Initial Concentration Research Articles

Influence of Sulfate and Nitrate for Lanthanum (III) Adsorption on Bentonite: Implications for Rare Earth Wastewater Disposal

The direct discharge of rare earth wastewater causes the waste of resources and heavy metal pollution. This paper compared the adsorption behaviors of lanthanide ions on bentonite under sulfate and nitrate systems by examining the factors affecting the adsorption, such as adsorption time, pH, background electrolyte concentration, and initial rare earth ion concentration. It was shown that the sulfate system was more favorable for the adsorption of rare earth ions on the bentonite surface. The maximum adsorption capacity in the sulfate system was about 1.7 times that in the nitrate system. In contrast, the adsorption under the nitrate system was more sensitive to the changes in pH and background electrolyte concentration. The adsorption processes under both systems are spontaneous physical adsorption processes (ΔGθ are from −27.64 to −31.48 kJ/mol), and both are endothermic (ΔHθ are 10.38 kJ/mol for the nitrate and 7.53 kJ/mol for the sulfate) and entropy-increasing (ΔSθ are 61.54 J/mol for the nitrate and 76.24 J∙mol−1 for the sulfate) processes. This study helps to provide information about the optimizing process parameters for the adsorption treatment of rare earth wastewater using bentonite.

Efficient phosphorus removal from ultra-low concentration wastewater by flow-electrode capacitive deionization

During the 14th Five-Year period, the stringent phosphorus emission standard puts forward higher requirements for the phosphorus removal. In this study, lotus leaf-based biochars were prepared by hydrothermal carbonization method and used as low-cost FCDI electrode materials to remove ultra-low concentration phosphorus in wastewater at the first time. The governing factors and optimal adsorption conditions were systematically investigated as 1.2 V applied voltage, 24 s HRT, 10 wt% content of biochars. The maximum removal efficiency reached 98.55 % under 20 mg/L initial phosphorus concentration, which ensured that the phosphorus concentration of the effluent could meet discharge standard (0.3 mg/L) of WWTPs. Furthermore, the microscopic and spectroscopic characterization revealed that phorphorus removal mechanism included physical adsorption, electrosorption, ion exchange, precipitation and ligand exchange, which may take place simultaneously or supplementing each other. Using in situ potential measurement method, the potential gradient and energy consumption contribution of each FCDI component were described. The results showed that total specific energy consumption was very low and the flow electrodes modules dominated (more than 50 %) in all FCDI components. The findings opened up a promising way for managing biowastes and confimed the application of engineering biochar in environmental pollution treatment field.

Ammonia emissions related to black soldier fly larvae during growth on different diets

Abstract Black soldier fly (Hermetia illucens) is considered a farmed animal. The larvae live in a moist substrate, which leads to a complex interaction with the microbial community. As such the combined metabolism of the insects and that of the microbial community can ultimately lead to all sorts of emissions such as ammonia and greenhouse gases. For ammonia emissions and associated depositions, it is known that this can lead to eutrophication of local ecosystems and the formation of particulate matter which can affect human health. This issue is known for intensive livestock farming where in some Western European countries this has led to specific regulations, for example limited number of livestock per farm, to control ammonia emissions. The production of black soldier fly larvae is a novel activity that could similarly lead to ammonia emissions. This study introduces a new method to quantify ammonia emissions in an industrial setting using an accumulation chamber and validates the findings with a nitrogen mass balance. Additionally, different feed substrates (Gainesville diet, chicken feed, artificial supermarket waste and brewers spent grains) were assessed with varying crude protein concentrations, hypothetically one of the driving factors affecting emissions. Results indicate significant ammonia emissions, the total emissions during larval growth ranged from 2.6 up to 83.6 g N/kg larvae (dry matter basis) and depend strongly on the diet. The rates at which these emissions are produced are negligible during the first three days. In the following days all diets emitted ammonia at a varying rate. The highest observed hourly emission rate for test substrates could be as low as 6.8 mg N/kg initial substrate (dry matter basis) and as high as 306 mg/kg. Different properties of the feed, such as the initial crude protein concentration, but also how the pH changes throughout larval growth, will affect emissions.

Functionalised graphene oxide dual nanocomposites for treatment of hazardous environmental contaminants

During the past few decades, water contamination has raised a huge concern due to rapid industrialization, agricultural wastes, metal galvanizations, and leather industries as a result of the discharge of organic pollutants, dyes and heavy metals. The present study investigates the synthesis of copper oxide nanoparticles (CuO-NPs) and graphene oxide-copper oxide nanoparticles (GO/CuO-NPs) for heavy metal ions adsorption like Ni2+ and Cd2+ from wastewater. For this purpose, batch and continuous adsorption studies were performed. The chemical and physical characteristics were analyzed by FTIR, XRD, SEM, and AFM. AFM analysis confirmed the hexagonal structure and an average diameter of 79.91, 82.01 and 21.45 nm for GO/CuO-NP, CuOn, and CuOm, respectively. In batch scale, it is concluded that GO/CuO-NPs showed the best adsorption capacity for Ni2+ and Cd2+ than CuOn and CuOm at pH value of 8, adsorbent dose of 250 mg, initial concentration of 50 mg/L, a contact time of 15 min. GO/CuO-NP showed the maximum Ni2+ and Cd2+ removal of 99.16 and 98.84 % respectively at 15 min contact time. Similarly, the maximum Ni2+ and Cd2+ ions removal of about 99.37 and 99.18 % was observed with GO/CuO-NPs at an adsorbent dose of 250 mg and 50 mg/L dye concentration. The adsorbent isotherm and kinetic analysis revealed that the results were best fitted with Langmuir isotherms and the Pseudo-second order model, respectively. While in continuous adsorption analysis, GO/CuO-NPs showed the best adsorption capacity for Ni2+ and Cd2+ than CuOn and CuOm at an initial concentration of 50 to 75 mg/L, a flow rate of 4 mL/min, and a bed height of 1.5 to 2 cm. However, the present study provides valuable insight into novel nanocomposites' development to eliminate Ni2+ and Cd2+ from industrial wastewater.

Degradation of Procion brilliant yellow H-E6G using ultrasonic and hydrodynamic cavitation combined with oxidants with demonstration at pilot scale.

The current study focuses on the degradation of Procion brilliant yellow H-E6G, an azo dye, using ultrasonic and hydrodynamic cavitation (HC), evaluating the impact of various parameters on the extent of degradation. The use of only ultrasound showed less oxidation capacity as indicated by only 19.1% degradation at an optimized power of 140 W, pH of 2.5, temperature of 40°C, and initial dye concentration of 15 ppm. The effectiveness of hybrid approaches involving US + H2 O2 , US + Fenton, and US + H2 O2 + potassium persulfate (KPS) was subsequently evaluated under optimized conditions. A notable enhancement in decolorization extent was observed for combined operations, including US + H2 O2 , US + Fenton, and US + H2 O2 + KPS (dual oxidant scheme) with the actual decolorization extents as 80.6%, 85%, and 92.2% respectively. An optimized scheme of US + H2 O2 + KPS was also utilized to decolorize the dye at a pilot scale using a US flow cell and also an HC reactor that yielded 91.8% and 88% reductions in initial concentration. The dye decolorization was elucidated to follow first-order kinetics for all the individual and combination approaches. The obtained values of the rate constants were also utilized for the evaluation of the synergistic index. A toxicity analysis was also performed on the dye, both before and following treatment, utilizing two bacterial strains. A comparative analysis of various treatment approaches has been presented focusing on factors such as cavitational yield, operational expenses, and energy requirements. The study elucidated that the combination of US + H2 O2 + KPS effectively removes Procion brilliant yellow H-E6G giving 92.2% as the maximum degradation at an operating cost of 0.1862 $/L. PRACTITIONER POINTS: First depiction of cavitative degradation of Procion brilliant yellow H-E6G Optimizing the equipment operating parameters and chemical oxidants Demonstration of optimized treatment scheme at pilot scale Evaluation of various approaches based on synergy and costs of treatment US + H2 O2 + KPS is the best approach for dye degradation.

Comparison of Acid- and Base-Modified Biochar Derived from Douglas Fir for Removal of Copper (II) from Wastewater

Copper is a non-biodegradable heavy metal, and high levels in water bodies cause serious environmental and health issues. Douglas fir biochar has a higher number of carboxylic, phenolic, and lactonic groups, which provide suitable active sites for copper removal. Douglas fir biochar (BC) was modified using 20% solutions of KOH (KOH/BC), H2SO4, (H2SO4/BC), and Na2CO3 (Na2CO3/BC). All materials were characterized using SEM, SEM-EDS, FTIR, TGA, XRD, BET, and elemental analysis. These modifications were done to compare the activations of those sites by measuring copper removal efficiencies. KOH/BC, H2SO4/BC, and Na2CO3/BC materials gave surface areas of 389.3, 326.7, and 367.9 m2 g−1, respectively, compared with pristine biochar with a surface area of 578.9 m2 g−1. The maximum Langmuir adsorption capacities for Na2CO3/BC, KOH/BC, BC, and H2SO4/BC were 24.79, 18.31, 17.38, and 9.17 mg g−1, respectively. All three modifications gave faster kinetics at 2 mg/L initial copper concentrations (pH 5) compared with pristine BC. The copper removal efficiency was demonstrated in four different spiked real water matrices. The copper removals of all four water matrices were above 90% at 2 mg/L initial concentration with a 2 g/L biochar dosage. The competitive effects of Pb2+, Zn2+, Cd2+, and Mg2+ were studied at equimolar concentrations of Cu2+ and competitive ions for all four materials.

Propagation characteristics of elastic longitudinal wave in a piezoelectric semiconductor metamaterial rod and its tuning

Elastic metamaterial structures have many distinct wave properties such as band gap structure and topological phase inversion. The coexistence and interaction of piezoelectricity and semiconductor behavior in piezoelectric semiconductor (PS) materials endow metamaterials with some new physical effects. We investigate the propagation characteristics of elastic longitudinal waves in a metamaterial rod made of n-type PS material and piezoelectric (PE) dielectric material. Based on one-dimensional rod model, we present the transfer matrixes for the PS and PE phases as well as the interfacial transfer matrix of unit cell. The analytical dispersion relations of the considered PS-PE metamaterial rod are obtained by utilizing Bloch's theorem. Numerical results show that band gap structures of the metamaterial rod are dependent on the initial electron concentration, length ratio of PE phase, interfacial condition, and capacitor connected with the PE phase. The selection of certain initial electron concentration, length ratio of PE phase, and capacitor can lead to the appearance of topological phase inversion, highlighting the potential for controlling and manipulating the wave propagation properties of PS metamaterial structures. This paper provides a theoretical guidance on the development of smart devices based on PS metamaterial structures. The novel combination of piezoelectricity and semiconductor behavior in these materials opens up new avenues for designing and engineering advanced devices with tailored wave properties and functionalities.

Loading organic phosphorus-degrading bacteria enhanced biochar performance for heavy metals adsorption

As a porous material, biochar has been endowed with high expectations to be the carrier for heavy metals-tolerant microorganism loading due to its excellent performance. Therefore, the biochar derived from green walnut husk was used in this study to load a screened heavy metal-tolerant organic phosphorus-degrading bacteria OPB3–6–1 for heavy metals remediation. The results suggested that biochar loaded with OPB3–6–1 (IOPB) exhibited a synergistic effect in adsorbing of Pb2+, Cu2+ and Cd2+, while IOPB500 (carrier prepared under 500℃ of pyrolysis temperature) obtained the highest adsorption potential as its adsorption capacities for Pb2+, Cu2+ and Cd2+ reached 591.0, 300.0 and 20.0 mg/g under a certain initial concentration, respectively. In addition, the carrier dosage, reaction temperature and pH posed different effects on IOPB500 in heavy metals adsorption, and the top adsorption capacity obtained under the condition of 1 g/L of dosage, 30℃ of reaction temperature and 6–7 of pH. The adsorption kinetics and isotherms suggested that monolayer chemical reaction dominated the whole adsorption process of IOPB500 for Pb2+, Cu2+ and Cd2+, while intra-particle diffusion process played a greater role in rate control. Compared with intracellular uptake, extracellular complexation accounted for the major contribution for Pb2+, Cu2+ and Cd2+ adsorption of OPB3–6–1, which facilitated the adsorption of heavy metals in IOPB since such functional groups as PO, P-OH and PO43- were detected in IOPB by FTIR. After applying IOPB500 into heavy metal contaminated soil, the exchangeable fraction of Pb2+, Cu2+ and Cd2+ decreased by 15.7%, 19.0% and 23.24%, while the residual content increased by 15.9%, 9.3% and 11.5%, respectively, thereby alleviated the toxicity and risks of heavy metals. Overall, the conclusion of this study proved the potential of biochar-bacteria coupled systems on heavy metal remediation applications.

Modified agricultural wastes as potential environmental decontaminants: finding possibilities for treating cadmium contaminated waters

ABSTRACT There is a need to find eco-friendly methods for preventing toxic heavy metals from subsuming into food chain due to their deadly impact on plants and animals. A study was employed to investigate cadmium adsorption efficiency of biowastes and their derived products. The bio-wastes included apple pomace and sawdust based vermicompost, later converted to biochar. The study elucidated the impact of changing pH, initial concentration and contact time on cadmium adsorption efficiency of biowastes. Among different adsorbents, the biochars efficiently removed Cd (II) and attained equilibrium at a faster rate. The equilibrium data best fitted to Freundlich and Langmuir isotherm. Among different adsorbents, maximum adsorption (qmax) (35.075 mg g−1) from Langmuir adsorption isotherm was reported for vermicompost derived from 100% sawdust. Among biochars highest qmax (3.0 mg g−1) was reported for biochar obtained from 100% apple pomace. All adsorption systems were exothermic, with AT values ranging from 0.05–0.75 J/mol at pH 8 and 0.118–0.485 J/mol at pH 2. The pseudo-second order kinetic model was best fit at all concentrations implying chemisorption of Cd2+ ions by bioabsorbents. The adsorption could complete in optimum time frame required for industrial application for treating contaminated water at large scale.

Process optimization of superior biosorption capacity of biogenic oyster shells nanoparticles for Congo red and Bromothymol blue dyes removal from aqueous solution: Response surface methodology, equilibrium isotherm, kinetic, and reusability studies

The essential use of natural materials or microbial biomass for effective dye removal from water, combined with simultaneous antimicrobial activity, is crucial for environmental and biomedical applications. Functionalized oyster shell waste nanoparticles (OY-NPs) were synthesized and utilized for efficient biosorption of Congo red (CR) and bromothymol blue (BB) dyes from solution, exhibiting promising antibacterial properties against gram-negative bacteria, specifically Escherichia coli (E. coli), in wastewater. Employing response surface methodology and central composite design, the impact of key process variables; pH, initial concentration, time, and adsorbent doses were investigated. Characterization through scanning electron microscopy, transmission electron microscopy, Fourier transform irradiation, and x-ray diffraction analyses revealed mesoporous crystalline structures rich in CaCO3, featuring prominent functional groups such as C–O, CO, and O-H. Optimization of batch experiments yielded peak efficiency at pH 3.3, initial concentration of 72.34 mg/L, contact time of 84.44 min, and a dosage of 0.1 for CR and BB, achieving a desirability coefficient of 1.0. Equilibrium studies aligned with the Langmuir isotherm model determined coefficient (R2 > 0.977), while kinetic experiments correlated well with the pseudo-second-order model (R2 > 0.9). OY-NPs demonstrated optimal adsorption capacities of 84.77 and 180.61 mg/g for CR and BB, respectively, with spontaneous and endothermic removal. Reusability studies showcased consistently high adsorption efficiency over 5 cycles, highlighting the eco-friendly and recyclable potential of OY-NPs for wastewater treatment applications. The observed antibacterial activity further supports their suitability for antimicrobial applications.

Selective Extraction and Determination of Hydrocortisone and Dexamethasone in Skincare Cosmetics: Analytical Interpretation Using Statistical Physics Formalism

Molecularly imprinted polymers (MIPs), as magnetic extraction adsorbents, are used for the selective, rapid determination and extraction of dexamethasone and hydrocortisone in skincare products. Therefore, in this paper, magnetic molecularly imprinted polymers (MMIPs) and magnetic non-molecularly imprinted polymers (MNIPs) were utilized as adsorbents to describe the adsorption phenomena of dexamethasone and hydrocortisone. This interpretation, based on a statistical physics theory, applies the multilayer model with saturation to comprehend the adsorption of the drugs. Results obtained via numerical simulation revealed that dexamethasone and hydrocortisone adsorption happens via a non-parallel orientation on the surfaces of MMIPs and MNIPs, and they also showed that the adsorption amount of the MMIPs for the template molecule was notably greater than that of the MNIPs at the same initial concentration. The adsorption energy values retrieved from the data analysis ranged between 7.65 and 15.77 kJ/mol, indicating that the extraction and determination of dexamethasone and hydrocortisone is a physisorption process. Moreover, the distribution of a site’s energy was calculated to confirm the physical nature of the interactions between adsorbate/adsorbent and the heterogeneity of the surfaces of the MMIPs and MNIPs. Finally, the thermodynamic interpretation confirmed the exothermicity and spontaneous nature of the adsorption of these drugs on the tested adsorbents.

Reactive species and mechanisms of perfluorooctanoic acid (PFOA) degradation in water by cold plasma: The role of HV waveform, reactor design, water matrix and plasma gas

The scope of this study was to optimize dielectric barrier discharge (DBD) plasma for the degradation of perfluorooctanoic acid (PFOA) in water by comparing several critical aspects such as pulsed-plasma waveform (nanosecond and microsecond high voltage (HV) pulses), reactor configuration (gas–liquid treatment and underwater plasma bubbles), water matrix and plasma gas. The physicochemical properties and species concentration of plasma-treated water, under the aforementioned conditions, were also determined and correlated with PFOA degradation. PFOA was more efficiently degraded by air–liquid DBD compared to DBD-based underwater air-plasma bubbles consistent with the surfactant nature of PFOA and the more intense plasma-liquid interaction and species formation prevailing during gas–liquid treatment compared to plasma bubbles treatment. After 30 min of gas–liquid DBD treatment, the degradation of PFOA in ultrapure water was >99.9, 98.8, 95.1 and 63% under air-, N2-, Ar- and O2-plasma respectively, whereas its degradation was almost equally effective in the whole range of its initial concentration (10 to 0.1 mg/L). Air was almost equally effective at degrading PFOA in ultrapure and tap water, while argon was much more effective at degrading PFOA in tap water (>99.9% after 20 min) possibly due to the prevailing alkaline conditions (pH ∼8.7) favoring its degradation. Faster PFOA degradation was achieved under HV micropulses compared to HV nanopulses. Nevertheless, in terms of energy requirements, HV nanopulses were superior to HV micropulses, with the lowest electrical energy per order achieved under nanopulsed-argon (∼23.6 kWh/m3). The results of this study could contribute important knowledge to the development of plasma-based treatment of PFOA-contaminated water.

Preparation of nZVI/MCM‐41/rGO for Adsorption of Nickel Ions from Water

AbstractEmissions of nickel (Ni) are harmful to the environment and people‘s health. Although nano zero‐valent iron (nZVI) has a lot of potential for treating water pollution, its instability and tendency for aggregation have limited its application. In order to improve its properties, composite adsorbent MCM‐41/rGO supported nZVI (nZVI/MCM‐41/rGO) is designed for improving the properties of nZVI, and it is characterized by SEM, XRD, FTIR and BET. The results show that it has an apparent Fe(0) crystallinity and modest rGO crystallinity, as well as a rough and porous structure. There are many oxygen‐containing groups found on the surface of nZVI/MCM‐41/rGO, such as −OH, −COOH, and Si−O. The pore diameter is concentrated at 23.82 nm, and the specific surface area is 15.94 cm2/g. The consequences of several parameters such as contact time, initial metal ion concentration, adsorbent dosage, and pH for adsorption efficiency were investigated. The best performance is occurred at pH 6, C0=80 mg/L with a 2 g/L adsorbent dosage, and after 180 min, a maximum adsorption capacity of 41.82 mg/g is reached at 333 K. The Dubinin‐Radushkevich isotherm and second order kinetic models fit the Ni(II) adsorption process well. It is determined through analysis of the thermodynamic parameters that the adsorption progress is endothermic (ΔH0>0) and spontaneous (ΔG0<0). nZVI/MCM‐41/rGO has proven to be an effective and alternative material for the removal of Ni(II) ions from aqueous media due to its excellent removal ability, availability, and low cost.

Removal of phosphorus from water bodies using high-performance ceramsite prepared from solid wastes

This study successfully prepared a high-performance ceramsite for phosphorus adsorption using the sintering method, incorporating regolith granite sand-washing sludge (RGSWS) and phosphate tailings as raw materials. The optimal conditions for ceramsite preparation were determined as a ratio of RGSWS to phosphate tailings at 6:4, and sintering at 900 °C for 30 min. The impacts of various factors, such as the prepared ceramsite dosage, different initial phosphorus concentrations, temperature, pH, and co-existing ions were explored, and the reusability and safety of the ceramsite were also investigated. The results show that the ceramsite has a high adsorption capacity for phosphorus (20.40 mg/g) at pH 7 with broad applicability in the pH range of 3–11 and good selective adsorption in the presence of coexisting ions. Additionally, the application of ceramsite does not cause secondary pollution, and the ceramsite still maintains a high removal rate after being reused five times. XRD, FT-IR, XPS, and SEM-EDS analysis showed that chemical precipitation, surface complexation, and electrostatic attraction were involved in the adsorption process. It can be well described by the pseudo-second-order kinetic model and the Langmuir model, and the phosphorus adsorption by ceramsite was a spontaneous endothermic reaction process with increasing chaos. This research presents an effective solution for phosphorus removal from water bodies and offers a sustainable approach toward solid waste utilization.

Locally enhanced mixed-order model for chloramine decay in drinking water disinfection

Chloramine is the second most popular disinfectant and is widely used in the disinfection of drinking water. For chloramine disinfection, some standards require the total chlorine concentration to be maintained in an appropriate range in the water distribution system. Therefore, exploring the mechanism of chloramine decay and deriving an accurate chloramine decay model helps to optimize the disinfection process and ensure water quality safety. This paper proposed a locally enhanced mixed-order(LEM) model consisting of the first order model and the mixed order model to describe chloramine auto-decomposition and decays caused by other reactions respectively. Via proving the parameter a and k2 related to temperatures instead of initial chloramine concentration, the model had been further simplified. Nine chloramine decay experiments with different initial chloramine concentrations and temperatures were designed and carried out to evaluate the new model performance for chloramine decay simulation. The research results showed that the simplified LEM model could simulate the whole process of chloramine decay well. Its accuracy evaluation indexes (R2 and SSE) were better than that obtained from the first order model and the mixed order model. This paper proposed a simple and accurate method to simulate the process of chloramine decay and had a guiding significance for water quality safety assurance.

Enhanced oxidation and adsorption of arsenite by porous Fe-Mn binary chitosan beads and its application in fixed-bed column

A novel porous Fe-Mn chitosan bead (PFMB) was fabricated through the freeze-drying technique for the enhanced oxidation and adsorption of arsenite (As(Ⅲ)) from aqueous solution. The porous internal structure of PFMB provided a significantly higher As(Ⅲ) oxidation and adsorption rate than solid Fe-Mn chitosan bead (FMB). The experimental results showed that FMB and PFMB exhibited the theoretical maximum As(Ⅲ) adsorption capacities of 27.42 and 49.80 mg/g, respectively. The real-time oxidation and adsorption progress of As(Ⅲ) onto PFMB was deeply evaluated: PFMB effectively oxidized As(Ⅲ) to As(Ⅴ) and the generated As(Ⅴ) was subsequently adsorbed. The operational parameters (initial pH, adsorbent dosage, ionic strength, and HA concentration) were thoroughly investigated and had no significant influence on As(Ⅲ) removal by PFMB. Finally, the regeneration experiment showed that PFMB can be easily regenerated and the recycled PFMB can successfully remove As(Ⅲ) in the following 5 cycles. Column experiments suggested that the column device could effectively remove the As(Ⅲ) in more than 3830 bed volume with the influent velocity at 0.5 mL/min before effluent concentration reached 0.05 mg/L. These results revealed the enhanced oxidation and adsorption performance of As(Ⅲ) onto PFMB and provided a reference for the future application of PFMB in arsenic-contaminated water treatment.

Enrichment, domestication, degradation, adaptive mechanism, and nicosulfuron bioremediation of bacteria consortium YM21

Nicosulfuron (NSR), a sulfonylurea herbicide, can easily enter water bodies, affecting aquatic life and human safety. Here, bacteria consortium YM2 was enriched and domesticated from the active sludge of a pesticide plant for the bioremediation of NSR wastewater. The response surface methodology data revealed that under optimal incubation conditions: 9.41 g L–1 maltodextrin, 21.37 g L–1 yeast extract, and 12.45 g L–1 NaCl, YM2 bacteria consortium degraded 97.49% of NSR within 4 d. The optimal degradation conditions were temperature 30°C, pH 6.0, inoculum 1%, and initial NSR concentration 20 mg L–1), The degradation system was tolerant to heavy metal ions such as Cd2+, Pb2+, Ni2+, and Zn2+ and mainly occurred through the bacterial extracellular enzymes (92.17%). Mechanistically, during the degradation process, reactive oxygen species, oxidative stress, cell membrane permeability, cell surface hydrophobicity, and apoptosis rate first increased and then decreased. Also, the expression of biofilm formation-related genes luxS, waaE, spo0A, and wza varied with time and concentration. NSR wastewater and soil were degraded to 1.92 mg L–1 and 2.72 mg L–1, respectively. In a simulated wastewater treatment unit (hydraulic retention time 12 h), YM2 degraded 84.55% of NSR after 10 d. This study provides a theoretical basis for the microbial remediation of NSR.

Removal of furosemide from water by emulsion liquid membrane: Influence of experimental conditions and real water matrices

This work investigates the removal of furosemide (FSM) from low pH aqueous phase by emulsion liquid membrane (ELM). The influence of various experimental conditions on FSM permeation rate and subsequent emulsion stability, such as surfactant concentration, diluent type, stripping solution concentration, feed solution pH, stripping solution/membrane solution volume ratio, emulsification time and speed, stirring rate, initial FSM concentration, and emulsion/feed solution volume ratio, was evaluated. The ability to extract FSM in different natural complex matrices was examined. The ELM system is formed by Span 80 (5% w/w) as surfactant, hexane as diluent, NaOH (0.01 N) as stripping agent, stripping solution/membrane solution volume ratio of 1/1, treatment volume ratio of 20/200, and mixing rate of 200 rpm. The treatment process demonstrates complete removal of FSM within a remarkably short time span of 20 min. In seawater and natural mineral water, the extraction efficiency is 94.3% and 96.8%, respectively, after 20 min. Additionally, the stripping efficiency of FSM is reported to be excellent (100%), demonstrating the remarkable ability of ELM to remove and recover FSM from water. For these reasons, the ELM technique is a particularly interesting process for treating FSM-contaminated water.

Competitive Adsorption of Cd(II) and Zn(II) on Biochar, Loess, and Biochar-loess Mixture

Combined heavy metal contamination in soil is a common phenomenon. Biochar amendment into the soil is considered to be an alternative for immobilization remediation of soil contaminated with heavy metals due to its adsorption and alkalization. However, much attention has been paid to the adsorption and immobilization of single heavy metals by biochar. In this paper, the competitive adsorption of Cd(II) and Zn(II) on biochar derived from cotton straw and pig manure at 500℃ (BCS500 and BPM500), loess and biochar-loess mixtures were investigated using the batch equilibrium method. The results showed that the adsorption capacities of biochars, loess, and biochar-loess mixtures to Cd(II) and Zn(II) in the mixed Cd-Zn systems increased with the increase of initial metal concentrations of Cd(II) and Zn(II). The adsorptive capacities of BCS500 and BPM500 to Cd(II) in mixed Cd-Zn system were 33% and 35% less than those in the single Cd(II)systems, while the adsorptive capacities to Zn(II) were 62% and 56% less than those in the single Zn(II) systems. The adsorptive capacities of loess to Cd(II) and Zn(II) in mixed Cd-Zn systems were 29% and 55% less than those in the single metal systems. The adsorptive capacities of loess-BCS500 (LBCS) and loess-BPM500 (LBPM) to Cd(II) in mixed Cd-Zn system were 40% and 38% less than those in the single Cd(II) systems, while the adsorptive capacities to Zn(II) were 63% and 60% less than those in the single Zn(II)systems. Moreover, the competitive adsorptive capacity of Cd(II) is greater than that of Zn(II). It can be seen that when heavy metal pollution with similar nature of multiple elements exists in soil, the amount of adsorbent should be increased to resist the possible weakened adsorption caused by competitive adsorption in order to guarantee an effective absorption treatment.

Cover crops affect pool specific soil organic carbon in cropland – A meta‐analysis

AbstractCover crops (CC) offer numerous benefits to agroecosystems, particularly in the realm of soil organic carbon (SOC) accrual and loss mitigation. However, uncertainties persist regarding the extent to which CCs, in co‐occurrence with environmental factors, influence SOC responses and associated C pools. We therefore performed a weighted meta‐analysis on the effects of CCs on the mineral‐associated organic carbon (MAOC), the particulate organic carbon (POC) and the microbial biomass carbon (MBC) pool compared to no CC cultivation in arable cropland. Our study summarized global research of comparable management, with a focus on climatic zones representative of Europe, such as arid, temperate and boreal climates. In this meta‐analysis, we included 71 independent studies from 61 articles published between 1990 and June 2023 in several scientific and grey literature databases. Sensitivity analysis was conducted and did not identify any significant publication bias. The results revealed that CCs had an overall statistically significant positive effect on SOC pools, increasing MAOC by 4.8% (95% CI: 0.6%–9.4%, n = 16), POC by 23.2% (95% CI: 13.9%–34.4%, n = 39) and MBC by 20.2% (95% CI: 11.7%–30.7%, n = 30) in the top soil, compared to no CC cultivation. Thereby, CCs feed into the stable as well as the more labile C pools. The effect of CCs on MAOC was dependent on soil clay content and initial SOC concentration, whereas POC was influenced by moderators such as CC peak biomass and experiment duration. For MBC, for example, clay content, crop rotation duration and tillage depth were identified as important drivers. Based on our results on the effects of CCs on SOC pools and significant moderators, we identified several research needs. A pressing need for additional experiments exploring the effects of CCs on SOC pools was found, with a particular focus on MAOC and POC. Further, we emphasize the necessity for conducting European studies spanning the north–south gradient. In conclusion, our results show that CC cultivation is a key strategy to promote C accrual in different SOC pools. Additionally, this meta‐analysis provides new insights into the state of knowledge regarding SOC pool changes influenced by CCs, offering quantitative summary results and shedding light on the sources of heterogeneity affecting these findings.