Batch Experiments Research Articles

Pilot-scale phosphorus recovery from mobile toilet wastewater in Bangkok, Thailand

The objective of this study is to enhance the capacity of struvite-phosphate forming reactor utilized in the production of phosphorus fertilizer from wastewater collected from mobile toilets, characterized by phosphorus (P) concentrations of 5.0 ± 1.1 g/l. The experimental procedure comprised three sequential phases: the first phase involved the precipitation of struvite-phosphate using the forming reactor; the second phase focused on pelletizing the P product with sugar milling wastes as filler; and the third phase involved assessing the bioavailability of P in agricultural soils. Experimental design entails batch experiments with the operational variables including the Mg:P molar ratio and pH. Results from nine experiments (3 × 3) indicate that (1) the percentage of phosphorus recovery ranged from 1.9 to 65.2, with a peak observed at high pH values, (2) optimal phosphorus recovery is attained at Mg:P ratio of 1.25 and pH of 9 during precipitation, and (3) the EDS analysis confirms the presence of major elements with phosphorus constituting the predominant component at 13.1%weight. Moreover, P leaching in soil predominantly occurred after the 7th day among the various soil types with the 90-days dissolution efficiency in soil of 97.7 ± 0.6, 86.9 ± 4.1, and 88.0 ± 3.0 for sandy loam, silt loam, and clay loam, respectively. These findings underscore the viability of achieving substantial phosphorus recovery through the utilization of a struvite-phosphate forming reactor via chemical precipitation, with additional evidence suggesting effective leaching of pellets in sandy loam soil, thereby highlighting its potential for widespread implementation in both phosphorus recovery and struvite fertilizer production on a large scale.

Pivotal Role of Multishelled Architecture in Nanoreactor with Spatial Confined Co3O4 for Peroxymonosulfate Activation and Contaminants Degradation

In recent years, cobalt‐based catalysts have been widely used in advanced oxidation technology to degrade pollutants in water environments. However, the reasons for the improved efficiency and performance of cobalt‐based catalysts with different shapes and structures on the activation of persulfate for contaminant degradation are still largely unknown. This study constructs different shapes and structures of cobalt‐based catalysts, namely, Co3O4 nanosphere, multishelled Co3O4 nanosphere (MSCONS), Co3O4 nanocube and multishelled Co3O4 nanocube, in combination with persulfate activation, on the degradation of tetracycline (TC) and bisphenol A (BPA), representative substances of antibiotics and endocrine disruptors in water environments. Batch experiments exhibit satisfactory TC (96.3%) and BPA (98.5%) degradation efficiency under MSCONS/peroxymonosulfate. Furthermore, MSCONS exhibits wide applicability under complex water matrix conditions. Consequently, an integration of density functional theory computations and intermediates analysis demonstrates that the synergy, rather than the isolated effects of radical and nonradical active species, broadens the degradation pathways of TC and BPA, thereby improving the removal efficiency. Overall, this study offers novel insights into the factors contributing to the enhanced performance of cobalt‐based catalysts with varying shapes and structures. Additionally, it proposes new research avenues for investigating the effects of shapes and structures on other transition metal‐based catalysts.

Limited reactivity of pyroxene and plagioclase in batch experiments with supercritical CO2 in the presence of NaCl and NaHCO3 in the context of CO2 sequestration via carbonation.

One-step high-pressure and high-temperature direct aqueous mineral carbonation of tailings derived from mining of Platinum Group Metals in South Africa requires a fundamental understanding of the reactivity of the most dominant mineral phases, i.e. pyroxene and plagioclase (66 wt. % and 12 wt. % of the bulk rock respectively) that are typically found in these tailings. The silicate minerals pyroxene and plagioclase were sampled from a pyroxenite footwall mined with the ore-bearing UG2 and from the Merensky Reefs outcropping in the eastern limb of the Bushveld Complex. These pyroxene and plagioclase grains were concentrated by gravity separation from the orthopyroxenite bulk rock and batch-reacted in a sodium chloride (NaCl) brine saturated with pure carbon dioxide (CO2) gas-only or seeded with sodium bicarbonate (NaHCO3; as an additional CO2 source) for 13days at 100°C and 10MPa. Pyroxene dissolved slightly but no weathering features were observed in plagioclase. Analyses of the filtrates obtained from the pyroxene sample in the absence of NaHCO3 showed an increased concentration of magnesium and calcium ions in the solution. However, they had also reached a cation saturation sealing. On the other hand, liquid samples from reactions where both CO2 gas and NaHCO3 were added to the solution exhibited a pronounced decrease in dissolved magnesium and calcium ions. XRD patterns of some of the post-reaction solids collected from the cation-depleted solution aliquots showed peaks of newly formed secondary magnesite and vermiculite. Moreover, the presence of magnesite was further confirmed by Raman shift analysis of the dried solid products. The formation of secondary magnesite was observed only in the experiments seeded with NaHCO3, specifically where the pre-reaction solid was pyroxene rich. Some of the resultant fluid chemistry was corroborated by the geochemical model that simulated the reaction parameters using the Geochemist Work Bench (GWB) software. Overall, the results indicate low pyroxene dissolution, which leads to limited carbonation. These findings suggest that the carbonation of PGM tailings may be constrained under the evaluated physicochemical conditions.

Optimizing regeneration techniques and fixed-bed column application for leachate treatment utilizing carbon mineral composite

The performance of carbon mineral-combined adsorbents in a batch and fixed column study was examined for removing chemical oxygen demand (COD) and ammoniacal nitrogen (NH3-N), which typically found in landfill leachate. The batch experiment was carried out using various factors including adsorbent dosages and retention time, while column performance was evaluated by optimizing the influent flow rate. The surface of the composite adsorbent was examined using X-ray fluorescence (XRF), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) to determine any changes before and after column operations. The XRF analysis of the composite adsorbent reveals a high concentration of calcium oxide and silica oxide as the primary compounds. The main functional groups in the composite adsorbent included O–H, N–H, O–C, C–N, C–O, and Si–O–Si. The SEM analysis revealed that the composite adsorbent contains heterogeneous pores and a rough surface. The reduction rates achieved were 86% for COD, with an optimum adsorption capacity of 31.3 mgg−1, and 80% for NH3-N, with an optimum adsorption capacity of 29.8 mgg−1. The breakthrough capacities for COD and NH3-N adsorption were 6.55 and 4.24 mgg−1, respectively. However, optimal empty-bed contact times (EBCTs) in minutes were 480. The performance efficiency of the column for COD and NH3-N was 0.9978% and 0.9913%, by utilizing fresh composite adsorbent, and these number figures increased to (≥ 0.9998%) respectively after the regeneration process. The Adams–Bohart constant for COD from 5.30 × 10–6 to 4.92 × 10–6 mL/min-mg and NH3-N from 2.90 × 10–5 to 4.52 × 10–5 mL/min-mg respectively was found to increase with increasing flow rates from 1.5 to 3.0 mLmin−1. Therefore, COD and NH3-N adsorption on composite adsorbent at flow rates of 1.5 mLmin−1 was considered appropriate from the context of this study. In summary, this research has successfully shown that the use of composites as an adsorbent is a viable and suitable for the removal of COD and NH3-N from leachate, indicating their potential for use in real-world industrial wastewater treatment could further enhance their practical applications.

Removal of Selenium from Aqueous Solutions Using Polymer/Hydrated Iron Oxide Composites

ABSTRACT In order to develop a process for efficient removal of selenium from wastewater, two composites were prepared by impregnating hydrated iron oxide within commercially available polymeric sorbents (Lewatit M600 and Purolite S110). Adsorption of selenium was investigated in both batch and dynamic column experiments. Both composites exhibited an improved sorption efficiency toward Se(IV) and Se(VI) compared to their matrixes. Effect of pH was investigated in a pH range of 3 to 8. On the Composite Purolite S110, removal of Se(IV) and Se(VI) decreased with increasing pH. In the case of Composite Lewatit M600, with increasing pH Se(IV) removal decreased while Se(VI) removal increased. The results of the batch experiments performed with the composites were compared with a commercially available composite and an inorganic sorbent. Column dynamic experiments suggested that satisfactory removal of Se(IV), Se(VI) or their mixture from 860 µg/L to less than 10 µg/L could be achieved by both composites in the presence of accompanying anions. The maximum breakthrough capacity for selenium removal was achieved for the Composite Lewatit M600, where it was 3.4 g Se/L for Se(IV), 1.1 g Se/L for Se(VI) and 1.2 g Se/L for their mixture. The exhausted composites were regenerated with alkaline brine and reused.

Ganoderma lucidum Immobilized on Wood Demonstrates High Persistence During the Removal of OPFRs in a Trickle-Bed Bioreactor

Emerging pollutants such as organophosphate flame retardants (OPFRs) pose a critical threat to environmental and human health, while conventional wastewater treatments often fail to remove them. This study addresses this issue by evaluating the bioremediation potential of white-rot fungi for the removal of two OPFRs: tris(2-chloroethyl) phosphate (TCEP) and tributyl phosphate (TBP). Three fungal species—Ganoderma lucidum, Trametes versicolor, and Phanerochaete velutina—were screened for their degradation capabilities. Among these, G. lucidum and T. versicolor demonstrated removal efficiencies exceeding 99% for TBP, while removal rates for TCEP were significantly lower, with a maximum of 30%. The exploration of the enzyme role showed that cytochrome P450 is involved in the degradation while the extracellular laccase is not involved. Continuous batch experiments were performed using a trickle-bed reactor (TBR) operating under non-sterile conditions, a setting that closely resembles real-world wastewater treatment environments. G. lucidum was immobilized on oak wood chips, and the removal efficiencies were measured to be 85.3% and 54.8% for TBP and TCEP, respectively, over 10 cycles. Microbial community analysis showed that G. lucidum remained the dominant species in the reactor. These findings demonstrate the efficacy of fungal-based trickle-bed bioreactors, offering a sustainable and efficient alternative for addressing environmental pollution caused by highly recalcitrant pollutants.

Eco-nano solutions for rapid phosphorus recovery: Closing the loop for sustainable agriculture.

Efficient phosphorus (P) removal from agricultural drainage is crucial for making its removal and recovery economically viable and operationally feasible. This study evaluated cost-effective, green-synthesized nanoparticles (using grass extract) for rapid and efficient P adsorption. Batch experiments were conducted to assess the effect of pH, P concentration, adsorbent dosage, contact time, and temperature on P adsorption. The nanoparticles removed 20mg/L of P in 5min, demonstrating their significant potential for effective adsorption in short retention time. They achieved a maximum adsorption capacity of 77.5mgg-1, outperforming their chemically synthesized counterparts. Moreover, smaller particles exhibited faster initial adsorption, while larger ones contributed more to overall adsorption over time. Modeling results revealed that rapid initial P adsorption was driven by physisorption, while chemisorption controlled the rate of adsorption in the later stages. After five regeneration cycles, the nanoparticles retained over 50% of their adsorption capacity, demonstrating strong reusability potential. Further research is needed to optimize these nanoparticles for P removal from dynamic agricultural drainage, offering a cost-effective and sustainable solution for P management.

Discarded floral foam as a source for green preparation of sustainable adsorbent for quick and efficient removal of phenoxyacetic acid herbicides from waters.

Due to the high toxicity and increasing consumption, efficient removal of phenoxyacetic acid herbicides (PAAHs) from water is imperative. In current study, a new adsorbent was prepared by modifying porous carbon derived from disused floral foam with chitosan (CS) (ACFC). Density functional theory (DFT) calculation uncovered that the amino and hydroxyl groups in the introduced CS played a critical role in the efficient adsorption of ACFC towards PAAHs. Batch experiments were performed to study the adsorption behaviors and removal mechanism. Under the optimal adsorption conditions, the PAAHs residues in various environmental waters were efficiently removed within 20 min by the ACFC, the removal rates varied from 81.9 % to 93.8 %, which remarkably better than that achieved on unmodified carbon (32.5-56.5 %). The maximum adsorption capacities were in the range of 172-221 μg/g. In addition, the prepared adsorbent presented excellent preparation repeatability and acceptable reusability. In comparison with reported adsorbents, the ACFC displayed some merits such as low cost, green, short removal period and high removal rate. The current study not only supplies a cost-effective and sustainable adsorbent for the removal of PAAHs residues from waters, but also opens up a new route for the recycle utilization of disused floral foam.

Preparation of ZnAl layered double hydroxides supported by silica for the treatment of Cr(VI) and Cu(II) in aqueous solution

A novel adsorbent ZnAl–LDHs/SiO2 (ZA/SiO2) was prepared by blending urea mixture of ZnSO4 and Al2(SO4)3 while using SiO2 as a support form. The adsorption properties of ZA/SiO2 for the removal of toxic metal ions (Cu(II) and Cr(VI)) from water were evaluated. By batch experiment method to investigate the ZA/SiO2 adsorption of Cu(II) and Cr(VI) solution treatment effect. The sorption kinetics curves of Cu(II) and Cr(VI) on ZA/SiO2 were L-shaped. What’s more, the solid concentration effect was found in the process of sorption kinetics. Langmuir and Freundlich sorption isotherm models were used to analyze the adsorption data. The results showed that the adsorption conforms to Langmuir and Freundlich adsorption isotherm models. However, the adsorption capacity of ZA/SiO2 compounds for Cu(II) and Cr(VI) is greatly improved. The adsorption capacity of Cu(II) is 158 mg·g−1 and of Cr(VI) is 176 mg·g−1, which were 3.6 and 1.8 times of ZnAl-LDHs (ZA), respectively. Density functional theory (DFT) was utilized for the analysis of intrinsic mechanism and specific pathways. The primary mechanism for removing Cr(VI) from water mainly included the intercalation of Cr2O72− and exchange between Cr2O72− and OH−, excluding Cr(OH)3 precipitation. Regarding the primary mechanism for eliminating Cu(II) from water, it involves isomorphic substitution as the predominant process, except for the formation of Cu(OH)2 precipitates.

Microaerobic biodegradation of aromatic hydrocarbon mixtures: strategies for efficient nitrate and oxygen dosage

The biodegradation of organic aromatic compounds in subsurface environments is often hindered by limited dissolved oxygen. While oxygen supplementation can enhance in situ biodegradation, it poses financial and technical challenges. This study explores introducing low-oxygen concentrations in anaerobic environments for efficient contaminant removal, particularly in scenarios where coexisting pollutants are present. An innovative strategy of alternating nitrate-reducing and microaerobic conditions to stimulate biodegradation is proposed, utilizing nitrate initially to degrade easily-degradable compounds, and potentially reducing the need for additional oxygen. Batch experiments were conducted to assess the biodegradation of a BTEX, indene, indane, and naphthalene mixture using groundwater and sediments from an anaerobic contaminated aquifer. Two set-ups were incubated for 98 days to assess the redox transitions between microaerobic (oxygen concentrations < 0.5 mg O2 L−1) and nitrate-reducing conditions, aiming to minimize external electron acceptor usage while maximizing degradation. Comparative experiments under fully aerobic and fully anaerobic (nitrate-reducing) conditions were conducted, revealing that under microaerobic conditions, all compounds were completely degraded, achieving removal efficiencies comparable to fully aerobic conditions. A pre-treatment phase involving nitrate-reducing conditions followed by microaerobic conditions showed more effective utilization of oxygen specifically for contaminant degradation compared to fully aerobic conditions. Contrarily, under fully anaerobic conditions, without oxygen addition, partial degradation of ethylbenzene was observed after 400 days, while other compounds remained. The outcomes of this study can provide valuable insights for refining strategies involving oxygen and nitrate dosages, thereby enhancing the efficacy of in situ bioremediation approaches targeting complex hydrocarbon mixtures within anaerobic subsurface environments.Key points• BTEX, indene, indane, and naphthalene mix biodegraded under microaerobic conditions• Subsurface microorganisms swiftly adapt from nitrate to microaerobic conditions• More oxygen directed to hydrocarbon biodegradation via a pre-anaerobic treatment

Resource recovery from wastewater by directing microbial metabolism toward production of value-added biochemicals.

Dynamic oxygen fluctuations in activated sludge were investigated to enhance valuable biochemical production during wastewater treatment. Batch experiments compared constant aeration with rapid cycling between oxygen-rich and oxygen-poor states. Fluctuating oxygen concentrations (0-2 mg/L) significantly increased production of valuable biochemicals compared to constant oxygen concentration (2 mg/L). Continuous oxygen perturbations increased free amino acids by 35.7 ± 7.6 % and free fatty acids by 76.4 ± 13.0 %, while intermittent perturbations with anoxic periods enhanced free amino acids by 42.4 ± 8.1 % and free fatty acids by 39.3 ± 7.7 %. Fourteen standard amino acids showed significant increases, and most fatty acids had carbon chain lengths between C12-C22. Mechanistically, oxygen perturbations activated FNR and ArcA regulons, resulting in lower relative abundances of TCA cycle enzymes and higher abundances of amino acid and fatty acid biosynthetic enzymes. These findings demonstrate that controlled oxygen fluctuations in wastewater treatment can enhance the biochemical value of activated sludge with minimal process modifications, facilitating resource recovery.

Dolomite dissolution, pH neutralization, and potentially toxic element immobilization in stormwater bioretention beds.

The importance of pH in stormwater bioretention beds cannot be overstated since it impacts plant and microbial populations and removal of potentially toxic elements (PTEs) from stormwater runoff. This study investigated the effects of dolomite amendment on pH neutralization and subsequent PTE immobilization in bioretention media. To assess dolomite dissolution, pH neutralization, and PTE immobilization, engineered bioretention media was amended with different dolomite ratios and samples of dolomite-amended media were collected from two bioretention beds, one and two months after installation. The effects of inflow conditions and operational time on dolomite dissolution and PTE immobilization were investigated through a column study. Laboratory batch experiments revealed that pH neutralization was fast and reached the recommended pH range of 5 to 8 within 5min. Among the 1-D column conditions, intermittent inflow had the highest porewater Mg and Ca concentrations, indicating greater dolomite dissolution. Batch experiments on field-collected media showed that pH neutralization was substantial within 1month, and continued during the second month, due to dolomite dissolution. Dissolved (batch experiments) and column porewater Mg and Ca concentrations supported instantaneous Ca and a relatively slow Mg dissociation during dolomite dissolution. Among the monitored PTEs, dissolved and porewater concentrations (μg/L) were found to decrease with time, in the order Mn>Fe>Zn>Cu>Pb>Cd, with Cr mainly undetected in all experimental conditions. However, as pH became neutralized to slightly basic (pH~8), dissolved and porewater As concentrations increased. The study suggests that pH neutralization and PTE immobilization depend on the soil-to-dolomite ratio and hydrological properties such as inflow rate, dry-wet cycle, and soil-water contact time. Dolomite amendment to engineered media can be an effective measure for intercepting contaminants, improving ecosystem health, and enhancing biochemical contaminant breakdown, though consideration should be given to bioretention bed design features and system hydrology.

A Comparative Kinetic and Thermodynamic Adsorption Study of Methylene Blue and Its Analogue Dye on Filter Paper.

A comparative adsorption study was carried out for methylene blue (MB) and its 3,7-bis(N,N-(2-hydroxyethyl)amino)-phenothiazinium dye analog (MBI). Batch experiments employed aqueous solutions and commercial filter paper. Out of seven kinetic models tested by means of four quality statistical indicators, the pseudo-second-order, the double-exponential, and the bi-linear Weber-Morris equations were best fits. For both dyes, the process was described as a succession of two diffusion-controlled steps. The Freundlich isotherm was chosen from 11 models describing a variety of mechanism assumptions. Physisorption was considered responsible for the dye removal from liquid. Adsorption of MB is thermodynamically favored, whereas that of MBI is sterically hindered. Both processes are exothermic and exhibit reduced randomness at the S-L interface. The paper was found suitable for retaining MB but served rather filtration/purification purposes for MBI.

Preparation of Silicon-based Magnetic Biochar and Its Remediation Mechanism for Cd（Ⅱ） and As（Ⅲ） Co-contaminated Water

Cadmium （Cd） and arsenic （As） often coexist in water and agricultural soils around mining areas, and it is difficult to remove them at the same time due to their opposite chemical behaviors. Therefore, this study employed a co-precipitation-pyrolysis method to synthesize silica-based magnetic biochar （SMB） materials for the remediation of water contaminated with both Cd and As. The optimization of preparation conditions involved introducing three different types of silicates （Na2SiO3, CaSiO3,and SiO2） into the biomass-magnetite mixture, followed by pyrolysis at various temperatures （300℃, 500℃, and 700℃）, and the optimal preparation conditions were determined based on the composite batch experiments. Finally, batch experiments in both single-element and composite systems were used to systematically investigate the impact of initial pH, adsorption time, and initial concentration on the adsorption behavior of SMB for Cd（Ⅱ） and As（Ⅲ）. The adsorption mechanism was elucidated by combining it with characterization analyses, such as SEM, FT-IR, and XRD. The composite adsorption test determined that the material obtained from a pyrolyzing biomass-magnetite mixture containing 5% CaSiO3 at 700℃ exhibited the most effective adsorption, with removal rates reaching 92.04% for Cd（Ⅱ） and 60.59% for As（Ⅲ） in Cd（Ⅱ） and As（Ⅲ） solutions with initial concentrations of 30 and 10 mg·L-1. Characterization including SEM, FT-IR, XRD, and BET showed that the material had a significant surface area, rich functional groups, and magnetic properties. In the single-element batch experiment, the optimal adsorption pH for Cd（Ⅱ） and As（Ⅲ） was 6, with equilibrium reached at 1 h and 8 h, respectively. The quasi-secondary kinetic model effectively described the adsorption process of Cd（Ⅱ） and As（Ⅲ） by SMB. In the composite system, the optimum adsorption pH was 7. The Freundlich model better fitted the isothermal adsorption processes of Cd（II） and As（III） by the materials. The results of the batch experiments in the composite system revealed that both synergistic and antagonistic effects existed between Cd（Ⅱ） and As（Ⅲ）. Synergistic effects were manifested through the formation of A-type and B-type ternary surface complexes during the adsorption of As（Ⅲ） and Cd（Ⅱ） by SMB. The formation of A-type ternary surface complexes significantly enhanced the material's adsorption capacity for As（Ⅲ）. However, in the coexistence system, the synergistic effect was primarily controlled by electrostatic interaction, co-precipitation, and the formation of B-type ternary surface complexes due to the preference for adsorbing As（Ⅲ）. Antagonistic effects resulted from the competition between the two heavy metal elements for binding sites with hydroxyl groups. In summary, the synthesized SMB material demonstrated effective adsorption of both Cd and As in water, presenting a promising approach for the efficient remediation of water bodies co-contaminated with Cd（Ⅱ） and As（Ⅲ）.

Sorption and Transport of Antibiotics in Manured Upland Agricultural Soils

Sorption and transport are important environmental behaviors of antibiotics in soils and can determine the fate of antibiotics in environments； however, limited relevant studies have been conducted on long-term manured soils. In this study, batch and repacked soil column experiments were conducted to examine the sorption and transport behavior of four veterinary antibiotics, including sulfamethazine （SMT）, florfenicol （FFC）, doxycycline （DOX）, and enrofloxacin （ENR）, in red soils, yellow soils, and calcareous soils with long-term amendment of chicken or pig manure collected in Zhejiang Province. The results showed that the sorption isothermal data of the four target antibiotics all conformed well to the linear and Freundlich models. The performance of the linear model was better for the weakly-sorbing antibiotics （SMT and FFC）, whereas the performance of the Freundlich model was better for the strongly-sorbing antibiotics （DOX and ENR）. The sorption of target antibiotics was governed by both soil and manure types. The linear sorption parameter （Kd） of SMT and FFC were positively related to the organic carbon content and pH of soils, and their sorption was mainly controlled by soil organic matter, indicating that non-electrostatic interactions （e.g., hydrogen bonding, hydrophobic interactions） played dominant roles in their sorption to the soils. Contrastingly, DOX and ENR did not show significant relationships with soil pH, organic carbon content, and cation exchange capacity, indicating that multiple mechanisms （e.g., hydrophobic interactions, hydrogen bonding, and electrostatic interactions） worked jointly in their sorption into the soils. SMT and FFC exhibited high recoveries of breakthrough curves （in ranges of 37.5%-92.3% and 45.8%-112.6%, respectively） in column transport experiments, reflecting their high leaching potentials. Contrastingly, no soil column breakthrough of DOX and ENR was observed, reflecting that the injected antibiotics were completely retained inside the soil columns. The maximum relative concentrations and breakthrough recoveries of SMT and FFC showed significant negative linear relationships with Kd. This indicates that the leaching potential of antibiotics can be predicted from sorption parameters using the regression equations established by batch and column experiments.

Highly porous activated carbon derived from the papaya plant (stems and leaves) for superior adsorption of alizarin red s and methylene blue dyes from wastewater.

In this study, stems and leaves of the papaya plant were employed to prepare a high-quality porous adsorbent via carbonization and chemical activation using phosphoric acid. This adsorbent demonstrates superior adsorption capabilities for the efficient removal of hazardous alizarin red s (ARS) and methylene blue (MB) dyes. Thus, it contributes to waste reduction and promotes sustainable practices in environmental remediation, aligning with global efforts to develop sustainable materials that address water pollution while supporting circular economy principles. The structural properties of the activated carbon were characterized through various techniques, including BET surface area, FTIR, SEM, XPS, zeta potential measurements, and determination of the zero-point charge. The characterization results confirmed the preparation of highly porous activated carbon from papaya stems with a high surface area of 1053.52 m2 g-1. The batch experiments revealed that the maximum adsorption capacities for the stem-activated carbon (SAC) were 931 mg g-1 for ARS and 990 mg g-1 for MB. For the leave-activated carbon (LAC), the capacities were 410 mg g-1 for ARS and 642 mg g-1 for MB. SAC exhibited 100% removal of MB or ARS with concentrations lower than 150 ppm in 15 min. The data fitted well with the Langmuir model and pseudo-second-order model. Moreover, the reusability revealed that the SAC can be reused over 5 cycles without significant change in the removal efficiency. Overall, SAC and LAC derived from papaya plants exhibited excellent dye adsorption performance, suggesting potential for large-scale applications.

Equisetum alkaloids degradation in biogas fermentation of E. palustre contaminated plant material.

The current expansion of Equisetum palustre in wetlands across the Northern Hemisphere has led to an increase in reports of adverse effects in livestock. In light of the limited reduction potential of toxic Equisetum alkaloids through feed conservation measures, it is essential to identify effective strategies to manage E. palustre infested biomass. This study examined the impact and efficacy of biomethanization processes on the biodegradation of Equisetum alkaloids. To monitor the biodegradation in such complex matrices, a sample preparation method and a high-performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS/MS) method were established. The developed method was successfully employed to quantify the total residual content of Equisetum alkaloids in fermentation residues following biomethanization in batch experiments. It was demonstrated that under such conditions a degradation greater than 95 % was achieved. The biomethanization process described here is currently the most effective biological treatment for reducing Equisetum alkaloids. It is notable that the methane yields remained largely unaffected, indicating that field cuttings contaminated with E. palustre can be safely and economically processed via biomethanization which would be a key prerequisite for a circular bioeconomy.

Exploration of biomass ashes (BA) to decontaminate highly metal-rich acid mine drainages (AMDs): Column and batch experiments

Exploration of biomass ashes (BA) to decontaminate highly metal-rich acid mine drainages (AMDs): Column and batch experiments

Photocatalytic removal of U(VI) from aqueous solution under visible light by bismuth oxyiodide/graphitic carbon nitride composite.

Applicable to convert soluble U(VI) into the less mobile U(IV) form, the photocatalytic process is widely regarded as an efficient solution to uranium pollution. In the present study, BiOI/g-C3N4 (BICN) composites were produced through uncomplicated hydrothermal synthesis, followed by U(VI) photocatalytic reduction. Batch experiments were conducted to demonstrate the exceptional capability of BICN to address uranium contamination. Specifically, the 5%-BICN composite exhibited higher photocatalytic efficiency in U(VI) reduction, with its performance improved by 1.5 times over BiOI and 3.0 times over g-C3N4. Characterized by p-n heterojunction, BICN composites enhance the movement and separation efficiencies of photogenerated carriers, which significantly promotes the production of •O2- radicals that are critical for U(VI) photocatalytic reduction. These results provide crucial guidance on the potential application of BICN composites in environmental remediation processes.

Evaluation of the efficacy of papaya seed-based natural adsorbent for synthetic textile wastewater treatment

This study explored the application of papaya seed-based activated carbon for removing methylene blue dye from synthetic textile effluent. Batch experiments are used in the study to investigate the adsorption potential of activated carbon. The results demonstrate that papaya seeds derived from activated carbon have the greatest potential for methylene blue adsorption, with an average removal effectiveness of 89.4%. The effects of several parameters such as pH, contact time, adsorbent dose, adsorbent-adsorbate temperature, and starting dye amount or concentration were examined to optimize the adsorption conditions. Maximum dye removal was achieved after 60 minutes of contact time at pH 6.5. The carbon dosage and pH of the solution were discovered to have the greatest influence on the adsorption process. Based on the experimental data, the Langmuir and Freundlich models were identified as the most appropriate fits for the adsorption investigation. In conclusion, activated carbon derived from papaya seeds is a viable and natural bio-adsorbent for removing methylene blue from synthetic textile wastewater.