Natural Organic Matter In Water Research Articles

Constant-pH Simulations of a Coarse-Grained Model of Polyfunctional Weak Charged Biopolymers

A coarse-grained model of linear polyfunctional weak charged biopolymers was implemented, formed of different proportions of acid-base groups resembling the composition of humic substances. These substances are mainly present in dissolved organic matter in natural water. The influence of electrostatic interactions computing methods, factors concerning the structure of the chain, different functional groups, and the ionic strength on polyelectrolytes were studied. Langevin dynamics with constant pH simulations were performed using the ESPResSO package and the Python-based Molecule Builder for ESPResSo (pyMBE) library. The coverage was fitted to a polyfunctional Frumkin isotherm, with a mean-field interaction between charged beads. The composition of the chain affects the charge while ionic strength affects both the charge and the radius of gyration. Additionally, the parameters intrinsic to the polyelectrolyte model were well reproduced by fitting the polyfunctional Frumkin isotherm. In contrast, the non-intrinsic parameters depended on the ionic strength. The method developed and applied to a polyfunctional polypeptide model, that resembles a humic acid, will be very useful for characterizing biopolymers with several acid-base functional groups, where their structure, the composition of the different functional groups, and the determination of the main intrinsic proton binding constants and their proportion are not exactly known.

Research on the operational efficiency and mechanism of integrated photocatalytic/coagulation system for the removal of natural organic matter (NOM)

Natural organic matter (NOM) widely exists in natural water bodies and threat drinking water safety. This study aims to construct an integrated photocatalytic/coagulation system and explore its treatment efficiency for NOM in source water. Morphological characteristics of the floc complex were studied based on the machine vision detection system. In addition, structural change characteristics of the floc complex in the integrated photocatalytic/coagulation system were revealed from microscopic perspective to clarify the mechanism of its effect in source water treatment process. And recycling and recycling method of photocatalyst was optimized. The results showed that the integrated photocatalytic/coagulation system can effectively reduce generation of DBPs at concentration level of μg·L−1, and the formed petal-like BiFeO3-core floc complex can achieve rapid sedimentation and had excellent recycling performance. The construction of integrated photocatalytic/coagulation system in this study is expected to provide a theoretical basis for achieving low consumption and high efficiency improvement of source water quality.

MnFe2O4 composited polyvinylidene fluoride catalytic ultrafiltration membrane via peroxymonosulfate activation for humic acid treatment: Exploration of synergistic mechanisms

Membrane separation has become the most promising technology in the field of wastewater purification, but there will inevitably be membrane fouling. Catalytic polymer membranes combining membrane filtration and advanced oxidation technologies (AOPs) offered an alternative for mitigating membrane fouling. This work successfully synthesized a MnFe2O4 catalytic polyvinylidene fluoride (MnFe2O4-PVDF) ultrafiltration membrane and systematically investigated the performance of peroxymonosulfate (PMS)/MnFe2O4 membrane oxidation filtration system for removing humic acid (HA). The results showed that the PVDF@MnFe2O4/PMS synergistic system oxidized HA into small molecules and further repelled them to the membrane surface by size exclusion to form a filter cake layer. The PVDF@MnFe2O4/PMS system exhibited the lowest irreversible fouling (0.414 × 1010m−1) and the highest HA removal efficiency (83.4 %) compared with PVDF single filtration. After hydrodynamic cleaning, PVDF@MnFe2O4 can achieve 73.2 % water flux recovery. The membrane fouling mitigation mechanisms were investigated by the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and the combined pore blockage-cake filtration model. Quenching experiment and density functional theory calculation (DFT) revealed the HA degradation as a result of the synergistic action of free radicals (SO4⋅-, ⋅OH) and non-free radicals(1O2) in PVDF@MnFe2O4/PMS system. Additionally, we evaluated the effectiveness of the system in the removal of natural organic matter (NOM) from surface water. The results suggested that the PVDF@MnFe2O4/PMS system could validly remove the main fluorescent matters from surface water. In conclusion, this work provides a promising route for solving the membrane fouling caused by NOM in water.

Development of Tannic Acid Coated Polyvinylidene Fluoride Membrane for Filtration of River Water Containing High Natural Organic Matter

River water can be used as a source of drinking water. However, it is vital to consider the existence of natural organic matter (NOM) and its possible influence on water quality (low turbidity, high color). The level of NOM in river water significantly impacts the ecosystem’s health and the water’s quality, and needs to be removed. A membrane-based approach is attractive for treating NOM successfully, but is still hindered by the membrane fouling problem. This study aims to develop polyvinylidene fluoride (PVDF)-based membranes customized for NOM removal from river water. The anti-fouling property was imposed by a coating of tannic acid (TA) and Fe3+ on the pre-prepared PVDF membrane. The results show that the TA–Fe coatings were effective, as demonstrated by the FTIR spectra, SEM, and EDS data. The coatings made the membrane more hydrophilic, with smaller pore size and lower clean water permeability. Such properties offer enhanced NOM rejections (up to 100%) and remarkably higher fouling recovery (up to 23%), desirable for maintaining a long-term filtration performance.

Colloid-bound radicals formed in NOM-enhanced Fe(III)/peroxymonosulfate process accelerate the degradation of trace organic contaminants in water

The omnipresence of natural organic matter (NOM) in water bodies traditionally hinders the degradation of trace organic contaminants (TrOCs) in peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs). This study elucidates the positive role of NOM in enhancing the degradation of TrOCs through the Fe(III)/PMS process. During this process, NOM reduces Fe(III), yielding semiquinone-like radical (NOM•) and concurrently forming NOM-Fe(III) colloids. In addition to the Fe(II)-mediated activation pathway, Fe(III) sites on NOM-Fe(III) colloids effectively transfer electrons from NOM• or some redox-active moieties to PMS, resulting in the generation of long-lived colloid-bound SO4•−, which can readily undergo hydrolysis to produce HO•. The stabilization of SO4•− and HO• by NOM-Fe(III) colloids, combined with their moderate adsorption of TrOCs, results in surface-confined reactions that significantly enhance TrOC removal, despite the presence of concurrent quenching reactions between radicals and NOM. Further, the significant positive correlation between the phenolic contents of eight NOM types and TrOC degradation kinetics suggests phenolic moieties as the primary electron source for PMS activation. By in-situ utilizing NOM in raw water, a PMS-amended iron coagulation process with 0.2 mM Fe(III) and PMS effectively removes 90–100 % of six coexisting TrOCs. This study unveils the previously unrecognized role of colloid-bound radicals in decontamination processes, offering valuable insights into harnessing NOM's influence in advanced oxidation water treatment processes.

How suitable is the gold-labelling method for the quantification of nanoplastics in natural water?

Abstract Nanoplastics are detected in surface water, yet accurately quantifying their particle number concentrations remains a significant challenge. In this study, we tested the applicability of a gold-labelling method to quantify nanoplastics in natural organic matter (NOM) containing water matrices. Gelatin-coated gold nanoparticles (Au-gel NPs) form conjugates with nanoplastics via electrostatic interaction which produces peak signals which can be translated into particle number concentration using single-particle inductively coupled plasma–mass spectrometry (SP-ICP-MS). We used water samples with various NOM concentrations, with and without the addition of 1 × 107 particle–1 nanoplastics. Our results indicate that nanoplastics in low NOM samples (<1 mg·C L−1) could be successfully quantified. However, in high NOM samples (>15 mg·C L−1), only 13–19% of added nanoplastics were successfully quantified. Further digestion to remove NOM yielded only 10% of spiked nanoplastics. This discrepancy in high NOM samples could likely be attributed to the competition between nanoplastics and NOM existing in the water sample to bind with Au-gel NPs. Our study highlights the suitability of the Au-gel labelling method for quantifying nanoplastics in low NOM water samples. Nevertheless, further optimization, including pre-digestion steps, is essential to apply this method for high NOM water samples effectively.

A UVA light-emitting diode microreactor for the photocatalytic degradation of humic acids and the control of disinfection by-products formation potential

Chlorination is one of the most applied technologies for drinking water disinfection. However, the generation of disinfection by-products (DBPs) in the chlorination process is threatening drinking water safety, especially when the concentration of natural organic matter (NOM) is high in source water. Climate change increases the fluctuation of NOM in source water, which further challenges water safety in small and rural communities. In this study, environmental microfluidics was introduced to a UVA-LED photocatalytic oxidation system for a rapid oxidation of NOM. The results showed that HA adsorption and degradation, and DOC degradation were more favored in low pH. At pH 5, 56.9% of HA and 58.1% of dissolved organic carbon (DOC) were removed in 3.4 min by the microreactor. DBP formation potential was efficiently reduced, with the highest reduction of THM and HAA formation potentials by 76% and 70.7%, respectively. Compared with the bottle reactor, the degradation rate constants of HA and DOC by UVA-LED microreactor were increased by 2.99 – 15.8 times, and 6.8 – 170.2 times, respectively. Homogenous irradiation and rapid mass transfer in the microreactor accelerated the inhibited oxidation of HA in acidic and base solutions and increased the apparent quantum yields of photocatalysis. Further, the microfluidic photocatalytic oxidation was much more efficient in the reduction of DPBs formation potential in a source water sample. The process was rapid and had low chemical and energy consumption. Approaches on system scale-up, system simplification, and energy conservation would increase potential of microfluidic photocatalytic oxidation in water purification for households and small communities.

Effect of microplastics on the adherence of coexisting background organic contaminants to natural organic matter in water

Microplastics (MPs) may interact with background organic substances (including natural organic matter and organic pollutants) after entering the aquatic environment and affect their original binding. Thus, the interaction of MPs with background organic substances (i.e., humic acid (HA), polychlorinated biphenyls (PCBs), and hydroxy PCBs) were elucidated. According to the results, PCB and hydroxy PCB displayed a strong propensity to adhere to HAs in the absence of MPs. However, the PCBs and hydroxy PCBs that were initially bound to HAs shifted from HAs to MPs in the presence of MPs. Further analysis demonstrated that this transfer was dominated by van der Waals interactions, with hydrogen bond interactions as an additional driving force. Upon the interaction, large MPs-HA-PCB/ hydroxy PCB aggregates with MPs as the core and HAs as the outermost layer were formed. Significant changes in the properties of background organic matter, including the distribution of PCB/hydroxy PCB around HA, diffusion coefficient, and hydrogen bond networks in the HA-PCB/ hydroxy PCB domains, occurred during the MP–HA–PCB/hydroxy PCB interaction. These results provide molecular-level evidence that the intrusion of MPs changes the binding preference of background organic pollutants and can lead to a redistribution of background organic pollutants.

A Comprehensive Review on the Progress of Coagulation for Natural Organic Matter Removal in Water Treatment

Natural organic matter (NOM) seriously challenges the drinking water supply. It typically exists as complex organic substances generated in the natural water ecosystem as part of hydrologic, biological, and geological cycles. The significant variation, composition, and abundance of NOM in natural water or wastewater necessitate the implementation of robust and adaptive technologies, particularly in addressing even more stringent standards of drinking water supply or treated water discharge. Coagulation is one of the most common processes for water and wastewater treatments. It is highly desirable to treat feed containing NOM because it prevents the disinfection of by-products formation. Therefore, current dynamics of NOM in terms of varying compositions and concentrations demand improvement in handling the coagulation process through optimization of operational parameters (dosing and the control of pH), application of novel and more effective coagulants, and as a combination with other processes through process intensification. This review provides a comprehensive analysis of recent literature on developments of coagulation for NOM removal. The coagulants are grouped systematically and assessed. Next, enhanced coagulation via process intensification with other processes (membrane filtration, oxidation, adsorption, and ion exchange) is discussed. Lastly, the future outlook on research direction on sustainable coagulation process is listed to support circular and bioeconomy.

Photoaging mechanism of microplastics: a perspective on the effect of dissolved organic matter in natural water

Photoaging mechanism of microplastics: a perspective on the effect of dissolved organic matter in natural water

Role of visible light photocatalysis in alleviation and mechanism transformation of ultrafiltration membrane fouling caused by natural organic matter

In this study, a novel composite based on bismuth oxide, reduced graphene oxide and titanium dioxide (labeled as BRGT) was utilized for visible light photocatalysis to mitigate ultrafiltration membrane fouling caused by natural organic matter (NOM). The results show that the coexistence of NOM and the BRGT composite (without photocatalysis) did not aggravate membrane fouling, and the membrane preferentially retained a high molecular weight, hydrophobic component of NOM that formed a dense cake layer with BRGT composite. As the photocatalysis time increased, the extent of membrane fouling was alleviated. The maximum specific flux recovered from 0.21 to 0.73 at 60 min, and the hydraulic reversible and irreversible resistances ere 1.15 × 1010 and 4.23 × 1010 m−1, respectively. The reduction of NOM in the feed water, especially the removal of UV254, played a significant role in the alleviation of membrane fouling. Additionally, the changes in the properties of NOM, including the reduction of fluorescent humic and protein/polyphenol components corresponding to reversible and irreversible fouling, respectively, the photo-degradation of high molecular weight NOM into low molecular weight NOM (such as low molecular weight-acids), and the conversion of hydrophobic fractions into hydrophilic fractions, contributed to the mitigation of membrane fouling. We also found a strong negative correlation between the roughness of the cake layer and irreversible fouling. Overall, the changes in the properties of NOM in feed water can hinder or even inhibit the formation of the cake layer, and the use of visible light photocatalysis of the BRGT composite has great potential to alleviate ultrafiltration membrane fouling caused by natural organic matter.

TreatEEM—A Software Tool for the Interpretation of Fluorescence Excitation-Emission Matrices (EEMs) of Dissolved Organic Matter in Natural Waters

Fluorescence excitation-emission matrices (EEMs) are a useful tool in aquatic sciences for monitoring and studying the biogeochemistry of organic matter in natural waters and engineered systems. Yet, the interpretation of the wealth of information available in EEMs requires the use of appropriate software. Existing software tools for the analysis of EEMs, offered by instrument producers, have limited treatment capabilities, while other freely available tools are based on the MATLAB or R programming languages, which require a certain level of programming skills and a pre-installation of MATLAB or R. Here, we present TreatEEM, the first non-commercial, stand-alone Windows-based software tool that provides comprehensive treatment of EEMs. Its greatest advantage is its user-friendly and interactive graphical user interface, providing a convivial and responsive graphical feedback on any action performed on either a single spectrum (recorded at one excitation wavelength) or EEM. The capabilities of TreatEEM, including (a) basic EEM treatment, such as simple inner filter correction, scatter removal, blank subtraction, Raman normalisation, smoothing, drift alignment etc., (b) extraction of useful parameters for DOM characterisation (Coble peaks and fluorescence indices) and (c) preparation of data for PARAFAC analysis plus presentation/manipulation of obtained PARAFAC components, are described in detail, along with a basic theoretical background on these most commonly used treatment steps of EEMs.

Application of mathematical models for predicting the trihalomethanes content in drinking water in the city of Kumanova, North Macedonia

Trihalomethanes (THMs) are created as a result of the reaction between chlorine used to disinfect drinking water and natural organic matter in water. At high levels, THMs have been associated with cancer. As a consequence, THMs must be constantly monitored. They are mainly determined by the method of gas chromatography, which is a more difficult procedure and at a higher cost. In recent years, however, mathematical models have been used to predict THMs. These models work by measuring some physico-chemical parameters of drinking water, those values ​​of these parameters are replaced in mathematical models and the THMs content in drinking water can be predicted. The main purpose of this paper was to predict the content of THMs in the drinking water of the city of Kumanova. The measured parameters were: temperature, residual chlorine, pH, electrical conductivity, chemical oxygen, total dissolved solids and chlorides. Measurements were made during the spring season 2022 in the four sampling points. Ten mathematical models were used for prediction and of them the average value with standard deviation of THM was 26.9532 ± 10.03 μg/L. From the result we can conclude that content of THM does not pose a risk to the health of the population.

Enhanced virus inactivation by copper and silver ions in the presence of natural organic matter in water

Natural organic matter (NOM) is present in water matrix that serves as a drinking water source. This study examined the effect of low and high NOM concentrations on inactivation kinetics of a model RNA virus (MS2) and a model DNA virus (PhiX 174) by copper (Cu2+) and/or silver (Ag+) ions. Cu and Ag are increasingly applied in household water treatment (HHWT) systems. However, the impact of NOM on their inactivation kinetics remains elusive despite its importance for their application. The presence of NOM in water led to faster virus inactivation by Cu2+ but slower by Ag+. The fastest inactivation kinetics of MS2 (Kobs = 4.8 h−1) were observed by Cu in water containing high NOM (20 mg C/L). Meanwhile, for PhiX 174, the fastest inactivation kinetics (av. Kobs = 3.5 h−1) were observed by Cu and Ag synergism in water containing high NOM. Altogether, it can be concluded that the combination of Cu and Ag is promising as a virus disinfectant in treatment options allowing for multiple hours of residence time such as safe water storage tanks.

Spatial and temporal dynamic response of abundant and rare aerobic denitrifying bacteria to dissolved organic matter in natural water: A case study of Lake Baiyangdian, China

Revealing the responses of abundant and rare aerobic denitrifying bacteria to dissolved organic matter (DOM) composition is essential for understanding the aquatic N cycle ecosystems. In this study, fluorescence region integration and high-throughput sequencing techniques were used to investigate the spatiotemporal characteristics and dynamic response of DOM and aerobic denitrifying bacteria. The DOM compositions were significantly different among the four seasons (P < 0.001) without spatial differences. Tryptophan-like substances (P2, 27.89–42.67%) and microbial metabolites (P4, 14.62–42.03%) were the dominant components, and DOM exhibited strong autogenous characteristics. Abundant (AT), moderate (MT), and rare taxa (RT) of aerobic denitrifying bacteria showed significant and spatiotemporal differences (P < 0.05). The responses of α-diversity and niche breadth of AT and RT to DOM differed. The DOM explanation proportion for aerobic denitrifying bacteria exhibited spatiotemporal differences based on redundancy analysis. Foliate-like substances (P3) had the highest interpretation rate of AT in spring and summer, while humic-like substances (P5) had the highest interpretation rate of RT in spring and winter. Network analysis showed that RT networks were more complex than AT networks. Pseudomonas was the main genus associated with DOM in AT on a temporal scale, and was more strongly correlated with tyrosine-like substances (P1), P2, and P5. Aeromonas was the main genus associated with DOM in AT on a spatial scale and was more strongly correlated with P1 and P5. Magnetospirillum was the main genus associated with DOM in RT on a spatiotemporal scale, which was more sensitive to P3 and P4. Special operational taxonomic units were transformed between AT and RT with seasonal changes, but not between the two regions. To summarize, our results revealed that bacteria with different abundances utilized DOM components differently, and provides new insight on the spatiotemporal response of DOM and aerobic denitrifying bacteria in aquatic ecosystems of biogeochemical significance.

Study on the role of AlOOH in fluorescence correction and depth purification of Cyclops water

Protein-like substances produced by biochemical reactions after disinfection of Zooplankton like Cyclops and humic substances in natural water are the main components of NOM (Natural organic matter). To eliminate early warning interference in the fluorescence detection of organic matter in natural water, a clustered flower-like AlOOH (aluminum oxide hydroxide) sorbent was prepared. HA (humic acid) and amino acids were selected as mimics of humic substances and protein-like substances in natural water. The results demonstrate that the adsorbent can selectively adsorb HA from the simulated mixed solution and restore the fluorescence properties of tryptophan and tyrosine. Based on these results, a stepwise fluorescence detection strategy was developed and used in natural water rich in zooplanktonic Cyclops. The results show that the established stepwise fluorescence strategy can well overcome the interference caused by fluorescence quenching. The sorbent was also used for water quality control to enhance coagulation treatment. Finally, trial runs of the water plant demonstrated its effectiveness and suggested a potential control method for early warning and monitoring of water quality.

Synergistic effect of GO/ZnO loading on the performance of cellulose acetate/chitosan blended reverse osmosis membranes for NOM rejection

Declining freshwater resources along with their pollution are threatening the life existence on earth. To meet the freshwater demand, one of the most appropriate and possible ways which has been adopted all over the world is to reuse wastewater by removing its impurities. Among many water pollutants, natural organic matter (NOM) is found to be responsible as major precursor for the formation of other pollutants. Removal of NOM from wastewater is being done by using membrane filtration systems incorporated with certain nanofillers to increase membranes efficiency and permeability. In this study, novel nanocomposite reverse osmosis (RO) membranes were prepared using cellulose acetate and chitosan in N,N-Dimethyl formamide. Graphene oxide (GO) nanosheets and zinc oxide (ZnO) in different concentration were loaded to modify the membranes for tuning their RO performance. The confirmation of the functional groups is demonstrated by Fourier transform infrared spectroscopy which revealed the specific peaks indicating the formation of the nano-composite membranes. The surface morphology was studied by scanning electronic microscopy which shows a gradual transformation of the membrane surface from voids-free to macro-voids filled surface up to threshold concentration of GO and ZnO. The thermal properties of GO based membranes were analyzed using thermogravimetric analysis and differential scanning calorimetry. The uniform interaction of the GO and ZnO with polymers induced the remarkable thermal properties of the synthesized membranes. Permeate flux and contact angle measurements were considered to estimate their water content (96%) capacity and NOM rejection (96%) using 0.1 ppm humic acid solution. The permeate flux, NOM rejection and the water content changed directly with GO and inversely with ZnO wt% in the membranes up to GO5 (GO:0.14: ZnO:0.03) whereas the contact angle exhibited the inverse relationship with GO and ZnO concentration in casting solution of the synthesized membranes. Hence it can be concluded that prepared RO membranes are suitable for NOM rejection and recommended for water treatment.

Biogeochemistry of Natural Organic Compounds in Terrestrial Waters: Distribution and Variability during Climate Warming

The paper discusses the distribution and origin of organic matter in natural waters with regard to the latitudinal geographic zoning in the European territory of Russia (ETR) and Western Siberia (WS) and demonstrates how conditions on the catchments and climate affect the content of autochthonous and allochthonous organic matter. Conditional coefficients of the ratios of these forms are calculated. The influence of the temperature factor on the content of autochthonous organic matter in the waters of the southern territories of the ETR and WS was proved by multivariate statistical methods of analysis. General trends and relations are identified in the distribution of lipids, proteins, and carbohydrates of the autochthonous and allochthonous organic compounds. The mechanism of biochemical transformation of bound carbohydrates of allochthonous organic compounds into free autochthonous ones via the microbial decomposition is demonstrated, which is more typical of waters in the southern regions of WS. The paper discusses how natural and climatic conditions can influence changes in concentrations of organic compounds in the lake waters and structural characteristics of these compounds (contents of aromatic and aliphatic fragments).

Efficient degradation of triclosan by aluminium acetylacetonate doped polymeric carbon nitride photocatalyst under visible light

Triclosan (TCS), as a typical toxic and harmful micro-pollutant, has been frequently detected in various water bodies, and its threat to the aquatic environment has raised significant concerns. In this study, aluminium acetylacetonate doped polymeric carbon nitride photocatalysts (PCN-AA) were synthesized to investigate the degradation properties of TCS under simulated visible light. The results showed that the best ratio material PCN-AA30 (k = 0.0529 min−1) can degrade 99.29 % of TCS in 90 min, which is 2.45 times the degradation of the original polymeric carbon nitride material PCN-AA0 (k = 0.0216 min−1). The degradation process of TCS presented different rules under the changing conditions of catalyst dosage, initial concentration of TCS, pH, common inorganic anions and natural organic matter in water. The results of radicals quencher experiment showed that ·O2- played the most important role in the photocatalytic degradation in the reaction system. This study also identified 10 degradation products of TCS using UPLC-Q-TOF technology and proposed the possible degradation pathways. In addition, the acute biotoxicity of PCN-AA materials were tested by luminescent bacteria method, indicating that the safety of PCN-AA was relatively high. These results demonstrated that the polymeric carbon nitride material doped with aluminium acetylacetonate is a promising catalyst for the degradation of micro-pollutants in water under visible light.

Chlorine Dioxide: Friend or Foe for Cell Biomolecules? A Chemical Approach.

This review examines the role of chlorine dioxide (ClO2) on inorganic compounds and cell biomolecules. As a disinfectant also present in drinking water, ClO2 helps to destroy bacteria, viruses, and some parasites. The Environmental Protection Agency EPA regulates the maximum concentration of chlorine dioxide in drinking water to be no more than 0.8 ppm. In any case, human consumption must be strictly regulated since, given its highly reactive nature, it can react with and oxidize many of the inorganic compounds found in natural waters. Simultaneously, chlorine dioxide reacts with natural organic matter in water, including humic and fulvic acids, forming oxidized organic compounds such as aldehydes and carboxylic acids, and rapidly oxidizes phenolic compounds, amines, amino acids, peptides, and proteins, as well as the nicotinamide adenine dinucleotide NADH, responsible for electron and proton exchange and energy production in all cells. The influence of ClO2 on biomolecules is derived from its interference with redox processes, modifying the electrochemical balances in mitochondrial and cell membranes. This discourages its use on an individual basis and without specialized monitoring by health professionals.