Facies analysis of the Uppermost Kubang Pasu Formation, Perlis: a wave-and storm-influenced coastal depositional system

A detailed sedimentological study and facies analysis of the Permian age, uppermost succession of the Kubang Pasu Formation in Perlis was conducted in order to reconstruct the palaeo-depositional environment. Four stratigraphic sections of the uppermost Kubang Pasu Formation were logged at Bukit Chondong and Bukit Tungku Lembu, Perlis. The sections were divided into facies based on lithology and sedimentary structures. Large scale patterns in the form of facies associations and facies successions were also identified. The uppermost Kubang Pasu Formation can be divided into several coarsening upward facies successions. Each facies succession grades upward from an offshore facies association (FA1) composed of bioturbated mudstone and minor thin sandstone, into a distal lower shoreface facies association (FA 2) composed primarily of mudstone interbedded with hummocky cross-stratified sandstone (HCS) and finally a proximal lower shoreface facies association (FA 3) composed of amalgamated hummocky cross-stratified sandstone beds. The facies succession is interpreted as representing a wave- and storm-influenced coastal depositional environment. The gradual transition from siliciclastics to carbonates is probably related to post rift thermal subsidence and tectonic quiescence due to separation of Sibumasu from Gondwana during the Permian

A facile crush-and-sieve treatment for recycling end-of-life photovoltaics

The shift towards renewable energy mix has resulted in an exponential growth of the photovoltaic (PV) industry over the past few decades. Parallelly, new recycling technology developments are required to address the incoming volume of waste as they gradually approach their end-of-life (EoL) to realize the concept of a circular economy. Typical recycling processes involve high-temperature burning for separation and release of the PV cells for metal recovery processes. However, this thermal process generates gaseous by-products that cause serious health and environmental issues. Eschewing the need for burning, we demonstrate a simple crush-and-sieve methodology to strategically aids the separation of polymeric and metallic contents. The proposed approach showcased the efficient size-selective separation and generated polymer- and metal-rich fractions. More than 90 % of the total polymer present within the studied wastes was found to be retained in larger sized-particle fractions (F1 and F2). Metal content analysis highlighted the enrichment of highly valuable silver into the smallest sized-particle fraction (F4), accounting up to 70 % and 80 % of total silver present respectively for EVAc and MP. The benefits ripe through this simple crush-and-sieve method offers an attractive pathway for PV recycling process to obtain metal-rich fractions and allow focused recovery of valuable materials through an environmentally friendlier manner.National Environmental Agency (NEA)National Research Foundation (NRF)This research/project is supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop Funding Initiative (Award No. USS-IF-2018- 4)

Simplified silicon recovery from photovoltaic waste enables high performance, sustainable lithium-ion batteries

Conventional recycling methods to separate pure silicon from photovoltaic cells rely on complete dissolution of metals like silver and aluminium and the recovery of insoluble silicon by employing multiple leaching reagents. A common approach that eschews hydrofluoric acid (HF) treatment is the double reagent approach which utilizes nitric acid (HNO3) and potassium hydroxide (KOH) to separate the metals from silicon cell. However, the double reagent approach is unable to remove the anti-reflective coating and use of KOH leads to formation of insoluble precipitates, in turn affecting the purity of recovered silicon. Herein, we report a single reagent approach for a streamlined process for recovery of high purity silicon with unmatched recovery yield. Phosphoric acid, (H3PO4) identified as a reagent for this approach, directly targets the anti-reflective coating and separates the Ag and Al present on the Si wafer surfaces. This approach led to an impressive recovery rate of 98.9% with a high purity of 99.2%, as determined by X-ray fluorescence and Inductively-coupled plasma optical emission spectroscopy. Such high-purity of recovered silicon enables upcycling into anodes for lithium-ion battery, with the battery performance comparable to as-purchased silicon. Such recovered silicon lithium-ion battery anodes demonstrated a high specific capacity of 1086.6 mAh g−1 (62.3% of its initial specific capacity), even after 500 cycles at a high charging rate of 1.0C while maintaining high coulombic efficiency (>99%).National Environmental Agency (NEA)National Research Foundation (NRF)This research/project is supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop Funding Initiative (Award No. USS-IF-2018-4)

Purification and characterization of recombinant malate synthase enzymes from streptomyces coelicolor a3(2) and s. clavuligerus Nrrl3585

10.1038/sj.jim.7000240Journal of Industrial Microbiology and Biotechnology284239-243JIMB

Upcycling end of life solar panels to lithium-ion batteries via a low temperature approach

The massive adoption of renewable energy especially photovoltaic (PVs) panel is expected to create a huge waste stream once it reaches end-of-life (EoL). Despite having the highest embodied energy, present photovoltaic recycling neglected the high purity silicon found in the PV cell. Herein, a scalable and low energy process was developed to recover pristine silicon from EoL solar panel through a process which avoids energy-intensive high temperature processes. The extracted silicon was upcycled to form lithium-ion battery anodes with performances comparable to as-purchased silicon. The anodes retained 87.5 % capacity after 200 cycles while maintaining high coulombic efficiency (>99 %) at 0.5 Ag -1 charging rate. This simple and scalable process to upcycle EoL-solar panels into high value silicon-based anode can narrow the gap towards net-zero waste economy.National Environmental Agency (NEA)National Research Foundation (NRF)Submitted/Accepted versionThis research/project is supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop Funding Initiative (Award No. USS-IF-2018-4)

Upcycling silicon photovoltaic waste into thermoelectrics

Two decades after the rapid expansion of photovoltaics, the number of solar panels reaching end-of-life is increasing. While precious metals such as silver and copper are usually recycled, silicon, which makes up the bulk of a solar cells, goes to landfills. This is due to the defect- and impurity-sensitive nature in most silicon-based technologies, rendering it uneconomical to purify waste silicon. Thermoelectrics represents a rare class of material in which defects and impurities can be engineered to enhance the performance. This is because of the majority-carrier nature, making it defect- and impurity-tolerant. Here, the upcycling of silicon from photovoltaic (PV) waste into thermoelectrics is enabled. This is done by doping 1% Ge and 4% P, which results in a figure of merit (zT) of 0.45 at 873 K, the highest among silicon-based thermoelectrics. The work represents an important piece of the puzzle in realizing a circular economy for photovoltaics and electronic waste.Agency for Science, Technology and Research (A*STAR)Ministry of National Development (MND)National Environmental Agency (NEA)A.S. acknowledges funding from A*STAR (Agency of Science, Technology and Research) Career Development Fund (CDF) no. C210112022. J.X acknowledges A*STAR “Sustainable Hybrid Lighting System for Controlled Environment Agriculture programme”: A19D9a0096. Z.L. would also like to express gratitude to the financial support from the A∗STAR’s Science and Engineering Research Council (SERC) Central Research Fund (Use-inspired Basic Research) for this work. N.M. and Q.Y. acknowledge grant award from NEA (National Environmental Agency, Singapore) and Ministry of National Development (MND, Singapore) titled “Singapore–CEA Alliance for Research in Circular Economy (SCARCE, award number USS-IF-2018-4),” which is a joint lab set up between Nanyang Technological University (NTU, Singapore) and the French Alternative Energies and Atomic Energy Commission (CEA, France)