Natural pH Research Articles

Efficient removal of recalcitrant naphthenic acids with electro-cocatalytic activation of peroxymonosulfate by Fe(III)-nitrilotriacetic acid complex under neutral initial pH condition

This work investigated the activation of peroxymonosulfate by electrochemical (EC) system assisted with Fe(III)-nitrilotriacetic acid (NTA) complex for degradation of persistent naphthenic acids (NAs) under neutral initial pH conditions. As NAs are a complicated mixture, 1-adamantanecarboxylic acid (ACA) was selected as the model NA compound for degradation experiment. The addition of NTA is to chelate with Fe(III), gaining stability under neutral pH condition to facilitate the circulation of Fe(II)/Fe(III) by the electrochemical process to activate PMS. The EC/Fe(III)-NTA/PMS system was explored with applicable pH range of 3–9 and an optimized molar ratio 1: 2 for Fe: NTA. Results of quenching and chemical probe experiment together with results of electron paramagnetic resonance (EPR) analysis revealed the main reactive species of the system, including •OH, SO4•−, 1O2 and possibly Fe(IV). With the addition of NTA, the yields of •OH, SO4•−, 1O2 were enhanced. Results of mass spectrometry analysis and DFT calculations indicated the formation of 9 degradation byproducts of ACA via three primary degradation pathways such as hydroxyl substitution, carbonyl substitution, and decarboxylation. Furthermore, the EC/Fe(III)-NTA/PMS system could achieve excellent removal efficiency of ACA with different anions such as Cl-, HCO3-, NO3- and H2PO4- in the background. The practical applicability of the system was also verified with the high removal of commercial NAs mixture standard. Overall results have indicated the EC/Fe(III)-NTA/PMS system could be utilized for efficient reclamation of authentic oil and gas industrial wastewater under natural pH conditions.

Evaluation of Ti/Pt Anode Efficiency and Energy Consumption in Turbidity and Suspended Solids Removal from Paper Industry Wastewater: The Effect of pH and Support Electrolyte Type

In the research, different experimental setups were used to examine the treatment of wastewater from the paper industry using the electrooxidation method, one of the electrochemical treatment methods in the batch system. In the 2000 mL volume jacketed glass reactor utilized for the treatment of wastewater from the paper industry, 4 anode and 4 cathode sieve type plates of 7 cm x 10 cm dimensions were positioned at 0.5 cm intervals, and 1200 mL wastewater was used in the tests. Coated sieve type Ti/Pt electrodes were employed as the anode in the electrooxidation studies, and uncoated sieve type Ti electrodes were used as the cathode. It was determined that the active anodic wet surface area was 1078 cm2 . The removal rates of pollutant parameters such as turbidity and SS (Suspended Solids) in the experiments; the effects of wastewater initial pH value and supporting electrolyte type parameters were investigated. According to the results, the most effective pH value for Ti/Pt anode type at 400 rpm mixing speed was determined to be waste water natural pH (7.5), and 0.50 M NaCl was the most successful supporting electrolyte type. 96.92% Suspended Solids removal efficiency and 95.38% turbidity removal efficiency for Ti/Pt anode were achieved under ideal conditions. In addition, 312.05 kW-hour/kg COD is determined as the energy consumption value.

Polymer film synthesis from an aqueous latex of polymerization-induced self-assembly (PISA) derived nanofibers

Polymerization-induced self-assembly (PISA) derived spheres and worms (fibers) comprising poly(n-butyl acrylate) as core-forming block (Tg ≈ −49 °C) were synthesized using a poly(acrylic acid-stat-poly(ethylene glycol) methyl ether acrylate) macroRAFT agent. The nanoparticle morphology varied depending on the pH of the system, i.e. spheres at natural pH (≈ 2.5) and worms at pH 5. The core-sections of the particles (both spheres and worms) were crosslinked using ethylene glycol diacrylate. Films were prepared from the synthesized aqueous latexes via simple drop casting in the absence of volatile organic compounds. The influence of the original nanoparticle morphology on the mechanical properties of the films was subsequently explored – “worm film” displayed 1670 % higher tensile strength and 1290 % higher strain at break compared to “sphere film”. These results demonstrate that film properties can be significantly influenced by the original nanoparticle morphology, despite the nanoparticles comprising very similar polymer chains in terms of composition and molecular weight distribution.

Use of copper sheet in a solar photo-Fenton-like process applied in the treatment of landfill leachate.

It is known that copper can be used as catalyst in photo-Fenton-like process; however, there is a lack of information related with its use in the treatment of landfill leachate (LL) in solar photo-Fenton-like processes. Here, we studied the effect of the mass of a copper sheet, the pH of the solution, and the concentration of LL in the removal of the organic matter present in this water. Before the reaction with landfill leachate, the copper sheet used in the reaction was constituted by Cu+ and Cu2O, respectively. The results showed that in a volume of 0.5 L of a pretreated LL, the higher removal of organic matter resulted using a mass of 2.7g of the copper sheet, a pH of solution of 5, and a concentration of LL of a 10%, obtaining a final value of C/C0of chemical oxygen demand (COD) of 0.34, 0.54, 0.66, and 0.84 for concentrations of 25%, 50%, 75%, and 100%, respectively, and 0.0041, 0.0042, 0.0043, and 0.016 for concentration of 25%, 50%, 75%, and 100%, respectively, of C/C0 of humic acids. The photolysis on LL at its natural pH using solar UV removes very little humic acid and COD, going from 9.4 to 8.5 and 7.7 Abs254 for photolysis and UV + H2O2, obtaining 8.6 and 17.6% of removal, respectively, and 2.01 and 13.04% removal of COD, respectively. Copper sheet applied under Fenton-like conditions results in 65.9% removal and an increase of 0.2% for humic acid and COD, respectively. Removal using only H2O2 for Abs254 and COD was 11.95 and 4.3%, respectively. Raw LL produced a 29.1% inhibition of the biological activated sludge rate after the adjustment to pH 7 and the final process of inhibition was 0.23%.

Photocatalytic properties of ZnFe-mixed oxides synthesized via a simple route for water remediation

Abstract ZnFe photocatalysts have been increasingly investigated for water remediation due to the high demands in this field, such as activity, toxicity, cost, and stability. The presented study was focused on the simple, safe, non-toxic, and eco-friendly synthesis and characterization of ZnFe-mixed metal oxides in correlation with their functional properties. Photocatalytic performance of these materials was evaluated by rhodamine B photodegradation under simulated solar light irradiation. The synthesized mixed oxides contained hexagonal wurtzite ZnO as the predominant phase, whereas, after thermal treatment, the formation of the spinel-structured ZnFe2O4 phase was observed. The photocatalysts with the additional spinel phase and thermally treated at 300°C and 500°C exhibited superior photocatalytic activity probably due to the highest amount of the ZnFe2O4 spinel phase, favourable mesoporous structure, and an optimal energy band gap of ∼2.30 eV that initiated higher light-harvesting efficiency. The rhodamine B photodegradation followed zero-order kinetics, indicating complete coverage of active sites by the pollutant substrate. Additionally, photocatalysts showed the highest efficiency at the natural pH (6.8), being in accordance with green synthesis principles. Simple, green route assembling synthesis method, high photodegradation efficiency, and good reusability make these ZnFe-mixed oxides great candidates for potential application in practical wastewater treatments.

Fixed-bed column for phosphate adsorption combining experimental observation, mathematical simulation, and statistics: Classical and Bayesian

The purpose of this work is to investigate the removal of phosphate in a fixed-bed column, using a layered double hydroxide (CaMgAl-LDH) as adsorbent, applying experimental observation, mathematical simulation and statistical analysis. Also, an experimental design was carried out in order to evaluate the influence of the operational conditions applied in the column on its adsorption efficiency. At a natural pH of 7.5, three independent parameters were considered: initial phosphate concentration (15, 30, and 60 mg L-1); feed flow rate (2.5, 5, and 10 mL min−1); and solid adsorbent mass (0.2, 0.5, and 1 g). As response variables the saturation time and the concentration of saturation in the column were evaluated. For the study of the fixed-bed column performance, through its breakthrough curves, a mathematical simulation, applying Bayesian statistics, was built in order to estimate its parameters, these being: the Peclet number (Pe), the equilibrium Langmuir constant (KL) and the kinetic coefficient (KS). To illustrate the model that was used to describe the mass transport through the fixed-bed, differential partial equations were obtained by the mass balance of the column. The results obtained in this research demonstrated that the Peclet number, for all operational conditions, suggests that the dispersion and the advection forces present in the column are approximately equal to each other. Also, the Langmuir isotherm represented well the adsorption equilibrium in all operational conditions and the kinetic coefficient ranged between 4.52 and 0.81 mL mg−1 min−1, these values shows that the kinetic effect has little interference in the breakthrough curves evaluated in the present work. Then, the estimated parameters were validated by the experimental design applied. Therefore, it was shown that the technique used to estimate the parameters and the mass balance model applied in this work, to describe the adsorption process, was robust, since the model was able to predict the breakthrough curves. In this way, this approach can be used to design columns based on the desired operational conditions, as well as for scaleup studies.

Persulfate promoted visible photocatalytic elimination of bisphenol A by g-C3N4–CeO2 S-scheme heterojunction: The dominant role of photo-induced holes

In the last few years, coupling heterogeneous photocatalysis with persulfate (PDS) activation process is an efficient approach to generate abundant reactive oxidative species towards organic contaminant removal in water, however, the key role of PDS in photocatalytic process remains ambiguous. Herein, a novel g-C3N4–CeO2 (CN–CeO2) step-scheme (S-scheme) composite was constructed to photo-degrade bisphenol A (BPA) with the presence of PDS under visible irradiation. At 2.0 mM PDS, 0.7 g/L CN–CeO2 and natural pH 6.2, 94.2% of BPA could be eliminated in 60 min under visible light (Vis) illumination. Aside from the previous view of free radical generation, it tends to assume that most of PDS molecules acted as electron sacrificial agents for capturing photo-induced e− to form sulfate ions, greatly improving the charge carrier separation and thus enhancing the oxidation capacity of nonradical hole (h+) for the removal of BPA. Good correlations are further found between the rate constant and descriptor variables (i.e., Hammett constant σ−/σ+ and half-wave potential E1/2), exhibiting selective oxidation for organic pollutants in the Vis/CN–CeO2/PDS system. The study brings more insights into mechanistic understanding of persulfate-enhanced photocatalytic process for addressing water decontamination.

Bioremoval of fast green FCF dye from aqueous solution using cranberry kernel (Cornus mas L.) as a lignocellulosic biowaste: equilibrium, kinetics, and mechanism

ABSTRACT In this study, the biosorption properties of fast green FCF (FG) dye in an aqueous solution were investigated using cranberry (Cornus mas L.) kernel (CK) as lignocellulosic biowaste. The biosorbent performance of the cranberry (Cornus mas L.) kernel biomass for FG dye molecules was optimized: 500 mg L−1 at natural pH: 6.0 at 25°C. The maximum biosorption capacity for CK biomass was found to be 21.6 mg g−1 from the Langmuir isotherm model. Biosorption thermodynamics showed that FG dye biosorption to CK biomass was spontaneous, entropy-increasing, and endothermic. The kinetic data were described by the PSO and IPD kinetic models. Thermodynamic parameters were calculated, and it was seen that the biosorption process is spontaneous and endothermic. FT-IR spectrum after biosorption provided data supporting the formation of electrostatic interactions, n-π interactions, and H-bonds between anionic FG dye molecules and CK biomass. When the results of this study were evaluated as a whole, it was concluded that CK biosorbent is a natural, abundant, low-cost, effective, and potential biosorbent for the removal of FG dye molecules from wastewater.

Adsorptive properties of highly porous activated carbon from açaí (Euterpe oleracea) towards the toxic herbicide atrazine

The great variety and possibilities of consumption of açaí pulp (Euterpe oleracea) have made its consumption increase considerably in recent years, mainly in Brazilian territory. The big problem is the generation of tons of waste that characterizes the fruit stone. This waste was converted into a highly porous activated carbon and employed to remove the herbicide atrazine. The characterization analyses confirmed that the applied methodology generated an adsorbent with good textural characteristics (specific surface area 920.56 m² g−1, pore volume 0.467 cm3 g−1; average pore diameter 1.13 nm). Furthermore, it was found that the adsorption of atrazine reached satisfactory results at natural pH and with an adsorbent mass of 0.54 g for each liter of solution. The Redlich-Peterson model presented the most satisfactory fit with the equilibrium data. This study found that the evolution of system temperature increased the concentration in the solid phase of 178 mg g−1 at 328 K. Regarding adsorption kinetics, the linear driving force model can represent the experimental data. Also, the predicted adsorption data of the model follows the experimental data. The application of the adsorbent in the removal of the herbicide mixture presented an efficiency of 81.45%. Therefore, using residual açaí fruit seeds as biomass for producing activated carbon employing zinc chloride as an agent activator is the possible application of the material. The material showed high efficiency and affinity with the target molecule.

Evaluation of the Efficiency of Ti/IrO2/RuO2 Anode in COD Removal from Paper Industry Wastewaters by Electrooxidation Method

In the research, the electrooxidation method of the electrochemical treatment methods in thebatch system was explored a variety of experimental conditions for the treatment of wastewater from thepaper sector. 4 anodes and 4 cathodes sieve type plates with dimensions of 7 cm x 10 cm were positionedat 0,5 cm intervals in the 2000 mL volume jacketed glass reactor used for the treatment of wastewater fromthe paper industry, and 1200 mL wastewater was used in the testing. 4 coated Ti/IrO2/RuO2 electrodes ofthe sieve type were used as the anode material and 4 uncoated Ti electrodes of the sieve type were utilizedas the cathode material in the electrooxidation of effluent from the paper industry. In the experiments, theremoval rate of the COD (Chemical Oxygen Demand) pollutant parameter; The effects of supportingelectrolyte types and concentrations such as KCl, NaCl, NaNO3, and Na2SO4, and parameters such as initialpH value and current density of wastewater without supporting electrolyte were investigated. According tothe results obtained; In the experiments conducted at the natural pH value of wastewater, 18.55 mA/cm2was the most effective current density, 0.50 M NaCl was the most effective supporting electrolyte type andconcentration. The COD removal rate at the best conditions (37.11 mA/cm2current density) was 90.62%.In optimum conditions; 73.20% COD removal efficiency has been achieved.

A new tool for the determination of humic substances in natural waters: Pulsed voltammetry approach

Humic substances (HS) in natural waters can be determined with a new, simple and sensitive method based on their influence on the background current in a differential pulse - adsorptive cathodic stripping voltammetry. The proposed method, termed PB-HS (pulsed background - humic substances) is discussed in detail, including its application in natural samples from the Krka River estuary. The method was additionally compared with absorbance measurements as well as with the typical electrochemical HS quantification in natural waters based on HS complexation with molybdenum (Mo). A good correlation between methods was observed, with PB-HS showing slightly better sensitivity to humic compounds than classical spectrophotometry. Higher HS concentrations measured with the Mo-method may be due to the enhanced hydrophobicity reached at pH 2 that is required by the method. Advantages of the proposed PB-HS method, compared to existing voltammetric methods for HS quantification, are that it does not require any reagent addition (except buffer) and that it can be used at the natural pH of water as well as in a wide salinity range, which is crucial for its application in estuarine waters.

Effects of nitrogen deposition on carbon and nutrient cycling along a natural soil acidity gradient as revealed by metagenomics.

Nitrogen (N) deposition and soil acidification are environmental challenges affecting ecosystem functioning, health, and biodiversity, but their effects on functional genes are poorly understood. Here, we utilized metabarcoding and metagenomics to investigate the responses of soil functional genes to N deposition along a natural soil pH gradient. Soil N content was uncorrelated with pH, enabling us to investigate their effects separately. Soil acidity strongly and negatively affected the relative abundances of most cluster of orthologous gene (COG) categories of the metabolism supercategory. Similarly, soil acidity negatively affected the diversity of functional genes related to carbon and N but not phosphorus cycling. Multivariate analyses showed that soil pH was the most important factor affecting microbial and functional gene composition, while the effects of N deposition were less important. Relative abundance of KEGG functional modules related to different parts of the studied cycles showed variable responses to soil acidity and N deposition. Furthermore, our results suggested that the diversity-function relationship reported for other organisms also applies to soil microbiomes. Since N deposition and soil pH affected microbial taxonomic and functional composition to a different extent, we conclude that N deposition effects might be primarily mediated through soil acidification in forest ecosystems.

Three-dimensional graphene anchored nZVI hybrid MnO2 as a dissolved oxygen activated Fenton-like catalyst for efficient mineralization of oxytetracycline

This work is dedicated to achieving the high mineralization efficiency of oxytetracycline (OTC) in a dissolved oxygen (DO) activated Fenton-like system by constructing a catalyst with unique catalytic performance. Three-dimensional graphene anchored nZVI hybrid MnO2 (3D-rGO@nZVI/MnO2) with layered and porous structures was synthesized and characterized by field emission scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), Brunner-Emmet-Teller (BET) analysis, X-ray diffraction (XRD) measurement and Raman spectroscopy. The experimental results showed that the removal efficiency of OTC could reach 100.0% with outstanding TOC decrease of 84.0% at natural pH in the 3D-rGO@nZVI/MnO2-DO system. Moreover, negligible harmful intermediates were detected by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) after the reaction in the 3D-rGO@nZVI/MnO2-DO system. Reactive oxygen species (ROSs) detection, electrochemical measurements and X-ray photoelectron spectroscopy (XPS) analysis confirmed that the elimination mechanism of OTC was the unique catalytic degradation caused by the synergism of •OH and 1O2. The unprecedented synchronous generation of •OH and 1O2 by DO activation provides an innovative strategy for further exploration of Fenton-like system toward more effective degradation of organic pollutants.

The Role of Gold Nanoparticles/Au-PEG-PAMAM as Drug Delivery System for Treatment of Breast Cancer

To enhance the cellular uptake and chemotherapeutic efficacy of a current chemotherapeutic medication, a nanoparticle drug carrier technology has been designed. Due to their distinctive electrical and optical characteristics, gold nanoparticles (Au NPs) have recently demonstrated intriguing medical and military uses. In the event that they come into touch with a biological system, little is known about their biocompatibility. Metallic nanoparticles have been successfully utilized for a kind of biological applications. A drug delivery system known as Au – PEG – PAMAM – DOX was produced by conjugating the dendrimer with the anti-cancer chemical doxorubicin (DOX) via an amide bond. The amount of DOX released from Au – PEG – PAMAM – DOX at a natural pH was negligible, but this amount significantly increased in an environment with a weak acidic milieu, according to studies on the release of medicines from acellular sources. A research into the intracellular release of the medication was carried out with the assistance of confocal laser scanning microscopy (CLSM). Recently conjugation to the nanosystem, in vitro viability experiments revealed an increase in the associated DOX cytotoxicity that could not be attributable to carrier components. This indicates that the effectiveness of the DOX was increased. In light of this, it has been hypothesized that the newly created pH-triggered multifunctional Au NPs- DOX nanoparticle system could pave the way for a viable platform for the intracellular delivery of a range of anticancer medicines. In the current study, the common Au NPs synthesis techniques and their well-established uses in diverse needs, particularly in biological sensing applications.

Preparation of activated carbon from pine (Pinus radiata) sawdust by chemical activation with zinc chloride for wood dye adsorption

Wastewater containing dyes are released into water bodies generating serious problems in human health and marine life. To contribute to the solution of this problem, a novel activated carbon was prepared from untreated pine (Pinus radiata) sawdust by dry chemical activation with ZnCl2 and was used for wood dye adsorption. The carbon was characterized by point of zero charge, N2 and CO2 adsorption isotherms, SEM-EDX, and FTIR. N2 and CO2 surface areas were 471.4 and 319.5 m2 g−1, respectively, with 91% of micropores. Wood dye adsorption was studied in function of pH (2–12), adsorbent dose (0.1–4 g L−1), time (up to 48 h for blue and red and 12 h for black), and initial concentration (5–500 mg L−1). The equilibrium data for the blue and black dyes were satisfactorily fitted to the Freundlich model while those for the red dye to the Langmuir model. Kinetic data were explained by the pseudo-second order (chemisorption process) and intraparticle diffusion models. At 5 mg L−1, a 100% removal efficiency was achieved at all pH for the blue dye, whereas for the red and black, natural pH (5.1) and pH = 2, respectively, led to the best removal efficiencies, 96 and 56%. Increasing concentration above 25 mg L−1 significantly reduced adsorption efficiency for blue and red dyes. For the black dye increasing the dose to 1 g L−1, the adsorption efficiency reached 82% at 25 mg L−1. High removal efficiencies were achieved for all dyes at 25 mg L−1 and 4 g L−1.

Application of Deep Eutectic Solvents (DES) for the Synthesis of Iron Heterogeneous Catalyst: Application to Sulfamethoxazole Degradation by Advanced Oxidation Processes

The development of novel approaches to the remotion of pharmaceuticals in wastewater is a subject of concern due to their effect on living beings and the environment. Advanced oxidation processes and the use of relevant catalysts are feasible treatment alternatives that require further development. The development of suitable heterogeneous catalysts is a necessity. This work proposes the synthesis of an iron catalyst in a deep eutectic solvent (Fe-DES) composed of choline chloride and citric acid, which was physically and chemically characterized using SEM-EDS and TEM, FTIR, RAMAN, XRD and XPS. The characterisation confirmed the presence of iron in the form of hematite. Fe-DES was shown to be a multipurpose catalyst that can be applied in the removal of sulfamethoxazole as a reagent in the Fenton and electro-Fenton processes and as an activator of peroxymonosulfate (PMS) processes. After testing the catalyst with the aforementioned techniques, the best result was achieved by combining these processes in an electro-PMS, with great efficiency achieved by dual activation of the PMS with the catalyst and electric field, attaining total elimination at natural pH in 90 min. Furthermore, the degradation was confirmed by the detection of short-chain carboxylic acids (oxalic, succinic, and acetic) and reduction in toxicity values. These results confirm the suitability of Fe-DES to degrade high-priority pharmaceutical compounds.

High taxonomic diversity and miniaturization in benthic communities under persistent natural CO2 disturbances.

Metabarcoding techniques have revolutionized ecological research in recent years, facilitating the differentiation of cryptic species and revealing previously hidden diversity. In the current scenario of climate change and ocean acidification, biodiversity loss is one of the main threats to marine ecosystems. Here, we explored the effects of ocean acidification on marine benthic communities using DNA metabarcoding to assess the diversity of algae and metazoans. Specifically, we examined the natural pH gradient generated by the Fuencaliente CO2 vent system, located near La Palma Island (Canary Islands). High-resolution COI metabarcoding analyses revealed high levels of taxonomic diversity in an acidified natural area for the first time. This high number of species arises from the detection of small and cryptic species that were previously undetectable by other techniques. Such species are apparently tolerant to the acidification levels expected in future oceans. Hence and following our results, future subtropical communities are expected to keep high biodiversity values under an acidification scenario, although they will tend toward overall miniaturization due to the dominance of small algal and invertebrate species, leading to changes in ecosystem functions.

Finding the Stability Constants for the Colored Compounds Resulting from The Reaction of Five Food Dyes with the Diazotized Para-Nitro Aniline Reagent at their Natural pH

Finding the Stability Constants for the Colored Compounds Resulting from The Reaction of Five Food Dyes with the Diazotized Para-Nitro Aniline Reagent at their Natural pH

The Combination of Anaerobic Digestion and Electro-Oxidation for Efficient COD Removal in Beverage Wastewater: Investigation of Electrolytic Cells

The world’s ever-growing population is driving an increased demand for clean water, which makes treating and reusing wastewater an essential practice. In recent years, biological and physicochemical methods have been preferred for wastewater treatment, with combined systems proving particularly effective. In this study, the combination of anaerobic digestion (AD) and electro-oxidation (EO) was investigated as a process for removing chemical oxygen demand (COD) from actual beverage wastewater. The effect of hydraulic retention time (HRT) on AD, electrolysis time, sodium chloride (NaCl) dosage, initial pH, and electro-properties on EO was investigated. At optimum conditions, namely an HRT of 2 days for AD, NaCl concentration of 3 g L−1, 80 min of EO time, natural pH (7.45), and applied voltage of 20 V for EO, the removal efficiency for COD was an impressive 96.47%, with energy consumption and specific energy consumption calculating 177.33 kWh m−3 and 33.79 kWh kgCOD−1, respectively. The amount of by-product gases (CH4 and H2) were also meagerly determined in this study. The results confirm that combining the AD and EO methods is an effective COD removal solution that can benefit the industry, while also offering a sustainable solution to combat water scarcity and meet the growing demand for clean water.

Field development of Posidonia oceanica seedlings changes under predicted acidification conditions

Ocean acidification has been consistently evidenced to have profound and lasting impacts on marine species. Observations have shown seagrasses to be highly susceptible to future increased pCO2 conditions, but the responses of early life stages as seedlings are poorly understood. This study aimed at evaluating how projected Mediterranean Sea acidification affects the survival, morphological and biochemical development of Posidonia oceanica seedlings through a long-term field experiment along a natural low pH gradient. Future ocean conditions seem to constrain the morphological development of seedlings. However, high pCO2 exposures caused an initial increase in the degree of saturation of fatty acids in leaves and then improved the fatty acid adjustment increasing unsaturation levels in leaves (but not in seeds), suggesting a nutritional compound translocation. Results also suggested a P. oceanica structural components remodelling which may counteract the effects of ocean acidification but would not enhance seagrass seedling productivity.