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Given the criticality of indium (In) in high-tech applications, spent LCD screens can represent a viable secondary In resource. In this work, an innovative and alternative technology to selectively leach In from spent LCD screens using a microbial chelating agent, desferrioxamine E (DFOE), was developed. Indium was concentrated from spent LCD screens by implementing an adapted pre-treatment procedure, allowing the isolation of an indium-rich glassy fraction. During leaching, the competition between aluminum (Al) and In for complexation with DFOE leads to the precipitation of In(OH) 3 at low DFOE concentrations (12–240 µM). After adjusting the optimal conditions (fraction size: 0–36 μM, pH: 5.5, S/L ratio: 1 g/L, 25 °C), the In leaching yield reached 32%, ten times higher than Al over 90 days with 5 mM DFOE. Thus, achieving high In recovery is possible through i) prolonging leaching durations, ii) selective leaching, and iii) minimizing Al interference. This is the first attempt to selectively leach In using a selected siderophore from end-of-life products with high concentrations of non-targeted elements (i.e. Al, Si, and Ca). This study demonstrates the potential of generating indium-rich leachates, which can be subsequently processed through the GaLIophore technology for In refining. [Display omitted] • A novel bio-based indium leaching method is proposed. • Model elucidates indium leaching mechanism. • Improved n(DFOE)/n(In) ratio lessens aluminum competition in indium leaching. • Optimal conditions yield high indium leaching. [ABSTRACT FROM AUTHOR]

Liquid crystal monomers (LCMs), identified as emerging contaminations, have been detected in soils and plants, but their accumulation characteristics in plants haven't been studied. Therefore, this study systematically investigated the accumulation characteristics of LCMs in plants from four dimensions (i.e., plant fruit species, soil types, plant growth stages, and LCMs categories) for the first time. The LCMs concentrations (9.96 × 10−4 to 114.608 ng/g) in 22 plant fruits were predicted by the partition-limited model. Grains with the highest lipid content showed the highest LCMs accumulation propensity. Plants grown in paddy soil showed a strong LCMs accumulation capacity. Results showed that the LCMs accumulation capacity in plants from soils decreased when the soil organic matter content increased. A preferential accumulation of LCMs in plant root systems during growth was found by the molecular dynamics simulations. Compared to polychlorinated biphenyls (as the reference contaminants of LCMs), LCMs exhibit higher accumulation in plant roots and lower translocation to shoots. For the fourth dimension, lipophilicity was found to be the main reason of LCMs accumulation by intergraded stepwise linear regression with sensitivity analysis. This is the inaugural research concentrating on LCMs accumulation in plants, providing insights and theoretical guidance for future LCMs management strategies multidimensionally. Liquid crystal monomers (LCMs) are one of the essential materials for liquid crystal displays and have been identified as emerging containments, with detections now confirmed in soils and plants. However, the mechanism of their bioaccumulation in plants has not been established. Consequently, this paper presents the first comprehensive study on LCMs accumulation mechanisms in plants, identifying the patterns of LCMs accumulation in plants from various dimensions such as different plant species, soil types, plant growth stages, and LCMs categories, enhancing the understanding of the environmental behavior of LCMs and providing a theoretical reference for the formulation of LCMs management strategies. [Display omitted] • The first study focuses on the accumulation characteristics of LCMs in plants. • Plants with higher lipid contents may lead to higher accumulation of LCMs. • The higher the SOM content in the soil, the lower the LCMs uptake rate by plants. • LCMs exhibit a higher accumulation propensity in plant roots than that in shoots. • LCMs' lipophilicity contributes the most to the accumulation capacity in plants. [ABSTRACT FROM AUTHOR]

Liquid crystal monomers (LCMs), one of the key materials for liquid crystal displays, have been considered as emerging pollutants in recent years. However, the environmental behaviors of LCMs have not yet been well investigated. The toxicity data of 1173 LCMs were calculated by integrated computational simulation methods in this study. It showed that 64.6% LCMs exhibited PBT (persistent, bioaccumulative, and toxic) properties. Based on the results, 1173 LCMs were identified as molecules possessing the highest level of acute toxicity to aquatic organisms. Among which, and a human health risk priority control list about LCMs was generated in this study, among which 435 were classified as requiring priority control LCMs. It was confirmed that LCMs could eventually accumulate in the human body along the aquatic food chain or penetrate the bloodstream through the dermis, thereby causing harm to health by identifying the exposure pathways of LCMs in humans. Additionally, the electronegativity of the side chain group of LCMs is the main factor causing toxicity differences; therefore, the LCMs containing halogens presented significant acute and chronic toxic effects. This study provided a more comprehensive understanding of LCMs for the public and scientific strategies for controlling LCMs. [Display omitted] • The environmental behaviors of 1173 LCMs reported in the literature were identified. • All LCMs exhibited the highest level of acute toxicity, especially for crustaceans. • LCMs can bind to various receptors, 435 LCMs pose significant risks to human health. • LCMs accumulate in human bodies through biomagnification and dermal permeation. • The electronegativity of the side chain group of LCMs leads to toxicity differences. [ABSTRACT FROM AUTHOR]

Waste liquid crystal display (LCD) panels mainly contain inorganic materials (glass substrate with indium-tin oxide film), and organic materials (polarizing film and liquid crystal). The organic materials should be removed beforehand since the organic matters would hinder the indium recycling process. In the present study, pyrolysis process is used to remove the organic materials and recycle acetic as well as and triphenyl phosphate (TPP) from waste LCD panels in an environmental friendly way. Several highlights of this study are summarized as follows: (i) Pyrolysis characteristics and pyrolysis kinetics analysis are conducted which is significant to get a better understanding of the pyrolysis process. (ii) Optimum design is developed by applying Box–Behnken Design (BBD) under response surface methodology (RSM) for engineering application which is significant to guide the further industrial recycling process. The oil yield could reach 70.53 wt% and the residue rate could reach 14.05 wt% when the pyrolysis temperature is 570 °C, nitrogen flow rate is 6 L min −1 and the particle size is 0.5 mm. (iii) Furthermore, acetic acid and TPP are recycled, and then separated by rotary evaporation, which could reduce the consumption of fossil energy for producing acetic acid, and be reused in electronics manufacturing industry. [ABSTRACT FROM AUTHOR]

Based on the significant advantages of hydrothermal technology, it was applied to treat polarizer from the waste LCD panel with the aim of transforming it into organic acids (mainly acetic acid and lactic acid). Investigation was done to evaluate the effects of different factors on yields of organic acids, including the reaction temperature, reaction time and H 2 O 2 supply, and the degradation process of polarizer was analyzed. Liquid samples were analyzed by GC/MS and HPLC, and solid-phase products were characterized by SEM and FTIR. Results showed that at the condition of temperature 300 °C and reaction time 5 min, the organic materials reached its highest conversion rate of 71.47% by adding 0.2 mL H 2 O 2 and acetic acid was dominant in the products of organic acids with the yield of 6.78%. When not adding H 2 O 2 to the system, the yields of lactic and acetic acid were respectively 4.24% and 3.80% at a nearly equal degree, they are suitable for esterification to form ethyl lactate instead of separating them for this case. In the hydrothermal process, polarizer was first decomposed to monosaccharides, alkane, etc., and then furfural and acids are produced with further decomposition. [ABSTRACT FROM AUTHOR]

Liquid crystal display (LCD) panels mainly consist of polarizing film, liquid crystal and glass substrates. In this study, a novel pyrolysis model and a pyrolysis mechanism to recover the reusable resource from polarizing film of waste LCD panels was proposed. Polarizing film and its major components, such as cellulose triacetate (TAC) and polyvinyl alcohol (PVA) were pyrolyzed, respectively, to model the pyrolysis process. The pyrolysis process mainly generated a large ratio of oil, a few gases and a little residue. Acetic acid was the main oil product and could be easily recycled. The pyrolysis mechanism could be summarized as follows: (i) TAC, the main component of polarizing film, was heated and generated active TAC with a low polymerization, and then decomposed into triacetyl-D-glucose. (ii) Some triacetyl-D-glucose generated triacetyl-d-mannosan and its isomers through an intramolecular dehydration, while most triacetyl-D-glucose generated the main oil product, namely acetic acid, through a six-member cyclic transition state. (iii) Meanwhile, other products formed through a series of bond cleavage, dehydration, dehydrogenation, interesterification and Diels-Alder cycloaddition. This study could contribute significantly to understanding the polarizing film pyrolysis performance and serve as guidance for the future technological parameters control of the pyrolysis process. [ABSTRACT FROM AUTHOR]

Tetramethylammonium hydroxide (TMAH) is a toxic photoresist developer used in the photolithography process in thin-film transistor liquid crystal display (TFT-LCD) production, and it can be removed through anaerobic treatment. TMAH cannot be released into the environment because of its higher toxicity. A tight membrane, such as a forward osmosis (FO) membrane, together with an anaerobic biological process can ensure that no TMAH is released into the environment. Thus, for the first time, an anaerobic osmotic membrane bioreactor (AnOMBR) hybrid system was developed in this study to treat a low-strength TMAH wastewater and to simultaneously investigate its microbial community. Microfiltration extraction was used to mitigate the salinity accumulation, and a periodically physical water cleaning was utilized to mitigate the FO membrane fouling. The diluted draw solute (MgSO 4) was reconcentrated and reused by a membrane distillation (MD) process in the AnOMBR to achieve 99.99% TMAH removal in this AnOMBR-MD hybrid system, thereby ensuring that no TMAH is released into the natural environment. Moreover, the membrane fouling in the feed and draw sides were analyzed through the fluorescence excitation-emission matrix (FEEM) spectrophotometry to confirm that the humic acid-like materials were the primary membrane fouling components in this AnOMBR. Additionally, 16S rRNA metagenomics analysis indicated that Methanosaeta was the predominant contributor to methanogenesis and proliferated during the long-term operation. The methane yield was increased from 0.2 to 0.26 L CH 4 /g COD when the methanogen species acclimatized to the saline system. [Display omitted] ● TMAH removal is achieved 99.99% in this AnOMBR hybrid system. ● Humic acid-like materials is the major membrane fouling components in this AnOMBR. ● Methanosaeta is the predominant microorganism for this TMAH treatment. ● Methanomethylovorans played the major role for TMAH biodegradation. ● Methane yield is increased when the microorganism acclimatize to the saline system. [ABSTRACT FROM AUTHOR]

It is essential to understand the atmospheric fate of liquid crystal monomers (LCMs), an important component in liquid crystal displays (LCDs); however, limited information is available at present. In this study, the atmospheric reaction mechanism, kinetics and toxicity evolution of three fluorinated biphenylethyne LCMs (1,2,3−trifluoro−5−(2−(4−methylphenyl)ethynyl)benzene (m−TEB), 1,2,3−trifluoro−5−(2−(4−ethylphenyl)ethynyl)benzene (e−TEB), 1,2,3−trifluoro−5−(2−(4−propylphenyl)ethynyl)benzene (p−TEB)) are investigated by theoretical calculations. Results show that the initial reactions of·OH addition to −C ≡ C− groups and hydrogen abstraction from alkyl groups (−CH 3 , −C 2 H 5 , −C 3 H 7) are dominant pathways. The resulting transformation products (TPs) for m-TEB are mainly highly oxidized multi-functional compounds such as benzil-based compounds, benzoic acid, alcohols, aldehydes, diketone and epoxy compounds. Results also show that some TPs exhibit higher aquatic toxicity than the parent. The calculated rate constants of m−TEB, e−TEB and p−TEB with·OH at 298 K are in the ranges of (1.3 −8.6) × 10−12 cm3 molecule−1 s−1, and the corresponding atmospheric half-lives are 3.8−9.3, 2.2−5.4 and 0.6−1.4 days, respectively. This evidences that m−TEB and e−TEB may have atmospheric persistence and could undergo long-range transport. The results herein could be helpful for clarifying the atmospheric fates, persistence and risks of fluorinated LCMs with ethynyl benzene center. [Display omitted] • The reaction kinetics and mechanism of three LCMs initiated by·OH is investigated. • ·OH addition to alkynyl and H-abstraction from alkyl groups are dominant pathways. • m−TEB and e−TEB with atmospheric half-lives > 2 days can persist in the atmosphere. • The major degradation products are a range of oxidized multi-functional compounds. • Some transformation products show enhanced toxicity compared with the parent LCM. [ABSTRACT FROM AUTHOR]

With a huge amount of waste liquid crystal displays (LCDs) generated annually, their proper recycling raises continuous concern to realize pollution control (heavy metal and liquid crystal) and resource recovery (indium). However, due to their multi-metal feature, traditional hydrometallurgy lacks of sufficient selectivity, which makes the recycling route lengthy, costly, and generate more waste. Electrodeposition acts as a promising technique for selective metal extraction from multi-metal system due to its high selectivity and electron as clean reagent. To fully develop its application in metal recovery, stepwise Cu/MoO 2 and In electrodeposition from In-Cu-Mo-Fe waste LCD leachate is explored in depth. Electrochemical behavior analysis shows Cu and MoO 2 can be first electrodeposited for their higher electroreduction potential. Cl- plays a key role in accelerating indium electroreduction kinetics, which largely shortens the extraction time without the sacrifice of current efficiency. This accelerating effect is attributed to the increased concentration of electroactive species or collision frequency. Under optimized condition, 99.41% of indium (> 99% purity) can be electrodeposited within 13 h with high current efficiency. This study provides a cleaner approach for waste LCDs recycling and gives implications for the potential application of electrochemical technique in e-waste recycling. [Display omitted] • Stepwise electrodeposition of Cu/MoO 2 and In from LCD leachate was achieved. • Cl- can accelerate indium electrodeposition, improving recovery efficiency. • Increased surface concentration/collision frequency lead to the acceleration. • 99.41% of indium (> 99% purity) was recovered with current efficiency > 70%. [ABSTRACT FROM AUTHOR]

Recycling activity for waste electrical and electronic equipment is always accompanied with leaching solution containing copper. Its selective extraction is of environmental and economic significance, and is beneficial for subsequent resource purification procedure. Compared with techniques such as chemical precipitation and solvent extraction, potentiostatic electrodeposition is outstanding with the advantage of high selectivity, electron as clean reagent, and minimal chemical usage. However, key factors affecting copper electrodeposition behavior as well as its kinetic process remain unclear, which blocks its further application. In this study, selective copper electrochemical extraction from multi-metal leaching solution of waste liquid crystal display panels is explored. Copper electrodeposition is analyzed from electrochemical and mass transport point of view, and the main results are summarized: (i) copper can be first electrodeposited due to its higher reduction potential compared with indium; (ii) applied potential and agitation are the most influential factors towards space-time yield and current efficiency; (iii) a semi-empirical kinetic model could quantitatively describe the influence of agitation and the time-current-concentration relationship. The model-predicted extraction rate agreed well with experimental data throughout electrodeposition; (iv) electrodeposition experiments show over 95% of copper can be selectively extracted as ultrafine copper powder (~150 nm) at 0.05 V (vs. SHE). ga1 • Cu can be fully separated from In and Mo by electrodeposition. • Moderate applied potential and agitation are crucial for high efficiency. • Cu electrodeposition kinetics can be depicted by a semi-empirical model. • Deposited nanosized Cu can increase the risk of hydrogen evolution. [ABSTRACT FROM AUTHOR]

• Iodide recovery was achieved in the form of triiodide from the TFT-LCD wastewater. • Partial oxidation was used to convert iodide to iodine then triiodide. • With preoxidation, iodide removal of 98.5% was achieved by the FO process. • EDTA-2Na was used as the draw solutes to avoid excess draw solute replenishment. Triiodide, a larger charged molecule compared to iodide, is thermodynamically favored with the presence of both iodide and iodine, and is easier to be retained by membrane processes. For the first time, iodide was recovered in the form of triiodide by forward osmosis (FO) for thin-film transistor liquid crystal display industries by preoxidation of iodide to triiodide. Partial oxidation by NaOCl was used to convert the iodide to iodine and then to form triiodide. Ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), a commonly used chelating agent in the industry, was used as the draw solute because of its low reverse salt flux. The results revealed that the ideal efficiency of iodide recovery was at pH 3 with a preoxidation (adding 0.0150 M NaClO) for the 0.048 M iodide wastewater with a recovery of 98.5%. Additionally, the Pourbaix diagram and starch indicator were used to verify the formation of triiodide. Membrane distillation was demonstrated to recover the EDTA-2Na draw solute, and more than 99% of recoveries for the draw solutes with initial water flux of 12.0 L/m2 h were achieved, indicating that simultaneous recovery of the EDTA-2Na draw solute and water is feasible. [ABSTRACT FROM AUTHOR]

• Microwave-assisted hydrothermal method can effective decompose liquid crystal. • The decomposition rate of liquid crystal reaches 100 % under the optimized condition. • Reaction kinetic analysis of liquid crystal under optimized conditions is studied. • Two possible decomposition processes of liquid crystal are proposed. • The liquid crystal mixture is treated sufficiently into non-hazardous products. Liquid crystal (LC), as a crucial component of liquid crystal display (LCD), improperly treatment of which will possibly impair ecosystems and human health. In view of the advantages of hydrothermal reaction and microwave irradiation, this paper intensively studied the process of microwave-assisted hydrothermal (MWAH) decomposition of LC wastes. The experimental materials include a kind of refractory fluorinated liquid crystal commonly used in thin-film transistor LCD, and its mixture with the other two typical liquid crystal monomers in the waste low-end display panels. Under the MWAH process, the optimized condition for thorough decomposition of 0.67 g.L−1 fluorinated liquid crystal is 0.653 mol.L−1 H 2 O 2 , 1 g.L−1 AC, 300 mL water, 250 °C and 7 min. The superiority of microwave in enhancing hydrothermal treatment efficiency was verified by the first-order kinetic reaction equation fitted for the decomposition process under optimal condition, along with two possible decomposition pathways tentatively proposed after characterizing the intermediate products. Under the same condition, 1 g.L−1 mixture of fluorinated liquid crystal and the other two liquid crystal monomers were entirely decomposed with no harmful byproduct detected, suggesting that microwave irradiation could effectively promote the hydrothermal decomposition of liquid crystal wastes. [ABSTRACT FROM AUTHOR]

• Concurrent In leaching and Sn precipitation were achieved during acid leaching. • The leaching behavior and mechanism of In, Sn was studied in detail. • A kinetic model was deduced to depicting In leaching in thin film situation. • Pure Cu and In were separately extracted via electrodeposition. Since indium (In) was the most valuable resource in waste liquid crystal panels (LCDs), most researches only focused on preliminary recovery of In, while those coexisting metal elements (Cu, Sn, Al) raised little concern. This could lead to waste of resources, potential risk of heavy metal pollution, and also complexation of following In purification procedures. Besides, current hydrometallurgy processes for In purification are complicated, consume more reagents and generate more wastewater. Therefore, this research applied simple acid leaching and two-step electrodeposition for In-Sn and In-Cu-Al separation with minimum waste generation and input. Considering the special doping structure of indium-tin oxide (ITO), feasibility for concurrent In leaching and Sn precipitation was explored based on the unique Sn species' dissolution and precipitation behavior during acid leaching. Since the behavior of Sn was more sensitive to acidity and temperature, 97.07% of Sn removal and 99.25% of In recovery could be achieved using 1 mol/L H 2 SO 4 at 70 ℃ for 1 h. A specific kinetic model depicting In leaching in thin ITO film situation was developed referring to avrami equation. Then, the application of two-step electrodeposition enabled 95.32% extraction of Cu and deposition of In with a purity over 99 wt% at respective potential. [ABSTRACT FROM AUTHOR]