Batch and Fixed Bed Biosorption of Copper by Acidified Algae Waste Biomass

Multi-pollutant biosorption of organic and inorganic pollutants by brown algae waste from alginate production: batch and fixed-bed investigation

The reuse of biomass waste has been gaining attention in adsorption processes to remove pollutants of emerging concern from water and wastewater. In this work, the potential of alginate-extracted macro-algae waste to uptake synthetic dyes and metal cations was evaluated in comparison with raw algae. In affinity assays, both materials were able to remove metal cations and cationic dyes up to maximum rates, and no significant removal was observed for an anionic dye in an acidic medium. Competition was observed in multi-component systems of metal cations and dyes. For binary samples containing organic and inorganic contaminants, kinetic modeling evidenced the distinct nature of both types of adsorbates. Pb(II) biosorption was best described as a first-order process, while second-order and Elovich models better fitted methyl blue (MB) uptake data. For equimolar binary samples, the Sips isothermal model fitted the experimental data more satisfactorily at room temperature. Isotherms for 20, 30, 40, and 60 °C exhibited favorable adsorption profiles with spontaneous ΔG values for both raw macro-algae and waste from alginate extraction. Maximum adsorption capacities were competitive with previous reports in the literature for a wide range of biomaterials, pointing to the slightly higher efficiency with algae waste in batch experiments. In elution tests, HNO3 (0.5 M) showed the best recovery rates of metal cations. Continuous biosorption operation revealed the performance of the brown algae waste was considerably more efficient than raw algae with breakthrough biosorption capacities up to 3.96 and 0.97 mmol.g-1 for the removal of Pb(II) and MB, respectively. A total of 3.0 g of algae and algae waste were able to deliver 1.20 and 1.62 L of contaminant-free water, respectively. XPS analyses corroborate previous assays that pointed to the prevalence of physisorption with evidence of complexation, ionic exchange, and hydrogen displacement mechanisms.

Efficient removal of copper and silver ions in electroplating wastewater by magnetic-MOF-based hydrogel and a reuse case for photocatalytic application

Direct discharge of electroplating wastewater containing hazardous metal ions such as Cu2+ and Ag + results in environmental pollution. In this study, we rationally prepare a magnetic composite hydrogel consisted of Fe3O4, UiO-66-NH2, chitosan (CTS) and polyethyleneimine (PEI), namely Fe3O4@UiO-66-NH2/CTS-PEI. Thanks to the strong attraction between the amino group and metal cations, the Fe3O4@UiO-66-NH2/CTS-PEI hydrogel shows the maximum adsorption capacities of 321.67 mg g-1 for Cu2+ ions and 226.88 mg g-1 for Ag + ions within 120 min. As real scenario, the Fe3O4@UiO-66-NH2/CTS-PEI hydrogel exhibits excellent removal efficiencies for metallic ions even in the complicated media of actual electroplating wastewater. In addition, we explore the competitive adsorption order of metal cations by using experimental characterization and theoretical calculations. The optimal configuration of CTS-PEI is also discovered with the density functional theory, and the water retention within hydrogel is simulated through molecular dynamics modeling. We find that the Fe3O4@UiO-66-NH2/CTS-PEI hydrogel could be reused and after 5 cycles of adsorption-desorption, removal efficiency could maintain 80%. Finally, the Ag+ accumulated by hydrogel are reduced to generate a photocatalyst for efficient degradation of Rhodamine B. The novel magnetic hydrogel paves a promising path for efficient removal of heavy metal ions in wastewater and further resource utilization as photocatalysts.

Use of COMSOL software for modeling and simulation of copper removal in a dynamic mode on a new biowaste

The main purpose of this investigation is to model the results related to biosorption using COMSOL (Multiphysics 4.3a), and to solve the advection-dispersion equation by using both linear and Langmuir models. A bidimensional model was then proposed to study the mass transfer in the process of copper ions sorption in a dynamic mode on cider vinegar residues. Sorption tests were realized by evaluating the influence of flow rate (0.75, 1, and 2.65 ml min^-1 ), bed height (3.5, 7 and 8.5 cm), and copper initial concentration (169 and 300 mg L^-1 ). For all cases, the mathematical formulation was solved by assuming that the column is homogeneous and the sorption is instantaneous. The corresponding results were exploited through breakthrough curve profiles, where it was shown that the solutions obtained by the "Langmuir COMSOL" model coincide with the experimental values. In contrast, the linear model has been unable to fit them. The optimal results were analyzed by Thomas, Adam-Bohart Yoon Nelson, and Ogata-Bank models, which proves that the Thomas method is well adapted with a satisfactory correlation coefficient (0.93). Further, the model validation was performed by determining the residual root mean square error, which was found less than 0.3, thereby indicating a reasonable concordance between the estimated and experimental points. The high sorption capacity obtained was around of 41.37 mg g^-1 , which suggests that the cider vinegar residues can be exploited as a low-cost, available, and effective sorbent biomass in the field of the treatment of industrial effluents. PRACTITIONER POINTS: Cider vinegar residues (CVR) as low cost biosorbent were studied for continuous biosorption. A successful COMSOL model was proposed and validated. CVR is an effective biosorbent for copper fixed bed biosorption. High sorption capacity was around of 41.37 mg g^-1 under optimal conditions.

Application of alginate extraction residue for Al(III) ions biosorption: a complete batch system evaluation

The residue derived from the alginate extraction from S. filipendula was applied for the biosorption of aluminum from aqueous medium. The adsorptive capacity of the residue (RES) was completely evaluated in batch mode. The effect of pH, contact time, initial concentration, and temperature was assessed through kinetic, equilibrium, and thermodynamic studies. The biosorbent was characterized prior and post-Al biosorption by N₂ physisorption, Hg porosimetry, He pycnometry, and thermogravimetry analyses. Equilibrium was achieved in 60 min. Kinetics obeys pseudo-second-order model at aluminum higher concentrations. Isotherms followed Freundlich model at low temperature (293.15 K) and D-R or Langmuir model at higher temperatures (303 and 313 K). Data modeling indicated the occurrence of both chemical and physical interactions in the aluminum adsorption mechanism using RES. The maximum adsorption capacity obtained was 1.431 mmol/g at 293 K. The biosorption showed a spontaneous, favorable, and exotherm character. A simplified batch design was performed, indicating that the residue is a viable biosorbent, achieving high percentages of removal using low biomass dosage.

Nanomodified sugarcane bagasse biosorbent: synthesis, characterization, and application for Cu(II) removal from aqueous medium

Biosorption is a technique widely used in the remediation of contaminated effluents, and its main advantages are its easy applicability, high efficiency rate, versatility, and its economic viability. Associated with nanotechnology, this work proposes the use of nanocomposites of sugarcane bagasse (SB) and ferromagnetic nanoparticles (Fe₃O₄) in the removal of metallic ions present in contaminated water. SB is a promising adsorbent material since it is an abundant agricultural residue, easily accessed. By using the coprecipitation method, two nanocomposites were obtained from in natura (SB-NP) or acid-treated (MSB-NP) sugarcane bagasse. These materials were synthetized by impregnation of Fe₃O₄ to gain paramagnetic properties and to facilitate the removal of the contaminant-containing adsorbent. The characterization of the nanocomposites was performed using pH_PCZ, FTIR, XRD, and SEM/EDS techniques, to evaluate the synthesis efficiency and investigate the morphology of the materials. The efficiency of magnetite impregnation on the SB was assessed by SEM/EDS and XRD, while the main functional groups (carbonyl, carboxyl, hydroxyl, amine, amide, and nitrate) responsible for adsorption were found by FTIR. In the surface charge characterization by pH_PCZ sorption of dyes, it was found that negative charges are predominant. The pH_PCZ for SB-NP and MSB-NP was 5.95 and 5.59, respectively, and the chosen Cu(II) adsorption pH was 6.2 ± 0.1. The adsorption equilibrium was reached between 10 and 60 min of contact time. The maximum experimental sorption capacity (SC_exp) was 2.53 ± 0.09 (SB-NP) and 2.61 ± 0.01 mg/g (MSB-NP). The isotherm models applied to the experimental data were Langmuir, Freundlich, Sips, Temkin, and Dubinin-Radushkevich, and Temkin best described the adsorption phenomena for Cu(II) by SB-NP (r² = 0.9976 and χ² = 3.965) and MSB-NP (r² = 0.9990 and χ² = 1.816). Reuse cycles of the nanocomposites were also performed employing ten cycles of sorption using 50 mg/L Cu(II) solutions, after which the materials showed SC_exp = 7.47 ± 0.04 mg/g (SB-NP) and 7.82 ± 0.04 mg/g (MSB-NP). Therefore, the investigated materials exhibited promising results to be used as biosorbents in the remediation of effluents contaminated with toxic metal ions, such as copper.

Equilibrium, Thermodynamic, Reuse, and Selectivity Studies for the Bioadsorption of Lanthanum onto Sericin/Alginate/Poly(vinyl alcohol) Particles

In a scenario of high demand, low availability, and high economic value, the recovery of rare-earth metals from wastewater is economically and environmentally attractive. Bioadsorption is a promising method as it offers simple design and operation. The aim of this study was to investigate lanthanum bioadsorption using a polymeric bioadsorbent of sericin/alginate/poly(vinyl alcohol)-based biocomposite. Batch system assays were performed to evaluate the equilibrium, thermodynamics, regeneration, and selectivity of bioadsorption. The maximum capture amount of lanthanum at equilibrium was 0.644 mmol/g at 328 K. The experimental equilibrium data were better fitted by Langmuir and Dubinin-Radushkevich isotherms. Ion exchange mechanism between calcium and lanthanum (2:3 ratio) was confirmed by bioadsorption isotherms. Thermodynamic quantities showed that the process of lanthanum bioadsorption was spontaneous (-17.586, -19.244, and -20.902 kJ/mol), endothermic (+15.372 kJ/mol), and governed by entropic changes (+110.543 J/mol·K). The reusability of particles was achieved using 0.1 mol/L HNO₃/Ca(NO₃)₂ solution for up to five regeneration cycles. The bioadsorbent selectivity followed the order of lanthanum > cadmium > zinc > nickel. Additionally, characterization of the biocomposite prior to and post lanthanum bioadsorption showed low porosity (9.95 and 12.35%), low specific surface area (0.054 and 0.019 m²/g), amorphous character, and thermal stability at temperatures up to 473 K. This study shows that sericin/ alginate/poly(vinyl alcohol)-based biocomposites are effective in the removal and recovery of lanthanum from water.

Rapid pyrolysis of Cu2+-polluted eggshell membrane into a functional Cu2+-Cu+/biochar for ultrasensitive electrochemical detection of nitrite in water

Bioremediation is one of efficient methods to solve the issues of water or soil contaminated by metal ions. However, the harvested biowaste is often troublesome to handle owing to the second pollution. Herein, the waste eggshell membrane was used to adsorb Cu²⁺ in wastewater, which was then converted into biochar containing copper ions (Cu²⁺-Cu⁺/Biochar) via a rapid pyrolysis. By integrating the collective advantages of eggshell membrane and Cu²⁺-Cu⁺, such as superior electrical conductivity, enlarged electrochemically active surface area, unique three-dimensional porous network characteristics, and fast charge transport, the Cu²⁺-Cu⁺/Biochar system can be used as a self-supporting sensor for detection of nitrite (NO₂^-). The sensor demonstrated superior electrochemical sensing abilities accompanied by a broad linear range (1-300 μM), ultralow detection limit (0.63 μM), and high sensitivity (30.0 μA·mM^-1·cm^-2). In addition, the fabricated electrochemical sensor has excellent stability, good reproducibility, and strong anti-interference performance. More importantly, the sensor has a high recovery rate when it is used to detect nitrite in tap water, mineral water, and sausage, indicating the feasibility of using this sensor in practical applications. This study provides a green and sustainable approach for simultaneous treatment of biomass waste eggshell membrane, remedy of heavy metals, and electrochemical detection of nitrite.

Removal of propranolol hydrochloride by batch biosorption using remaining biomass of alginate extraction from Sargassum filipendula algae

Propranolol hydrochloride is a popular anti-hypertensive and pollutant of emerging concern because of potential ecological risks to aquatic environment. In this study, biosorption is presented as an advanced approach for propranolol uptake from aqueous media. The remaining biomass of alginate extraction from brown seaweed (RSF) was tested as biosorbent owing to its key binding sites, namely carboxyl and hydroxyl functional groups. The high 93% removal efficiency achieved consolidates RSF as effective biosorbent for propranolol environmental remediation and values this waste material, which has been largely discarded in industry after alginate extraction. RSF had morphology, porosity, chemical composition, and thermal behavior characterized prior and post to application in propranolol biosorption. Molecular sieving effects were excluded by assessing the molecular geometry of propranolol. The kinetics was inspected by both rate laws and mass transfer models. Langmuir, Freundlich, and Dubinin-Radushkevich equations were tested for experimental isotherms. Propranolol biosorption onto RSF was further inspected by thermodynamic parameters, including isosteric heat.

Fixed bed biosorption of silver and investigation of functional groups on acidified biosorbent from algae biomass

This work investigated the use of acidified dealginated residue from Sargassum filipendula algae for biosorption of silver in fixed bed column. This biosorbent was esterified for carboxyl and sulfonate groups to investigate the influence of these groups on silver removal percentage. Potentiometric titration was also evaluated on acidified and esterified biosorbents. Porosity and specific weight were determined by helium picnometry and mercury porosimetry techniques. The results showed that carboxyl and sulfonate groups were significant on silver biosorption. Potentiometric titration showed that esterified and acidified biosorbents presented different acid groups. The porosity of the acidified biosorbent was around 40%. Fixed bed assays were conducted to evaluate the influence of inlet concentration and feed flow rate of silver. Higher percentage removal of silver was obtained at 1.0 mmol · L-1 and 0.5 mL · min-1. Modified dose-response model obtained the best prediction of experimental data among breakthrough curve models.

Competitive biosorption of Cu2+ and Ag+ ions on brown macro-algae waste: kinetic and ion-exchange studies

The application of biosorption operation has gained attention in the removal and retrieval of toxic metal ions from water bodies. Wastewater from industrial activity generally presents great complexity due to the coadsorption of cations to the inactive biomass binding sites. In this work, the competitive biosorption of Cu(II) and Ag(I) ions was studied in batch systems. A kinetic study applying a non-acidified and acidified waste of Sargassum filipendula in equimolar and non-equimolar metal samples was carried out and the acidified biosorbent was selected due to higher removal rates and selectivity of silver ions. The assays were performed with 2 g L^-1 of biosorbent concentration at 25 °C for 12 h and pH was controlled at around 5.0. Copper presented higher affinity for the biosorbent and a fast biosorption kinetic profile, while silver equilibrium times exhibited dependence on the copper concentration. External diffusion is the rate-limiting step in Cu(II) ion removal and it might also limit the kinetic rates of Ag(I) ions with intraparticle diffusion, depending on the initial concentration of metal cations. The ion-exchange mechanism is evidenced and complexation and electrostatic attraction mechanisms might be suggested, explained by simultaneous chemisorption and physisorption processes during the operation. Calcium and sodium were released in considerable amounts by the ion-exchange mechanism. Characterization analyses confirmed the role of several functional groups in the competitive biosorption accompanied by a homogenous covering of both metal ions on the surface of the particles. Particle porosity analyses revealed that the material is macroporous and an appreciable amount of macropores are filled with metal cations after biosorption.

Biosorption technology for removal of toxic metals: a review of commercial biosorbents and patents

In last decades, the biosorption process has become one of the main alternative treatment technologies for the removal of pollutants from dilute aqueous solution. Among these pollutants, toxic metals have drawn attention due to their negative effects in human body and food chain. Even though biosorption is considered a cost-effective and eco-friendly technology to remove toxic metals from dilute wastewaters, there are still obstacles that restrain its commercialization. For this reason, various scientific articles and patents have been published each year to make more effective and economical this technology. This review reports an overview of past achievements, current research of biosorption studies, and future trends for the development of the biosorption as sustainable cleaner technology. Mechanisms of metal uptake, recovery and biosorbent regeneration, process design, commercial application of biosorbents, and patents registered are presented. Finally, future aspects in biosorption research and suggestions for its application will be discussed.