Nitrate Adsorption Research Articles

WITHDRAWN: Study of hydro chemical parameters of surface water for the irrigation purposes and its visualization using Google earth pro and Bhuvan earth

Surface water is an important source of water in agriculture. Google Earth Pro is a computer application software that provides a three dimensional Earth presentation based on satellite imagery. Google Earth Pro's thematic maps relate to agricultural, water, disaster, and processed satellite data. It also provides visualization and earth observation services to users in public. Bhuvan is an Indian web-based benefit that permits users to survey a group of map-based content prepared by an Indian space research organization. The present study is conducted to evaluate the hydrochemical parameters of surface water in a few tanks of the Ramanathapuram block and its suitability for irrigation purposes. The water samples were collected from 10 minor irrigation tanks to investigate the water quality parameters. The collected samples are stored in a refrigerator at 4 °C and tested within the week. The hydrochemical parameters including pH, Electrical conductivity, Nitrate, Chlorides, Sulphates, Phosphates, Calcium, Sodium, Magnesium, Hardness, and Sodium adsorption ratio are tested in the laboratory and results are arrived. The results are imported in Google earth pro and Bhuvan earth to visualize the parameters. Except for hardness and magnesium all other parameters tested are within the range and near the standard values. Hardness value exceeds the standard value recommended for the irrigation purpose only because of an increase in the concentration of magnesium. Hence the water should be treated before supplying to the field for reducing hardness and magnesium.

Adsorption of ammonium, nitrite, and nitrate onto rice husk biochar for nitrogen removal

This study aims to investigate the adsorption capacity of ammonium NH4+, nitrite NO2- and nitrate NO3- onto rice husk biochar (RHB) obtained from 550 °C pyrolysis temperature in the context of using low-cost absorbent for recirculating aquaculture system (RAS). Raw RHB at its original size 5–8 mm has been choosen for testing its adsorption capacity as well as several key material properties (pHPZC, surface area, and elemental analysis). From surface functional group analysis, there existed the O–H group (at frequency 3443 cm-1), –CH3 (2360 cm-1), and either –C=O or C=C group (in the range of frequency 1600–1650 cm-1) as well as –COOH (1456 cm‒1) that helped enhance chemical adsorption. The experimental adsorption data has been roughly consistent with Langmuir and Freundlich models that used to calculate the maximum saturated monolayer adsorption capacity Q0max of ammonium, nitrite, and nitrate were 0.1003, 0.2477, and 0.1290 mg/g respectively. Therefore, RHB could be a potential candidate for biofilter application in both targets cost-efficient and sustainable that worth applied at scale.

Abstraction of nitrates and phosphates from water by sawdust- and rice husk-derived biochars: Their potential as N- and P-loaded fertilizer for plant productivity in nutrient deficient soil

Biochars were produced by pyrolyzing the rice husk and sawdust at two temperatures of 300 °C (low-temperature) and 700 °C (high-temperature) and tested for the removal performance for nitrates and phosphates in water via batch sorption experiments. The resulting N- and P-loaded biochars were then applied to soil to evaluate their impact on maize growth. Adsorption kinetics experiments indicated a relatively high rate of adsorption of nitrates (up to 2.469 mg g−1 h−1) onto biochars than phosphates (up to 0.456 mg g−1 h−1). The high-temperature biochar showed greater adsorption capacity (up to 95.42 mg g−1) for nitrates, while low-temperature biochar exhibited more adsorption (up to 47.18 mg g−1) for phosphates. Chemisorption was the dominant mechanism for the adsorption of nitrate onto high-temperature biochars, as indicated by the best fitting of the sorption data to the pseudo-second-order model (R2 > 0.96). Phosphate adsorption onto low-temperature biochars was mainly governed by pore diffusion and chemisorption, as predicted from the best fits to the intra-particle diffusion (R2 ≥ 0.96) and pseudo-second-order (R2 ≥ 0.84) models, respectively. The results of plant growth experiments indicated positive effects on maize productivity in soils amended with N- and P-loaded biochars, which was confirmed by the increase in the fresh and dry biomass weights (up to 803 and 733 %, respectively) and greater uptake of essential nutrients (Zn up to 554 %, Mn up to 954 %, Fe up to 325 %, Ca up to 537 % and Mg up to 531 %) in maize plants as compared to the control.

Kinetic, isotherm, and mechanism investigations of the removal of nitrate and nitrite from water by the synthesized hydrotalcite Mg–Al

The objective of this work is to test the effectiveness of hydrotalcite as an adsorbent for the retention of nitrate and nitrite ions and to study the influence of various reaction parameters such as pH, adsorbent dose, contact time and initial ion concentration. Hydrotalcites (HTx) of different Mg/Al ratios (x was Mg/Al ratio; 2, 3, 4) were synthesized by the co-precipitation method at constant pH and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR). The results obtained indicate that hydrotalcite (HT3) allows good retention of nitrate and nitrite ions with no pH adjustment. Adsorption increases with decreasing mass of the adsorbent and increases with increasing initial concentration of nitrate and nitrite ions. When the Mg/Al ratio changes from 2 to 4; the electrical charge density between layers weakens; the inter-layer spacing increases and the material shows greater adsorption capacity. The equilibrium isotherm showed that the Langmuir model provided a better fit to the experimental data than the Freundlich model for nitrates and nitrites. The adsorption capacity of HT3 for nitrates and nitrites was found to be 6.92 mg/g and 9.26 mg/g, respectively. The XRD analysis after adsorption showed that materials that had undergone nitrate and nitrite ions adsorption, maintain the hydrotalcite structure.

Surface characterization of mesoporous biomass activated carbon modified by thermal chemical vapor deposition and adsorptive mechanism of nitrate ions in aqueous solution

The mesoporous activated carbon derived from moso biomass was selected to be modified to efficiently and rapidly remove aqueous phase nitrate ions. The bamboo was activated by H3PO4 and pyrolyzed at 500℃, marked as BAP6. Via various steps including thermal chemical vapor deposition (CVD), 7 types of surface modified biochar were obtained. Surface characterization of all the samples was investigated by Brunauer-Emmett-Teller method, elemental analyzer, and X-ray photoelectron spectroscopy. The quaternary nitrogen (N–Q) as strong adsorptive sites was deposited successfully on the surface of BAP6 (Davg = 6.8 nm, SBET = 1024 m2/g) by CVD doping nitrogen on it. The optimal modified mesoporous activated carbon BAP-8AN20-9.5HT30-8ST30 (Davg = 4.4 nm, SBET = 995 m2/g) owned nitrate adsorption capacity of 0.46 mmol/g in nitrate concentration of 200 mg/L at solution pH 3 and surface adsorption rate of 0.47 μmol/m2. The adsorption principle was also discussed. Adsorption kinetics were examined and analyzed by the pseudo-first-order and pseudo-second-order model. All powdery samples BAP6-8AN20-9.5HT30-8ST30 and reference samples KF-8ST10-8AN20-9.5HT30-8ST30 and HP555 were fitted by second-order model well (R2 = 0.995, 0.999 and 0.999). The results showed that BAP-8AN20-9.5HT30-8ST30 was the most rapid adsorbent to arrive at equilibrium, which took only 8 min with a Qe of 0.43 mmol/g.

Adsorption capacity of nitrate from artificial fertilizers and soil on pyrophyllite

The study at hand presents for the first time the use of pyrophyllite as adsorbent for nitrate removal from soil and artificial fertilizers. A series of column and batch adsorption experiments were conducted to examine the effects of the adsorbent’s various parameters, the contact time, pH of the solution, the initial concentration of nitrate, concentration and adsorbent granulometry. Pyrophyllite fractions of 0.25, 0.50 and 1.00 mm had very similar pH values of aqueous suspensions and were in the weakly basic range. Nitrate adsorption capacity on pyrophyllite expressed by recovery factor values ranges from 93.14 to 99.77%. High recovery factor values from 90.44 to 97.45% for 1, 3, 5 and 8 mL min−1 flow rates were obtained using all pyrophyllite fractions. Nitrate removal was very effective by the contact time of 1 and 2 h, and the recovery factor values were in the range of 90.38–91.47% and 92.15–93.18% for a contact time of 1 h and 2 h, respectively. In addition, elution of nitrate from pyrophyllite was performed using the following solution with different pH values: 1.70 (synthetic gastric juice), 6.40 (rainwater), 7.70 (distilled water), 9.30 and 12.50 (NaOH solution). Elution was very low for all used solutions and was the highest at the pH 9.30. The results show that the use of pyrophyllite for removal of nitrate from artificial fertilizers and soil was an adequate approach because it has a high nitrate adsorption capacity, while the nitrate elution from the pyrophyllite was very low.

Adsorption and leaching characteristics of ammonium and nitrate from paddy soil as affected by biochar amendment

Biochar plays a key role in nitrogen cycling, potentially affecting nitrogen adsorption and leaching when applied to soils. The laboratory experiments were conducted to investigate the adsorption characteristics of rice straw biochar (RSBC) to ammonium (NH<sub>4</sub><sup>+</sup>) and nitrate (NO<sub>3</sub><sup>–</sup>) and the influence of RSBC on leaching characteristics of NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>–</sup> at different soil depths using multi-layered soil columns. The results showed that the adsorption characteristics were significantly fitted with Freundlich and Langmuir adsorption isothermal curve models. The Freundlich isotherm model indicated that RSBC has relatively higher adsorption capacity and adsorption intensity to NH<sub>4</sub><sup>+</sup> than NO<sub>3</sub><sup>–</sup>. Moreover, the Langmuir isotherm model showed that the maximum adsorption capacity of RSBC to NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>–</sup> were 31.25 and 10.00 mg/g, respectively. The leaching experiments showed that the contents of NH<sub>4</sub><sup>+</sup> in the leachates from the soil columns showed significant differences at different depths depending on the application amount of RSBC. Compared with CK (0% RSBC amendment), the overall cumulative losses of NH<sub>4</sub><sup>+</sup> via leaching were decreased by 23.3, 35.1 and 13.7% after adding 2, 4 and 6% RSBC, respectively. Correspondingly, the contents of residual soil NH<sub>4</sub><sup>+</sup> in the soil column were increased significantly with the RSBC amendment at different depths. However, the losses of NO<sub>3</sub><sup>–</sup> via leaching from the soil columns could not be retarded obviously by RSBC. Therefore, the application of an appropriate biochar rate is beneficial to retard the losses of soil NH<sub>4</sub><sup>+</sup> from paddy soil.

Reduction of Nitrate Content in Water by the Use of Banana Peels Biochar

The intensification of agricultural, domestic and industrial activities leads to the increasing contamination of groundwater and surface water by nitrates. Indeed, agricultural runoff, septic tank effluents, landfill leachates or wastewater treatment plant effluents contribute to this nitrification, yet drinking water containing high nitrate content can cause health problems. The study examines the improvement of nitrate removal in synthetic water solution by adsorption on banana peel’s activated carbon (BPAC). Different effects of physicochemical parameters, such as the optimal contact time of BPAC in solution, the pH of the nitrate solution, the initial concentration of nitrate solution, the BPAC mass, and the temperature were evaluated. The study revealed that BPAC has a low nitrate adsorption capacity under normal laboratory conditions. However, this adsorption capacity of BPAC increases with increasing of temperature and initial content of nitrate, while it decreases with increasing BPAC mass. For a content of 100 mg/L nitrate solution, the maximum adsorption capacity was 0, 687 mg/g for an equilibrium time of 180 min. Nitrate adsorption is optimal in acidic media (pH=3). The application of kinetic models to the experimental data showed that the mechanism of nitrate adsorption on BPAC obeys pseudo-first order kinetics. The Freundlich isotherm perfectly describes the mechanism of nitrate adsorption on BPAC.

A Green Synthesis of Ru Modified g-C 3 N 4 Nanosheets for Enhanced Photocatalytic Ammonia Synthesis

Nitrate is a crucial environmental pollutant, and its risk on ecosystem keeps increasing. Photocatalytic conversion of nitrate to ammonia can simultaneously achieve the commercialization of environmental hazards and recovery of valuable ammonia, which is green and sustainable for the planet. However, due to the thermodynamic and kinetic energy barriers, photocatalytic nitrate reduction usually involves a higher selectivity of the formation of nitrogen that largely limits the ammonia synthesis activity. In this work, we reported a green and facile synthesis of novel metallic ruthenium particle modified graphitic carbon nitride photocatalysts. Compare with bulk graphitic carbon nitride, the optimal sample had 2.93-fold photocatalytic nitrate reduction to ammonia activity (2.627 mg/h/g cat ), and the NH 3 selectivity increased from 50.77% to 77.9%. According to the experimental and calculated results, the enhanced photocatalytic performance is attributed to the stronger light absorption, nitrate adsorption, and lower energy barrier for the generation of ammonia. This work may provide a facile way to prepare metal modified photocatalysts to achieve highly efficient nitrate reduction to ammonia.

The effects of exhaust gas recirculation on NOx storage pathway

A LNT (lean NOx trap) model coupled with EGR (exhaust gas recirculation) was developed based on the Langmuir–Hinshelwood mechanism to investigate the EGR effects on NOx adsorption pathway of LNT catalysts with temperature changed in range 150℃~550℃. Both the nitrate and nitrite adsorption paths were considered for the NOx storage process in the model as well as the spillover of stored NOx between Ba and Pt sites. The data and validation for modelling were from literatures of predecessors and our previous lean-burn gasoline engine experiment*. The model quantified the contributions of both nitrate route and nitrite route to the NOx storage with change of EGR rate (0%~30%) under raw emission atmosphere from tested gasoline engine. The model captured key feature of different trends of nitrate route and nitrite route with increasing temperature (150℃~550℃) under EGR rate varying from 0% to 25%. The LNT model provided insight of reaction mechanism for interpreting the behaviour of NOx storage with change of GER rate and temperature, which contributed to improve the NOx storage capacity when mapping EGR rate for lean-burn engine and catalyst operation strategy optimization.

Synergy between copper and iron sites inside carbon nanofibers for superior electrocatalytic denitrification.

Developing low-cost electrocatalysts for the nitrate reduction reaction (NO3RR) with superior performance is of great significance for wastewater treatment. Herein, we synthesized bimetal Cu/Fe nanoparticles encased in N-doped carbon nanofibers (Cu/Fe@NCNFs) through simple electrospinning followed by a pyrolysis reduction strategy. Metallic copper is beneficial for reducing nitrate to nitrite, and the existence of Fe is conducive to convert nitrate and nitrite into nitrogen. Additionally, the nitrogen-doped carbon nanofibers also facilitate the adsorption of nitrate, and the continuous and complete fiber structure enhances the stability of the catalyst and prevents the corrosion of the active sites. Therefore, the synergetic effect of bimetal Cu/Fe and N-doped carbon fiber plays a key role in promoting the efficiency of nitrate reduction. The obtained Cu/Fe@NCNF catalyst exhibits a satisfactory nitrate conversion efficiency of 76%, removal capacity of 5686 mg N g-1 Cu/Fe and nitrogen selectivity of 94%.

The ability of layered double hydroxides for nitrate absorption and desorption in crop and fallow rotation

BACKGROUND AND OBJECTIVES: This study aims down to evaluate the ability of chloride magnesium- aluminium- layered double hydroxides (4:1) for nitrate adsorption from the soil solution in successive cropping periods. METHODS: The study was conductedunder long-term cropping periods, including first crop): bell pepper; second crop: mentheae; third crop: cherry tomato; and fort h crop: wheat), absorption of soil mineral nitrate in fallow periods and nitrate absorption from plants by layered double hydroxides. The effect of layered double hydroxides on qualitative and quantitative characteristics of plants was also studied. FINDING: Results indicated that layered double hydroxides were able to induce long-term nitrate exchange in crop and fallow sequences. Layered double hydroxides can adsorb soil excessive nitrates in cropping periods and reduce nitrate concentration in the soil solution. Compared to control, the treatment with 16 gram layered double hydroxide/kilogram soil could reduce nitrate concentration in the soil solution by 95%. During two-week fallow periods, the amount of nitrates mineralized in the soil solution was increased, but layered double hydroxides treatments could adsorb them well and maintained the N-nitrate concentration in the soil solution at a low level. Additionally, Results indicated that application of 2, 4, 8 and 16 gram layered double hydroxides/kilogram soil led to 34%, 44%, 58% and 69% reduction in N-nitrate concentration of soil leachates, respectively, compared to control. By increasing nitrogen availability, layered double hydroxides improved the quantitative and qualitative properties of plants. Application of 2, 4, 8 and 16 gram layered double hydroxides/ kilogram soil increased the plant height (cherry tomato) by 14%, 26%, 50% and 80%, respectively. CONCLUSION: It is concluded that the layered double hydroxides has a potential to be used as a long-term nitrate exchanger to control the movement of nitrate in soil, and thereby reduce risks of nitrate leaching in crop production in sensible areas.

Investigation on the removal of nitrate from water using different types of biosorbents

Eutrophication due to excessive leaching of dissolved nitrogen is a principal cause of water quality degradation. Among different types of removal methods, adsorption is contemporarily deemed favourable due to its simplicity, efficiency and reusability. In this study, six biosorbent candidates, namely rambutan skin (RS), passion fruit skin (PFS), longan seeds (LS), chia seeds (CS), papaya seeds (PS), and luffa (L) were investigated for nitrate removal from water at pH 3.0, room temperature, initial nitrate concentration of 50 mg/L, biosorbent particle size of 425 μm, contact duration of 4 h, shaking speed of 120 rpm, and biosorbent dosage of 0.1 g. Shake flask method was carried out in the adsorption experiments to investigate the effect of heat treatment and acid treatment on the uptake of nitrate from water. The results showed that acid- and heat-treated passion fruit skin biosorbent (biochar, PFSBC) has the best biosorption performance for nitrate uptake of 5.179 mg/g. This biochar possessed high porosity, and abundant surface functional groups for nitrate adsorption.

Removal of nitrate using modified pumice as adsorbent for reducing groundwater pollution

Nitrate adsorption onto the physically and chemically modified pumice was investigated as an effort for reducing groundwater pollution. The treatments were heating at temperatures of 300°C, 450°C, and 600°C for physical and soaking in acid solutions (HCl, H2SO4, and HNO3) for chemical treatments. The adsorption was performed in a batch system at room temperature (25±1°C) with the optimum condition (pH 4; 0.3 g/L of adsorbent dose; <63 µm of adsorbent diameters and 30 minutes of contact time). The results indicated that the physically and chemically modified pumice resulted in increasing removal efficiency and nitrate uptake compared to the natural pumice. The highest removal efficiency and nitrate uptake were achieved from 300°C of heating temperatures (62.04% and 155.09 mg/g) and H2SO4 for the acid solution (83.30% and 208.25 mg/g), while by using the natural pumice only reached 57.02 % and 142.55 mg/g. The SEM images of the modified pumice confirmed the change in the surface morphology of pumice including the pore structure and surface area which can be proper sites for adsorption of pollutants. This study demonstrated that physical and chemical modification could be the potential treatment to increase the removal efficiency and nitrate uptake of the natural pumice, thus can solve the problem of groundwater pollution.

Synthesis of cation exchange resin-supported iron and magnesium oxides/hydroxides composite for nitrate removal in water

In this study, we reported on the concept and practical use of cation exchange resin (CER) for removing anions in water via pretreating the CER with metal salts. The cation exchange resin-supported iron and magnesium oxides/hydroxides composite (Fe-Mg/CER) was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment. Characteristics of Fe-Mg/CER were determined by techniques such as Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The results showed that Fe-Mg/CER material had a high nitrate adsorption capacity of 200 mg NO3−·g−1 with a fast equilibrium adsorption time of 30 min at pH 5. In addition, it had good durability of at least 10 times of regeneration, which could be applied to practical water and wastewater treatment.

Adsorption of nitrate and phosphate in an aqueous solution on composites of PVA and chitosan prepared from a Somanniathelphusa sinensis shell

Abstract In this study, chitosan was prepared from the shell of Somanniathelphusa sinensis, which is a crab ubiquitous in Vietnam. The 3-level, 3-factor Box–Behnken design was applied to the preparation of chitosan to investigate effects of factors such as the HCl solution concentration, protein removal time and deacetylation time on the degree of deacetylation (%DD). Scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and gel permeation chromatography were employed to examine the chitosan structure, as well as pH titration and antibacterial testing of the chitosan solution. Results revealed that as-p chitosan comprises specific functional groups, with almost no impurities. Its average molecular weight was ∼225,000 g/mol, and %DD was ∼89.7%. The chitosan/PVA composite was prepared and investigated for the adsorption of nitrate and phosphate ions in water. Experimental results revealed that the adsorption capacity of a chitosan/PVA (1:2) composite is better than that of chitosan. Accordingly, the theoretical maximum adsorption capacities of nitrate and phosphate ions on chitosan were 122.0 mg/g and 344.8 mg/g, respectively. The corresponding values on the chitosan/PVA (1:2) composite were 135.1 mg/g and 384.6 mg/g. Adsorption kinetics data at 25 °C were well fitted to the pseudo-second-order model (R2 > 0.998). These results revealed that crab shell chitosan and the chitosan/PVA (1:2) composite can be used for the adsorption of nitrates and phosphates in aqueous solutions.

Adsorption of Phosphate and Nitrate Using Modified Spent Coffee Ground and Its Application as an Alternative Nutrient Source for Plant Growth

Phosphate (PO43-) and Nitrate (NO3-) are two main nutrients that cause water eutrophication. In the other hand, the presence of PO43- and NO3- is needed for plant growth. The aims of this study are to recycle Spent Coffee Ground (SCG) modified with calcium hydroxide for adsorption PO43- and NO3-. The optimum adsorption capacity for PO43- and NO3- is 36.74 mg/L and 20.21 mg/L, respectively. The Freundlich isotherm model was suitable for PO43- and NO3- adsorption. The kinetic model for adsorption was linear using Pseudo-second order. The application of modified SCG after enrichment with PO43- and NO3- for plant growth (Raphanus sativus) showed optimum growth at a dose of 0.3% with value of germination index was 203%.

Investigation of Kinetic and Isotherm Models for the Removal of Nitrate and Nitrite Ions on MNPs@PIL Adsorbent from Aqueous Solution

In the previous work synthesis and characterization of magnetic nanoparticles modified with poly ionic liquid and its application in magnetic solid phase extraction of nitrate and nitrite was reported. In the present work, the kinetics of adsorption of nitrate and nitrite on the synthesized adsorbent was investigated by four kinetics models including pseudo first order, pseudo second order, Elovich and Intra particle diffusion models. The rate constants of all these models were calculated. The results showed that, the pseudo second order and the pseudo first order models were suitable to describe the adsorption kinetics of nitrate and nitrite, respectively. Also four isotherm models including Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models were applied to find the best model which fitting the experimental data. The results showed that adsorption of both anions followed Langmuir isotherm model. Equilibrium parameters such as maximum adsorption capacity, adsorption constant and equilibrium concentration were calculated.

Synthesis and characterization of Ce(III) decorated Duolite resin and its removal performance of toxic anions from aqueous solutions

Nitrate and phosphate are major threats for water/ wastewater which grounds eutrophication's and methemoglobinemia diseases, respectively and also severely hazards the safety of aquatic beings and public health's. To deal with the purging of aqueous nitrate and phosphate contamination, a low-cost Ce(III) decorated Duolite A 368 Plus resins (Ce-DA) were used. The influence of various adsorption factors was studied, such as adsorbent dosage, shaking time, pH, initial concentrations of nitrate and phosphate ions, competitive co-ions, isotherms and kinetic studies at different experimental temperatures etc. Ce-DA resin formed complexation with target nitrate and phosphate ions by adsorption via ion exchange and electrostatic attractions. Results from nitrate and phosphate adsorption showed that Ce-DA was greatly pH adjustable with an optimum pH of 3 to 7. The kinetic study revealed the pseudo-second-order and the Langmuir isotherm assessed a maximum adsorption efficiency of 138.67 and 156.26 mg/g for nitrate and phosphate ions respectively, which was higher than unloaded DA resin. The adsorption-desorption operations, demonstrating a great recovering performance of the adsorbent upto five successive cycles. This work highlights the cost-effective method to prepare promising adsorbent for efficient removal of toxic ions nitrate and phosphate from water. • Ce(III) decorated Duolite resins were fabricated and applied for the removal of toxic ions from water. • Electrostatic interaction, ion exchange and complexation are main mechanisms. • Ce-DA resin obeyed for pseudo-second-order kinetic and Freundlich isotherms. • Field studies were opted to analyze the performance of the Ce-DA resin.

Aqueous nitrate ion adsorption/desorption by olive solid waste-based carbon activated using ZnCl2

ZnCl2 activated carbon (ZnCl2-AC, with specific surface area ~1480 m2/g) effectively adsorbs nitrate from water with uptake capacity (~5.5 mg/g) four-fold that for other commercial activated carbons (CACs). Kinetics show a small activation energy value (~7 kJ/mol) consistent with a diffusion-controlled process. This is further confirmed by intra-particle diffusion study. Negative thermodynamic parameters (ΔH° −13.859 kJ/mol, ΔS° −43.8 J/mol K, and ΔG° −0.808 kJ/mol) indicate spontaneous nitrate adsorption. The high specific surface area rationalizes the high uptake capacity for the ZnCl2-AC. A Langmuir type adsorption, is observed. ZnCl2-AC effectively adsorbs the nitrate from water, even at high concentrations, and brings the concentration to allowed maximum values. Despite these advantages, the ZnCl2-AC exhibits low desorption (~20%) of pre-adsorbed nitrate ions into concentrate solutions. Up to ~40% desorption is observed by grinding the pre-saturated ZnCl2-AC. Developing other methods to completely recover the adsorbed nitrate and the adsorbent for multiple use is needed.