The rational design of metal-free catalysts capable of efficiently converting CO2 under atmospheric pressure remains a significant challenge in sustainable chemistry. Herein, we report a series of clamp-shaped dihydrogen-bonded iodide catalysts (CDBI catalysts) featuring a preorganized bifunctional framework that integrates dual hydrogen-bond donors and an intrinsic iodide nucleophile within a single molecular scaffold. Systematic structural variation revealed that catalytic activity is highly sensitive to electronic modulation, steric accessibility, and precise spatial arrangement between the hydrogen-bonding units and the iodide center. The optimal catalyst enabled solvent-free cycloaddition of CO2 with epoxides at 1 atm CO2, affording up to 99% conversion and >99% selectivity at 80 degrees C within 12 h. Substrate scope studies demonstrated efficient transformation of a wide range of terminal epoxides, while sterically demanding substrates exhibited reduced reactivity consistent with a confined activation mode. Mechanistic investigations support a cooperative pathway in which dual hydrogen-bond activation and proximal halide nucleophilicity operate synergistically within a preorganized clamp-shaped pocket. Comparative analysis with representative catalytic systems highlights the ability of this metal-free design to achieve high efficiency under atmospheric CO2 without cocatalysts or solvents. These findings demonstrate that structural preorganization represents an effective strategy for promoting sustainable CO2 utilization under operationally simple conditions.

To simultaneously address the pressing challenges of sewage sludge (SS) disposal and coffee grounds (CG) valorization, herein, co-hydrothermal carbonization (Co-HTC) of SS and CG was performed at a dry mass ratio of 1:2 over a temperature range of 180–260 °C to evaluate hydrochar properties and synergistic interactions. Results revealed that hydrochar produced from SS alone (SS260) exhibited poor fuel quality with an ash content of 64.04% and a higher heating value (HHV) of merely 8.56 MJ·kg− 1. In contrast, co-hydrochar (SC260) demonstrated substantially enhanced fuel characteristics: ash content reduced to 38.53%, fixed carbon increased to 10.53%, and HHV elevated to 15.11 MJ·kg− 1 (a 76.5% increase relative to SS260), achieving an overall energy recovery efficiency of 64%. Combustion performance was also markedly improved, with SC180 exhibiting a combustibility index (Ci) of 1.06 and a comprehensive combustion index (S) of 6.37, values far exceeding those of raw SS (0.75 and 2.92, respectively). Notably, significant synergistic effects were observed during Co-HTC: SC260 achieved a carbon retention synergy coefficient of 7.92% and a yield synergy coefficient of 3.05%. Additionally, the resulting co-hydrochar possessed a higher specific surface area (31.54 m2·g− 1) and more developed porous structure compared to single-feedstock hydrochar. These findings demonstrate that Co-HTC of SS and CG is an effective strategy to upgrade hydrochar fuel quality, offering a technically viable approach for the clean and sustainable co-valorization of these two problematic organic wastes.

The control of algal blooms remains a significant challenge in global water environment management. Addressing the lack of hydrodynamic data and small-scale constrained river segments, this study proposes a novel framework for an algal growth dynamics model that incorporates meteorological, water quality, and hydrodynamic factors. The model parameters were optimized using a genetic algorithm for construction. Water quality in the Jiuqu River, located in the upper reaches of the Yangtze River, was monitored through field investigations. By combining Gradient Boosting Decision Tree analysis with SHapley Additive exPlanations, the key environmental factors affecting algal growth in the watershed were identified, and the model’s effectiveness was validated. This method combines mechanistic approaches with data-driven optimization, reliance on large data sets is reduced while model generalization is enhanced. It provides an early warning system for algal bloom outbreaks in the Jiuqu River Basin. The model, optimized through time-lag correction, demonstrated a 7.2% improvement in predictive performance for algal biomass compared to the non-optimized model. Furthermore, its performance significantly surpassed that of traditional data-driven models, showcasing robust adaptability and scalability. Finally, using the Copula function, a joint distribution model of key environmental factors and algal biomass was constructed. The relationships between environmental factors and algal bloom outbreaks were explored, and the environmental thresholds for algal bloom outbreaks in the Jiuqu River Basin were determined (COD Cr : 18.78 mg/L, COD Mn : 5.2 mg/L, TP: 0.09 mg/L, T: 11.48°C, Runoff: 0.08 mm). These findings provide guidance for the timely and effective prevention and control of algal bloom pollution.

Sediment is a critical component of aquatic ecosystems, that acts as a natural sink for diverse pollutants such as heavy metals and phosphorus (P). However, the current research on sediment remediation has predominantly focused on single contaminants. In this study, a novel composite material, calcium peroxide/lanthanum-loaded hydrochar (CaO2-LaHyd), was synthesised through the hydrothermal carbonisation of water purification sludge, followed by the sequential loading of lanthanum ions and nano-calcium peroxide. The adsorption capacities of CaO2-LaHyd for P and Pb were evaluated via adsorption experiments, and their passivation mechanisms were investigated through sediment capping simulations. Materials were characterised using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and energy-dispersive spectroscopy. Results indicated that CaO2-LaHyd exhibited maximum adsorption capacities of 66.05 mg·g⁻¹ for P and 230.41 mg·g⁻¹ for Pb. In the simulated capping experiments, the addition of 5% CaO2-LaHyd significantly reduced the phosphate concentrations in the overlying water. The slow release of oxygen from calcium peroxide improves sediment redox conditions, suppresses endogenous P release, and decreases interstitial P levels. Speciation analysis revealed that CaO2-LaHyd promoted the endogenous P transformation into stable forms while reducing the bioavailable P fractions. Concurrently, it enhanced Pb passivation, thereby mitigating Pb leaching risks from the sediment.

A novel granular waterworks-derived sludge composite (GT La-WDS) was synthesized via green and low-carbon hydrothermal carbonization combined with a calcination-free granulation method, demonstrating exceptional phosphate adsorption performance and potential as constructed wetland filler. Comprehensive characterization (SEM, XRF, BET, FTIR, XRD) revealed its hierarchical porous morphology, chemical composition, and hydroxyl/ligand-functionalized surfaces. Optimal phosphate adsorption capacity (20.11 mg/g) was achieved at pH 4, with adsorption mechanisms dominated by ligand substitution and formation of inner-sphere complexes, as supported by quasi-second-order kinetic modeling and Freundlich isotherm conformity. Dynamic column tests showed prolonged breakthrough (from 168 h to 432 h) and exhaustion times (from 588 h to 2088 h) with increasing bed heights (10 cm to 30 cm), achieving total adsorption capacities of 9.276 mg/g. Effluent phosphate concentrations remained below 0.5 mg/L (Chinese National Effluent Standard Class 1B) for 588 h, with sustained removal efficiency over 2088 h, indicating remarkable longevity. This sludge-derived composite presents a cost-effective solution for phosphorus sequestration, offering dual benefits of eutrophication mitigation and sustainable sludge valorization, with particular relevance to low-carbon constructed wetland systems.

Phosphorus pollution primarily causes water eutrophication. Adsorption, avoiding secondary pollution, is a key research focus for advanced phosphorus removal. Drinking water treatment sludge (DWS) is low-cost and readily available, but its modification relies on inefficient trial-and-error. This study used 657 datasets from 14 sources to evaluate six machine learning models for predicting modified DWS phosphorus removal performance. An improved Hybrid Encoding Genetic Algorithm (HEGA) was developed to inversely optimize modification parameters. Results showed the Gradient Boosting Decision Tree (GBDT) had the highest prediction accuracy (R2 = 0.992). Calcium-aluminum layered double oxides (Ca-Al LDOs) prepared via GBDT-HEGA demonstrated outstanding performance: 96.81 % phosphate removal and effluent concentration of 0.064 mg/L, meeting China's Class III Surface Water Standard (≤0.2 mg/L). In actual lake water tests, removal remained at 87.09 %. Feature importance analysis identified the Ratio as the most critical factor. Optimized material cost was extremely low ($0.8 per kg phosphorus removed). This data-driven approach overcomes traditional optimization inefficiency. The GBDT-HEGA framework provides a novel paradigm for complex environmental process optimization. The Ca-Al LDOs modification technique offers a feasible low-cost solution for water treatment targeting low phosphorus effluent, demonstrating significant practical value.

Lanthanum (La) emerged as a promising candidate for phosphate removal due to its inherent high affinity towards phosphates. However, addressing issues related to lanthanum aggregation often required loading lanthanum onto suitable carriers. While composite La with nanomaterials showed effective enhancement in adsorption performance, their practical environmental applicability remained limited. In this study, lanthanum was immobilized onto polyacrylonitrile (PAN) fibers modified with triethylenetetramine. The resulting lanthanum-loaded polyacrylonitrile (La@PAN) fibers exhibited a remarkable maximum phosphate adsorption capacity of 83.33 mg P g- 1, significantly higher than most previously reported fiber-based adsorbents. Moreover, these fibers achieved adsorption equilibrium within 20 min and demonstrated excellent adsorption capabilities within a broad pH range of 3-6. Even after five regeneration cycles using NaCl solution, the adsorption capacity retained 82.51 % of its initial value, indicating excellent environmental applicability. Importantly, these fiber adsorbents possessed unique flexibility and weavability, allowing them to be tailored into different shapes according to dynamic application demands, thus offering customized solutions for specific environmental challenges.

In this study, we investigated the effects of combined conditioning of water treatment sludge (WTS) with activated persulfate on enhancing dewaterability, phosphorus enrichment, and heavy metal stabilization during sludge treatment. The optimal parameter combinations obtained by Response Surface Methodology were 0.63 mmol/g DS of sodium persulfate (SPS), 0.61 mmol/g DS of Fe2+ and 50

Biochar was derived from rice straw pyrolyzed at 400°C, and biochar was added to the excess sludge at the ratio of 10% DS, 25% DS, and 50% DS as a supplementary skeleton for sludge Fenton pre-treatment. Rice husk biochar mixed with fungus residue as compost conditioner. In this study, we explored the effects of seven groups of composting materials on the composting effect and fertilizer quality under different pre-treatment methods of Fenton-pretreated sludge cake and conventional dewatered sludge cake, and different biochar additions. Specifically, we conducted a 22-day composting experiment using a composting reactor to investigate the effect of rice husk biochar combined with Fenton oxidation on the physicochemical properties of sludge composting. The results of this study showed that the FB50 group significantly increased the composting rate. Nutrient analysis showed that the FB50 group was rich in fertilizer nutrients, such as available phosphorus, and alkali-hydrolyzable nitrogen content increased. Heavy metals (Cu, Cd, Cr, Pb, Zn, Ni) met China's 'Agricultural Sludge Pollutant Control Standard' GB 4284-2018 Grade A standard, with obvious passivation and significantly reduced bioavailability. All these results suggested that biochar coupled with Fenton oxidation was more beneficial to sludge composting.

In this study, hydrochars were prepared at varying temperatures with distinct mixing ratio, and then the hydrochars were characterized and evaluated for heavy metals to ascertain its potential as a soil conditioner. The application of elevated temperatures resulted in a reduction in the yield of hydrochars, whereas the incorporation of coffee grounds led to an increase in the yield. The blended hydrochar displays elevated ash, fixed carbon, and diminished H/C, O/C, and (O + N)/C ratios, indicating enhanced stability in soil treatment and potential for enhanced soil fertility. The application of hydrothermal carbonization facilitated the stabilization of heavy metals within the sewage sludge, with the stabilizing effect being enhanced by the addition of coffee grounds. Following the application of SCC as a soil conditioner to the heavy metal-contaminated soil for a period of 90 days, it was observed that the heavy metals Cu, Cr, and Ni present in the contaminated soil underwent a transition from an unstable to a stable speciation. Of the treatments tested, AK15 was identified as the most effective, demonstrating a significant reduction in the risk of leaching and biotoxicity associated with Cu, Cr, and Ni in the contaminated soil. [GRAPHICS] .

In this study, the heat modified water purification sludge(WTS 400-4 ) was prepared by 400 ℃ and 4 h pyrolysis using water treatment sludge as raw material. The adsorption characteristics of phosphate in water and the effects of different dosage（2.5%, 5%, 10%） on the controlled release and the form of phosphate in the sediment were discussed. At the same time, combining with SEM, BET and other characterization methods, the stabilization mechanism of WTS 400-4 on phosphorus in sediment was explored. The results showed that WTS 400-4 had more developed pore structure and specific surface area than WTS, which strengthened the phosphate adsorption capacity. The adsorption process conformed to the quasi-second-order kinetic model. Freundlich model was more suitable to describe the phosphate adsorption process on WTS 400-4 , the parameter n higher than1 indicated that the WTS 400-4 was easy to adsorb phosphate. The addition of WTS 400-4 could cause the transformation of the weakly adsorbed phosphorus（NH 4 Cl-P）, redox-sensitive phosphorus（BD-P）,organophosphorus（Org-P） and other readily released phosphorus to stable metal oxide bound phosphorus（NaOH-rP） in sediment, and the conversion amount increased with the increase of WTS 400-4 dosage, which could contribute to inhibiting the release of phosphorus from the sediment. In addition, the addition of WTS 400-4 could reduce the contents of WSP（water-soluble phosphorus） and Olsen-P（sodium bicarbonate extractable phosphorus） in the sediment. Adding WTS 400-4 to the sediment, on the one hand, could reduce the contents of potential active phosphorus and bioavailable phosphorus in the sediment and reduce the risk of endogenous phosphorus release from the sediment to the overlying water. On the other hand, the phosphorus in interstitial water could be directly removed through the adsorption on WTS 400-4 , so as to reduce the phosphorus concentration gradient between overlying water and interstitial water and inhibit the release of phosphorus from interstitial water to overlying water. The results showed that WTS 400-4 could be used as a sediment amendment to control the phosphorus content in water and sediment.

Using water treatment sludge and lanthanum chloride as raw materials, lanthanum-modified water treatment sludge hydrothermal carbon was prepared through one-step hydrothermal carbonization and loading lanthanum. SEM-EDS, BET, FTIR, XRD, and XPS were used to characterize the materials. The initial pH of the solution, adsorption time, adsorption isotherm, and adsorption kinetics were investigated to study the adsorption characteristics of phosphorus in water. The results showed that the specific surface area, the pore volume, and the pore size of the prepared materials were significantly increased, and the phosphorus adsorption capacity was greatly improved compared with that of the water treatment sludge. The adsorption process conformed to the pseudo-second-order kinetic model, and the Langmuir model fitted the maximum phosphorus adsorption capacity to 72.69 mg·g-1. The main adsorption mechanisms were electrostatic attraction and ligand exchange. Adding lanthanum-modified water treatment sludge hydrochar into the sediment could effectively control the release of endogenous phosphorus from the sediment to the overlying water. According to the analysis of phosphorus forms in sediment, the addition of hydrochar promoted the transformation of unstable NH4Cl-P, BD-P and Org-P into the very stable HCl-P in the sediment, which reduced the content of potential active phosphorus and also significantly reduced the content of biologically available phosphorus. This indicated that lanthanum-modified water treatment sludge hydrochar could effectively adsorb and remove phosphorus in water and could also be used as sediment improvement material to effectively stabilize endogenous phosphorus in sediment and control phosphorus content in water.

Lanthanum-modified drinking water treatment sludge (DTSLa) and thermal-modified drinking water treatment sludge (TDTS) were prepared from drinking water treatment sludge(DTS). The adsorption properties of DTSLa and TDTS on phosphate in water and the effects on the controlled release and morphology of phosphorus in sediment at different dosages (0%, 2.5%, 5%) were discussed. Combining with SEM, BET, XRD, FTIR, and XPS characterization methods, the immobilization mechanism of DTSLa and TDTS on phosphorus in sediment was explored. The addition of TDTS can transform NH4Cl-P (loosely sorbed P), BD-P (bicarbonate-dithionite extractable P), and Org-P (organic P) into stable NaOH-rP (metal oxide-bound P) in sediment, and the conversion amount will increase with the increase of TDTS supplemental amount. DTSLa converted NH4Cl-P, BD-P, Org-P, and NaOH-rP to more stable HCl-P (calcium-bound P). At the same time, the content of WSP (water-soluble phosphorus) and olsen-P (NaHCO3 extractable P) in sediment can be reduced by the addition of DTSLa and TDTS, reducing the risk of the release of phosphorus from the sediment to the overlying water. In addition, phosphorus can be directly removed from the interstitial water by DTSLa and TDTS, so as to reduce the phosphorus concentration gradient between the overlying water and the interstitial water, thus inhibiting the release of phosphorus from interstitial water to overlying water. The results showed that DTSLa is better than TDTS in terms of its adsorption capacity and adsorption effect on endogenous phosphorus in water, so DTSLa is more suitable to be used as a sediment conditioner to control the phosphorus content in water and sediment.

Using water treatment sludge and lanthanum chloride as raw materials, lanthanum-modified water treatment sludge hydrothermal carbon was prepared through one-step hydrothermal carbonization and loading lanthanum. SEM-EDS, BET, FTIR, XRD, and XPS were used to characterize the materials. The initial pH of the solution, adsorption time, adsorption isotherm, and adsorption kinetics were investigated to study the adsorption characteristics of phosphorus in water. The results showed that the specific surface area, the pore volume, and the pore size of the prepared materials were significantly increased, and the phosphorus adsorption capacity was greatly improved compared with that of the water treatment sludge. The adsorption process conformed to the pseudo-second-order kinetic model, and the Langmuir model fitted the maximum phosphorus adsorption capacity to 72.69 mg·g-1. The main adsorption mechanisms were electrostatic attraction and ligand exchange. Adding lanthanum-modified water treatment sludge hydrochar into the sediment could effectively control the release of endogenous phosphorus from the sediment to the overlying water. According to the analysis of phosphorus forms in sediment, the addition of hydrochar promoted the transformation of unstable NH4Cl-P, BD-P and Org-P into the very stable HCl-P in the sediment, which reduced the content of potential active phosphorus and also significantly reduced the content of biologically available phosphorus. This indicated that lanthanum-modified water treatment sludge hydrochar could effectively adsorb and remove phosphorus in water and could also be used as sediment improvement material to effectively stabilize endogenous phosphorus in sediment and control phosphorus content in water.

In this study, readily available inexpensive water treatment sludge (WTS) was used to prepare adsorbent for the removal of Congo red (CR) and tetracycline (TC) from aqueous solutions. The structural characteristics and adsorption properties of WTS biochar were characterised via scanning electron microscope, energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller and Fourier Transform infrared spectroscopy. In batch experiments, the adsorption factors, kinetics, isothermal curves and thermodynamics of the adsorption properties were investigated. The optimum preparation condition of WTS biochar was 400 °C for 4 h under O2-limited pyrolysis, which exhibited increased specific surface area and pore structures. The best adsorption was observed when the pH of the CR and TC solutions was 7 and 4, respectively. The adsorption process followed the pseudo-second-order model, indicating that the main control step was the chemical adsorption process. Isotherm data were best described by the Langmuir model, and the maximum adsorption capacities for CR and TC were 116.4 and 58.5 mg·g-1, respectively. Thermodynamic parameters revealed that the adsorption process was spontaneous and endothermic. According to the analysis, the adsorption mechanism of CR could be attributed to electrostatic attraction, π-π conjugation and hydrogen bonding, whereas that of TC was potentially associated with cation exchange, complex precipitation, π-π conjugation and hydrogen bonding.

在pH为3和5的条件下,研究了芬顿氧化钙体系联合十二烷基二甲基苄基氯化铵(DDBAC)对污泥破解效果及脱水性能的影响,以期减少CaO的用量并同时提高芬顿反应的适用pH.以脱水泥饼含水率(WC)、毛细吸水时间(CST)、过滤时间(TTF)、污泥沉降比(SV)和胞外聚合物(EPS)中蛋白质(PN)与多糖(PS)的含量作为评价指标,对DDBAC投加量做单因素分析,找出其最佳投加量;并比较在不同pH条件下,DDBAC对污泥脱水性能的影响.结果表明,在pH为3条件下,H2O2、Fe2+、CaO、DDBAC投加量分别为60、30、60、60 mg·g-1(DS)时,污泥脱水效果最佳,其Wc为68.57％、CST为24 s、TTF为44 s、SV为72％.最佳脱水条件污泥EPS中的PN、PS总量大幅降低,其中T-EPS含量变化相较于S/L-EPS与污泥脱水性能的变化有更强的联系.在pH为5的条件下,该联合体系也有较好的脱水效果,对芬顿体系在弱酸性环境下使用有一定的参考价值.该联合体系能有效降低CaO的用量,同时能避免处理后的污泥pH过高、易板结的问题,且不会造成二次污染.

该文分别设置不同反应温度(120、150、180、210、240℃)和不同反应停留时间(0.5、1.0、2.0、4.0、8.0h),采用控制变量法对污泥进行水热处理.研究水热处理对污泥中氮、磷、钾含量及重金属形态分布的影响,且对重金属进行风险评估.结果表明,随着水热处理温度升高和时间延长,滤液的pH值逐渐降低,溶解性COD(SCOD)浓度逐渐升高.此外,液相中总氮(TN)、氨氮(NH4+-N)、总磷(TP)、磷酸盐(PO43-)浓度呈现递增趋势,而固相中总氮和钾呈现递减趋势.固相产物中OP向IP转化,NAIP向AP转化,TP、IP和AP含量升高,OP和NAIP含量下降.水热处理对Cu、Ni、Zn、Pb4种重金属具有稳定化作用,Zn由极高污染风险等级降为高污染风险等级,Cu由中度污染风险降为低污染风险,Ni和Pb的风险值都有所下降.总体来说,水热温度对污泥的影响效果比水热时间更显著.