Utilization of battery waste derived ZnO in the removal of dye from aqueous solution: A waste to wealth approach.

Every year a huge amount of zinc carbon batteries is discarded as waste and the management of such waste has become a growing concern all over the world. However, from these waste carbon batteries different kinds of valuable materials could be recovered. On the other hand, different industries discharged large volumes of dye wastewater into the environment which has a profound impact on environment and as well as human health. In this study, ZnO was recovered from the waste carbon batteries through pyrometallurgy process and utilized it for the treatment of methylene blue and methyl orange dye water. The batch adsorption process was carried out to observe the effect of adsorbent dosage, pH, contact time, stirring speed and temperature. Under the obtained optimal conditions adsorption kinetics (Pseudo-first order and pseudo-second order) and adsorption isotherms (Langmuir, Freundlich and Temkin) were analyzed. The results disclosed that 0.5 g and 0.6 g of ZnO showed maximum removal efficiency for MB and MO dye solution (50 ppm) whereas pH 13 and 6 were the optimal for MB and MO respectively. Kinetic studies indicate that both the adsorption processes were pseudo-second order. It was also revealed that based on regression coefficient R2 value the adsorption of MB and MO on ZnO is followed Langmuir model. Furthermore, the findings revealed that the MO adsorption on ZnO is a chemical adsorption process and MB adsorption is a physical adsorption process.

CT-guided vs. fluoroscopically guided transforaminal epidural steroid injections for lumbar radiculopathy: a comparison of efficacy, safety and cost.

INTRODUCTION: There are no formal guidelines for whether CT-guided or fluoroscopy-guided TFESI should be undertaken for patients with symptoms of lumbar nerve root irritation and corresponding nerve impingement. Here, we sought to compare the efficacy, safety and cost of computer tomography (CT)-guided and fluoroscopically guided transforaminal epidural steroid injection (TFESI). MATERIALS AND METHODS: All patients who underwent lumbar TFESI at our institution between June 2016 and June 2018 were identified. Six-week follow-up outcomes were categorised. The radiation doses and associated cost was retrieved from our institution's costing system. RESULTS: One hundred and sixteen patients were included (CT-50; fluoroscopy-56). There were no complications. More patients were discharged 6 weeks after CT-guided lumbar TFESI when compared with fluoroscopically guided TFESI (CT-23, fluoroscopy-14 (P = 0.027)). There was no difference in the number of patients who were referred to surgery (P = 0.18), for further pain management (P = 0.45), or for further TFESI (P = 0.43). The effective radiation dose was significantly higher for CT-guided TFESI (CT-5.73 mSv (3.87 to 7.76); fluoroscopy-0.55 mSv (0.11 to 1.4) (P < 0.01)). The total cost for CT-guided lumbar TFESI was £237.50 (£235 to £337), over £800 less than under fluoroscopic guidance (£1052 (£892.80 to £1298.00), P < 0.01)). Removing cost associated with staff and theatre use (staffing, theatre, medical indemnity and overheads) revealed CT-guided lumbar TFESI to be less expensive than if the procedure was fluoroscopy-guided-CT-guided: £132.6 (130.8 to 197.5); fluoroscopy: £237.4 (£209.2 to £271.9) (P = 0.019). CONCLUSIONS: CT-guided TFESI was associated with a higher discharge rate, a lower cost, but a ten times higher radiation dose when compared with fluoroscopically guided TFESI. Prospective studies are required to compare the efficacy of these procedures and to investigate how the radiation dose of CT-guided TFESI can be reduced without jeopardising efficacy or safety.

Utilising problematic waste to detect toxic gas release in the environment: fabricating a NiO doped CuO nanoflake based ammonia sensor from e-waste.

Using problematic electronic waste to synthesise high-purity nanomaterials can enable sustainable production and create opportunities to divert waste from landfills. Reported here is a simple strategy for the controllable synthesis of in situ NiO doped CuO nanoflakes from waste flexible printed circuit boards (FPCBs) using a chemothermal microrecycling process, and the nanomaterial is then utilised for an ammonia (NH3) sensor at room temperature. Characterisation of the nanoflakes confirmed the purity of the CuO phase with a monoclinic structure without the formation of the Cu2O phase. The NiO doped CuO 2D nanoflakes made of an assembly of 1D nanorods with a high surface area of 115.703 m2 g-1 are selectively synthesised from the waste FPCBs and have outstanding gas sensing characteristics such as a high response, a fast response (11.7 s) and a recovery time of (21.5 s), good stability, and superior selectivity towards 200 ppm of NH3 gas at room temperature (RT, 20 °C). From a broader perspective, the process opens up exciting new avenues explore the production of toxic gas sensing functional materials from toxic and problematic waste.

Value-added fabrication of NiO-doped CuO nanoflakes from waste flexible printed circuit board for advanced photocatalytic application.

The disposal of electronic waste (e-waste) presents a number of environmental problems. However, there are great opportunities to use this problem waste as a source of value-added metals. These metals could be recovered and transformed for use in beneficial applications, such as the manufacture of nanomaterials for the generation of hydrogen through thermodynamic water-splitting. This study used microrecycling techniques to synthesise Nitrogen oxide (NiO) doped copper oxide (CuO) nanoflakes from waste flexible printed circuit boards (FPCBs) using microrecycling techniques. Several precise characterisation and experimental analysis were used to validate the synthesised nanoflakes' phase purity, surface chemistry, morphology and optical properties. XRD analysis confirmed the nanoflakes produced in the system were predominantly Tenorite, CuO (98.5% ± 4.5) with a dopant of NiO (1.5% ± 0.1). The nanoflakes had a specific surface area of 115.703 m2/g and mesoporous structure with an average pore diameter of 11 nm. HRTEM analysis confirmed that the nanoflakes were not a single structure but assembled from 2D nanorods. The width of the nanorods varied from ∼ 10 to 50 nm, and the length from ∼ 30 to 80 nm. After rapid thermal processing, the photocurrent response of the synthesised material was assessed, revealing a higher photocurrent density (- 1.9 mA/cm2 at 0.6 V vs. reversible hydrogen electrode (RHE) under 1.5G AM). Mott Schottky analysis and electrochemical impedance spectroscopy showed that the synthesised nanomaterial had the potential thermodynamic water-splitting capability. These results were an encouraging indication of the promise of techniques which use e-waste to produce nanomaterials with valuable properties. This has the potential to both decrease problem waste and preserves dwindling natural resources.

Waste battery disposal and recycling behavior: a study on the Australian perspective.

Consumer behavior is a critical consideration for the development of sustainable waste management systems, including waste batteries, which pose a serious threat to human health and the environment if disposed of improperly. This study investigates the consumers' perspective on the waste battery collection and recycling behaviors in Australia, and analyses their implications for the development of recycling schemes. The results show that, although general awareness exists among consumers about the negative impacts of improper disposal, this awareness was not reflected during the disposal of waste batteries among the participants. Insufficient knowledge about the waste battery collection points and convenience were the most important factors affecting the inappropriate disposal behavior from most of the consumers. Over 50% of participants were unaware of the collection points for waste batteries. The most-preferred battery collection systems involved a deposit return system similar to that used for bottle recycling in the state of New South Wales (NSW) or collection at supermarkets/retailers. The most preferred methods for providing an incentive to recycle batteries were "old-for-new" battery swaps, "vouchers that could be used for other items in a store," and "cash payments." Several policy implications have been highlighted from this pioneering study that could shape the future development of sustainable waste battery management systems in Australia.

Selective Thermal Transformation of Automotive Shredder Residues into High-Value Nano Silicon Carbide.

Automotive waste represents both a global waste challenge and the loss of valuable embedded resources. This study provides a sustainable solution to utilise the mixed plastics of automotive waste residue (ASR) as a resource that will curtail the landfilling of hazardous waste and its adverse consequences to the environment. In this research, the selective thermal transformation has been utilised to produce nano silicon carbide (SiC) using mixed plastics and glass from automotive waste as raw materials. The composition and formation mechanisms of SiC nanoparticles have been investigated by X-ray diffraction (XRD), X-ray-Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The as synthesised SiC nanoparticles at 1500 °C has uniform spherical shapes with the diameters of the fixed edges of about 50-100 nm with a porous structure. This facile way of synthesising SiC nanomaterials would lay the foundations for transforming complex wastes into value-added, high-performing materials, delivering significant economic and environmental benefits.

Microrecycled zinc oxide nanoparticles (ZnO NP) recovered from spent Zn-C batteries for VOC detection using ZnO sensor.

Non-intrusive techniques for diagnosis and biomonitoring - for example, breath testing to detect biomarkers - have the potential to support the advancement of versatile and remote point-of-care (PoC) diagnostics. This paper investigates tuning the sensitivity and selectivity performance of chemo-resistive sensors to detect volatile organic compound (VOC) biomarkers using a hybridized material of pristine graphene (pG) and zinc oxide nanoparticles (ZnO NP) recovered from spent Zn-C batteries. This hybridized graphene nanocomposite material of ZnO nanoparticles showed enhanced sensing performance because of high conductive property of graphene along with the synergetic interplay between graphene composite materials and ZnO NPs. The elevated surface area as well as adsorption capability of ZnO NPs provided improved sensitivity and selectivity for particular VOCs. It was proposed that this hybridized material could be used to fabricate chemo-resistive sensors with sensing performances tailored for VOC biomarker detection. To test this hypothesis, the ability of graphene hybrid nanocomposites with ZnO NPs to improve the sensing characteristics and efficiency of distinguishing diverse VOC biomarkers such as ethanol, acetone, methanol, chloroform, acetonitrile and terahydrofuran (THF) was investigated. Results demonstrated that the microrecycled ZnO based hybrid sensor has good selectivity along with the sensitivity towards ethanol and chloroform VOCs at room temperature (20 °C).

Material Microsurgery: Selective Synthesis of Materials via High-Temperature Chemistry for Microrecycling of Electronic Waste.

This study aims to establish a novel pathway for transforming complex electronic waste into advanced hybrid materials by leveraging high-temperature reactions. This research utilized silica (SiO2) sourced from computer monitor glass; carbon obtained from plastic components of spent monitor shells; and copper (Cu) recovered from waste printed circuit boards (PCBs) to produce a high-quality hybrid layer on a steel substrate. The transformation process consisted of two steps. In the first step, silicon carbide (SiC) nanowires were produced from the spent monitor's glass and plastic. In the second step, these nanowires were combined with Cu obtained by grinding waste PCBs to produce the hybrid layer over the steel surface. The Cu-SiC hybrid layer on a steel substrate was produced successfully by the judicious selection of waste sources and by selecting a microrecycling technique, which resulted in superior mechanical properties for the end product. This technique, proposed as 'material microsurgery', has the potential to transform waste materials into new hybrid surface coatings, which endows the base materials with superior properties to those seen in the source materials. For example, the SiC-nanowire-reinforced Cu layer added to steel in this study improved the hardness of the base material.

Recycle, Recover and Repurpose Strategy of Spent Li-ion Batteries and Catalysts: Current Status and Future Opportunities.

The disposal of hazardous waste of any form has become a great concern for the industrial sector due to increased environmental awareness. The increase in usage of hydroprocessing catalysts by petrochemical industries and lithium-ion batteries (LIBs) in portable electronics and electric vehicles will soon generate a large amount of scrap and create significant environmental problems. Like general electronic wastes, spent catalysts and LIBs are currently discarded in municipal solid waste and disposed of in landfills in the absence of policy and feasible technology to drive alternatives. Such inactive catalyst materials and spent LIBs not only contain not only hazardous heavy metals but also toxic and carcinogenic chemicals. Besides polluting the environment, these systems (spent catalysts and LIBs) contain valuable metals such as Ni, Mo, Co, Li, Mn, Rh, Pt, and Pd. Therefore, the extraction and recovery of these valuable metals has significant importance. In this Review, we have summarized the strategies used to recover valuable (expensive) as well as cheap metals from secondary resources-especially spent catalysts and LIBs. The first section contains the background and sources of LIBs and catalyst scraps with their current recycling status, followed by a brief explanation of metal recovery methods such as pyrometallurgy, hydrometallurgy, and biometallurgy. The recent advances achieved in these methods are critically summarized. Thus, the Review provides a guide for the selection of adequate methods for metal recovery and future opportunities for the repurposing of recovered materials.

Revealing the mechanism of extraordinary hardness without compensating the toughness in a low alloyed high carbon steel.

There is a continuous quest for discovery of a steel grade which has better properties and lower production cost. To design steel with superior properties for industrial application, it is essential to understand the effect of microstructure and engineer it to fit the purpose. In this study, a counter intuitive strategy has used to reveal the mechanism of high carbon steel with ultrahard structure. High compact force has been used to produce a structure which has ceramic-like hardness without compensating the toughness significantly. The behaviour of high carbon low-alloy steel as the starting material under different stages of deformation has been studied to differentiate various deformation paths and microstructural transformation processes. Microscopy investigation by secondary electron microscopy, high-resolution electron backscattered diffraction (HR-EBSD) analysis and Transmission electron microscopy (TEM) showed that the key point to achieve ~75% increased hardness in this steel is through generation of nano-structured martensite of less than 50 nm grains size which can be formed due to high impact force. In this paper, we reveal a nano grained steel structure with excellent mechanical properties resulting from phase transformation, uniform dislocation distribution, grain refinement and recrystallization.

Effect of selective-precipitations process on the corrosion resistance and hardness of dual-phase high-carbon steel.

It is commonly known that precipitation of secondary phase in non-ferrous alloys will affect the mechanical properties of them. But due to the nature of dual-phase low-alloy high-carbon steel and its high potential of precipitation of cementite, there is limited study on tailoring the mechanical and corrosion properties of this grade of steel by controlling the precipitation of different phases. Predicting and controlling precipitation behaviour on this grade of steel is of great importance towards producing more advanced applications using this low-cost alloy. In this study the new concept of selective-precipitation process for controlling the mechanical and corrosion behaviour of dual-phase low-alloy high-carbon steel has been introduced. We have investigated the precipitation of different phases using in-situ observation ultra-high temperature confocal scanning laser microscopy, image analyser - ImageJ, scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and electron probe microanalysis (EPMA). Volume fraction of each phase including retained austenite, martensite and precipitated phases was determined by X-ray diffraction (XRD), electrochemical corrosion test by Tafel extrapolation method and hardness performance by nanoindentation hardness measurement. The experimental results demonstrated that, by controlling the precipitations inside the matrix and at grain boundaries through heat treatment, we can increase the hardness of steel from 7.81 GPa to 11.4 GPa. Also, corrosion resistance of steel at different condition has been investigated. This new approach will open new possibility of using this low-cost steel for high performance applications.

From waste to surface modification of aluminum bronze using selective surface diffusion process.

When corrosion is the dominant failure factor in industrial application and at the same time high mechanical properties are required, aluminum bronze is one of the best candidates. Hence, there is a continuous quest for increasing the lifetime of aluminum bronze alloys through enhancing the abrasion and corrosion resistance. Existing methods are based on modifying the bulk properties of alloy or surface modification which required sophisticated equipment and process control. This approach has limited application for advanced components because of high price and difficulty to apply. In this research, we developed an innovative approach to enhance the corrosion and abrasion resistance of aluminum bronze through selective surface diffusion process. In this process, we have used waste materials as input and the modified surface has formed in a single and green process. New surface structure consists of finely dispersed kappa phase (χ ) in uniform alpha (α) solid solution matrix. Results have demonstrated that this uniform diffused modified surface layer has improved hardness of the base material and both corrosion and abrasion resistance has increased. This novel surface modification technique has opened a pathway for using waste materials as input for surface modification of aluminum bronze to meet the needs of industrial applications in a cost effective and environmentally friendly way.

Direct Transformation of Metallized Paper into Al-Si Nano-Rod and Al Nano-Particles Using Thermal Micronizing Technique.

The abundant application of metallized paper and the quick growth of their wastes lead to the removal of a huge amount of valuable resources from economic cycle. In this work, for the first-time, the thermal micronizing technique has been used to directly transform the metallized paper wastes to Al-Si nano-rod and Al nano-particles for use as the input in different manufacturing sectors such as additive manufacturing or composite fabrication. Structure of metallized paper has been investigated using FT-IR analysis and first-principle plane-wave calculation. Then, based on the structure of metallized paper, thermal micronizing technique has been modified to directly transform this waste into nano materials. Structure of nano-particles and nano-rods has been investigated using SEM, TEM, and XPS analysis. Results showed two main Al-Si nano-rod and Al nano-particle morphologies created as a result of the different surface tensions, which facilitate their separation by Eddy current separation technique. These quick transformation and facile separation together make this technique a unique process to deal with this complex waste and producing value-added products which can re-capture these high value materials from waste and make the reforming economically viable.

Hybrid structure of white layer in high carbon steel - Formation mechanism and its properties.

This study identifies for the first time, the hybrid structure of the white layer in high carbon steel and describes its formation mechanism and properties. The so-called 'white layer' in steel forms during high strain rate deformation and appears featureless under optical microscopy. While many researchers have investigated the formation of the white layer, there has been no definitive study, nor is there sufficient evidence to fully explain the formation, structure and properties of the layer. In this study, the formation, morphology and mechanical properties of the white layer was determined following impact testing, using a combination of optical and SE- microscopy, HR-EBSD, TKD and TEM as well as nano-indentation hardness measurements and FE modelling. The phase transformation and recrystallization within and near the white layer was also investigated. The microstructure of the steel in the white layer consisted of nano-sized grains of martensite. A very thin layer of austenite with nano sized grains was identified within the white layer by HR-EBSD techniques, the presence of which is attributed to a thermally-induced reverse phase transformation. Overall, the combination of phase transformations, strain hardening and grain refinement led to a hybrid structure and an increase in hardness of the white layer.

Enhancing steel properties through in situ formation of ultrahard ceramic surface.

Abrasion and corrosion resistant steel has attracted considerable interest for industrial application as a means of minimising the costs associated with product/component failures and/or short replacement cycles. These classes of steels contain alloying elements that increase their resistance to abrasion and corrosion. Their benefits, however, currently come at a potentially prohibitive cost; such high performance steel products are both more technically challenging and more expensive to produce. Although these methods have proven effective in improving the performance of more expensive, high-grade steel components, they are not economically viable for relatively low cost steel products. New options are needed. In this study, a complex industrial waste stream has been transformed in situ via precisely controlled high temperature reactions to produce an ultrahard ceramic surface on steel. This innovative ultrahard ceramic surface increases both the hardness and compressive strength of the steel. Furthermore, by modifying the composition of the waste input and the processing parameters, the ceramic surface can be effectively customised to match the intended application of the steel. This economical new approach marries industry demands for more cost-effective, durable steel products with global imperatives to address resource depletion and environmental degradation through the recovery of resources from waste.