Mechanisms of Adsorption of Heavy Metal Cations from Waters by an Amino Bio-Based Resin Derived from Rosin

Investigation on Applying Biodegradable Material for Removal of Various Substances (Fluorides, Nitrates and Lead) from Water

Sapropel was used as a biodegradable material for water treatment. Sapropel is a sedimentary layer of a mix of organic and inorganic substances accumulated in the bottoms of lakes for thousands of years. It is a jelly-like homogeneous mass and has properties of sorption. Sapropel is used as a biosorbent and an environment-friendly fertiliser, and it is used in building materials and in the beauty industry as well. In water, there are abundant various solutes that may cause a risk to human health. Such substances include fluorides, nitrates and lead in different sources of water. The goal of this investigation is to explore and compare the efficiencies of removal of different pollutants (fluorides, nitrates and lead) from aqueous solutions upon using sapropel as a sorbent. In this research, various doses of sapropel (0.1, 0.5, 1, 5, 10, 20, 50, 100 and 200 g/L) and various mixing times (15, 30, 60, 90 and 120 min) were used for removal of fluorides, nitrates and lead from aqueous solutions. It was found that the maximum efficiency (up to 98.57%) of lead removal from aqueous solutions by sapropel was achieved when the minimum doses of it (0.1 and 0.5 g/L) were used. The most efficient removal of fluorides (64.67%) was achieved by using 200 g/L of sapropel and mixing for 120 min. However, sapropel does not adsorb nitrates from aqueous solutions.

Coordination-Assisted Construction of Ultra-Fine Metal Nanoparticle Composites for Stable Sodium-Ion Battery Anodes

Ultra-fine nanoparticles (uf-NPs) embedded in hierarchical porous carbon (HPC) have been proven to possess intriguing properties for various energy storage applications, but effective synthetic control is still lacking. Herein, we present an efficient coordination anchor activation (CAA) strategy for the scalable synthesis and elaborate control of a series of uf-NPs embedded in HPC (Sb@HPC and FeSb2@HPC as examples), which is achieved by taking advantage of the coordination capability of industrial ionic exchange resins. The in situ coordination-anchored uf-NPs and the tailored hierarchical porous HPC enables superior rate capability (533.1 mA h g-1 at 3.30 A g-1 for Sb@HPC, 276.0 mA h g-1 at 5.37 A g-1 for FeSb2@HPC), enhanced cycling stability, and high reversible areal capacity (5.02 mA h cm-2). Our study demonstrates a potentially scalable uf-NP synthesis strategy with industrial raw materials that can be applied to a large variety of energy materials.

Novel aspartic-based bio-MOF adsorbent for effective anionic dye decontamination from polluted water

In this study, a cost-effective powdered Zn l-aspartic acid bio-metal organic framework (Zn l-Asp bio-MOF) was reported as an efficient adsorbent for Direct Red 81 (DR-81) as an anionic organic dye. The prepared bio-MOF was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission transmission electron microscopy (FETEM), surface area analysis (BET), and thermal gravimetrical analysis (TGA). The resulting bio-MOF has a large surface area (180.43 m2 g-1) and large mesopore volume (0.144 cm3 g-1), as well as good chemical inertness and mechanical stability. The optimum dosage from the Zn l-Asp bio-MOF was 1.0 g L-1 at pH = 7 for 95.3% adsorption of 10 ppm DR-81 after 45 min. Thermodynamic analysis results demonstrated that the decontamination processes were done with spontaneous, thermodynamically, and exothermic nature onto the fabricated bio-MOF. Kinetic parameters were well-fitted with pseudo-second-order kinetics, and the adsorption process was described by the Freundlich isotherm. The adsorption data proved that Zn l-Asp bio-MOF is an effective adsorbent for DR-81 from aqueous solutions with high stability and recycling ability for eight cycles, as well as the easy regeneration of the sorbent.

Poly (Amidehydrazide) Hydrogel Particles for Removal of Cu2+ and Cd2+ Ions from Water

Poly(amidoamine)s (PAMAM) are very effective in the removal of heavy metal ions from water due to their abundant amine and amide functional groups, which have a high binding ability to heavy metal ions. We synthesized a new class of hyperbranched poly(amidehydrazide) (PAMH) hydrogel particles from dihydrazides and N,N'-methylenebisacrylamide (MBA) monomer by using the A2 + B4 polycondensation reaction in an inverse suspension polymerization process. In Cd2+ and Cu2+ ion sorption tests, the synthesized dihydrazide-based PAMH hydrogel particles exhibited sorption capacities of 85 mg/g for copper and 47 mg/g for cadmium. Interestingly, the PAMH showed only a 10% decrease in sorption ability in an acidic condition (pH = 4) compared to the diamine-based hyperbranched PAMAM, which showed a ~90% decrease in sorption ability at pH of 4. In addition, PAMH hydrogel particles remove trace amounts of copper (0.67 ppm) and cadmium (0.5 ppm) in water, below the detection limit.

Adsorption Evaluation for the Removal of Nickel, Mercury, and Barium Ions from Single-Component and Mixtures of Aqueous Solutions by Using an Optimized Biobased Chitosan Derivative

In this experimental study, the use of 5-hydroxymethyl-furfural (HMF) organic compound as a grafting agent to chitosan natural polymer (CS) was examined. One optimized chitosan derivative was synthesized, and then tested (CS-HMF), in order to uptake nickel, mercury, and barium metal ions from single- and triple-component (multi-component) aqueous solutions. The characterization of the material before and after the metal uptake was achieved by scanning electron microscopy (SEM). The ability of the adsorption of CS-HMF was tested at pH = 6. The adjusting of temperature from 25 to 65 °C caused the increase in the adsorption capacity. The equilibrium data were fitted to the models of Langmuir and Freundlich, while the data from kinetic experiments were fitted to pseudo-1st and pseudo-2nd order models. The best fitting was achieved for the Langmuir model (higher R²). The adsorption capacity for nickel, mercury, and barium removal at 25 °C (single component) was 147, 107, and 64 (mg/g), respectively. However, the total adsorption capacity for the multi-component was 204 mg/g. A thermodynamic study was also done, and the values of ΔG⁰, ΔH⁰, and ΔS⁰ were evaluated.

Improvement of PBAT Processability and Mechanical Performance by Blending with Pine Resin Derivatives for Injection Moulding Rigid Packaging with Enhanced Hydrophobicity

Polybutylene adipate-co-terephthalate (PBAT) is a biodegradable polymer with good features for packaging applications. However, the mechanical performance and high prices of PBAT limit its current usage at the commercial level. To improve the properties and reduce the cost of PBAT, pine resin derivatives, gum rosin (GR) and pentaerythritol ester of GR (UT), were proposed as sustainable additives. For this purpose, PBAT was blended with 5, 10, and 15 wt.% of additives by melt-extrusion followed by injection moulding. The overall performance of the formulations was assessed by tensile test, microstructural, thermal, and dynamic mechanical thermal analysis. The results showed that although good miscibility of both resins with PBAT matrix was achieved, GR in 10 wt.% showed better interfacial adhesion with the PBAT matrix than UT. The thermal characterization suggested that GR and UT reduce PBAT melting enthalpy and enhance its thermal stability, improving PBAT processability. A 10 wt.% of GR significantly increased the tensile properties of PBAT, while a 15 wt.% of UT maintained PBAT tensile performance. The obtained materials showed higher hydrophobicity than neat PBAT. Thus, GR and UT demonstrated that they are advantageous additives for PBAT–resin compounding for rigid food packaging which are easy to process and adequate for industrial scalability. At the same time, they enhance its mechanical and hydrophobic performance.

Polystyrene Magnetic Nanocomposites as Antibiotic Adsorbents

There are different ways for antibiotics to enter the aquatic environment, with wastewater treatment plants (WWTP) considered to be one of the main points of entrance. Even treated wastewater effluent can contain antibiotics, since WWTP cannot eliminate the presence of antibiotics. Therefore, adsorption can be a sustainable option, compared to other tertiary treatments. In this direction, a versatile synthesis of poly(styrene-block-acrylic acid) diblock copolymer/Fe3O4 magnetic nanocomposite (abbreviated as P(St-b-AAc)/Fe3O4)) was achieved for environmental applications, and particularly for the removal of antibiotic compounds. For this reason, the synthesis of the P(St-b-AAc) diblock copolymer was conducted with a reversible addition fragmentation transfer (RAFT) method. Monodisperse superparamagnetic nanocomposite with carboxylic acid groups of acrylic acid was adsorbed on the surface of Fe3O4 nanoparticles. The nanocomposites were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) analysis. Then, the nanoparticles were applied to remove ciprofloxacin (antibiotic drug compound) from aqueous solutions. The effects of various parameters, such as initial drug concentration, solution pH, adsorbent dosage, and contact time on the process were extensively studied. Operational parameters and their efficacy in the removal of Ciprofloxacin were studied. Kinetic and adsorption isothermal studies were also carried out. The maximum removal efficiency of ciprofloxacin (97.5%) was found at an initial concentration of 5 mg/L, pH 7, adsorbent's dosage 2 mg/L, contact time equal to 37.5 min. The initial concentration of antibiotic and the dose of the adsorbent presented the highest impact on efficiency. The adsorption of ciprofloxacin was better fitted to Langmuir isotherm (R2 = 0.9995), while the kinetics were better fitted to second-order kinetic equation (R2 = 0.9973).

Nitrate removal from aqueous solutions by adsorption onto hydrogel-rice husk biochar composite

In the present study, we investigated the performance of hydrogel-rice husk biochar composites, as low-cost, alternative, and biocompatible adsorbents for separating nitrate ions from aqueous solutions. Hydrogel-biochar composite was synthesized at dosages of 2.5%, 3.6%, 4.8%, and 9.6% weight ratios of biochar. The composite was characterized by several common methods including FTIR, SEM, TEM, TGA, and DSC. In addition, the effect of contact time, initial concentration of nitrate ions, and solution pH were considered. The maximum removal of nitrate was about 34.3% at acidic pH (pH = 3) using 0.02 g of adsorbent in 25 ml of nitrate solution with the initial concentration (20 mg/L) and temperature of 25°C for 60 min. Based on the findings, 5% biochar in the composite was the optimal dosage. Adsorption kinetic study revealed that this process followed the first-order kinetic model. The experimental equilibrium adsorption data were tested by the Temkin isotherm model with R²  > 0.97. Based on the thermodynamic studies, the adsorption process was endothermic and spontaneous. Overall, the results suggested that the obtained composite can be specifically employed for removal of contaminations from aqueous solutions. PRACTITIONER POINTS: Hydrogel-biochar composite provides a biocompatible and cost-effective adsorbent. Hydrogel-biochar composite was applied to eliminate nitrate from aqueous solutions. Nitrate removal increased in the synthesized composite upon elevation of the weight ratio of biochar to 0.2 g.

Chitosan Grafted with Biobased 5-Hydroxymethyl-Furfural as Adsorbent for Copper and Cadmium Ions Removal

This work investigates the application of 5-hydroxymethyl-furfural (HMF) as a grafting agent to chitosan (CS). The material produced was further modified by cross-linking. Three different derivatives were tested with molecular ratios CS/HMF of 1:1 (CS-HMF1), 2:1 (CS-HMF2) and 10:1 mol/mol (CS-HMF3)) to remove Cu²⁺ and Cd²⁺ from aqueous solutions. CS-HMF derivatives were characterized both before, and after, metal ions adsorption by using scanning electron microscopy (SEM), as well as Fourier-transform infrared (FTIR) spectroscopy thermogravimetric analysis (TGA), and X-Ray diffraction analysis (XRD). The CS-HMF derivatives were tested at pH = 5 and showed higher adsorption capacity with the increase of temperature. Also, the equilibrium data were fitted to Langmuir (best fitting) and Freundlich model, while the kinetic data to pseudo-first (best fitting) and pseudo-second order equations. The Langmuir model fitted better (higher R²) the equilibrium data than the Freundlich equation. By increasing the HMF grafting from 130% (CS-HMF1) to 310% (CS-HMF3), an increase of 24% (26 m/g) was observed for Cu²⁺ adsorption and 19% (20 mg/g) for Cd²⁺. By increasing from T = 25 to 65 °C, an increase of the adsorption capacity (metal uptake) was observed. Ten reuse cycles were successfully carried out without significant loss of adsorption ability. The reuse potential was higher of Cd²⁺, but more stable desorption reuse ability during all cycles for Cu²⁺.

New Materials for 3D-Printing Based on Polycaprolactone with Gum Rosin and Beeswax as Additives

In this work, different materials for three-dimensional (3D)-printing were studied, which based on polycaprolactone with two natural additives, gum rosin, and beeswax. During the 3D-printing process, the bed and extrusion temperatures of each formulation were established. After, the obtained materials were characterized by mechanical, thermal, and structural properties. The results showed that the formulation with containing polycaprolactone with a mixture of gum rosin and beeswax as additive behaved better during the 3D-printing process. Moreover, the miscibility and compatibility between the additives and the matrix were concluded through the thermal assessment. The mechanical characterization established that the addition of the mixture of gum rosin and beeswax provides greater tensile strength than those additives separately, facilitating 3D-printing. In contrast, the addition of beeswax increased the ductility of the material, which makes the 3D-printing processing difficult. Despite the fact that both natural additives had a plasticizing effect, the formulations containing gum rosin showed greater elongation at break. Finally, Fourier-Transform Infrared Spectroscopy assessment deduced that polycaprolactone interacts with the functional groups of the additives.