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Precipitation of magnesium hydroxide [Mg(OH)2] from bischofite (MgCl2·6H2O) using lime milk, i.e., the traditional lime milk method, features a low cost. However, insoluble impurities such as CaO in the lime limit the purity of the magnesium hydroxide product. For this reason, a new method has been developed, using saturated lime supernatant instead of lime milk. The insoluble impurities in lime cannot dissolve in saturated lime supernatant, thus improving the purity of the produced magnesium hydroxide. This improved lime method, which achieves high Mg(OH)2 purity of 99% with CaO content of 0.094%, offers better performance in comparison with the traditional lime milk method. Besides, the optimum processing parameters including pH, crystal seed amount, agitation speed, reaction temperature, MgCl2 concentration, reaction time, aging time, and polyacrylamide (PAM) addition are reported. High-purity light magnesia (MgO) is obtained from magnesium hydroxide by carbonation and calcination, with quality fulfilling the HG1-324-77 standard. This improved lime method represents a promising approach for production of high-purity magnesium hydroxide and light magnesia from bischofite.

A novel process of recovery of Mn as lithium ion-sieve from H2SO4 leaching liquor of spent lithium-ion batteries was developed. After precipitation of Fe3+ and Cu2+ in the leaching liquor, Mn was recovered with D2EHPA extraction followed by two-step stripping with H2SO4 solution. Lithium ion-sieve was synthesized by oxidation of the stripping solution using KMnO4, then roasting at atmosphere followed by acid leaching. The effects of solvent extraction parameters on Mn recovery rate and Co doping content on the performance of lithium ion-sieve were investigated. The result indicates that through secondary countercurrent solvent extraction, Mn is fully separated from Ni and a MnSO4 solution containing a small amount of Co is obtained. Co can incorporate into the lattice of lithium ion-sieve and improve the structure stability and adsorption capacity. The Co doped lithium ion-sieve shows Li adsorption capacity of 33.1 mg g−1 and Mn dissolution rate of 1.39%. The total recovery efficiency of Mn is 84.6%. The process provides a simple method for recovery and utilization of Mn in the spent lithium-ion batteries.

According to the solubility isotherms of the ternary system (LiCl + NH 4 Cl + H 2 O), fractional crystallization including primary crystallization and secondary crystallization, was designed to remove the maximum amount of NH 4 + from Cha'erhan tail brine and raise the concentration of Li + . The particle size and surface topography during fractional crystallization were studied by XRD and SEM techniques. Then, sodium hydroxide was used for the removal of magnesium, and high purity sodium carbonate was obtained by the method of carbonation from Cha'erhan tail brine.

Fe–Co alloy was successfully prepared in chloride-sulfate solutions containing sodium propargyl sulfonate using electrodeposition method. The phase composition, surface morphology and magnetic properties of Fe–Co alloy were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), respectively. Linear sweep voltammetry and chronoamperometry was used to investigate the electrodeposition behavior. The iron content of Fe–Co alloy decreases and the surface of film becomes smoother with an increase of sodium propargyl sulfonate. The film structure shows no dependence on sodium propargyl sulfonate. The film exhibits a body-centered cubic (BCC) structure and shows no dependence on sodium propargyl sulfonate. With 0.6 g/L sodium propargyl sulfonate, the Fe–Co alloy has a saturation magnetization of 1.91 T and a coercivity of 5.02 Oe. The initial electrodeposition potential shows negative shift and the apparent activation energy increases from 39.57 kJ/mol to 112.47 kJ/mol. The nucleation mechanism of Fe–Co alloy is gradually changed from instantaneous to progressive with the addition of sodium propargyl sulfonate.

A comprehensive utilization process of Fe, Mn, Ni and Co in the acid leaching liquor of spent lithium ion batteries was put forward. Fe and part of Mn were extracted to synthesize Fe-doped lithium ion-sieve. Ni, Co and the rest of Mn were coprecipitated to prepare ternary lithium ion battery cathode material precursor NixCoyMn1-x-y(OH)2. After removing Cu2+ ions in acid leaching liquor by adding MnS, two-stage counter current extraction and one-stage stripping were used to extract all Fe3+ and 40.3% of Mn2+ ions in sulfuric acid leaching solution to obtain a MnSO4 stripping solution containing Fe3+ ions. Iron-doped lithium ion-sieve was synthesized by oxidation of the resulting MnSO4 solution with KMnO4 followed by roasting and acid leaching. Fe incorporates into the lattice of lithium ion-sieve and improves the structure stability. Fe-doped lithium ion-sieve shows Li adsorption capacity of 35.29 mg.g−1 and Mn dissolution loss of 1.66%. The Li+ adsorption in salt lake brine with the Fe-doped ion-sieve follows a pseudo-second-order kinetic model. NixCoyMn1-x-y(OH)2 is regular spherical particles with β-Ni(OH)2-like structure. This process provides a simple method for recovery and utilization of Mn, Fe, Ni and Co in spent lithium ion batteries.

PurposeThe purpose of this paper is to obtain iron‐enriched Fe‐Ni alloy foil on Ti substrates with good quality from a chloride‐sulfate bath used in a normal DC plating mode. The effects of iron content on the hardness, surface morphology and microstructure of the foil were clarified.Design/methodology/approachFe‐Ni alloy foil was prepared by electrodeposition in a chloride‐sulfate based solution. The effects of current density, temperature, stirring rate and sodium propargyl sulfonate concentration on the iron contents of the Fe‐Ni alloy foils were studied. The phase composition and surface morphology with various iron contents were characterized by X‐ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Cathodic polarization curves were used to evaluate the role of sodium propargyl sulfonate (PS).FindingsNanocrystalline Fe‐Ni alloy foil containing up to 64 wt. percent iron can be obtained from a chloride‐sulfate based solution. The foil converts from a face‐centered cubic (fcc) Fe3Ni2 phase to a mixture of fcc and body‐centered cubic (bcc) Fe7Ni3 with increase in iron content from 55.0 wt. percent to 63.5 wt. percent. AFM studies revealed that the foil had a fine grain structure with a roughness of 30 nm and grain size of 30 nm. With iron increasing to 63.5 wt. percent some islands appeared on the surface. This structure was related to the development of a (200) fiber texture in the BCC phase. Sodium propargyl sulfonate accelerates the discharge of nickel and inhibits the discharge of Fe.Practical implicationsThe foil has many industrial applications in the area of memory devices for computers, laser components and precise instruments.Originality/valueThe paper presents a process to produce a foil with iron up to 64 wt. percent from a chloride‐sulfate based solution used in normal DC mode. The dependence of microstructure and surface morphology on iron contents also is presented. Until now, there has been little research or reports on this subject.

Li 1.6 Mn 1.6 O 4 was prepared by calcinating orthorhombic LiMnO 2 at 410 °C, which was synthesized using a hydrothermal reaction with LiOH and Mn 2 O 3 as the starting reagents. After the Li 1.6 Mn 1.6 O 4 had been leached with diluted hydrochloric acid, an ion-sieve for lithium (H 1.6 Mn 1.6 O 4 ) was obtained. The pickling reaction reached balance quickly, the ratio of extracted lithium was above 90% and the loss ratio of dissolved Mn was under 2.5%. Physical analysis showed that the basic microstructure and surface topography of the materials remained unchanged in the process of pickling and adsorption. The chemical stability of the materials was sufficiently high. The adsorption capacity rose sharply when the pH value was greater than 11; a buffer system was essential to increase the adsorption capacity in weak acidic solution. The adsorption reaction could reach balance quickly in brine because of an increase in temperature; the maximum uptake of lithium from brine was 27.15 mg/g at 50 °C. Dissolved Mn did not affect the adsorption capacity. The adsorption rate of lithium from brine was over 99% under certain conditions in brine. Circulation tests showed that the adsorption capacity decreased as the number of cycles increased. The adsorption and desorption capacity were still more than 20 mg/g after 10 cycles. Larger separation coefficients indicated that high concentrations of Mg 2+ , Na + , and K + in brine had a slight adverse effect on lithium recovery using an ion-sieve, and the final lithium carbonate of reagent grade was obtained by a series of steps.

The extraction of molybdenum from low-grade Ni–Mo ore in sodium hypochlorite solution under mechanical activation was studied. The results show that the following parameters such as leaching time, liquid-to-solid ratio, pH value, sodium hypochlorite and sodium carbonate concentrations have significant effects on the recovery rate of molybdenum. The recovery rate of molybdenum reaches 96.3%, which is much higher than conventional agitation system (73.0%). It is suggested that an increase of surface area and phase transformation under mechanical activation should be responsible for the improved leaching recovery of molybdenum. After purification, the leaching liquor was acidified with HCl to precipitate ammonium molybdate followed by calcination to obtain high purity MoO 3 .

The leaching of gold in thiourea–thiocyanate solutions has been studied by the rotating-disc technique using ferric sulfate as oxidant. The effects of initial concentrations of ferric, thiourea (Tu) and thiocyanate as well as temperature and pH on gold leaching rates were studied. An initial gold leaching rate in the order of 10− 9 mol cm− 2 s− 1 was obtained at 25 °C, which was higher than rates obtained when either ferric–thiocyanate or ferric–thiourea solutions were used separately. The synergistic effect was attributed to the formation of a mixed ligand complex Au(Tu)2SCN. Determinations of apparent activation energy indicate that the process was controlled by a combination of chemical reaction and diffusion in the mixed lixiviant system. Open circuit potentials show that thiocyanate stability is increased in the mixture.

The mechanism of gold dissolution in acidic thiourea (Tu) solutions was investigated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). CV over the potential range of −0.3 to 0.75 V vs. SCE shows peaks for the Tu/FDS (formamidine disulfide) and Au / Au ( Tu ) 2 + redox reactions. An oxidation peak associated with gold dissolution occurs at ϕ ⩾ 0.36 V vs. SCE. This peak is often not observed in the first scan and its presence and magnitude are sensitive to the positive sweep potential limit of the first scan. FDS addition to the solution or adsorbed on the electrode has a strong catalytic effect and makes gold dissolution peak shift to lower potential during the first scan. This catalytic effect is identical to that exerted by scanning to higher potential. Tu/FDS ratio has a significant effect on thiourea stability, and it should be about 10:1 for the minimum thiourea decomposition and maximum gold dissolution rate. EIS results at 0.5−0.7 V vs. SCE with only Tu initially present in solution reveal a high-frequency capacitive loop associated with double layer charging, a medium-frequency inductive loop associated with FDS adsorption, and a low-frequency capacitive loop related to Tu oxidation. It appears that FDS adsorption on the gold surface activates the dissolution of gold and inhibits the oxidation of Tu.

Gold dissolution in acidic solutions containing thiourea (Tu) and thiocyanate was studied using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). In the presence of Tu, but in the absence of thiocyanate, passivation of gold occurred due to thiourea adsorption. When the solution also contained thiocyanate, passivation was significantly alleviated and gold dissolution enhanced. EIS revealed only one capacitive loop at 0.3 and 0.4V vs. SCE. The combination of the lixiviants lowered the polarization resistance for gold dissolution. A molar SCN:Tu ratio of 5:1 produced the lowest polarization resistance.

Gold dissolution in acidic solutions containing thiourea (Tu) and thiocyanate was studied using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and surface enhanced Raman spectroscopy (SERS). A synergistic response found in that mixed ligand system promoted a higher dissolution rate than either lixiviant alone. The passivation of gold occurs in a Tu only solution, but when thiocyanate is mixed with Tu, passivation is significantly alleviated. The dissolution rate of gold in the mixed lixiviant system increases with increasing Tu and thiocyanate concentration. Results from LSV and EIS indicate that gold dissolution is controlled by a combination of charge transfer and diffusion in the mixed lixiviant system. The optimum concentration for Tu and thiocyanate is about 5 mM and 0.05 M, respectively for the rate of gold dissolution. SERS results suggest a possible formation of a mixed ligand complex involving the interaction of Au(Tu) 2 + and SCN − . Further study is necessary to identify the mixed ligand complex.

The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H2SO4 concentration, particle size of crude ore and agitation rate on the leaching efficiency of copper were also evaluated. And the kinetic equations of the leaching process were obtained. The results show that the leaching process can be described with a reaction model of shrinking core. The reaction can be divided into three stages. The first stage is the dissolution of free copper oxide and copper oxide wrapped by hematite-limonite ore. At this stage, the leaching efficiency is very fast (leaching efficiency is larger than 60%). The second stage is the leaching of diffluent copper oxides, whose apparent activation energy is 43.26 kJ/mol. During this process, the chemical reaction is the control step, and the reaction order of H2SO4 is 0.433 84. The third stage is the leaching of copper oxide wrapped by hematite-limonite and silicate ore with apparent activation energy of 16.08 kJ/mol, which belongs to the mixed control.

The kinetics of Fe3O4 formation by air oxidation of slightly acidic suspension of Fe(OH)2 was studied. The effects of initial concentration of Fe(II), temperature, partial pressure of oxygen, air flow rate and stirring rate on the oxidation rate were investigated. The results show that Fe3O4 formation is composed of two-step reaction, the first step is the formation of Fe(OH) 2 + by oxidation of Fe(OH)+ complex ions, the second step is the formation of magnetite by dehydration and deprotonation of Fe(OH)+ and Fe(OH) 2 + . The oxidation reaction is zero-order with respect to the concentration of Fe(II) and around 0.5-order with respect to partial pressure of oxygen, and oxygen transfer process is rate-limiting step of oxidation reaction with apparent activation energy of 2.74 kJ · mol−1.

A novel chitosan coated poly(butyl cyanoacrylate) (PBCA) nanoparticles loaded doxorubicin (DOX) were synthesized and then conjugated with folic acid to produce a folate-targeted drug carrier for tumor-specific drug delivery. Prepared nanoparticles were surface modified by folate for targeting cancer cells, which is confirmed by FTIR spectroscopy and characterized for shape, size, and zeta potential measurements. The size and zeta potential of prepared DOX-PBCA nanoparticles (DOX-PBCA NPs) were almost 174 ± 8.23 nm and +23.14 ± 4.25 mV, respectively with 46.8 ± 3.32% encapsulation capacity. The transmission electron microscopy study revealed that preparation allowed the formation of spherical nanometric and homogeneous. Fluorescent microscopy imaging and flow cytometry analysis revealed that DOX-PBCA NPs were endocytosed into MCF-7 cells through the interaction with overexpressed folate receptors on the surface of the cancer cells. The results demonstrate that folate-conjugated DOX-PBCA NPs drug delivery system could provide increased therapeutic benefit by delivering the encapsulated drug to the folate receptor positive cancer cells.