Increasing demands for environmental accountability and energy efficiency in industrial practice necessitates significant modification(s) of existing technologies and development of new ones to meet the stringent sustainability demands of the future. Generally, development of required new technologies and appropriate modifications of existing ones need to be premised on in-depth appreciation of existing technologies, their limitations, and desired ideal products or processes. In the light of these, published literature mostly in the past 30 years on the sealing process; the second highest energy consuming step in aluminum anodization and a step with significant environmental impacts has been critical reviewed in this systematic review. Emphasis have been placed on the need to reduce both the energy input in the anodization process and environmental implications. The implications of the nano-porous structure of the anodic oxide on mass transport and chemical reactivity of relevant species during the sealing process is highlighted with a focus on exploiting these peculiarities, in improving the quality of sealed products. In addition, perspective is provided on plausible approaches and important factors to be considered in developing sealing procedures that can minimize the energy input and environmental impact of the sealing step, and ensure a more sustainable aluminum anodization process/industry.

/pdf/the-sealing-step-in-aluminum-anodizing-a-focus-on-11dzf1jz53.pdf

The Sealing Step in Aluminum Anodizing: A Focus on Sustainable Strategies for Enhancing Both Energy Efficiency and Corrosion Resistance

Synthesis and certification of lanthanum oxide extracted from monazite sand have been carried out. This research aimed to increase the added value of monazite sand and obtain the lanthanum oxide in-house certified reference material (CRM). Synthesis of lanthanum oxide consists of several stages, namely: monazite sand digestion, rare-earth elements hydroxide [REE(OH) 3 ] precipitation, Ce separation, Nd separation, lanthanum oxalate precipitation, and calcination. Certification of lanthanum oxide was carried out by determining the average concentration of the oxides and its uncertainty from the seven accredited laboratories by the ISO 35-2006 statistical method. Two other minerals in the lanthanum oxide analyzed by the XRD method were cerium hydroxide [Ce(OH) 3 ] and neodymium yttrium oxide fluoride (Nd 2 Y 2 O 3 F 16 ). Lanthanum oxide certified contains ten oxides, with the two highest concentrations of La 2 O 3 (91.662 ± 0.007)% and Nd 2 O 3 (3.949 ± 0.002)%. Lanthanum oxide has met the qualification in-house CRM since it contained water less than 1%, was homogeneous, stable, and certified. La 2 O 3 concentration in the lanthanum oxide in-house CRM from CSAT-BATAN, Indonesia was not significantly different in comparison to that from the Department of Chemical Engineering, Srinakharinwirot University, Thailand. Lanthanum oxide extracted from monazite sand can be used as reference material in determining the lanthanum oxide quality from the pilot plant process.

/pdf/synthesis-and-certification-of-lanthanum-oxide-extracted-d7pw9vk8f0.pdf

Synthesis and Certification of Lanthanum Oxide Extracted from Monazite Sand

Pure cerium sulfate was prepared from economic natural resources using Egyptian monazite rare earth cake. About 90% of the former was extracted by tri-butyl phosphate in kerosene at the optimum conditions: 15% solvent concentration, equilibrium pH of 1.7, equilibrium time 7 min and O/A ratio of 1/1. The aim of the present work was studying the corrosion inhibition properties of cerium sulfate towards aluminum alloy AA6061 in two solutions; 1.0 M disodium hydrogen orthophosphate and 3.5 % sodium chloride (simulation of sea water). The corrosion inhibition was evaluated using electrochemical techniques under different experimental conditions. The results showed that, in the presence of cerium sulfate, the AA6061 surface is well protected due to formation of passive film composed of Ce2O3/Ce(OH)3 which precipitated on the electrode surface.

https://ejchem.journals.ekb.eg/article_148664_22f66fd4b6c5dbfbe2837d44731f682f.pdf

Cerium sulfate preparation from Egyptian monazite's rare earth cake for its application as corrosion inhibitor of aluminum alloy AA6061

Bangka Tin Slag (BTS) was a tin-smelting waste containing high silica and other elements that have high economic value, including cerium, which is a rare earth element. Silica and Ce 2 O 3 contents in BTS were 32.86 % and 1.35 % respectively. Other elements that have high concentrations in BTS include 15.46 % of CaO, 10.88 % of Al 2 O 3 , and 9.20% of Fe 2 O 3 . The objective of this study was to determine the optimum conditions for cerium extraction using HCl, which includes HCl concentration, temperature, particle size, stirring speed, and dissolution time. In addition, the effect of these parameters on Ce extraction was also studied. The one-factor-at-time method was used to determine the optimum conditions. Pretreatment of BTS with the alkaline fusion method and water leaching was done to reduce both the silica content and increasing its porosity. Alkaline fusion carried out at 700 ℃ using NaOH converts the silica into water-soluble sodium silicate. Characterization of the slag structure before and after the pretreatment process was completely carried out by using X-ray diffraction (XRD), X-ray fluorescence (XRF), Scanning electron microscope (SEM), and optical microscope. Furthermore, measurement of Ce content in the filtrate of the dissolution process was performed with inductively coupled plasma – optical emission spectrometry (ICP-OES). The results showed that the optimum of 75.16 % Ce was extracted by using some parameter conditions, namely by 2.5 M of HCl concentration, at the temperature of 40 ℃, with the particle size of –325 mesh, stirring speed of 150 rpm, and dissolution time of 180 minutes. Each parameter gives a significant effect on Ce extraction, wherein the initial stage, the increase in the value of each parameter gives an increase in Ce extraction and begins to decrease when equilibrium occurs

/pdf/a-study-of-cerium-extraction-from-bangka-tin-slag-using-ru38bpbpxp.pdf

A study of cerium extraction from Bangka tin slag using hydrochloric acid

Rare earth elements (REEs) is the name given to 15 elements from the lanthanide group and 2 elements have the same chemical properties that make them included in the REEs, namely scandium and yttrium. The use of rare earths triggers the development of new materials for application, one of which is cerium metal. Currently, cerium is widely applied in industry to improve product quality, one

Oksidasi Serium Berdasarkan Agen Pengoksidasi Oxidation of Cerium Based on Oxidizing Agents

The present work describes the development of an efficient and relatively simple process to obtain high grade Ce(OH)4 from REOH (Rare earth hydroxide). The Rare earth hydroxide was obtained through base digestion of monazite. The steps investigated in the process for obtaining Ce(OH)4 were: (i) i) dissolution RE hydroxide (REOH) with HNO3 and oxidation of ce+3 to ce-4 , (ii) selective precipitation of Ce(OH)4 with Na2CO3, (i i i) selective precipitation of Nd(OH)3 with ammonium hydroxide (iv} precipitation of La with oxalic acid. The main variables affecting the cerium oxidation were: the ratio of the K MnO4 /REOH, temperature and oxidation time. A ratio of 1 .25110 of KMnO4 I R EOH was necessary for full cerium recovery. The recovery of cerium increases as temperature and oxidation time rises, the purity of the product Ce(OH)4 at the pH above 4. The process conditions were achieved in the use of 1.25/ I 0, KMnO4/REOH ratio, at the 1 20°C and the oxidation time of 75 minutes. The composition of the final product Ce(OH)4 was 97.98 wt.% Ce(OH)4, i n a process yielding a recovery of Ce greater than 93%, were obtained. The composition of the final product Nd(OH)3 was 37 wt.% Nd(OH)3, in a process yielding a recovery of Nd greater than 98%, were obtained. The composit ion of the final prod uct La2(C2O4)3 was 90 wt.% La2(C2O4)3, in a process yielding a recovery of La greater than 93%. were obtained. The oxidation of Ce3+ to Ce4 ' using KMnO4 follows first order reaction. The value of reaction rate constant of Ce was 0.0291 minutes.

https://iopscience.iop.org/article/10.1088/1742-6596/1198/3/032003/pdf

M V Purwani

Papers

Separation of Ce, La and Nd in Rare Earth Hydroxide (REOH) by Oxidation with Potassium Permanganate and Precipitation