Publications

Cement kiln co-processing always became one of the predominate approaches to dispose hazardous solid waste containing heavy metals. The volatilization and morphology of heavy metals should be paid to more concern during the cement production due to the environmental risk of heavy metals. In this study, the volatilization characteristics and the solidification effect of heavy metals (Pb, Zn Cd and As) during cement kiln co-processing were explored by the lab and pilot scale experiments. At same experimental conditions, the volatilization rate followed as As > Pb > Cd > Zn. Both limestone and cement raw meal have been demonstrated the capability to mitigate the rates of heavy metal volatilization. Notably, cement raw meal displays a more pronounced effect compared to limestone in suppressing volatilization processes. Over 50% of heavy metals were transformed into residual state at 1400 °C, and Cd, As and Zn were easy to be solidified than Pb. A pilot scale experiment proved that more than 80% of heavy metals was solidified, and Zn reached nearly 100%. Moreover, around 80% of Cd, As and Zn were remained in clinker and the rest was distributed in kiln dust particles, only very few amount was released into the exhaust flue gas. This study provides a comprehensive and extensive understanding of the volatilization characteristics and migration patterns of heavy metals in the cement kiln environment. It offers theoretical support for the control of heavy metals during the co-processing of hazardous solid waste in cement kilns.

Advanced aerogel materials with lightweight, flame retardant, and rapid cooling properties are urgently needed as thermal insulators in harsh environments. Herein, Cr2O3 − Al2O3 aerogels (CrAAs) were fabricated through a simple method and an ambient pressure drying process. A large number of pores were produced in the microstructure of the sample by the carbonization of soluble starch during calcination. The porous structure decreases the density of the prepared CrAA (Cr2O3 − Al2O3 aerogel) to as low as 0.143 g cm−3, and increases the thermal conductivity to as high as 0.125 W m−1 K−1, indicating the good thermal dissipation and rapid cooling performance of the sample. The prepared CrAAs possess a variety of composite properties such as good flame retardancy, rapid cooling, and colour restore after flame is extinguished. Moreover, after being subjected to flame treatment at ∼ 1300 °C using a butane blowtorch for 5 min, the CrAAs can be rapidly cooled to about 39.2 °C in about 1–2 min. The mechanism of the rapid cooling property was herein analysed, and we anticipate the potential application of CrAAs in flame–retardant cooling coatings.

The safe disposal of lead‐acid batteries has emerged as a critical environmental challenge of global concern. The development of innovative treatment technologies is crucial for addressing the imminent surge in spent lead‐acid battery waste. This work presents an innovative strategy for fabricating porous functional monolithic aerogels (PFMA) derived from spent lead paste anode materials. PFMA was synthesized via a facile sol‐gel method by reacting spent lead paste anode material with AlCl 3 ·6H 2 O and C 8 H 12 O 8 Zr at a mild temperature (98 °C). Aluminum dihydrogen phosphate (AHP) was employed as an inorganic binder to enhance high‐temperature stability in the composite system. The as‐prepared PFMA exhibits a monolithic structure with excellent thermal insulation and good electromagnetic interference (EMI) shielding properties. The as‐synthesized PFMA exhibits a low thermal conductivity of 0.16 W/(m·k), demonstrating comparable thermal insulation performance to conventional refractory ceramic composites (Al 2 O 3 ‐ZrO 2 and Al 2 O 3 ‐Cr 2 O 3 ). When subjected to butane flame exposure (∼1300 °C) for 3 min, the 16 mm thick PFMA sample exhibited only a modest front surface temperature increase to 140 °C, demonstrating exceptional thermal insulation. Moreover, PFMA exhibits good EMI shielding performance in the range of 12–18 GHz, which corresponds to satellite and radar bands suggesting a promising potential application in this field.

Discarding PET plastic (dPET) causes serious environmental pollution and enormous fossil resources waste. Processing techniques have mainly focused on the conversion of dPET into monomers, with minimal reports highlighting their transformation into high–value materials. This work intends to transform dPET into a high–performance material with potential alternative value in harsh production environments. The soft and hard segments of the thermoplastic polyester elastomeric (TPEE) molecular structure are reacted and cross–linked with dPET using a facile one–pot process, and two main polymers, (C8H4O4)n and ((C16H18O4)0.76·(C4H8O)0.24)n are generated after the reaction. Through chemical reactions between TPEE and dPET, new characteristic products and chemical bond–crossing structures are formed, while the resulting product particles or multiple TPEE particles are anchored by the high viscosity of dPET, which endows the material with superior tensile strength (34.21 MPa) and impact resistance. The glass transition temperature (T g) of the material implies that neither the molecular chain nor the chain segments can move, while only the atoms or groups composing the molecule vibrate at their equilibrium positions. The development of this new treatment method may contribute to the reduction of environmental pollution and the improvement of the high–value conversion and utilization of dPET.

The introduction of dyeing sludge in the fired brick production is an economic and practical disposal approach. Wet dyeing sludge with high moisture usually produces block mass during mixing process of raw materials, not only reduces the production efficiency but negatively impacted products engineering properties. This study proposed a highly efficient method, wet sludge firstly being pelleted and then introduced in the production of fired bricks, to reduce the negative impacts on mixing process and the products quality. It was proved that the introduction of dyeing sludge pellets remarkably improved physical and mechanical properties of fired bricks. Especially, water absorption declined by 12% and compressive strength increased by 35% comparing with dyeing sludge without pelleting. The engineering properties of fired bricks containing 25 wt% sludge pellets are similar with that containing 15 wt% sludge without pelleting. The decrease in water absorption and porosity is mainly attributed to the reduction in number and volume of pores with diameter below 100 nm. It was considered that pellets with greater density and higher strength might play a role as aggregate to improve compressive strength. However, the introduction of sludge pellets with particle size over 8 mm is adverse to improving properties of products, because a large amount of macropore with diameter over 100 μm is produced, and destroys the homogeneous and compact structure of products. The optimal sludge pellet size is in the range of 2–6 mm based on products performance. The leaching toxicity of heavy metals from products is far lower than regulatory limitation. This study provides an advanced method to promote the disposal efficiency of solid waste and improve the engineering quality of products.

The introduction of electroplating sludge in the manufacturing of clay brick can be considered a feasible method to consume it, while physical-mechanical performances would degrade significantly and the potential leachability of heavy metals remain. This study proposed an alternative to remedy these negative impacts by adding Na2SiO3. The addition of Na2SiO3 decreased water absorption and promoted compressive strength substantially. Water absorption of bricks fired at 1050 °C for 3 h decreased from 6.05 to 0.56% and compressive strength increased dramatically from 22 to 46 MPa with the adding amount of Na2SiO3 raising from 0 to 20 wt%. The porosity analysis demonstrated the apparent porosity, surface area, pore volume, and pore size decreased significantly, especially at 1050 °C. The mineralogical phase analysis showed the Na2SiO3 reacted with quartz and formed albite, and the albite played an important role in decreasing porosity and enhancing mechanical property. Additionally, Na2SiO3 decreased the leachability of heavy metals, it was mainly due to the decrease in water absorption, surface area, pore volume, and pore size. Prolonging the firing time can also decrease water absorption and enhance compressive strength in the presence of Na2SiO3. These results proved that the addition of Na2SiO3 is a feasible strategy for enhancing the properties and environmentally safe of fired bricks when solid waste was introduced to produce bricks or ceramics.

The primary challenge in incorporating municipal solid waste incineration (MSWI) fly ash into the production of fired brick lies in enhancing the solidification and stabilization of chlorides and heavy metals. This study proposed a novel method to suppress the evaporation and leaching of Cl salts and heavy metals by confining MSWI fly ash in pellets and incorporating Cl salts into stable Cl-containing phase. The palletization process of MSWI fly ash before mixing clay to mold raw brick could effectively reduce the volatilization and leaching of Cl salts and improve the mechanical strength of the brick. Moreover, the addition of glass powder during pelleting MSWI fly ash further enhanced the physical-mechanical properties of bricks and substantially reduced the leaching risks of Cl salts and heavy metals. Specifically, Cl volatilization and leaching ratios were reduced by 31.09–48.11 % and 18.13–30.99 %, Cl solidification efficiency was increased over 93 %. The improvement in solidification/stabilization of Cl salts and heavy metals relies primarily on physical confinement into pellets and chemical transformation of into stable Cl-containing mineral phases (Ca10Si6O21Cl2 and Ca3SiO4Cl2). Anyway, pelleting mixtures of fly ash and glass powder is proved to enhance both the property performance and environmental safety of the bricks, which could be regarded as an efficient solution with the practical and theoretical significance for the utilization of fly ash in construction materials.

The catalyst Mo–Ni/Al2O3 is commonly used in the hydrodesulfurization of petroleum fractions. The catalyst is discarded when its catalytic activity does not meet the requirement of the process, and the spent catalyst is usually classified as hazardous waste due to its significant heavy-metal content. The spent catalyst usually has a high commercial recovery value as a secondary resource for high-value metals, but the simple and high efficiency recovery method is still lacking. A high-efficiency recovery method for Mo and Ni from spent Mo–Ni/Al2O3 catalyst via soda roasting and solvent extraction was developed in this study. MoO3 interacts with Al2O3 and forms a new phase, Al2(MoO4)3, during blank roasting at 600–700 °C. Al2(MoO4)3 further transforms into NaMoO4 during soda roasting at 950 °C, and over 99.1% of Mo can be leached using hot water (60 °C). Solvent extraction with the trioctyl tertiary amine (N235) is employed to separate Mo from the leaching solution, and approximately 99.45% of Mo can be enriched through single-stage extraction. Around 99.2% of Mo can be stripped from loaded N235 using 8 M NH3•H2O. Further, PO4 3− and SiO3 2− can be removed from the stripping solution using Mg(NO3)2, and Mo is recycled in the form of MoO3, i.e., a product of the ammonium precipitation and calcining process. Over 99.3% of Ni can be leached from the solid residue using 30% volume fraction of H2SO4 and the solvent extraction can be enriched using diiso-octylphosphate (DP). Ni is finally recycled from the stripping solution as NiSO4•2H2O via evaporative crystallization. The total Mo and Ni recovery efficiencies of the newly developed integrated approach are 97.8% and 98.1%, respectively. Al is also recycled in the form of α-Al2O3 via chemical precipitation and calcination. The proposed approach is simple, with a high recovery rate and high selectivity, and can be applied to the recycling and disposal of spent Mo–Ni/Al2O3 catalyst.

High–temperature resistant aerogel coating usually prevents damage to walls and equipment in a harsh high–temperature environment, but these coating still has some disadvantages in practical application, such as short time of high–temperature resistance or low stability. In this work, ZrO2–Al2O3 composite aerogel coating with prominent high–temperature resistance and rapid heat dissipation was successfully fabricated by employing (Al(H2PO4)3, AHP) as high–temperature adhesive to form stable phosphates products. The thermal conductivity and thermal diffusivity of the obtained ZrO2–Al2O3 composite aerogel coating are 0.1602–0.1623 ​W/mK and 0.3488–0.4702 ​mm2/s, respectively. The resultant aerogel coating with a thickness of 1.4 ​cm showed good performance in heat resistance with tolerance of flame up to ∼1300oC for 15 ​min, and rapid heat dissipation that can be cooled to 32.7–38.4oC within 60–70 ​s. Phosphate products, such as AlPO4 and ZrP2O7, are mainly formed at high temperature with the introduction of AHP, which fundamentally improves the high–temperature resistance and flame retardant of aerogel coating. Different microstructure and pore structure are responsible for the heat dissipation performance of the aerogel coating, which shows high thermal diffusivity of 0.3488–0.4702 ​mm2/s. Overall, this work provides a new strategy for preparing aerogel coating with high–temperature resistance, flame retardant, thermal stability and rapid heat dissipation suitable for harsh conditions.

The use of tunnel kiln firing in clay brick production offers a promising approach for disposing of Cl-containing solid waste, with lower chlorine (Cl) and heavy metal volatilization compared to cement kiln processes. However, the effects of Cl salts on brick properties and the volatilization mechanisms remain unclear. This study investigates the behaviors of NaCl, KCl, and CaCl2 during sintering. Adding 15 wt% Cl salts significantly alters pore structure, increasing water absorption by 80–100% and reducing compressive strength by 70–80%. At 1050 °C, 10.8–16.4% of Cl volatilizes mainly as HCl (g), 24.4–26.2% remains in original salt form, and over half is immobilized within the brick matrix. Thermodynamic and TG-MS analyses reveal Cl salts are stable below 800 °C but release HCl (g) at higher temperatures due to lower reaction energy barriers than Cl2 (g). Density functional theory (DFT) calculations show that H+ for HCl (g) formation primarily originates from water vapor (H2O), with organic decomposition having minimal effect. The presence of Cl salts promotes feldspar and silicate phase formation, enhancing densification but increasing porosity from HCl release. To reduce HCl emissions, a two-stage temperature control strategy is proposed: organic decomposition and moisture removal below 600 °C, followed by sintering at 800–1000 °C. This work clarifies the volatilization mechanisms of Cl salts and provides guidance for optimizing industrial brick production using Cl-containing waste.

Algicidal bacteria is known as efficient and environmentally friendly in treating Microcystis aeruginosa ( M. aeruginosa ). However, the practical application of algicidal bacteria in the natural water is limited by the interference of external factors and the low reuse capability. In this study, a biodegradation capsule for M. aeruginosa is prepared by biocompatible sodium alginate (SA) compositing with eco-friendly ethyl cellulose (EC). Bacterial strain HL was immobilized and the capsule was obtained under optimal usage concentrations of SA, Calcium chloride (CaCl 2 ) and EC at 2%, 3% and 3%. It has been observed that capsules immobilizing bacteria HL shows considerable advantages over traditional bio-treatment systems (free-living bacteria) and good reusability performance. A better dissolution rate of 77.67% ± 1.14% on the 7th day was obtained with the embedding of algicidal bacteria at 50 mL, which enhanced algae dissolution rate by 11.05% compared with free-living bacteria, and the dissolution rate for M. aeruginosa still reaches 68.57% ± 2.88% after three times repetitive use. Algicidal bacteria capsules were examined on the fluorescence and antioxidant system of M. aeruginosa . It was indicated that photosynthetic mechanisms of M. aeruginosa were destroyed, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) were all significantly induced as antioxidant response, and malondialdehyde (MDA) content increased. Overall, capsules prepared in this study can provide a desirable environment for algicidal bacteria HL and ensure algicidal bacteria to in-situ work well in the inhibition of algae.

The behavior of chloride (Cl) salts in high-temperature environments is critical for various industrial processes, including waste treatment and material synthesis. However, the influence of different atmospheric conditions on the volatilization and interaction of Cl salts with clay minerals remains poorly understood. Previous studies have primarily focused on individual salt types under limited conditions, leaving a gap in the comprehensive understanding of how atmosphere composition affects Cl salt volatilization at high temperatures. This work addresses this gap by systematically investigating the volatilization behaviors of NaCl, KCl, and CaCl2 in different atmospheres (air, N2(g), NH3(g), and H2O(g)) across temperatures from 750 to 1050 °C. The results revealed significant differences in volatilization rates, with H2O(g) atmosphere significantly enhancing Cl volatilization, especially for NaCl and KCl, while CaCl2 showed notably lower volatilization. N2(g) and NH3(g) atmospheres exhibit a similar, moderate effect on Cl volatilization, while the air atmosphere suppressed Cl volatilization due to the formation of stable oxide structures. Thermodynamic simulations confirmed the formation of HCl(g) as the primary volatile species, with metal cations forming stable silicates and feldspar compounds with clay minerals. DFT calculations highlighted that H2O(g) lowers the energy barrier for chloride salt decomposition, accelerating volatilization by weakening the bond between metal cations and Cl ions. These findings provide valuable insights into the impact of atmospheric conditions on the volatilization of Cl salts in high-temperature environments.