Enhanced copper removal from aqueous solution by hydrous TiO2/zeolite composite
Hui Deng, Yu Zhang and Sheng Geng
College of Chemistry, Chemical Engineering and Environmental Engineering, Liaoning Shihua University, Fushun, People’ s Republic of China
ABSTRACT
Hydrous titanium dioxide was impregnated on the surface of zeolite to obtain a kind of hydrous TiO2/zeolite (HTiO2/ZFA) adsorbent using the hydrothermal method. HTiO2/ZFA was characterised by scanning electron microscopy combined with energy-dispersive spectrometer, X-ray diffraction, Fourier transform infrared, particle size distribution; and the pH of zero point charge measurement and its performance for Cu(II) adsorption were investigated. It was shown that Ti was not inserted into the skeleton of ZFA and hydrous TiO2 loaded on the surface was amorphous. The pHzpc of HTiO2/ZFA decreased to pH 5.5
from pH 6.5 of ZFA. Cu(II) adsorption was favoured in a pH range of 3.0–6.0, and 90% copper could be removed in first 30 min for 60 mg L–1 Cu(II) solution. The Langmuir isotherm model could well describe the adsorption isotherm data and the maximal Cu(II) adsorption capacity reached 251.9 mg g–1 . Moreover, the HTiO2/ZFA could be desorbed by HCl solution for further use, which implied an effective application in wastewater treatment.
KEYWORD S
HTiO2/ZFA; Cu(II) adsorption; hydrothermal method
From cation flexibility to multifaceted industrial adoptability: a voyage to the
resourceful spinel*
Debasmita Dwibedi
Faraday Materials Laboratory, Materials Research Centre, Indian Institute of Science, Bangalore, India
ABSTRACT
Signature of cation flexibility associated with the order– disorder structure of three spinel families, namely aluminates (MgAl2O4/ZnAl2O4), ferrites (NiFe2O4/ZnxNi1 −xFe2O4), and titanate (Li4Ti5O12) was probed using the X-ray diffraction and Raman spectroscopy. Cation flexibility
(also known as antisite defects or (dis)order structural transitions) is a unique feature of many oxide AB2O4 spinel systems in which the cations exchange their sites under external influence. This feature generates functionality in many different ways. In some cases, such as ferrites, the flexibility of zinc to occupy tetrahedral sites enhances the magnetic properties, whereas the flexibility of lithium in lithium titanate brings exotic electrochemical feature with zero strain. Similarly, cation flexibility of magnesium and aluminium makes the structure tolerant towards nuclear irradiation. Some such salient features of spinel systems are described highlighting the underlying crystal structures. Enriched with enormous chemical versatility, order–disorder structure, vacancy, interstitials and mixed-cation occupancy, ‘Spinel is a world in itself’. This is why, exploring its huge accomplishments never gets enough. Ever wonder, where from this versatility stems in! This review endeavours to seek the answer by combining the flexible order–disorder structure, supporting diagnosis tools and tuneable properties of this versatile class: The Spinels.
KEYWORD S
Cation flexibility; spinel structure; Raman spectroscopy; XRD
Glass-ceramic proppants from sinter-crystallisation of waste-derived glasses
Nicoletta Tonioloa,b, Acacio Rincon Romero a, Mauro Marangonia, Mohammed Binhussain c,
Aldo R. Boccaccini b and Enrico Bernardo a
aDipartimento di Ingegneria Industriale, University of Padova, Italy; bInstitute of Biomaterials, University of Erlangen, Germany;
cNational Program for Advanced Materials and Building System, KACST, Riyadh, Saudi Arabia
ABSTRACT
The present investigation aims at evidencing the feasibility of glass-ceramic spheres by sintercrystallisation of fine glass powders (<100 μm), in turn obtained by the melting of inorganic waste, such as red mud from Bayer process or municipal solid waste incinerator fly ash, or low-cost minerals. While dense and highly crystallised monoliths may be achieved by sintering pressed glass powders just at the glass crystallisation temperature (TC), applying fast heating and short holding times, dense glass-ceramic beads could be obtained only by firing well above Tc (Tc + 100°C). An increased sintering temperature was applied in order to
enhance the viscous flow and promote the spheroidisation of powder clusters, previously formed by casting fine powders on a rotating drum. The high degree of crystallinity and the uniform microstructure were found to contribute positively to the mechanical properties (compressive strength exceeding 120 MPa, for beads with a diameter of 1 mm, approximately).
KEYWORD S
Glass-ceramics; sintering; crystallisation; hydraulic fracking; proppant
High-performance ceramic parts with complex shape prepared by selective
laser sintering: a review
An-Nan Chena,b, Jia-Min Wua,b, Kai Liuc, Jing-Yan Chena,b, Huan Xiaoa,b, Peng Chena,b, Chen-Hui Lia and
Yu-Sheng Shia
aState Key Laboratory of Material Processing and Die & Mould Technology, School of Material Science and Engineering, Huazhong University of Science and Technology, Wuhan, China; bResearch Institute of Huazhong University of Science and Technology in Shenzhen, Shenzhen, China; cSchool of Material Science and Engineering, Wuhan University of Technology, Wuhan, China
ABSTRACT
Selective laser sintering (SLS) is an additive manufacturing technology which has shown great advantages in direct formation of the polymer, metal and their composites. However, ceramic parts prepared by the SLS still exhibit some fatal defects, including low density and poor mechanical properties. In this respect, recent advances for preparing ceramics have improved the final density and performance by adopting post-processing methods. In this review, three commonly used powder preparation approaches (i.e. mechanical mixing, solvent evaporation and dissolution-precipitation process) and two powder sintering mechanisms for the SLS are introduced. Porous ceramic parts are prepared directly through the SLS by virtue of their high porosity. And dense, high-performance Al2O3, ZrO2, kaolin and SiC ceramic parts with complex shape are prepared by introducing CIP technology into the SLS, indicating that the hybrid technology could be the promising route for preparing highperformance ceramic parts used in various fields.
KEYWORD S
Selective laser sintering; cold isostatic pressing; porous ceramics; dense ceramics; mechanical properties
Self-propagating high-temperature synthesis, phase composition and aqueous
durability of Nd– Al bearing zirconolite-rich composites as nuclear waste form
Kuibao Zhanga,b, Dan Yina, Xirui Lub and Haibin Zhangc
aState Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang, People’s Republic of China; bNational Defense Key Discipline Lab of Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang, People’s Republic of China; cInstitute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, People’s Republic of China
ABSTRACT
In this study, the zirconolite-rich composite was rapidly synthesised from self-propagating hightemperature synthesis plus quick pressing using MoO3 as the oxidant and Ti as the reductant. As a surrogate of trivalent actinides, Nd was introduced to substitute the Ca site of zirconolite and Al was employed as the charge compensator to replace the Ti site (nominally Ca1 −xNdxZrTi2 –xAl
xO7). The phase composition and Nd occupancy were analysed after Nd2O3 addition. Ndbearing zirconolite was produced as the major ceramic phase. Nd mostly substitutes the Ca sites of zirconolite, which results in waste loading higher than 8.6 wt-% Nd. The aqueous durability of Nd–Al codoped sample (with 15 at.-% Nd substitutes the Ca site of zirconolite) was evaluated at 90°C as well.The 42 days normalised leaching rates of Mo, Ca and Nd were measured to be 3.70, 1.90 × 10 −2 and
3.46 × 10 −4 g m −2 d −1 .
KEYWORD S
Self-propagating hightemperature synthesis; zirconolite; MoO3; nuclear waste immobilisation; aqueous durability
