Reduction-Sulfurization Smelting Process of Waste Hydrogenation Catalysts, Automotive Exhaust Purifier Waste Catalysts, and Laterite Nickel Ore.

Reduction-sulfurization smelting is an effective method for treating solid hazardous waste and recovering valuable components from them. In this work, a waste hydrogenation catalyst (WHC), an automotive exhaust purifier waste catalyst (AEPWC), a vulcanizer, and laterite nickel ore were mixed, and the reduction smelting behavior of this solid waste was investigated. XRD (X-ray diffractometry), TG-DSC (thermogravimetric/differential scanning calorimetry), SEM-EDS (scanning electron microscopy-energy dispersive spectroscopy), OM (optical microscopy), and ICP-OES (inductively coupled plasma-optical emission spectrometry) methods were used to examine the chemical composition, thermal stability, structure, and morphology, as well as the metal content of the samples. Under the Al2O3-FeO-SiO2 ternary slag system, at a smelting temperature of 1450 °C, smelting time of 2 h, mass ratio of coke, pyrite, and CaO to waste catalysts of 16, 25, and 0%, respectively, nickel (Ni) and molybdenum (Mo) recovery reached 91.1 and 92.9%, respectively, where average PGMs (platinum group metals, platinum (Pt), palladium (Pd), rhodium (Rh)) recovery reached 96%, although vanadium (V) recovery was only 25.1%. The characterization of the slag shows that Al, Si, and Fe are mainly bound in the form of chemical compounds, while V is intercalated with ferro- or aluminosilicate, which hinders the reduction and sulfurization of V. A series of tests using reduction smelting without sulfurization were also conducted, after which the Ni, Mo, and V recovery reached 96.8, 96.6, and 89.7%, respectively, while PGMs (Pt, Pd, Rh) recovery ranges from 90.2 to 98.0%. The collaborative disposal of primary ore and multisource solid waste has been achieved through two process paths: reducing smelting and reducing sulfurization smelting, which provide reference for the collaborative smelting of multisource secondary resources.

Correction: Wu et al. Full-Color See-Through Three-Dimensional Display Method Based on Volume Holography. Sensors 2021, 21, 2698.

The authors make the following corrections to the published paper [...].

Optical Encryption Based on Computer Generated Holograms in Photopolymer.

An optical encryption method based on computer generated holograms printing of photopolymer is presented. Fraunhofer diffraction is performed based on the Gerchberg-Saxton algorithm, and a hologram of the Advanced Encryption Standard encrypted Quick Response code is generated to record the ciphertext. The holograms of the key and the three-dimensional image are generated by the angular spectrum diffraction algorithm. The experimental results show that large-size encrypted Quick Response (QR) code and miniature keys can be printed in photopolymers, which has good application prospects in optical encryption. This method has the advantages of high-density storage, high speed, large fault tolerance, and anti-peeping.

Full-Color See-Through Three-Dimensional Display Method Based on Volume Holography.

We propose a full-color see-through three-dimensional (3D) display method based on volume holography. This method is based on real object interference, avoiding the device limitation of spatial light modulator (SLM). The volume holography has a slim and compact structure, which realizes 3D display through one single layer of photopolymer. We analyzed the recording mechanism of volume holographic gratings, diffraction characteristics, and influencing factors of refractive index modulation through Kogelnik's coupled-wave theory and the monomer diffusion model of photopolymer. We built a multiplexing full-color reflective volume holographic recording optical system and conducted simultaneous exposure experiment. Under the illumination of white light, full-color 3D image can be reconstructed. Experimental results show that the average diffraction efficiency is about 53%, and the grating fringe pitch is less than 0.3 µm. The reconstructed image of volume holography has high diffraction efficiency, high resolution, strong stereo perception, and large observing angle, which provides a technical reference for augmented reality.

A novel composite of almandine supported humboldtine nanospheres, in situ synthesized from natural almandine, possesses high removal efficiency of Cr(â ¥) over a wide pH range.

Preparing a cost-effective material which can been applied in a wide pH range is very crucial for the remediation of Cr(Ⅵ) polluted water. In this study, a novel material, almandine/humboldtine nanospheres (AHN) composites, was synthesized directly from almandine by one-pot method. Characterizations of XRD and SEM/TEM showed that the structure changes of almandine to nano-humboldtine leaded to significant increase of Cr(Ⅵ) removal capacities. And 96.45% of Cr(Ⅵ) was removed by AHN-24 composite at pH value of 3, initial Cr(Ⅵ) concentration of 20 mg/L, temperature of 298.15 K and dosage of 0.6 g/L. Furthermore, Cr(Ⅵ) removal capacity was only decreased from 48.23 mg/g to 34.33 mg/g when the initial pH value increased from 3 to 11, which demonstrated that the synthesized composite had a wide pH application range in Cr(Ⅵ) removal. The thermodynamic parameters (ΔG0 < 0, ΔH0 > 0 and ΔS0 > 0) illustrated that Cr(VI) removal process was spontaneous and endothermic. FTIR and XPS revealed that the Cr(Ⅵ) removal mechanisms included reduction-precipitation and reduction-complexation. Combined with cost analysis, all of results implied that the synthesized composites were a high efficient and low cost material for Cr(Ⅵ) pollution remediation in a wide pH range.

Heavy metal ions removed from imitating acid mine drainages with a thermoacidophilic archaea: Acidianus manzaensis YN25.

Metals in acid mine drainages (AMD) have posed a great threat to environment, and in situ economic environment-friendly remediation technologies need to be developed. Moreover, the effects of acidophiles on biosorption and migrating behaviors of metals in AMD have not been previously reported. In this study, the extremely thermoacidophilic Archaea, Acidianus manzaensis YN25 (A. manzaensis YN25) was used as a bio-adsorbent to adsorb metals (Cu2+, Ni2+, Cd2+ and Zn2+) from acidic solutions which were taken to imitate AMD. The values of their maximum biosorption capacities at both high (1 mM) and low (0.1 mM) metal concentrations followed the order: Cu2+ > Ni2+ > Cd2+ > Zn2+. With the elevations of temperature and pH value, the adsorption amounts of metals increased. The results also indicated that A. manzaensis YN25 had the highest adsorption affinity to Cu2+ in coexisting system of quaternary metals. Acid-base titration data revealed that carboxyl and phosphoryl groups provided adsorption sites for metals via deprotonation. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) further corroborated that amino played an important role in the biosorption process. The fitted Langmuir model illustrated monolayer adsorption occurring on cell surface. The possible adsorption mechanism of A. manzaensis YN25 mainly involved in electrostatic attraction and complexes formation. This study gives a profound insight into the biosorption behavior of heavy metals in acidic solution by thermoacidophilic Archaea and provides a probable novel strategy for in situ remediation of heavy metals pollution in AMD.