This paper reports the solid-liquid phase equilibria of the CoSO4-H2O and CoSO4-H2SO4-H2O systems at low temperatures. Binary and ternary phase diagrams, including the stable solid phases CoSO4·6H2O and CoSO4·7H2O were established using experimental data and thermodynamic modeling applying the mixed-solvent electrolyte (MSE) model. The results showed that the addition of H2SO4 shifts the eutectic temperature and concentration to lower values for cobalt sulfate and ice crystallization. The trends obtained from the experimental data and the modeling are consistent for the binary CoSO4-H2O system with good agreement, but the ternary CoSO4-H2SO4-H2O system shows some deviations. In general, the MSE model is shown to be reliable for inferring and establishing the phase diagram of the low-temperature system. The phase diagrams are helpful for designing the pathways of cooling crystallization and eutectic freeze crystallization and assessing the performance of the low-temperature crystallization process in the production of CoSO4 hydrates. In addition, some practical examples of cooling crystallization and eutectic freeze crystallization of CoSO4 solutions are provided.

Cellulose nanofibers (CNFs) were employed in the aqueous electrodeposition of nickel and cadmium for battery metal recycling. The electrowinning of mixed Ni-Cd metal ion recycling solutions demonstrated that cadmium with a purity of over 99% could be selectively extracted while leaving the nickel in the solution. Two types of CNFs were evaluated: negatively charged CNFs (a-CNF) obtained through acid hydrolysis (−75 μeq. g−1) and positively charged CNFs (q-CNF) functionalized with quaternary ammonium groups (+85 μeq. g−1). The inclusion of CNFs in the Ni-Cd electrolytes induced growth of cm-sized dendrites in conditions where dendrites were otherwise not observed, or increased the degree of dendritic growth when it was already present to a lesser extent. The augmented dendritic growth correlated with an increase in deposition yields of up to 30%. Additionally, it facilitated the formation of easily detachable dendritic structures, enabling more efficient processing on a large scale and enhancing the recovery of the toxic cadmium metal. Regardless of the charged nature of the CNFs, both negatively and positively charged CNFs led to a significant formation of protruding cadmium dendrites. When deposited separately, dendritic growth and increased deposition yields remained consistent for the cadmium metal. However, dendrites were not observed during the deposition of nickel; instead, uniformly deposited layers were formed, albeit at lower yields (20%), when positively charged CNFs were present. This paper explores the potential of utilizing cellulose and its derivatives as the world's largest biomass resource to enhance battery metal recycling processes.

Crystallization of cobalt sulfate within a typical hydrometallurgical process for the recycling of Ni-Mn-Co oxide or Ni-Co-Al oxide Li-ion batteries has been investigated. The cobalt sulfate salt was obtained by eutectic freeze crystallization (EFC) from a synthetic acidic cobalt strip liquor after solvent extraction. The ternary phase diagram of CoSO4–H2SO4–H2O was first established by the mixed-solvent electrolyte (MSE) model to predict and reveal the changes in the system during the freezing process and to assess the conditions required for EFC. Batch EFC experiments were then conducted for the cobalt strip liquor, which contained a low concentration of impurities. It is shown that with suitable control of supersaturation, seeding, and stirring, pure ice and salt crystals can be recovered as separate phases at the eutectic temperatures, with the crystalline salts in the form of a heptahydrate. The crystallization process can be described using the ternary phase diagram, but with certain deviations. The deviations might be related to insufficient data at the low temperatures in the MSE model and acid entrapment in crystals during the crystallization process. Finally, the performance of the EFC process has been compared to that of an evaporative crystallization (EC) using the same strip liquor. It was found that the CoSO4·7H2O product obtained by EFC was of slightly higher quality considering purity and crystal shape compared to that from EC.

The formation of zinc oxide particles of different hierarchical morphologies was investigated. By performing elemental analysis on samples extracted from the supernatant solution during precipitations yielding two distinctly different morphologies, the consumption of zinc ions was used to follow the liquid-to-solid phase formation. While a rapid Zn-ion consumption was synonymous with the formation of predominantly oxygen terminated flower-shaped ZnO-particles, with half of the zinc ions being precipitated during the first minute, less than 10% of the zinc ions were converted to sea urchin-shaped ZnO-particles (with mixed terminations) after 1 min of the reaction. The unique ZnO-particle morphologies may therefore be related to the precipitation rates, which can be further explored as a tool for understanding how ZnO-particles with differently facetted surfaces form. Interestingly, the different formation rates remained with identical patterns when 0.5 g/L cellulose (0.005 wt%) was added to the reactions as nucleating agent for improved yields. The controlled formation of specific functional ZnO-particle surfaces is an important method for recycling inexpensive zinc waste from batteries to high value materials useful in a variety of catalytic applications.

Biodegradable wheat gluten hydrolysates (WGH) and zinc oxide nanoparticles (ZNPs) with cross-linkers were prepared as nanocomposite films. The physiochemical analysis demonstrated the formation of ZNPs of size approximately 18.37 nm with spherical and hexagonal nanostructures. The ZNPs are endowed with different functional groups, as corroborated by X-ray diffractogram (XRD), field emission electron microscopy (FE-SEM), and fourier transform infrared spectroscopy (FT-IR), respectively. XRD and functional group patterns (IR) of WG and ZNPs exhibited minor changes during film development, indicating a successful interaction between the components. The SEM analysis revealed that the integration of ZNPs into the wheat gluten polymer promoted nano-aggregation on the film surface and the cross-section. The swelling capacity of films was found to be highest by WG/PVP/ZNPs with 265% (pH 7) and 198% (at pH 9). The antibacterial assessments revealed the sensitivity of Pseudomonasaeruginosa and E.coli toward WG/PVP/ZNPs with 14 and 13 mm zone of inhibition, demonstrating the maximum release of zinc ions from WG/PVP/ZNPs films. Furthermore, the WG/PVP/ZNPs film exhibits maximum oxidant scavenging (84%) and oxidant quenching potential (75%). The findings suggest that casting of WGH with ZNPs has a remarkable effect on the films’ physical and biological properties, allowing for their potential use as future bioplastics in biomedical and industrial sectors.

Elemental sulfur (S8) is an abundant and inexpensive by-product of petroleum refining. Polymeric sulfur is thermodynamically unstable and depolymerizes back to S8 with time, which limits its applications and causes megatons of sulfur to accumulate in nature. A novel sulfur-oleylamine copolymer, synthesized using the inverse vulcanization method, is reported for the selective recovery of Cu2+ from a complex mixture of transition metals. Adsorption studies have been performed using batch experiments in the simulated aqueous solution containing a mix of metal ions (Mx+= Fe, Al, Mn, Co, Ni and Cu). The effect of different adsorption parameters such as pH, time, adsorbent dose, sulfur content, and desorption have been studied. The results demonstrate that the sulfur-oleylamine copolymer shows high selectivity towards Cu2+, with excellent adsorption efficiency of >98 % in acidic pH (pH≈1) at room temperature, which is of practical relevance in the handling of battery leach liquors obtained from industrially derived blackmass. Finally, the sulfur-oleylamine copolymers were also applied to battery leach liquors with hydrochloric (HCl) or citric acid and which showed Cu2+ adsorption efficiency of >98 %±1 and > 95 %±7, respectively. This work presents a novel way to convert industrial waste into a stable sulfur polymer and demonstrates its use as a promising material for selective recovery of Cu ions from battery waste and industrial effluents in a simple and cost-effective manner. 

Numerous approaches have been used to prevent bacterial infection from injured skin, such as bandages and topical creams. However, the higher level of reactive oxygen species, bacterial infections, and excess wound exudates remain the major challenges for wound healing. In this study, we have tailored the structure of wheat gluten hydrolysates (WGH) as a continuous matrix by compositing it with a minimal amount of PVA, PVP, and PEG as polymer crosslinkers (0.5 wt%) to provide film structure integrity. Silver nanoparticles (AgNPs) were impregnated into the WGH to develop a control release matrix of the AgNPs. Scanning electron microscopy, X-ray diffractogram, and functional group patterns of WG and AgNPs indicate a successful integration of AgNPs into the wheat gluten matrix. The swelling capacity of the films was tested at acidic, neutral, and basic pH and was found to be highest in WG/PEG/Ag at pH 9 with 389%. The gradual release of Ag+/AgNPs from the films significantly scavenged free radicals and increased the antibacterial activity with up to a 12 mm inhibition zone against Pseudomonas aeruginosa. According to these findings, WGH with AgNPs has been successfully cast in films with increased absorption capacity, free radicals scavenging, oxidant quenching, and antibacterial capabilities, along with the sustained release of silver ions. The results, therefore, show the potential of the developed films in biomedical applications such as wound dressing.

Lithium-ion batteries (LIBs) are widely used everywhere today, and their recycling is very important. This paper addresses the recovery of metals from NMC111 (LiNi1/3Mn1/3Co1/3O2) cathodic materials by leaching followed by antisolvent precipitation. Ultrasound-assisted leaching of the cathodic material was performed in 1.5 mol L−1 citric acid at 50 °C and at a solid-to-liquid ratio of 20 g/L. Nickel(II), manganese(II) and cobalt(II) were precipitated from the leach liquor as citrates at 25 °C by adding an antisolvent (acetone or ethanol). No lithium(I) precipitation occurred under the experimental conditions, allowing for lithium separation. The precipitation efficiencies of manganese(II), cobalt(II) and nickel(II) decreased according to the order Mn > Co > Ni. The precipitation efficiency increased when a greater volume of antisolvent to the leachate was used. A smaller volume of acetone than ethanol was needed to reach the same precipitation efficiency in accordance with the difference in the dielectric constants of ethanol and acetone and their associated solubility constants. After adding two volumes of acetone into one volume of the leach liquor, 99.7% manganese, 97.0% cobalt and 86.9% nickel were recovered after 120 h, leaving lithium in the liquid phase. The metal citrates were converted into metal oxides by calcination at 900 °C. 

Cellulose nanofibers (CNF) are demonstrated as an effective tool for converting electrodeposits into more easily detachable dendritic deposits useful in recycling zinc ion batteries via electrowinning. The incorporation of CNF at concentrations ranging from 0.01 to 0.5 g/L revealed a progressively extensive formation of a nacre-like dendritic zinc structure that did not form in its absence. Increasing CNF-concentrations from 0.01 to 0.5 g/L resulted in more extensive dendritic structures forming. The explanation to the observed phenomenon is the CNFs ability to strongly interact with the metal ions, i.e., restricting the mobility of the ions towards the electrowinning electrode. At the highest concentration of CNF (0.5 g/L), in combination with the lowest current density (150 A/m2), the electrodeposition was limited to the extent that formed deposits were almost non-existent. The electrodeposition in the presence of CNF was further evaluated at different temperatures: 20, 40 and 60°C. The dendritic formation was increasingly suppressed with increasing temperatures, and at a temperature of 60°C, the electrodeposited morphologies could not be differentiated from the morphologies formed in the absence of the cellulose. The results stemmed from a greater mobility of the metal ions at elevated temperatures, while at the same time suggests an inability of the CNF to strongly associate the metal ions at the elevated temperatures. High-pressure blasted titanium electrodes were used a reference material for accurate comparisons, and electron microscopy (FE-SEM) and X-ray diffraction were used to characterize the zinc morphologies and crystallite sizes, respectively. The article reports the first investigation on how dispersions of highly crystalline cellulose nanofibers can be used as a renewable and functional additive during the recycling of battery metal ions. The metal-ion/cellulose interactions may also allow for structural control in electrodeposition for other applications. 

In this study, eutectic freeze crystallization (EFC) was investigated to recover NiSO4 and CoSO4 hydrates from aqueous and dilute sulfuric acid solutions of metal sulfates. Binary phase diagrams were established using a combination of thermodynamic modeling and experimental data. The mixed-solvent electrolyte (MSE) model was employed to model solid–liquid phase equilibria. The predicted binary phase diagrams from the model were in good agreement with the experimental results. Experimental eutectic temperatures and eutectic metal sulfate concentrations for the NiSO4-H2O and CoSO4-H2O systems are −3.3 °C and 20.8 wt% and −2.9 °C and 19.3 wt%, respectively. For NiSO4-H2SO4-H2O and CoSO4-H2SO4-H2O systems, the eutectic temperature and eutectic metal sulfate concentration decrease with increasing H2SO4 concentration. Batch experiments were performed to study the EFC of different sulfate solutions, including 25- wt% NiSO4 in H2O, 20- wt% NiSO4 in 0.5 mol/kg H2SO4, 25- wt% CoSO4 in H2O, and 20- wt% CoSO4 in 0.5 mol/kg H2SO4. The results show that controlling the supersaturation allows high-quality ice and salt crystals to be recovered as separate phases under eutectic conditions, with the crystalline salts in the form of heptahydrates. This study shows that EFC can be a promising alternative to evaporative crystallization for recovering NiSO4 and CoSO4 hydrates from sulfate solutions.