Route Recovery Research Articles

Recovery of nickel from spent multilayer ceramic capacitors: A novel and sustainable route based on sequential hydrometallurgical and photocatalytic stages

The depletion of primary metal sources and the extensive use of nickel necessitate its extraction from secondary resources. In this study, we employed a chloride-based solution containing cupric ions (NaCl/CuCl2) to enable a straightforward recovery process for nickel from Ni-containing waste materials. Prior to application in real systems, we evaluated different operating conditions using metallic nickel particles, including chloride and cupric ion concentrations, system temperature, and pH. Optimal efficiency was achieved at T = 60 °C, pH = 5.0, [Cu(II)]0 = 5.0 × 10−3 M, and [Cl]0 = 6.0 M, resulting in complete dissolution of metallic Ni (58 ppm) within 180 min. This optimized leaching system was then applied to exhausted nickel-containing multilayer ceramic capacitors (MLCCs) matrixes, leading to 80% Ni recovery. FESEM-EDX and XRD analysis characterized both synthetic and real matrixes. Additionally, we proposed a viable route for selective metal recovery through precipitation and photodeposition on titanium dioxide. Complete copper photodeposition occurred after 150 min, while Ni precipitation as Ni(OH)2 was achieved by adjusting the solution pH to 10. Experimental data from runs with the synthetic matrix were analyzed using a shrinking spherical particle model.

Sequential recovery of copper, nickel, gold, silver and zinc from WPCBs of obsolete mobile phones through hydrometallurgical recycling

Waste printed circuit board (WPCB) of an obsolete mobile phone is a valuable source of base and precious metals. Alternatively, WPCBs also contain various lethal and toxic constituents which introduce ecological impacts while landfilling and incineration. Recycling WPCB is essential to reduce the environmental effects and to recover valuable metals. This article employs a hydrometallurgical route for the sequential recovery of copper, nickel, gold, silver and zinc from WPCBs through leaching, solvent extraction and cementation processes. Initially, the metal clads of WPCBs are used for the leaching of copper, nickel and other base metals without any selective dissolution of gold and silver. Optimal results revealed that dilute nitric acid at room temperature provides effective leaching (99.9%) of copper, nickel and zinc by leaving precious metals gold and silver in the residue. The utilization of phenolic oxime as a solvent extraction reagent revealed the selective recovery of copper and nickel from the leach liquor individually. The availed residue is dissolved in the halide salts in the presence of acidic conditions showing the quantitative dissolution of gold and silver. Solvent extraction with amide-based reagents recovered gold by leaving the silver-rich raffinate. A cementation technique with copper powder is implemented for the precipitation of silver. The proposed approach delivers an effective, eco-friendly and economically feasible process for the sequential recovery of metallic values from WPCBs of obsolete mobile phones.

Slag valorization from electric arc furnaces in concrete paver formulation

Slag is produced in enormous amounts by steelworks, which are scrap metal recycling industries that produce steel wire rods and steel reinforcing bars. In the absence of a sustainable recovery route, the latter pose a possible environmental risk. This work is concerned with the valorization of this by-product in the production of concrete pavers. To accomplish so, the slag was previously evaluated using X-ray fluorescence, particle size analysis, density, absorption coefficient, and other criteria that are recommended for usage in this field. The pavers were then manufactured using the Dreux Gorisse recipe, with slag substituting the gravel. The results demonstrate that the slag is rich in iron, which is characterized by lime, silica, and magnesia rates of 31.73%, 16.33%, and 16.33%, respectively, low percentages of manganese and alumina. The water absorption rate is between 2.6% and 2.8%, and their density is similar to 3.6 kg/l. Los Angeles has a 20-coefficient. As a result of their inclusion in the design of the pavers, they were able to split in line with the NF EN 1338 standard and retained a reasonable degree of tensile strength.

Homogeneous catalysts: Efficient routes for precious metal recovery from complex homogeneous systems

Homogeneous catalysts: Efficient routes for precious metal recovery from complex homogeneous systems

Subcritical hydrothermal purification from oily sludge recovered from petroleum oily sludge by adding sodium hydroxide, sodium bicarbonate, and formic acid

AbstractSubcritical water upgrading has received a great deal of attention because of its high efficiency and environmental protection technology features, but its high temperature and high‐pressure reaction conditions have limited its further development. This article investigates the hydrothermal upgrading recovered oil from oily sludge at 350°C and for a residence time of 60 min recovered oil. The effects of the type and concentration of various additives sodium hydroxide (NaOH), sodium bicarbonate (NaHCO3) and formic acid (CH3COOH) on the yield and quality of recovered oil were analyzed and discussed. The addition of 2 wt % NaOH increases the recovered oil yield to 78.6%, due to the demulsification effect of alkaline additives. Meanwhile, the CH3COOH effectively increased the H/C ratio of the recovered oil to 1.69, which can be attributed to the hydrogenation of large molecules in the sludge with hydrogen generated from the added CH3COOH. The effect characteristics and mechanisms of adding additives on the increase in the recovered oil yield and quality of oil‐bearing sludge in a sub‐critical hydrothermal environment were revealed. Subcritical water upgrading technology provides a new technological route for resource recovery of oily sludge with mild reaction conditions and high efficiency and simplicity.

A comprehensive review of the production methods and effect of parameters for glycerol-free biodiesel production

This review appraises the latest scientific progress and the accomplishments of interesterification technology as an alternative to conventional transesterification reaction. The merits and limitations of various types of catalytic techniques as well as non-catalytic supercritical glycerol-free processes have been elucidated with a comprehensive comparison. Contrary to the cheap price of glycerol, the higher-revenue by-products, triacetin and glycerol carbonate, will boost the gross profit margin of biodiesel production. The influences of reaction parameters such as reactant ratio, catalyst loading, reaction time, temperature, and co-solvent addition are also addressed. According to the latest research, the alkali-catalyzed and non-catalytic supercritical interesterifications are preferable due to higher yield. Methyl acetate, ethyl acetate and dimethyl carbonate do not inhibit lipase activity, unlike typical alcohols. Acidic catalysis may be the way forward to resolve the extreme operating conditions of non-catalytic supercritical interesterification, high cost of enzymes and manage waste feedstocks with high free fatty acid and water contents under moderate conditions. Currently, the majority of interesterification reactions were undertaken on laboratory size, whereas just a handful was evaluated on a pilot scale. A continuous research in interesterification technology is necessary by conducting a thorough investigation of the feasibility of state-of-the-art technology to engage a wide array of feedstocks. Future study should also concentrate on microbes and agricultural waste as a sustainable route for energy recovery from renewable feedstocks.

Sustainable and facile process for Li2CO3 and Mn2O3 recovery from spent LiMn2O4 batteries via selective sulfation with waste copperas

Spent lithium-ion batteries (LIBs) are essential secondary resource, containing valuable metal elements including lithium, cobalt, nickel, manganese. Recovering valuable metals from spent LIBs is significant for achieving environmental protection and alleviating resource shortages. Herein, a sustainable and facile process for Li2CO3 and Mn2O3 recovery from spent LiMn2O4 batteries (LMO) was proposed via sulfation roasting with waste copperas. The leaching efficiencies of Li and Mn reached approximately 100 % and 82 % under the optimal conditions, and the final recovered products were Li2CO3 and Mn2O3 with high purities. The sulfation reaction between LMO and copperas was the transition from solid-solid to gas-solid reaction. During the sulfation reaction, LMO spinel structure was decomposed into MnO2 and Mn2O3 crystal structures, and the anti-fluorite structure Li2O embedded in the spinel structure was released. The Li2O was easily to be sulfated, while MnO2 was partly reduced by Fe2+ to more stable spinel structure Mn2O3. Furthermore, FeSO4 decomposed into SO2 gas, which greatly improved the sulfation reaction through permeating into the unreacted core of LMO. As a result, the spinel structure of Mn2O3 was broken, and Mn was escaped to combine with SO42- to form MnSO4. This research provided an alternative technological route for green recovery of spent LMO batteries, demonstrating high potential for broad application.

Waste heat recovery and cascade utilization of CO2 chemical absorption system based on organic amine method in heating season

In this paper, we proposed a waste heat recovery route of CO2 chemical absorption systems, which can realize waste heat recovery and cascade utilization in heating season. Simulation methods were used to study carbon capture systems and absorption heat pump, experimental methods were used to study the contact heat transfer characteristics of packed tower, and three organic amine solutions were involved: MEA (2-Aminoethanol), MEA& MDEA (N-Methyldiethanolamine) and AMP (2-Amino-2-methyl-1-propanol). The outlet gas temperature of carbon capture system is 47.7 °C∼58.8 °C, the temperature of lean solution is 73.3 °C∼95.0 °C, the absorption heat pump can increase the return water from 40 °C to 85 °C∼97 °C, the heat transfer end difference between flue gas and water in packed tower can be less than 1.0 °C. The system can achieve energy conservation and CO2 emission reduction effect, over 80% of the solution waste heat were recovered, the two-stage gas waste heat recovery process can improve boiler efficiency by over 19%.

Combined hydrometallurgical route for recovery of metals from spent LIB using hydrochloric acid and phosphonium ionic liquid

ABSTRACT This research explored the significance of Cyphos IL 101 in recovering metal values from waste LiMn2O4 batteries. Several leaching parameters were investigated to recover metals from the leach liquor of the battery material. The maximum leaching efficiency of Li (100%) and Mn (99.6%) was attained with 3.0 mol/L hydrochloric acid, 30°C, S/L ratio of 10 g/L, and 60 min leaching duration. The leaching process was diffusion-controlled. At pH 5.5, the separation of manganese and lithium exhibited excellent selectivity towards manganese over lithium using 0.1 mol/L Cyphos IL 101. 99.6% manganese extraction and negligible lithium extraction were obtained with two stages of counter-current extraction at A/O 1:1 predicted by the McCabe-Thiele plot. Using 0.1 mol/L hydrochloric acid, a stripping efficiency of 99.4% was attained for manganese.

Aqueous Pretreatment Effect to Improve Au, Ag, and Pt Recovery from Spent Automotive Catalysts

Automotive catalysts represent a secondary source for precious metals recovery. These elements are usually obtained from minerals. Recently, methods have been sought to recover them from waste materials. The main route consists of pyrometallurgical treatments at high temperatures with the generation of other pollutants and very high energy consumption. With hydrometallurgy, routes can be developed which favor the aqueous extraction of said elements at room temperature. In an automotive catalyst, there are different metals which can interfere in the recovery process. In this study, sodium citrate (Na3C6H5O7•H2O), nitric acid (HNO3), and hydrochloric acid (HCl) were evaluated as a hydrometallurgical pretreatment to dissolve Fe, Zn, and Pb contained in a spent automotive catalyst and to improve the subsequent extraction of the precious metals contained therein (Au, Ag, and Pt). Afterwards, the aqueous extraction of precious elements with thiourea (SC(NH2)2) was carried out, comparing the effect of the pretreatment reagents. Finally, the feasibility and effect of each pretreatment as a route for precious metals recovery were analyzed with the aim to avoid processes at high temperatures.

Grave-to-cradle upcycling of harmful algal biomass into atomically dispersed iron catalyst for efficient ammonia electrosynthesis from nitrate

Electrochemically converting nitrate, widely distributed in industrial wastewater and contaminated water bodies, into ammonia is a promising route for resource recovery and wastewater treatment. Meanwhile, treating harmful algal blooms (HABs) is presented worldwide, are time and resource-consuming, and carries a high CO2 footprint. Rather than considering this carbon and nitrogen-rich biomass as disposable waste, consider it a vast renewable resource. Therefore, this study presents a Fe-dispersed carbon-based catalyst derived from HABs biomass, with a maximum ammonia yield rate of 16449 μg h−1 cm−2 (1.2 mmol h−1 mgcat−1) and NH3 Faradaic efficiency of 87.3%. This catalyst also possessed decent stability with continuous operation over 50 h. Experimental and theoretical calculation results reveal that the Fe-N4 site facilitates electrocatalytic nitrate reduction reaction by reducing the energy barriers of the NO3--to-NH3 pathway. Thus, this strategy of upcycling HABs biomass waste into functional catalysts offers a multipronged approach to renewable and carbon-neutral energy technologies.

Evaluating glycine as an alternative lixiviant for copper recovery from waste printed circuit boards

Current hydrometallurgical processing routes for copper recovery from waste printed circuit boards (PCBs) utilise strong mineral acids, which pose environmental hazards. Glycine has been proposed as an alternate lixiviant with a lower environmental impact. This study aimed to investigate the effectiveness of glycine as lixiviant for copper dissolution from waste PCBs. Bench scale laboratory leaching tests were performed to investigate the effect of key process variables such as temperature, oxidant type and lixiviant concentration on the rate, extent and selectivity of copper leaching.In the presence of oxygen as oxidant, the glycine concentration did not have a significant effect on the rate or extent of copper leaching in the range 1 M to 2 M. Increasing the temperature from 25 °C to 60 °C increased copper dissolution after 22 h from 29.6% to 81.2% when using a glycine concentration of 1 M. When air instead of oxygen was used as oxidant, the copper dissolution achieved with 1 M glycine after 22 h at 60 °C decreased by 43.9 percentage points to 37.3%, due to the lower concentration of dissolved oxygen in the system. Using hydrogen peroxide instead of oxygen as oxidant, did not improve the overall extent of copper leaching achieved.Leaching with 1 M glycine and oxygen as oxidant at 60 °C is proposed as the most feasible operating conditions within the ranges investigated, because these conditions yielded the highest copper dissolution (81.2%) with relatively low (1.3%) gold co-extraction.

Application of leached iron ore tailings to produce sustainable cements

The use of iron ore tailings (IOT) is a trend for the future of mining. The adoption of alternatives that minimise the disposal of natural resources and add value to production processes strongly supports this effort. Hydrometallurgy, by means of acid leaching, has been investigated as a processing route for iron recovery from IOT. After the separation of the liquor, a solid fraction of insoluble quartz and kaolinite remains (the main mineralogical phases). In the same way, the cement industry is an intensive consumer of raw materials and a major emitter of greenhouse gases. As one of the main alternatives for reducing these impacts, clinker substitution by wastes from other industries is being extensively considered. Thus, this work aims to evaluate the properties of the solid product of IOT leaching (L-IOT) and its potential to produce sustainable cements. L-IOT main composition is based on silicon (≈35%), aluminium (≈8%) and iron (2%). After thermal activation, the L-IOT was incorporated into pastes, replacing the cement by up to 20 wt%. The rheological parameters, hydration kinetics, compressive strength, mineralogy through X-ray diffraction (XRD) and thermogravimetric analysis (TGA) of cement pastes were assessed. L-IOT increased cement pastes' dynamic yield stress and viscosity and anticipated its main heat flow peak by up to three hours. Replacement contents of up to 20 wt% showed an equivalent 28-d compressive strength in the control sample, associated with carboaluminates formation. Finally, a simplified carbon dioxide equivalent emission (CO2-eq) analysis was conducted to evaluate the L-IOT’s environmental feasibility. Reductions of up to 21% CO2-eq emissions were observed for an L-IOT content of 20 wt%, compared to plain cement. The hydrometallurgical route allowed the recovery of 95% of the iron content in IOT, and its by-product presented technical and environmental feasibility for cement replacement in cementitious matrices.

Spent lithium manganate batteries for sustainable recycling: A review

Lithium-ion batteries (LIBs) account for the majority of energy storage devices due to their long service life, high energy density, environmentally friendly, and other characteristics. Although the cathode materials of LIB led by LiFePO4 (LFP), LiCoO2 (LCO), and LiNixCoyMn1-x-yO2 (NCM) occupy the majority of the market share at present, the demand of LiMn2O4 (LMO) cathode battery is also increasing year by year in recent years. With the rising price of various raw materials of LIBs and the need of environmental protection, the efficient recycling of spent LIBs has become a hot research topic. At present, the recycling of spent LIBs mainly focuses on LFP, LCO, and NCM batteries. However, with the continuous improvement of people’s safety of LIBs, LiMnxFe1-xPO4 (LMFP) batteries show better potential, which also improves the recycling value of LMO batteries. Therefore, this paper reviews current methods of spent LMO recovery, focusing on the characteristics of the recovery and separation process, which can serve as a reference for subsequent research on LMO recovery, increasing environmentally friendly recovery routes. Finally, the future development direction of LIBs recycling is prospected. Overall, this review is helpful to understand the current progress of LMO battery recycling.

Sustainability Challenges to Springshed Water Management in India and Bangladesh: A Bird’s Eye View

Springshed management across mountainous states, such as India and Nepal, has paved the way for the groundwater recharge process. In contrast, despite introducing several interventions, the Bangladeshi government has never been officially exposed to such sustainable ideas for a spring revival. Therefore, this study aims to diagnose water security for the Himalayan region by applying an environmental security framework. Community perceptions documented through focus group discussions and key informant interviews, as well as water sample testing, helped highlight the existing issues of water scarcity, accessibility, quality, and governance structure. Exemplifying the condition of Bandarban in Bangladesh, notable gaps were found in spring-related scientific understanding. Specifically, the lack of adequate reservoirs, institutional coordination, water supply, utility maintenance, and accessibility hurdles were identified as areas requiring immediate attention. As a recovery route, a six-step protocol of springshed management shows more promising outcomes. However, Sikkim communities in India raised questions over its efficacy due to the improper execution of said protocols. A limited understanding of hill science, including inventory and inadequate inspections before implementation, were found to result in only partial success. Upgrading remains a challenge as maladaptation might increase landslides. Therefore, development plans demand rigorous science-based investigation, consideration of local community knowledge, and (pilot) monitoring before the upscaling of springshed projects can be successfully conducted.

Regeneration of raw materials for aluminum electrolysis from spent carbon anodes via a closed-loop environmentally-friendly process based on aluminum–fluorine complexation

Spent carbon anode (SCA) discharged from the aluminum electrolysis industry is an unavoidable solid waste with an estimated production of 700 kilotons in 2021, which has been widely identified as the hazardous solid waste. A new two-stage leaching scheme comprising an aluminum salt leaching and an alkali leaching has been investigated in this study, by which valuable elements have been extracted from SCA. Effect of reaction conditions on the first-stage aluminum salt leaching process was investigated in detail. Under the optimal leaching conditions, the leaching rates of F, Na, and Al reached 98.00%, 94.94%, and 93.94%, respectively, and the recovered carbon purity was 85.84%. The fluorine recovery route was followed by the preparation of aluminum hydroxyfluoride precursor, namely Al2F3.24(OH)2.76 1.65H2O, through the mixing of two filtrates. Then thermogravimetry-differential scanning calorimetry (TG-DSC) curves were used to explore its calcination temperature point in detail. The final product was obtained as a mixture of AlF3 and Al2O3 with 95.94% purity. The characterization results showed that the calcined product was very similar to the commercial aluminum fluoride. Finally, the neutralized filtrate will be prepared by freezing and crystallizing Na2SO4, and the crystallized solution will be returned to the aluminum salt leaching process for recycling, which is the promise of green, recyclable, and high-value technology for realizing the detoxification of SCA and its subsequent utilization.

Reliably Route IoT Packets in Software Defined mmWave Mesh Networks

Although millimeter wave (mmWave) mesh networks provide large bandwidth to deliver IoT packets, link failure caused by non-light-of-sight (NLoS) condition degrades network reliability. With the assistance of software defined networking (SDN), we propose a Fast link failure Recovery Routing (FastReRoute) framework to instantly re-route packets from the failed links to another ones minimizing packet loss. Upon a link fails, FastReRoute first re-routes packets via the pre-configured local backup path. FastReRoute conditionally re-routes packets again according to the management using the SDN controller. We integrate FastReRoute into Mininet for performance evaluation. This demonstrates FastReRoute effectively sustains the network reliability.

Environmental-friendly and effectively regenerate anode material of spent lithium-ion batteries into high-performance P-doped graphite

Recycling graphitefrom spentlithium-ionbatteries has been largely ignored.In the present work, we propose a novel purification process, which modifies the structure of graphite through phosphoric acid leaching-calcination to obtain high-performance phosphorus (P)-doped graphite (LG-temperature) and lithium phosphate products. The content analysis of X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF) and scanning electron microscope focused ion beam (SEM-FIB) indicates that the LG structure is deformed by the doped P atom. The results of In-situ fourier transform infrared spectroscopy (In-situ-FTIR), density functional theory (DFT) calculation and XPS analysis show that the surface of the leached spent graphite contains rich oxygen groups, which react with phosphoric acid at high temperatures and form stable C-O-P and C-P bonds, making it easier to form stable solid electrolyte interface (SEI) layer. The increase of layer spacing is confirmed by X-ray diffraction (XRD), Raman and transmission electron microscope (TEM), which is conducive to the formation of efficient Li+ transport channels. What is more, Li/LG-800 cells possess high reversible specific capacities of 359, 345, 330 and 289 mA h g−1 at 0.2C, 0.5C, 1C and 2C, respectively. After100cyclesat0.5C, the specific capacityis as high as 366 mAh g−1, demonstrating the outstanding reversibility and cycle performance. This study proves and highlights a promising recovery route for exhausted lithium-ion batteries anodes, making complete recycling possible.

Analyzing Multi-Channel and Single-Channel on Multi independent Paths of Ad-Hoc Sensor Network

The Ad Hoc routing protocols include the route rediscover algorithms. Thus, a desirable aim for any routing protocol is to design an effective and rapid route recovery technique to rebuild the broken link. This study presents Multiple Node Index in Multi-Channel (MNIMC) and Multiple Node Index in Single-Channel (MNISC) as two novel route discovery techniques. MNIMC integrates multiple pathways and channels to create an alternate path. MNIMC reroutes the data packet via a different route in previously detected channels. Furthermore, it works with numerous link failures. MNIMC nodes are considered multi-transceiver enabled, in contrast to MNISC, which enables several routes and a single channel. Using the Network Simulator 2 (NS2), the MNIMC and MNISC schemes are developed and thoroughly tested. Simulation results demonstrate that the suggested approach improves packet delivery ratio, throughput, and end-to-end latency.

Recovery of metallic oxide rich biochar from waste chicken feather

Over the years, the devastating impact of climate change has become pronounced due to inadequate regulation for waste disposal in a developing country like Nigeria. The chicken feather-based metal oxide-rich (MOR) biochar was produced using a top-lit updraft reactor at a peak temperature of 417.2 °C to give a yield of 28.19%. The results were analyzed using Brunauer-Emmett-Teller BET, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS), and X-ray fluorescence spectroscopy (XRF). The result shows that the sample is mesoporous (pore diameter of 2.132 nm) with a BET surface area of 105.7 m2/g. CaO (33.147 wt%) and SO3 (25.673 wt%) were the major oxides present in notable proportions on the material surface, which were evident in the SEM micrograph. The major elemental compositions of the raw sample were oxygen (36.917 wt%) and calcium (23.690 wt%), and the major minerals present were quartz, marialite, davyne, and graphite. The present study elucidates the successful and efficient material recovery route for the preparation of adsorbents and precursors for many product synthesis processes.Graphical