their use warrants further examination in contaminated drinking water.

Dye Removal Using Hairy Nanocellulose: Experimental and Theoretical Investigations.

Adsorption is a common technique for the treatment of dye-contaminated wastewater. Achieving a high dye removal capacity is a common challenge with sustainable, low-cost adsorbents. Recently, a class of easily functionalized, biorenewable cellulose nanoparticles called hairy nanocellulose has been developed. Electrosterically stabilized nanocrystalline cellulose (ENCC), which can be synthesized from wood pulp through a two-step oxidation by periodate and chlorite, is a form of hairy nanocellulose with a high negative charge density, and thus has the potential for a high adsorption capacity. In this work, the adsorption of methylene blue, a cationic dye, by ENCC was shown to occur up to charge stoichiometry (1400 mg dye/g adsorbent), at which point aggregation of ENCC-dye complexes is observed. A model is developed to show that the adsorption can be described by an ion-exchange mechanism and is influenced by the presence of other ions. Equilibrium dye removal is reduced at both high ionic strengths and low pH. To facilitate handling, composite hydrogel beads of sodium alginate and ENCC (ALG-ENCC beads) are developed, and their methylene blue removal capacity is shown to maintain a high removal capacity (1250 mg/g). ALG-ENCC beads provide a facile way to employ these nanoparticles on a larger scale, providing a potential means for the removal of dyes and other contaminants at larger wastewater volumes.

Facile preparation of N-O codoped hierarchically porous carbon from alginate particles for high performance supercapacitor

Biomass carbon materials which have the merits of green, low cost and renewability, can be obtained from sodium alginate (SA) beads crosslinked by polyvalent metal ions. SA beads are possible to be obtained using diammoniums as the crosslinking agents. In this work, N-O codoped porous carbon (NO-PC) was prepared from SA beads crosslinked by diammoniums through the electrostatic interaction between ammonium cations and carboxylate groups of SA chains. The using of diammoniums as the crosslinkers achieved N doping into NO-PC. Scanning and transmission electron microscope observations revealed that NO-PC possessed hierarchically porous characteristic. X-ray photoelectron spectroscopy identified the successful N-O codoping. Both the species and concentration of diammoniums strongly affected the porous structure, surface area and electrochemical performance of NO-PC. N2 adsorption-desorption results of NO-PC indicated that the highest surface area was up to 3794 m2/g. The NO-PC based supercapacitors showed high specific capacities up to 269.0 F/g at 1 A/g and excellent cycling stability (92.09% after 5000 cycles at 5 A/g). The energy density of the symmetric supercapacitor was up to 18.9 Wh/kg at a power density of 1380 W/kg with a voltage window of −1.4–0 V.