Winery and olive mill wastewaters treatment using nitrilotriacetic acid/UV-C/Fenton process: Batch and semi-continuous mode

In this work, both red and white winery wastewaters (WW) and olive mill wastewater (OMW) were submitted to a treatment by Fenton-based processes (FBPs). The main aim was to evaluate the most efficient and economic process. Initial tests, resorting to a batch reactor, demonstrated that UV-C/Fenton (λ = 254 nm) was the most effective process. Operational conditions such as pH, H2O2 and Fe2+ concentrations revealed to have a superior influence within dissolved organic carbon (DOC) removal as well as regarding the reactor's energy consumption. As a means to prevent iron precipitation, the addition of nitrilotriacetic acid (NTA) was tested. With experimental conditions pH = 3.0, [H2O2] = 194 mM, [Fe2+] = 1.0 mM, [NTA] = 1.0 mM, radiation UV-C (254 nm), time = 240 min, the kinetic rate related with DOC removal showed a kredWW = 0.0128 min-1 > kOMW = 0.0124 min-1 > kwhiteWW = 0.0104 min-1 and both the WW and OMW achieved the Portuguese legal limit values for wastewater discharge. Furthermore, comparative experiments were performed in a semi-continuous reactor, being that the results put in evidence that the concentration of H2O2 added and the flow rate of reagents' addition (F) had a significant effect on the efficiency of the reactor. Under an optimum experimental procedure pH = 3.0, [H2O2] = 97 mM, [Fe2+] = 1.0 mM, [NTA] = 1.0 mM, radiation UV-C (254 nm), F = 1 mL min-1, time = 240 min, there were observed higher DOC removal kinetic rates (kOMW = 15.20 × 10-3 min-1 > kredWW = 11.64 × 10-3 min-1 > kwhiteWW = 11.57 × 10-3 min-1) and a cost ranging between 0.0402 and 0.0419 €/g.DOC. These results showed that semi-continuous reactors have the potential to be applied to large scale treatments, with low reagents consumption and reduced energy requirements.

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.

Water disinfection by the UVA/electro-Fenton process under near neutral conditions: Performance and mechanisms

An efficient and thorough water disinfection is critical for human health. In this study, UVA-LEDs, nitrilotriacetic acid (NTA) and a boron-doped diamond anode were respectively used as the UVA source, the iron chelator and the anode for the UVA/electro-Fenton (E-Fenton) reaction to treat wastewater. The disinfection performance of the UVA/E-Fenton had been investigated. The mechanisms of the E. coli inactivation had been clarified. The results showed that complete disinfection (about 5.6-log removal) could be achieved within 50 min at a certain condition due to the synergistic effort of the UVA, anodic oxidation and the electro-Fenton. The quenching experiments and the electron paramagnetic resonance (EPR) detection indicated that •OH, •O₂^- and ¹O₂ play important roles for inactivating E. coli. The results of SEM images and genomic DNA electrophoresis suggested that both the cell structure and the DNA had been thoroughly destroyed during the UVA/E-Fenton process. Increasing the UVA irradiation, oxygen bubbling could improve the disinfection rate, while it also would increase the energy consumption. The appropriate Fe and NTA ratio was 1:2 to realize an efficient Fenton reaction under near neutral condition. Complete disinfection was also achieved within 50 min when it used for treating real wastewater. Thus, the UVA/E-Fenton process is a satisfied way for water disinfection.

A new solar photo-Fenton strategy for wastewater reclamation based on simultaneous supply of H2O2 and NaOCl

This study presents, for the first time, the concurrent supply of the oxidants H₂O₂ and NaOCl in solar-driven Fenton-like processes at neutral pH with ferric nitrilotriacetate (Fe³⁺-NTA) for wastewater reclamation. Simultaneous Escherichia coli (E. coli) inactivation and the removal of the antibiotic sulfamethoxazole (SMX) at 50 μg/L in municipal effluents were investigated in 5-cm deep raceway pond reactors. First, the individual effects of reagent concentrations (1.47, 2.94 and 4.41 mM for H₂O₂; 0.134, 0.269 and 0.403 mM for NaOCl; 0.1 and 0.2 mM for Fe³⁺-NTA) on the economic efficiency (in terms of mass of SMX eliminated per Euro and per hour to attain complete E. coli inactivation and more than 50% of SMX removal) were considered. The highest economic efficiencies were 141 mg_SMX/€·h with H₂O₂ and 222 with NaOCl, the reaction times being 105 and 60 min, respectively. Second, a new strategy for solar photo-Fenton with the combination of the most cost-effective conditions (1.47 mM H₂O₂ - 0.134 mM NaOCl - 0.1 mM Fe³⁺-NTA) was carried out in secondary effluents from two treatment plants with different technologies. Economic efficiency was substantially affected by wastewater composition, ranging from 178 to 1131 mg_SMX/€·h with treatment times between 60 and 10 min, significantly improving the reported results for conventional solar photo-Fenton to date.

Evaluation of the Effects of Nitrilotriacetic Acid as a Chelating Agent on the Biochemical Toxicity of Lead in Oreochromis niloticus

In the present research, the effects of sublethal lead (Pb) concentrations on total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI) levels, enzyme activities (aspartate transaminase, AST; alanine transaminase, ALT; lactate dehydrogenase, LDH), ion levels (magnesium, Mg; sodium, Na; potassium, K; chlorine, Cl; calcium, Ca), and some metabolite levels (cholesterol, triglyceride, HDL, LDL, albumin, total protein) in the blood serum of Oreochromis niloticus and the protective function of nitrilotriacetic acid (NTA) due to its chelating characteristic were investigated. O. niloticus, which has an important position in the food chain and is often preferred in toxicological studies, was exposed to 0.1 ppm Pb, 0.1 ppm Pb + 0.3 ppm NTA, 1 ppm Pb, and 1 ppm Pb + 3 ppm NTA concentrations for 7 and 21 days. At the end of the duration, serum TAS and TOS levels were measured spectrophotometrically with Rel Assay Diagnostics; other enzyme activities, ion levels, and metabolite parameters were done by an autoanalyzer using commercial kits. Depending on the exposure periods and concentrations, the changes in the parameters were determined. It is determined that, under the influence of high ambient concentration of lead, TOS, OSI, AST, ALT, LDH, LDL, triglyceride, and Mg levels increased, while TAS, albumin, and K levels decreased after 21 days. These increases/decreases in all serum biochemical parameters were generally higher in fish treated with Pb alone compared to fish treated with a mixture of Pb + NTA. This study shows that these changes in serum parameters could be used as an indicator to assess on metal toxicity.

Simultaneous preconcentration and pre-column derivatization for rapid analysis of nitrilotriacetic acid in environmental waters by high performance liquid chromatography

A simplified sample pretreatment procedure was developed for quantitative measurement of nitrilotriacetic acid (NTA) in environmental water. On the basis of coordination capacity between NTA and metal ions, aluminum-based metal organic framework (MOF, MIL-53(Al)) was adopted for the adsorption of NTA, followed by stripping with copper sulfate as the eluent. The adsorbed NTA was converted into Cu-NTA during the desorption process, which facilitated the ensuing measurement by high performance liquid chromatography (HPLC). A linear range within 0.10 - 10 mg L^-1 was achieved, along with a limit of detection (LOD, S/N=3, n=7) of 0.03 mg L^-1 and an enrichment factor of 10.4. The developed method was validated by the analysis of sea water, influent of wastewater treatment plant and industrial wastewater, with satisfactory recoveries (90.2 - 91.1%) obtained.

Effect of nitrilotriacetic acid and tea saponin on the phytoremediation of Ni by Sudan grass (Sorghum sudanense (Piper) Stapf.) in Ni-pyrene contaminated soil

Phytoremediation is commonly used in the remediation of soils co-contaminated by heavy metals and polycyclic aromatic hydrocarbons (PAHs) because of its economy and effectiveness. Sudan grass (Sorghum sudanense (Piper) Stapf.) has well-developed roots and strong tolerance to heavy metals, so it has been widely concerned. In this study, nitrilotriacetic acid (NTA) and tea saponin (TS) were used as enhancers and combined with Sudan grass for improving the remediation efficiency of Ni-pyrene co-contaminated soil. The results of the pot experiment in soils showed that enhancers promoted the enrichment of Ni in plants. With the function of enhancers, more inorganic and water-soluble Ni were converted into low-toxic phosphate-bonded and residual Ni, so as to reinforce the tolerance of Sudan grass to Ni. In the pot experiment based on vermiculite, it was found that enhancers increased the accumulation of Ni in cell wall by 49.71-102.73%. Enhancers also had the positive effect on the relative abundance of Proteobacteria, Patescibacteria and Bacteroidetes that could tolerate heavy metals at phylum level. Simultaneously, the study found that pyrene reduced the exchangeable Ni in soils. More Ni entered the organelles and transfer to more high-toxic forms in Sudan grass when pynere coexisted. The study manifested that enhancers improved the phytoremediation effect of Ni significantly, yet the co-existence of pyrene weakened the process. Our results provided meaningful references for remediating actual co-contaminated soil of heavy metals and PAHs.

The changes of rhizosphere characteristics contributed to enhanced Pb accumulation in Athyrium wardii (Hook.) Makino after nitrilotriacetic acid application

Chelant-assisted phytoremediation may modify plant rhizosphere, which is closely related to heavy metal (HM) accumulation in plants. This work focused on the effects of nitrilotriacetic acid (NTA) on rhizosphere characteristics to investigate the mechanisms of lead (Pb) accumulation in Athyrium wardii (Hook.) Makino with exposure to 800 mg kg^-1 Pb. After NTA application, Pb accumulation in the underground part of A. wardii increased by 14.3%, accompanying with some changes for the rhizosphere soils. Soil pH decreased by 0.37 units, and the dissolved organic carbon (DOC) content in the rhizosphere soils significantly increased by 7.6%. The urease, acid phosphatase, and catalase activities in the rhizosphere soils significantly increased by 104.8%, 19.7%, and 27.1%, respectively. However, a slight inhibition on microbial activities was observed in the rhizosphere of A. wardii after NTA application. Soil respiration decreased by 8.9%, and microbial biomass carbon decreased by 8.9% in the rhizosphere soils, indicating that NTA addition might recruit some microorganisms to maintain rhizosphere functions in Pb-contaminated soils while inhibiting others with low tolerance to Pb. Results suggest that lower pH, more DOC exudation, and higher soil enzyme activities after NTA application contributed to the increase of Pb accumulation in A. wardii. This study gave some preliminary evidence for NTA-assisted Pb remediation by A. wardii by modifying rhizosphere characteristics.

Effect of enhancers on the phytoremediation of soils polluted by pyrene and Ni using Sudan grass (Sorghum sudanense (Piper) Stapf.)

Remediation of heavy metal and polycyclic aromatic hydrocarbon (PAH)-co-contaminated soils has drawn much more attention; phytoremediation is an often-used technique. Sudan grass (Sorghum sudanense (Piper) Stapf.) with developed root system and strong PAHs and heavy metal tolerance is a potential choice for phytoremediation. In this study, the application of tea saponin (TS) (1 g kg^-1 soil) and nitrilotriacetic acid (NTA) (1 g kg^-1 soil) was to improve the removal efficiency of Ni and pyrene. TS and NTA had no obvious effects on the growth and soluble proteins of Sudan grass. Ni concentration in root was higher than that in the shoot. The addition of TS and NTA increased the Ni concentration in the root by 25.98% in Ni-contaminated treatment. Pyrene was mainly accumulated in the shoot of Sudan grass. Pyrene concentration in shoot increased by 20.14% with TS-NTA in pyrene-contaminated treatment and increased by 31.97% in Ni-contaminated treatment. TS and NTA had significantly improved dissolved organic matter and soil microbial activity. Microbial activity increased by 16.75%, 18.07%, and 23.364% in pyrene-contaminated, Ni-contaminated, and pyrene and Ni-co-contaminated treatment, respectively. This study showed that phytoremediation of pyrene and Ni-co-contaminated soil by Sudan grass could be enhanced by the application of TS-NTA and the interaction between pyrene and Ni impacted the accumulation of Ni and pyrene in Sudan grass.

Proteomics analysis of host cell proteins after immobilized metal affinity chromatography: Influence of ligand and metal ions

Different degrees of protein purity have been observed in immobilized metal affinity chromatography ranging from extremely high purity to moderate and low purity. It has been hypothesized that the host cell protein composition and the metal ligands are factors governing the purity of a protein obtained after immobilized metal affinity chromatography (IMAC). Ni nitrilotriacetic acid (NTA) has become the first choice for facile His-tagged protein purification, but alternative ligands such as iminodiacetic acid (IDA) with other immobilized metal ions such as Zn, Cu and Co are valuable options when the expected purity or binding capacity is not reached. Especially Cu and Zn are very attractive, due to their reduced environmental and safety concerns compared to Ni. Co and Zn are more selective than Ni and Cu. This increased selectivity comes at the cost of weaker binding. In this work, the influence of ligand choice on protein purity after IMAC was evaluated by several methods, including peptide mapping. His-tagged GFP was used as model protein. We found that host cell protein (HCP) content varies drastically between ligands, as IDA eluates generally showing higher HCP concentrations than NTA. The relative content of the key amino acids His, Cys and Trp in the sequence of the co-eluted protein does not suffice to explain co-eluting propensity. The co-elution of HCPs is mostly influenced by metal binding clusters on the protein surface and not by total content or surface concentration of metal interacting amino acids. Prediction of co-elution is not dependent on these clusters alone, due to protein-protein interactions, indicted by a relative low metal binding cluster score but high co-elution propensity and in a lot of cases these proteins are often part of complex such as ribosome and chaperones. The different co-eluting proteins were presented by a heatmap with a dendrogram. Ward's linkage method was used to calculate the distance between groups of co-eluting proteins. Clustering of co-eluting HCPs was observed according to ligand and by metal ions, with Zn and Co forming one cluster and Ni and Cu another. The co-elution of host cell proteins can be explained by clusters of metal interacting amino acids on the protein surface and by protein-protein interactions. While Ni NTA still appears to be highly advantageous, it might not be the cure-all for all applications.

A highly efficient flow-through electro-Fenton system enhanced with nitrilotriacetic acid for phenol removal at neutral pH

Low pH requirement is one of the biggest limitations of the application of traditional Fenton and electro-Fenton (EF) process because Fe^II/Fe^III would precipitate at high pH. In this study, a flow-through EF system operated in batch recirculation mode was constructed. Nitrilotriacetic acid (NTA) was used as a chelating agent in the EF system (NTA/EF) to keep iron soluble at high pH values, producing OH by reaction of H₂O₂ generated in situ with Fe^IINTA that obtained by the reduction of Fe^IIINTA at the cathode. This flow-through NTA/EF system accelerated the mass transfer of target molecules to the electrode surface and showed high efficiency for phenol removal at pH 5-8 with rate constants (k) at around 0.26 min^-1, higher than that of the batch test (k = 0.15 min^-1) and EF process without NTA (k = 0.16 min^-1). The influences of aeration rate, current, flow rate, Fe dose, the ratio of NTA to Fe, pH, and initial phenol concentration on the phenol removal were investigated. The system could be used for at least 3 times for phenol removal without obvious efficiency decline. The flow-through NTA/EF system is promising for the removal of organic contaminants in a wide pH range.

A comparative study for removal of cadmium(II) ions using unmodified and NTA-modified Dendrocalamus strictus charcoal powder

Release of cadmium, a non-essential and highly toxic heavy metal, into aquatic ecosystem through discharge of effluents from various industries such as electroplating, photographic, steel/iron production and tanneries, is of considerable environmental conern at global level. Hence, it is essential to develop economic methods to remove cadmium from industrial effluents before their discharge into water bodies. The aim of present study was to explore the efficiency of Nitrilotriacetic acid (NTA) for the surface modification of Dendrocalamus strictus charcoal powder (DCP) and application of both unmodified DCP and NTA modified DCP (NTA-MDCP) as adsorbents to remove cadmium (II) ions from aqueous solution. Isotherms, thermodynamic and kinetic studies were carried out to describe the adsorption behavior of both adsorbents for the removal of Cd(II) ions. Maximum adsorption capacity calculated from Langmuir isotherm was found to be higher for NTA-MDCP (166.66 mg/g) as compared to DCP (142.85 mg/g) which may be attributed to the complex formation (1:1 & 2:1) between NTA on the surface of adsorbent and Cd(II) ions in the solution at optimum conditions: pH = 6, temperature = 25 °C, adsorbent dose = 2 g/l and contact time = 2 h. Thermodynamic studies confirmed endothermic as well as spontaneous nature of adsorption process and kinetic investigation revealed that the adsorption process followed pseudo second-order for both DCP and NTA-MDCP. Physical characterization of both adsorbents before and after adsorption was studied using Scanning Electron Microscope, Brunauer-Emmett-Teller surface analyzer, Energy Dispersion X-ray Spectrometer, CHNS analyzer and X-Ray diffractometer which confirmed the adsorption of cadmium(II) ions. Further, the desorption studies for regeneration of adsorbents were successfully carried out using two eluents viz., 1 M sulfuric acid and 0.5% calcium chloride. The present study revealed that NTA-MDCP could be used as an effective adsorbent for the removal of cadmium(II) ions from aqueous solution.

Young leaf protection from cadmium accumulation and regulation of nitrilotriacetic acid in tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis)

Phytoextraction efficiency of cadmium (Cd) contaminated soil mainly depended upon the mechanism of plants in absorption, translocation, distribution, and detoxification of Cd. A pot experiment was designed to investigate Cd distribution and accumulation among the different leaves of tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis) and its regulation by Nitrilotriacetic acid (NTA), a biodegradable chelating agent. The results showed that Cd concentrations in the senescent and dead leaves were 3.2 and 5.3 fold of that in the emerging leaves of tall fescue, and 19.3 and 25.1 fold of that in the emerging leaves of Kentucky bluegrass, respectively. The lower Cd concentrations were maintained in the emerging and mature leaves to avoid Cd toxicity. In the emerging and mature leaves, Cd was mainly accumulated in the vascular bundles and epidermis. No Cd dithizonate color was observed in the mesophyll tissues of Kentucky bluegrass and only minor Cd was observed in the mesophyll tissues of tall fescue. In the senescent leaves, Cd dithizonate complexes were located in the protoplasts and cell walls of all leaf tissues. NTA greatly promoted Cd translocation and distribution to the senescent and dead leaves of tall fescue, but no significant effect was observed in Kentucky bluegrass. Our results indicate that a young leaf protection mechanism might be involved in their Cd hypertolerance. The Cd preferential accumulation could lead a novel phytoextraction strategy by the continuously harvesting the senescent and dead leaves of tall fescue and Kentucky bluegrass.

Effect of Bacillus subtilis and NTA-APG on pyrene dissipation in phytoremediation of nickel co-contaminated wetlands by Scirpus triqueter

A complex mix of organic pollutants and heavy metal made the remediation of contaminated wetlands more difficult. Few research focus on the remediation for pyrene enhanced by chemical reagents and pyrene degrading bacteria in the nickel co-contaminated soil. In this paper, the effect of chemical reagents (nitrilotriacetic acid and alkyl polyglucoside) and Bacillus subtilis on pyrene dissipation in phytoremediation of nickel co-contaminated soil by Scirpus triqueter was investigated. Similar seedlings of Scirpus triqueter were moved to uncontaminated soil and pyrene-nickel co-contaminated soil. The pots (14.8 cm diameter and 8.8 cm height) were set up in greenhouse and treated in different ways. After 60 days, plant biomass, radial oxygen loss (ROL), soil dehydrogenase activity (DHA) and pyrene concentration in soil were determined. Results showed that ROL rate and DHA in different groups was positively correlated with pyrene dissipation from soil. In the process of remediation, chemical reagents might have an indirect slight effect on pyrene dissipation (pyrene dissipation increased 21%) by affecting DHA firstly and redistributing pyrene fractions in the presence of pyrene degrading bacteria. Pyrene degrading bacteria were likely to affect pyrene dissipation by impacting ROL rate and DHA and played a more vital role in contributing to pyrene dissipation (pyrene dissipation increased 45%) from wetland. This study demonstrated that phytoremediation for pyrene in nickel co-contaminated soil by Scirpus triqueter can be enhanced by the application of NTA-APG and pyrene degrading bacteria and they could be reasonably restore the ecological environment of PAH-contaminated wetlands.

Cobalt-embedded carbon nanofiber derived from a coordination polymer as a highly efficient heterogeneous catalyst for activating oxone in water

Carbon fiber (CF) supported cobalt nanoparticles (NPs) are promising catalysts for activating Oxone because carbon is non-metal and earth-abundant, and CF-based catalysts exhibit a high aspect ratio, which affords more accessible and dense catalytic sites. Nevertheless, most of CF-supported catalysts are fabricated by post-synthetic methods, which involve complicated preparations. More importantly, metallic NPs are attached to the outer surface of CF rather than embedded within CF. However, there is still a great demand for developing Co-bearing carbon fibers for Oxone activation via simple and effective methods. Thus, this study proposes to develop a cobalt NP-embedded carbon nanofiber (CCNF) by a simple hydrothermal reaction of Co and nitrilotriacetic acid (NA), followed by one-step carbonization. Owing to the coordinative structure of CoNA, the derivative CCNF exhibits a fibrous carbon matrix embedded with evenly distributed and densely packed Co₃O₄ and magnetic Co⁰ nanoparticles. The fibrous structure, magnetism and embedded Co NPs enable CCNF to be a promising catalyst for Oxone activation. As degradation of Rhodamine B (RhB) is selected as a model reaction, CCNF not only rapidly activates Oxone to fully degrade RhB but also shows a much higher catalytic activity than the most common Oxone activator, Co₃O₄. CCNF also exhibits the lowest activation energy than any reported catalysts for Oxone activation to degrade RhB. In addition, CCNF could be re-used to activate Oxone for RhB degradation. These results indicate that CCNF is a conveniently prepared and highly effective fibrous Co/C hybrid material for activating Oxone to oxidize contaminants in water.

Increased accumulation of Pb and Cd from contaminated soil with Scirpus triqueter by the combined application of NTA and APG

Phytoremediation of heavy metals contaminated soils shows many advantages and it can be improved by adding chelating agents and surfactants. In this study, pot culture experiments were set up to explore the effect of alone application of nitrilotriacetic acid (NTA) and combined application of NTA and alkyl polyglucoside (APG) on changes in absorption and adsorption of heavy metals by root of Scirpus triqueter and bioaccumulation of metals in single or co-contamination. Different additives were added into the soils artificially after 10 d and heavy metals extracted from different plant tissues were analyzed after 60 d. Results showed that more cadmium (Cd) was adsorbed on the root surface while more lead (Pb) was absorbed in root interior with the combined application of NTA and APG during phytoremediation of single contaminated soil. In co-contaminated soils, such a combined application not only strengthened the plant growth, but also promoted accumulation of Pb and Cd by Scirpus triqueter. NTA improved absorption amounts of Pb (9.7-fold) and Cd (1.0-fold) in root interior significantly. APG induced more metals to gather on the root surface in the presence of NTA and the adsorption amounts of Pb and Cd ranged from 26.2 and 17.7 mg kg^-1 to 412 and 46.0 mg kg^-1 respectively. Besides, the coexistence metal increased bioaccumulation of another metal under combined application of NTA and APG in co-contamination of Pb and Cd. In conclusion, the combined application of NTA and APG would be beneficial to accumulate Pb and Cd from contaminated soils by Scirpus triqueter.

Layer by layer coating of NH2-silicate/polycarboxylic acid polymer saturated by Ni2+ onto the super magnetic NiFe2O4 nanoparticles for sensitive and bio-valuable separation of His-tagged proteins

Magnetic nanoparticles NiFe₂O₄ was synthesized and covered in the silicate lattice of (3-Aminopropyl) triethoxysilane (APS) by the sol-gel process. Subsequently, the EDTA-dianhydride was attached to the amino surface of magnetic nanoparticles (MNPs) during the nucleophilic attack. This polycarboxylic layer trapped the high level of nickel ions for selective bonding to the His-tagged recombinant protein. The surface of MNPs was investigated by TEM, XRD, SEM (EDSA), VSM, BET, FT-IR and zeta potential analysis which characterized the size, chemical lattice, morphology, magnetic strength, specific surface area, functional groups and charge of the surface of nanoparticles. The performance and validity of the nanoparticles were studied by the purification of His-tagged green fluorescence protein (His-GFP). Also, the safety of proposed Ni-MNPs in the purification procedure of His-tagged proteins for pharmaceutical applications was proved by the determination of the nickel leakage level in the purified final protein using atomic absorption spectroscopy. In vitro cytotoxicity of Ni-MNPs and trace metal ions was investigated by the MTS assay technique. In addition, the comparison of biological activity in purified protein (GM-CSF) and commercial sample did not show any toxic effect.

Comparison of classical fenton, nitrilotriacetic acid (NTA)-Fenton, UV-Fenton, UV photolysis of Fe-NTA, UV-NTA-Fenton, and UV-H2O2 for the degradation of cyclohexanoic acid

The treatment of a naphthenic acid model compound, cyclohexanoic acid, with classical Fenton, UV-H₂O₂, UV-Fenton, nitrilotriacetic acid (NTA)-Fenton, UV-NTA-Fenton, and UV photolysis of Fe-NTA processes at pHs 3 and 8 was investigated. At 1.47 mM H₂O₂, 0.089 mM Fe, and 0.18 mM NTA, the UV-NTA-Fenton process at pH 3 exhibited the highest H₂O₂ decomposition (100% in 25 min), CHA removal (100% in 12 min) with a rate constant of 0.27 ± 0.025 min^-1, and NTA degradation (100% in 6 min). Due to the formation of H₂O₂-Fe(III)NTA adduct, the total Fe concentration in the UV-NTA-Fenton system (0.063 mM at the end of the reaction) at pH 8 was much higher than that in the UV photolysis of Fe(III)NTA process (0.024 mM). The co-complexing effect of borate buffer helped to keep iron soluble; however, it imposed a negative influence on the CHA degradation in the UV-NTA-Fenton process (68% CHA removal in 60 min in the borate buffer compared to 92% in MilliQ water). The results demonstrated that the most efficient process for the CHA degradation under the experimental conditions was the UV-NTA-Fenton process at pH 3.

Nitrilotriacetic acid functionalized Adansonia digitata biosorbent: Preparation, characterization and sorption of Pb (II) and Cu (II) pollutants from aqueous solution

Nitrilotriacetic acid functionalized Adansonia digitata (NFAD) biosorbent has been synthesized using a simple and novel method. NFAD was characterized by X-ray Diffraction analysis technique (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analyzer, Fourier Transform Infrared spectrometer (FTIR), particle size dispersion, zeta potential, elemental analysis (CHNS/O analyzer), thermogravimetric analysis (TGA), differential thermal analysis (DTA), derivative thermogravimetric analysis (DTG) and energy dispersive spectroscopy (EDS). The ability of NFAD as biosorbent was evaluated for the removal of Pb (II) and Cu (II) ions from aqueous solutions. The particle distribution of NFAD was found to be monomodal while SEM revealed the surface to be heterogeneous. The adsorption capacity of NFAD toward Pb (II) ions was 54.417 mg/g while that of Cu (II) ions was found to be 9.349 mg/g. The adsorption of these metals was found to be monolayer, second-order-kinetic, and controlled by both intra-particle diffusion and liquid film diffusion. The results of this study were compared better than some reported biosorbents in the literature. The current study has revealed NFAD to be an effective biosorbent for the removal of Pb (II) and Cu (II) from aqueous solution.

Statistical investigation on the role of supporting electrolytes during NTA degradation on BDD anodes

This work reported a comparative study on the electrochemical incineration of nitrilotriacetic acid (NTA) in the presence of different supporting electrolytes (Na2SO4 and NaCl). Galvanostatic electrolyses were conducted in an undivided electrochemical cell containing boron-doped diamond (BDD) anode and platinum cathode. Initial solution pH, flow rate, applied current density, and supporting electrolyte concentration were selected as variables, besides the mineralization efficiency of NTA that was selected as response. Central composite rotatable design and response surface methodology were employed here to examine the statistical significance of the selected variables, as well as to determine the optimal conditions of the degradation process. Under the same operating conditions, two regression models were thus constructed to illustrate the differing impact of supporting electrolytes in BDD anode cells. The kinetics for NTA degradation followed different reaction orders for the two scenarios (in the absence and presence of NaCl), indicating the complex interaction between hydroxyl radicals and active chlorine. Despite this, the experimental results demonstrated that effective mineralization of NTA might also be achieved in the presence of chlorides (of lower concentrations). Besides, in the case of chlorides, the average mass transfer coefficient of the system was found to be strongly dependent on the initial solution pH. Lastly, a plausible reaction sequence concerning the electrolytic oxidation of NTA in chloride media was also proposed.

Efficient removal of free and nitrilotriacetic acid complexed Cd(II) from water by poly(1-vinylimidazole)-grafted Fe3O4@SiO2 magnetic nanoparticles

Poly(1-vinylimidazole)-grafted Fe3O4@SiO2 magnetic nanoparticles (FSPV) were developed to remove both free Cd(II) and nitrilotriacetic acid (NTA) complexed Cd(II) from water. The adsorption capacity of NTA-complexed Cd(II) (42.1 mg/g) was larger than that of free Cd(II) (24.8 mg/g). Free Cd(II) and NTA-complexed Cd(II) could be reduced from 50 μg/L to below 5 μg/L within 10 and 20 min, respectively. FSPV could effectively remove trace free and NTA-complexed Cd(II) over broad pH ranges of 5-10 and 5-11, respectively. Moreover, the presence of seven coexisting ions (up to 100 mM) including four cations (Na(+), K(+), Ca(2+), and Mg(2+)) and three anions (Cl(-), NO3(-), and SO4(2-)) all slightly promoted the removal of both free and NTA-complexed Cd(II) onto FSPV. The removal of free Cd(II) or NTA-complexed Cd(II) was not obviously affected by the presence of Ni(II) and Co(II) (50 μg/L), humic acid (up to 3 mg/L as TOC) or alginate (up to 8 mg/L as TOC). In addition, FSPV could be regenerated with 10 mM HCl in 10 min, and the removal of both types of Cd(II) maintained above 95% in five consecutive adsorption/regeneration cycles. Therefore, FSPV could be utilized as promising adsorbent for both free and NTA-complexed Cd(II).

Chemometric study on the electrochemical incineration of nitrilotriacetic acid using platinum and boron-doped diamond anode

This study investigated the electrochemical incineration of nitrilotriacetic acid (NTA) at boron-doped diamond (BDD) and platinum (Pt) anodes. Trials were performed in the presence of sulfate electrolyte media under recirculation mode. The parameters that influence the degradation efficiency were investigated, including applied current density, flow rate, supporting electrolyte concentration and reaction time. To reduce the number of experiments, the system had been managed under chemometric technique named Doehlert matrix. As a consequence, the mineralization of NTA demonstrated similar behavior upon operating parameters on these two anodes. Further kinetic study indicated that the degradations followed pseudo-first-order reactions for both BDD and Pt anodes, and the reaction rate constant of the former was found to be higher than that of the latter. Such difference could be interpreted by results from fractal analysis. In addition, a reaction sequence for NTA mineralization considering all the detected intermediates was also proposed.