Qiaozhi Zhang

National University of Singapore | NUS

Catalytic oxidation through the transfer of lattice oxygen from metal oxides to reactants, namely the Mars–van Krevelen mechanism, has been widely reported. In this study, we evidence the overlooked oxidation route that features the in situ formation of surface OH species on Cu catalysts and its selective addition to the reactant carbonyl group. We...

Pyrolysis vapor is an important byproduct in the production of biochar from biomass waste, and its emission may pose potential environmental risks. To achieve green production of biochar and efficient utilization of pyrolysis vapors, a novel strategy is proposed in this study to use pristine biochar as an adsorbent to adsorb the pyrolysis vapors. A...

Spent lithium iron phosphate batteries can be successfully regenerated via a pollution-free, short-range, and low-carbon hydro-oxygen repair route.

Arsenic (As) is a potentially toxic element with variable valence states. Due to high toxicity and bioaccumulation, As can pose a severe threat to the quality of the ecology as well as human health. In this work, As(III) in water was effectively removed by biochar-supported copper ferrite magnetic composite with persulfate. The copper ferrite@bioch...

Microplastics and biochar, as particulate matter that is prevalent in the water environment, will inevitably encounter and interact with each other during environmental aging. The potential interaction of microplastics and biochar, and the associated impact on their environmental behavior remains largely unknown. In this study, we exposed microplas...

In the recycling of retired lithium‐ion batteries (LIBs), the cathode materials containing valuable metals should be first separated from the current collector aluminum foil to decrease the difficulty and complexity in the subsequent metal extraction. However, strong the binding force of organic binder polyvinylidene fluoride (PVDF) prevents effect...

Oxidative extraction has become an economically viable option for recycling lithium (Li) from spent lithium iron phosphate (LiFePO4) batteries. In this study, the releases behaviour of Li from spent LiFePO4 batteries under different oxidizing conditions was investigated with sodium hypochlorite (NaClO) as the solid oxidant. We revealed that, due to...

Microwave (MW)-assisted catalytic degradation of organic pollutants draws increasing attention owing to its high efficiency in wastewater treatment. This work developed Cu-loaded biochar (CuBC) catalysts for time-efficient mineralization of refractory and high-concentration oxytetracycline (OTC). With only 1 min at 80 °C, Na2S2O8 achieved 100% tota...

Worldwide surge in crop residue generation has necessitated developing strategies for their sustainable disposal. Pyrolysis has been widely adopted to convert crop residue into biochar with bio-oil and gas being two co-products. The review adopts a whole system philosophy and systematically summarises up-to-date knowledge of crop residue pyrolysis...

Producing alternative drop-in bio-jet fuels from biomass provides a promising approach to achieve carbon neutrality. To upcycle biomass-based polyisoprene rubbers into jet-fuel range C10 cycloalkane, we proposed a cascade hydropyrolysis and vapor-phase hydrogenation process in a flow-through two-stage pressurized fixed-bed reactor. The hydropyrolys...

This study innovated the concept in designing an efficient and reusable microwave (MW) absorbent through concurrent exploitation of carbon graphitization, oxygen functionalization, and carbothermal iron reduction underpinned by an endothermic co-pyrolysis of wood waste and low-dosage iron. A powerful MW assimilation was accomplished from nanoscale...

Biomass valorization to chemicals is an important application of this renewable resource. This study reports the production of two versatile value-added organic acids, i.e., gluconic acid (GOA) and glucuronic acid (GUA), from biomass-derived glucose via microwave-assisted catalytic oxidation. A series of novel low-cost biochar-supported Cu-based ca...

Lignocellulosic paper waste constitutes a major waste stream globally, which should be valorised for chemical production. However, paper properties (e.g., feedstock composition, cellulosic crystallinity, and thermal stability/degradability) vary with raw materials and pulping processes. This study investigated levulinic acid (LA), hydroxymethylfurf...

Heteroatom doping is a promising technique to enhance biochar for effective environmental remediation. However, development of electroactive heteroatom-doped biochars, e.g., sulfur-doped biochar, has been hindered due to complex nature of non-stoichiometric biomass-derived carbon and changeable electrochemical state of dopants. Herein, we produced...

Gluconic acid (GOA) and glucaric acid (GAA) are valuable chemicals for a wide range of applications, yet conventional technologies for their production suffer from low efficiency, high cost, and especially environmental concerns. It is imperative to develop sustainable heterogeneous catalytic systems exhibiting promising catalytic activity and good...

BACKGROUND Lignocellulose is usually pretreated as a raw material, and then it undergoes hydrolysis, fermentation, and other processes to produce biofuels, which is conducive to improving the utilization of agricultural and forestry wastes. However, most pretreatments, such as acid–base, CO2 explosion, and microbial degradation, could enhance the y...

Corn stalk was pretreated by aqueous tetrabutylammonium hydroxide to enhance enzymatic hydrolysis process. The effects of temperature (20–80 °C), concentration of tetrabutylammonium hydroxide (10–40 wt%), time (5–60 min) and ratio of solid to liquid (1:4–1:8, wt/wt) were investigated to find the optimal operational condition, which was determined a...

Sorghum was pretreated by sole ultrasound or supercritical carbon dioxide (scCO2), as well as the method combining both to intensify enzymatic hydrolysis. The effect of the time (1–5 h) and temperature (30–70 °C) on ultrasonic pretreatment was investigated, and the best condition was determined as 5 h and 50 °C with the EH sugar yield of 33.69%. Th...

Various agricultural crop residues including corn stover, corn cob, and sorghum stalk with a moisture content of 75 wt% were subjected to a long pretreatment (12–60 h) with supercritical CO2 (scCO2), at low temperature (50–80 °C) and a pressure of 17.5–25.0 MPa. The sugar yields from the enzymatic hydrolysis (EH) of the pretreated samples were as m...

Ultrasound-assisted dilute aqueous ammonia pretreatment under mild operating conditions has been investigated for intensification of enzyme hydrolysis for corn cob, corn stover and sorghum stalk. The effect of the pretreatment temperature (40–70 °C), time (1–4 h) and aqueous ammonia concentration (1.0–4.0 wt%) on the enzymatic hydrolysis sugar yiel...