Molecules

Research

Jump to: Review

20 pages, 12650 KiB

Open AccessArticle

Study of the Process of Calcium Sulfide-Based Luminophore Formation from Phosphogypsum

by Marina A. Egorova, Daniil I. Monastyrskiy, Oleg A. Medennikov, Nina P. Shabelskaya, Zlatislava D. Khliyan, Vera A. Ulyanova, Sergey I. Sulima and Elena V. Sulima

Molecules 2024, 29(22), 5486; https://doi.org/10.3390/molecules29225486 - 20 Nov 2024

Viewed by 313

Abstract

One of the priority goals of sustainable socio-economic development for the period up to 2030 is providing food for the planet’s population. This entails an increase in the output of mineral fertilizers and, consequently, an increase in the quantities of solid industrial waste. [...] Read more.

One of the priority goals of sustainable socio-economic development for the period up to 2030 is providing food for the planet’s population. This entails an increase in the output of mineral fertilizers and, consequently, an increase in the quantities of solid industrial waste. Phosphogypsum, a by-product of phosphate fertilizer production from apatite ore, is one example of such waste. The problem of solid industrial waste recycling is urgent. The present study examines the process of converting calcium sulfate, in the form of a reagent, and phosphogypsum into a composite material of calcium sulfate/sulfide. An environmentally friendly material, sucrose, is used as a reducing agent. Reduced phosphogypsum (as well as calcium sulfate) luminescence is suggested to be associated with the formation of a CaS/CaSO₄ composite material. The synthesized materials are characterized by X-ray phase analysis, X-ray photoelectron spectroscopy, elemental analysis, and calcium sulfide qualitative and quantitative content in the samples. It is shown that in the reduction process at the phase contact point, crystal grids are formed with a significant number of defects, which contributes to the convergence of some of the energy levels of the calcium cation and sulfide anion, facilitating the transitions of electrons from the valence zone to the core zone and the formation of luminescence centers (cross-luminescence). Both samples of reduced phosphogypsum and alkaline earth metal sulfates are found to exhibit luminescence properties under ultraviolet radiation. The data obtained open up broad prospects for the use of solid industrial waste for the synthesis of new materials. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Graphical abstract

12 pages, 4143 KiB

Open AccessArticle

Efficient Extraction and Separation of Scandium from Scandium-Bearing Solid Waste and Acid by Synergistically Leaching Followed by Solvent Extraction

by Wen Cao, Jinmao Hua, Xi Jin, Minyu He, Yuntao Xin and Weizao Liu

Molecules 2024, 29(19), 4766; https://doi.org/10.3390/molecules29194766 - 9 Oct 2024

Viewed by 629

Abstract

The solid waste and waste acid generated during the production of titanium dioxide contain considerable amount of scandium, which are valuable secondary resources. In this study, the titanium dioxide waste acid was used to leach the scandium-containing solid waste, and the leached solution [...] Read more.

The solid waste and waste acid generated during the production of titanium dioxide contain considerable amount of scandium, which are valuable secondary resources. In this study, the titanium dioxide waste acid was used to leach the scandium-containing solid waste, and the leached solution was pretreated for iron removal by reduction-crystallization process. After that, scandium was recovered from the leached solution by using the P204-TBP co-extraction system. The process parameters were investigated systematically. The results showed that iron powder reduction-crystallization for iron removal at molar ratio of Fe:Fe³⁺ = 0.25 was most suitable for subsequent extraction, and the scandium extraction efficiency could reach 100% using 15% P204-5% TBP at 25 °C with A/O = 8. This study provided a novel process for treating scandium-bearing solid waste with scandium-bearing waste acid, showing great potential for industrial application. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Figure 1

14 pages, 2283 KiB

Open AccessArticle

Enhancing the High-Solid Anaerobic Digestion of Horticultural Waste by Adding Surfactants

by Wangliang Li, Zhikai Zhang, Shuzhen Mi and Shengyong Zhao

Molecules 2024, 29(17), 4061; https://doi.org/10.3390/molecules29174061 - 27 Aug 2024

Viewed by 705

Abstract

The influence of adding surfactants on the performance of high-solid anaerobic digestion of horticultural waste was extensively investigated in batch systems. Adding Tween series and polyethylene glycol series non-ionic surfactants had positive effects on biogas production, resulting in 370.1 mL/g VS and 256.6 [...] Read more.

The influence of adding surfactants on the performance of high-solid anaerobic digestion of horticultural waste was extensively investigated in batch systems. Adding Tween series and polyethylene glycol series non-ionic surfactants had positive effects on biogas production, resulting in 370.1 mL/g VS and 256.6 mL/g VS with Tween 60 and polyethylene glycol 300 at a surfactant-to-grass mass ratio of 0.20, while the biogas production of anaerobic digestion without surfactants was 107.54 mL/g VS. The optimal and economically feasible choice was adding Tween 20 at a ratio of 0.08 g/g grass in high-solid anaerobic digestion. A kinetics model reliably represented the relationship between surfactant concentration and biogas production. The mechanism of surfactants working on lignocellulose was investigated. The improvement in high-solid anaerobic digestion by adding surfactants was attributed to the interaction between lignocelluloses and surfactants and the extraction of biodegradable fractions from the porous structure. An economic analysis showed that adding Tween 20 was likely to make a profit and be more feasible than adding Tween 60 and polyethylene glycol 300. This study confirms the enhancement in biogas production from horticultural waste by adding non-ionic surfactants. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Graphical abstract

17 pages, 3616 KiB

Open AccessArticle

Synergistic Leaching of Titanium, Aluminum, and Magnesium Components during Dilute Acid Pressure Treatment of High-Titanium Blast Furnace Slag

by Ke Yuan, Siqi He, Bo Yu, Shiyi Qian, Xueyu Wu, Wenyi Li and Chunmeng Zhao

Molecules 2024, 29(14), 3336; https://doi.org/10.3390/molecules29143336 - 16 Jul 2024

Viewed by 950

Abstract

This study focuses on an improved leaching process through the combination of pressurized conditions and direct filtration of acid leaching slurry, which is conductive to improving the filterability of acid leaching systems and the extraction rates of Ti, Al, and Mg components. The [...] Read more.

This study focuses on an improved leaching process through the combination of pressurized conditions and direct filtration of acid leaching slurry, which is conductive to improving the filterability of acid leaching systems and the extraction rates of Ti, Al, and Mg components. The effects of sulfuric acid concentration, reaction temperature, particle size of materials, acid–slag ratio, and reaction time on the leaching efficiency were systematically investigated. The results showed that pressurization significantly enhances the filtration efficiency of the reaction slurry. Under the same filtration time, the filtration efficiency increased from 46% under ordinary pressure to 78% under pressurized conditions. Moreover, under the optimal reaction conditions, the extraction rates of Ti, Al, and Mg components were more than 88.21%, 97.8%, and 96.31%, respectively. Additionally, XRD and FTIR showed that titanium oxide sulfate hydrate crystals were produced in the acid-leached residues when the reaction temperature exceeded 190 °C, thereby reducing the extraction rate of Ti component. And the XRD pattern shows that when the reaction temperature is maintained at 190 °C and the reaction time is extended to 150 min, titanium oxide sulfate hydrate crystals will be formed to reduce the extraction rate of the Ti component. In summary, this study not only provides important theoretical support for the resource utilization of high-titanium blast furnace slag but also offers a feasible solution for efficient extraction and convenient filtration, thus holding significant academic and practical implications. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Figure 1

16 pages, 1518 KiB

Open AccessArticle

The Development of Innovated Complex Process for Treatment of Old Flotation Tailings of Copper-Zinc Sulfide Ore

by Khussain Valiyev, Aliya Bugubaeva, Aleksandra Nechaeva, Alena Artykova, Vitaliy Melamud, Devard Stom, Anna Boduen and Aleksandr Bulaev

Molecules 2024, 29(7), 1550; https://doi.org/10.3390/molecules29071550 - 29 Mar 2024

Viewed by 1144

Abstract

The possibility of selective Cu and Zn leaching from the sample of old pyrite tailings, which is one of the most widespread types of solid waste forming during non-ferrous metal production, using sulfuric acid solutions and water was studied. It was shown that [...] Read more.

The possibility of selective Cu and Zn leaching from the sample of old pyrite tailings, which is one of the most widespread types of solid waste forming during non-ferrous metal production, using sulfuric acid solutions and water was studied. It was shown that water leaching provided selective extraction of Cu and Zn and comparatively low iron ion extraction. At the same time, acid leaching provided the obtainment of pregnant solutions with high ferric ion concentration, which can be used for oxidative leaching of substandard copper concentrates. Water and acid leaching also provided increased Au recovery by cyanidation. The results suggest that acid leaching can be an effective approach for processing old flotation tailings, which allows the extraction of base metals from these wastes and treating flotation tailings for subsequent cyanidation. Effective flotation treatment methods should also provide environmental load reduction, which is caused by the long-term storage of metal-bearing wastes. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Figure 1

13 pages, 5186 KiB

Open AccessArticle

The Effect of Nitrogen Functional Groups on Pb⁰, PbO, and PbCl₂ Adsorption over a Carbonaceous Surface

by Liang Wang, Huaizhou Wen, Lei Guo, Ancheng Liang, Tingan Liu, Dongxu Zhao and Lu Dong

Molecules 2024, 29(2), 511; https://doi.org/10.3390/molecules29020511 - 19 Jan 2024

Cited by 2 | Viewed by 1280

Abstract

Lead (Pb) pollution, especially from the incineration of municipal solid waste (MSW), poses a significant threat to the environment. Among all the effective methods, activated carbon (AC) injection serves as an effective approach for lead removal from flue gas, while the modification of [...] Read more.

Lead (Pb) pollution, especially from the incineration of municipal solid waste (MSW), poses a significant threat to the environment. Among all the effective methods, activated carbon (AC) injection serves as an effective approach for lead removal from flue gas, while the modification of ACs emerges as a crucial pathway for enhancing Pb adsorption capacities. Density functional theory (DFT) is employed in this study to investigate the mechanisms underlying the enhanced adsorption of Pb species (Pb⁰, PbO, and PbCl₂) on nitrogen-functionalized carbonaceous surfaces. The results show that nitrogen-containing groups substantially enhance lead adsorption capacity, with adsorption energies ranging from −526.18 to −288.31 kJ/mol on nitrogen-decorated carbonaceous surfaces, much higher than those on unmodified surfaces (−310.35 to −260.96 kJ/mol). Additionally, electrostatic potential and density-of-states analyses evidence that pyridinic nitrogen atoms remarkably expand charge distribution and strengthen orbital hybridization, thereby augmenting lead capture. This research elucidates the role of nitrogen-containing functional groups in lead adsorption, offering valuable insights for the development of highly efficient biomass-derived activated carbon sorbents for lead removal. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Figure 1

14 pages, 4983 KiB

Open AccessArticle

Recycling Coal Fly Ash for Super-Thermal-Insulating Aerogel Fiber Preparation with Simultaneous Al₂O₃ Extraction

by Jie Gu, Lipeng Liu, Rongrong Zhu, Qiqi Song, Hanqing Yu, Pengjie Jiang, Changqing Miao, Yuxiang Du, Rui Fu, Yaxiong Wang, Yan Hao and Huazheng Sai

Molecules 2023, 28(24), 7978; https://doi.org/10.3390/molecules28247978 - 6 Dec 2023

Cited by 2 | Viewed by 1656

Abstract

A large quantity of coal fly ash is generated worldwide from thermal power plants, causing a serious environmental threat owing to disposal and storage problems. In this work, for the first time, coal fly ash is converted into advanced and novel aerogel fibers [...] Read more.

A large quantity of coal fly ash is generated worldwide from thermal power plants, causing a serious environmental threat owing to disposal and storage problems. In this work, for the first time, coal fly ash is converted into advanced and novel aerogel fibers and high-purity α-Al₂O₃. Silica–bacterial cellulose composite aerogel fibers (CAFs) were synthesized using an in situ sol-gel process under ambient pressure drying. Due to the unique “nanoscale interpenetrating network” (IPN) structure, the CAFs showed wonderful mechanical properties with an optimum tensile strength of 5.0 MPa at an ultimate elongation of 5.8%. Furthermore, CAFs with a high porosity (91.8%) and high specific surface area (588.75 m²/g) can inherit advanced features, including excellent thermal insulation, stability over a wide temperature range, and hydrophobicity (contact angle of approximately 144°). Additionally, Al₂O₃ was simultaneously extracted from the coal fly ash to ensure that the coal fly ash was fully exploited. Overall, low-cost woven CAFs fabrics are suitable for wearable applications and offer a great approach to comprehensively use coal fly ash to address environmental threats. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Graphical abstract

Review

Jump to: Research

53 pages, 8826 KiB

Open AccessReview

Recycling and Reuse of Spent LIBs: Technological Advances and Future Directions

by Long Lv, Siqi Zhou, Changqi Liu, Yuan Sun, Jubing Zhang, Changsheng Bu, Junguang Meng and Yaji Huang

Molecules 2024, 29(13), 3161; https://doi.org/10.3390/molecules29133161 - 2 Jul 2024

Viewed by 2074

Abstract

Recovering valuable metals from spent lithium-ion batteries (LIBs), a kind of solid waste with high pollution and high-value potential, is very important. In recent years, the extraction of valuable metals from the cathodes of spent LIBs and cathode regeneration technology are still rapidly [...] Read more.

Recovering valuable metals from spent lithium-ion batteries (LIBs), a kind of solid waste with high pollution and high-value potential, is very important. In recent years, the extraction of valuable metals from the cathodes of spent LIBs and cathode regeneration technology are still rapidly developing (such as flash Joule heating technology to regenerate cathodes). This review summarized the studies published in the recent ten years to catch the rapid pace of development in this field. The development, structure, and working principle of LIBs were firstly introduced. Subsequently, the recent developments in mechanisms and processes of pyrometallurgy and hydrometallurgy for extracting valuable metals and cathode regeneration were summarized. The commonly used processes, products, and efficiencies for the recycling of nickel–cobalt–manganese cathodes (NCM/LCO/LMO/NCA) and lithium iron phosphate (LFP) cathodes were analyzed and compared. Compared with pyrometallurgy and hydrometallurgy, the regeneration method was a method with a higher resource utilization rate, which has more industrial application prospects. Finally, this paper pointed out the shortcomings of the current research and put forward some suggestions for the recovery and reuse of spent lithium-ion battery cathodes in the future. Full article

(This article belongs to the Special Issue Solid Waste and Fly Ash Chemical Treatment Methods)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Solid Waste and Fly Ash Chemical Treatment Methods

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (8 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI