Publications

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.

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.

Biochar is a good adsorbent and has been widely used to repair heavy metal soils. However, aging will affect the physical and chemical properties of biochar, and then affect its adsorption performance on heavy metals. This study explored the impact of aging on the adsorption performance of biochar derived from bovine bone char, prepared at 350 °C and 550 °C through oxygen-limited carbonization. The bone chars were simulated aging by H2O2 and Na2S2O8, with Cd2+ as the target ions for adsorption. This study examined the effect on the physical and chemical properties of bone char prepared by different aging degrees, assessing its adsorption efficiency for Cd. The results showed that the oxidative aging led to a rough surface and increased Cd adsorption. The surface of bone char was smooth and bar like without obvious granular matter after acidification aging, inhibiting Cd adsorption. In addition, Oxidation aging increased the surface complexation of bone char and decreased ion exchange. The coprecipitation of bone char and the cationic Caution-π action were seriously inhibited by acidification aging. The findings of this study provide valuable insights and promising applications for the use of animal bones as a strategy for the remediation of Cd2+ pollution.

FeOCl is widely used in cathode of lithium ion battery, matrix material and reaction catalyst. In which, the interactive behavior of H2O on FeOCl surface is closely related with the property of FeOCl materials. In this study, the influences of S and Mo doping on H2O molecule adsorption and dissociation on FeOCl (010) were explored by DFT calculations and experiments. Both calculations and experimental proved S and Mo doping promote the adsorption and dissociation of H2O molecule on FeOCl (010) surface with different process mechanisms. The surface electronegativity decreases slightly due to S doping, which reduces the repulsion to H2O molecule and lower the adsorption energy compared with clean surface. While, after forming stable adsorption structure, S doping promotes the dissociation of H2O by changing the electrons distribution in H2O and competing the shared electrons to weak the O–H bond strength. In contrast, Mo doping enhances the electropositivity of the surface, which is more conducive to the molecular adsorption reaction and more exothermic via coulombic attraction. For dissociative adsorption, the strength of O-H bond is enhanced, and the dissociation process is inhibited by Mo doping due to the electrons polarization in H2O molecule. Furthermore, S and Mo atoms are proved to be incorporated into the FeOCl lattice which enhance of H2O dissociation on doped FeOCl nanosheets surface. This study presents a microscopic insight for effects of S and Mo doped FeOCl surface on H2O molecule behaviors, while provides a theoretical basis for further research of the FeOCl surface water.

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 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.

Chromium is widely presented in industrial solid wastes like tannery sludge, electroplating sludge and metallurgical slag. These industrial solid wastes usually undergo thermal treatment process to reduce volume and toxicity. However, a significant amount of low-toxicity and low-mobility Cr(III) is determined to be oxidized to highly-toxic and highly-mobile Cr(VI) at high temperature, posing a greater threat to humans and the ecological environment. This paper summarizes the forms of Cr in solid wastes containing Cr, redox reactions mechanisms for different Cr forms, and methods to inhibit Cr(VI) formation during thermal treatment process. The Cr(III) compounds in solid waste containing Cr mainly include Cr(III) hydrates, Cr(III) oxides, Cr(III) hosting spinels and Organic-Cr(III). Cr(III) hydrates are usually oxidized at temperatures above 100 °C, even without the induction of alkali and alkaline earth metals. Compared to the direct reaction of Cr(III) oxides and spinels with O2, Cr(III) can be induced to oxidize at lower temperatures by alkali and alkaline earth metals. A large amount of Cr(III) is oxidized usually at 600–900 °C. Organic-Cr is generally pyrolyzed to CrO3(g), CrO2Cl(g) and Cr2O3(s) at high temperature. CrO2Cl(g) can be released directly into the atmosphere with CrO3(g), or captured by CaO to form CaCrO4. The reduction of Cr(VI) at high temperatures includes the decomposition of unstable Cr(VI) compounds driven solely by temperature, as well as reduction facilitated by acidic oxides. The reduction of Cr(VI) at high temperatures involves the decomposition of unstable Cr(VI) compounds, driven solely by temperature, as well as reduction facilitated by acidic oxides. Typical unstable Cr(VI) compounds include CrO3 and CaCrO4, which begin to decompose at temperatures above 270 °C and 1000 °C, respectively. Cr(III) oxidation and Cr(VI) reduction at high temperature are strongly dependent on the system basicity and the temperature. Subsequently, reducing oxygen content in atmosphere and the system basicity by adding common acidic oxides such as silicon dioxide, phosphate and sulfates exhibited a significant effect on inhibiting Cr(VI) formation during heating solid waste containing Cr. However, Cr oxidation and reduction mechanisms at molecular level have not yet been explored, and more effective measures to inhibit Cr(III) oxidation during thermal treatment of solid waste also should be developed in further works.

Harmful algal blooms (HABs) impacted negatively the water ecosystem, and produced toxic microcystins that poses toxic effect on liver, nervous, and genital

No abstract is provided for this article.

Thermal drying (100–300 °C) is usually required to reduce moisture from chromium (Cr)-containing sludge before incineration, storage, or other resource recovery processes. Yet, part of trivalent chromium (Cr(III)) is oxidized to the toxic hexavalent chromium (Cr(VI)) during thermal drying. Currently, the molecular-level Cr(III) oxidization pathways during thermal drying remain poorly understood. In this paper, the molecular reaction pathway and the influence of Fe(III) substitution on CrxFe1–x(OH)3 oxidation in thermal drying are clearly elucidated. CrO3 is identified as a formed Cr(VI) product, and the oxidation pathway is heavily dependent on temperature and CrxFe1–x(OH)3 hydration. CrxFe1–x(OH)3 is oxidized through a well-defined pathway involving CrO3 as a key metastable intermediate, which sequentially decomposes into Cr5O12 and CrnFe2–nO3 at higher temperatures. The substitution of Fe(III) enhanced CrxFe1–x(OH)3 oxidation and lowered initial oxidation temperature, because Fe3d orbital hybridization with exogenous O2p orbitals facilitated electron transfer between Cr–O systems, and expanded electron transition regions. Since Cr(OH)O is an essential intermediate product during the Cr(VI) formation process, PO43–, SO42–, and Cl– ions were introduced to preferentially combine Cr(III) before the CrxFe1–x(OH)3 dehydration process, thereby preventing the generation of Cr(OH)O and subsequent Cr(VI) products. This study provides fundamental insights into the molecular-level mechanism of Cr(III) oxidation during thermal drying of Cr-containing sludge.

A large amount of estrogen is introduced into the feed to improve livestock growth, excessive residual estrogen would exist in the excrements. The accumula