Mechanism of highly efficient oil removal from spent hydrodesulfurization catalysts by ultrasound-assisted surfactant cleaning methods.

The removal of crude oil from spent hydrodesulfurization catalysts constitutes the preliminary stage in the recovery process of valuable metals. However, the traditional roasting method for the removal exhibits massive limitations. In view of this, the present study used an ultrasound-assisted surfactant cleaning method to remove crude oil from spent hydrodesulfurization catalysts, which demonstrated effectiveness. Furthermore, the study investigated the mechanism governing the process with calculation and experiments, so as to provide a comprehensive understanding of the cleaning method's efficacy. The surfactant selection was predicated on the performance in the IFT test, with SDBS and TX-100 finally being chosen. Subsequent calculations and analysis were then conducted to elucidate their frontier molecular orbitals, electrostatic potential, and polarity. It has been found that both SDBS and TX-100 possess the smallest LUMO-HOMO energy gap (ΔE), registering at 4.91 eV and 4.80 eV, respectively, and presenting the highest interfacial reactivity. The hydrophilic structure in the surfactant regulates the wettability of the oil-water interface, and the long-chain alkanes have excellent non-polar properties that promote the dissolution of crude oil. The ultrasonic-assisted process further improves the interface properties and enhances the oil removal effect. Surprisingly, the crude oil residue was reduced to 0.25% under optimal conditions. The final phase entailed the techno-economic evaluation of the entire process, revealing that, in comparison to the roasting method, this process saves $0.38 per kilogram of spent HDS catalyst, with the advantages of operational simplicity and emission-free. Generally, this study shed new light on the realization of efficient oil removal, with the salience of green, sustainable, and economical.

Postsynthetic of MIL-101-NH2 MOFs supported on PVDF membrane for REEs recovery from waste phosphor.

With the increasing demand for rare earth elements (REEs) due to their wide application in high technology, their recovery and separation from waste sources has gradually come onto the agenda. Herein, a new kind of MIL-101-NH2 (M1N) MOF functionalized with diethanol anhydride (DGA) incorporated into a polyvinylidene fluoride (PVDF) membrane (DGA-M1N@PVDF) has been fabricated for the sorption of REEs from a simulated acid leaching solution of waste phosphor, which contains a large amount of REEs. FTIR, TGA, XRD, fluorescence spectra and XPS analysis were used to characterize the synthesized composite membrane. Batch tests were employed to determine the optimal sorption conditions for Y and Eu adsorbed on DGA-M1N@PVDF adsorbent, such as pH (1-5), content of M1N MOFs (0-40 wt%), contact time (10-180 min) and ion concentration (0-20 mg L-1). Maximum adsorption capacities for Y and Eu on DGA-M1N@PVDF reached 991.7 µg g-1 and 98.76 µg g-1 for trace REE solution, respectively. Moreover, a pseudo-second-order kinetic model accurately described the sorption process, and the plotted isothermal data indicated that the Langmuir model was more suitable than the Freundlich model for Y and Eu sorption with monolayer and chemical adsorption. Meanwhile, FTIR and XPS analyses revealed that the Y and Eu adsorption on the DGA-M1N@PVDF composite membrane was mainly caused by the N and O atoms of the -CONH or -COOH groups coordinated with metal ions. Furthermore, after five cycles, the recovery efficiency by DGA-M1N@PVDF for REEs remains above 82% and the XRD patterns were consistent with the original sample, which implied that the DGA-M1N@PVDF membrane has preferable stability, recyclability and good efficiency in REE separation from waste phosphor solutions.

Phosphorous-functionalized PAMAM dendrimers supported on mesoporous silica for Zr(iv) and Hf(iv) separation.

To overcome the urgency of zirconium and hafnium separation, a novel mesoporous silica sorbent (PS-G1.0-MSNs) modified with phosphorous-functionalized G1.0 PAMAM dendrimers was prepared. The adsorption and separation behaviors of PS-G1.0-MSNs adsorbent on Zr(iv) and Hf(iv) were perfromed as a function of acidity, contact time, temperature, and ion concentrations by batch sorption methods. The maximum adsorption capacities for Zr(iv) and Hf(iv) were 25.7 mg g-1 and 5.36 mg g-1 under optimal experimental conditions, respectively, and the separation factor ß Hf/Zr = 2.0 > 1 demonstrated that the prepared sorbent had preferential selectivity for Hf(iv) in rich Zr(iv) solution. Moreover, kinetic data indicated that the sorption process on Zr(iv) and Hf(iv) achieved equilibrium within 120 min, and followed the pseudo-first-order model with a rate-determining step. The adsorption amount increased as temperature raised from 283 K to 303 K and the isothermal data plotted with the Langmuir model was better than the Freundlich model with monolayer behavior. Thermodynamic data analysis indicated that the sorption process was spontaneous and endothermic. Furthermore, XPS analysis revealed that the metal ion adsorption was mainly induced by the chemical coordination of Zr(iv) and Hf(iv) ions with N, O, P atoms of amide and phosphate groups. The present work provides good guidelines on the design of high efficient sorbent for the separation of Hf(iv) from Zr(iv) solutions.

Temperature-induced phase changes in bismuth oxides and efficient photodegradation of phenol and p-chlorophenol.

A novel, simple and efficient approach for photodegrading phenol and p-chlorophenol, based on BixOy, was reported for the first time. Monoclinic Bi2O4 was prepared by the hydrothermal treatment of NaBiO3·2H2O. A series of interesting phase transitions happened and various bismuth oxides (Bi4O7, ß-Bi2O3 and α-Bi2O3) were obtained by sintering Bi2O4 at different temperatures. The results demonstrated that the Bi2O4 and Bi4O7 phase had strong abilities towards the oxidative decomposition of phenol and p-chlorophenol and very high rates of TOC removal were observed. The characterization by XRD and XPS revealed that Bi(4+) in Bi2O4 and Bi(3.5+) in Bi4O7 were reduced to Bi(3+) during the reaction process. Singlet oxygen ((1)O2) was identified as the major reactive species generated by Bi2O4 and Bi4O7 for the photodegradation of p-chlorophenol and phenol. This novel approach could be used as a highly efficient and green technology for treating wastewaters contaminated by high concentrations of phenol and chlorophenols.

Synthesis and performance of Li[(Ni1/3Co1/3Mn1/3)(1-x)Mgx]O2 prepared from spent lithium ion batteries.

To reduce cost and secondary pollution of spent lithium ion battery (LIB) recycling caused by complicated separation and purification, a novel simplified recycling process is investigated in this paper. Removal of magnesium is a common issue in hydrometallurgy process. Considering magnesium as an important additive in LIB modification, tolerant level of magnesium in leachate is explored as well. Based on the novel recycling technology, Li[(Ni(1/3)Co(1/3)Mn(1/3))(1-x)Mg(x)]O(2) (0 ≤ x ≤ 0.05) cathode materials are achieved from spent LIB. Tests of XRD, SEM, TG-DTA and so on are carried out to evaluate material properties. Electrochemical test shows an initial charge and discharge capacity of the regenerated LiNi(1/3)Co(1/3)Mn(1/3)O(2) to be 175.4 mAh g(-1) and 152.7 mAh g(-1) (2.7-4.3 V, 0.2C), respectively. The capacity remains 94% of the original value after 50 cycles (2.7-4.3 V, 1C). Results indicate that presence of magnesium up to x=0.01 has no significant impact on overall performance of Li[(Ni(1/3)Co(1/3)Mn(1/3))(1-x)Mg(x)]O(2). As a result, magnesium level as high as 360 mg L(-1) in leachate remains tolerable. Compared with conventional limitation of magnesium content, the elimination level of magnesium exceeded general impurity-removal requirement.