Types Of Adsorbents Research Articles

Mortality and hyperkalaemia-associated hospitalisation in patients with chronic kidney disease: comparison of sodium zirconium cyclosilicate and sodium/calcium polystyrene sulfonate.

Sodium zirconium cyclosilicate (SZC), a novel drug used for treating hyperkalaemia, is effective in reducing serum potassium levels. The effects of potassium adsorbents on the mortality and hyperkalaemia-associated hospitalisation rates remain unclear. We aimed to examine how mortality and hyperkalaemia-associated hospitalisation rates vary with usage of various potassium adsorbents. This retrospective study used patients' data between April 2008 and August 2021 obtained from a large-scale Japanese medical claims database. Consecutive patients with chronic kidney disease (CKD) prescribed potassium adsorbents were enrolled and divided into three groups according to the adsorbent type [SZC, calcium polystyrene sulfonate (CPS), and sodium polystyrene sulfonate (SPS)] and were observed for 1 year. The primary outcome was a composite of mortality and hyperkalaemia-associated hospitalisation. In total, 234, 54 183, and 18 692 patients were prescribed SZC, CPS, and SPS, respectively. The SZC group showed a higher event-free survival rate than the other two groups. The hazard ratio for the primary outcome in the CPS and SPS groups was similar in the analyses of the subgroups of patients who did not receive renal replacement therapy and those who received haemodialysis. The SZC group had a higher renin-angiotensin-aldosterone system inhibitors (RAASi) continuation rate compared to CPS and SPS groups, the difference being especially significant for SPS. This real-world study demonstrated the therapeutic effect of SZC in reducing mortality and hyperkalaemia-associated hospitalisations. The high RAASi continuation rate in the SZC group might be a contributing factor for improvement of the primary outcome.

Efficient and cost-effective adsorbent brick sand nanoparticles used for removal of heavy metals

ABSTRACT We are introducing cost effective, easily available brick sand nano-particles (BSNP) (44.208 nm) as an adsorbent in batch process for removal of heavy toxic metals such as Pb, Cd, and Cr from aqueous solution. We used two types of adsorbents, one is acid treated BSNP and other one is untreated BSNP, and investigated adsorbent properties with function of contact time, temperature, and pH. The efficiency or performance of adsorbent was characterized by AAS for percentage of removal from solution, EDS for elemental analysis to confirm the metals adsorption. The Langmuir, Freundlich, Temkin, Hill De Boer, Elovich, and Redlich-Peterson adsorption isotherms were studies to find out the quality of the adsorbent. At 5.68 to 7.6 pH, the maximum removal percentages of Pb, Cd, and Cr were 97% from the aqueous solution. The temperatures at 40℃ to 60℃, the Pb, Cd, and Cr experiments were carried out at their highest possible percentages (98%). The reaction process was pseudo-second order model and several thermodynamic factors, including Intraparticle diffusion, Elovich kinetic model, Boyd kinetic model, activation energy, Gibbs free energy, enthalpy change, and entropy change ensured the adsorbent efficiency of brick sand nanoparticles. The results of present research indicated that Brick Sand Nano-Particles (BSNP) may play a vital role as a cost-effective, efficient, and easily available adsorbent for the removal of Pb, Cd, and Cr from wastewater.

Taguchi method for optimization of Cr(VI) removal, isotherm, kinetic and thermodynamic studies

In this study, Taguchi optimization method was applied to determine the optimum operating conditions for batch adsorption of Cr(VI) from aqueous solution. Initial pH of solution, adsorbent dose, initial hexavalent chromium concentration, contact time and adsorbent type were selected as the variables, and the removal efficiency of Cr(VI) was chosen for the designated response. L18(35) orthogonal array, signal-to-noise (S/N) ratio and analysis of variance statistical procedures were applied to identify the effect of each operating parameter on the removal of Cr(VI) from aqueous solution. The signal-to-noise (S/N) ratio results showed that the optimal combination for Cr(VI) removal was at pH 1.0, adsorbent dose of 3.6 g.L−1, Cr(VI) concentration of 30 mg.L−1, contact time of 95 min and olive leaves as adsorbent type. A removal of 95.09% was obtained at these optimum conditions. The analysis of variance of the data revealed that initial pH of solution was the most dominant parameter affecting Cr(VI) removal efficiency, followed by adsorbent type, adsorbent dose, contact time and initial metal concentration. Under optimal conditions, adsorption kinetic of Cr(VI) was studied and modeled using the pseudo first-order, pseudo-second-order and intraparticle diffusion models. It was found that the pseudo-second-order model fitted the adsorption data most with the highest determination coefficient (R2 = 0.996). Freundlich isotherm model, with regression coefficient R2 of 0.953, fit well with the equilibrium isotherm data. The Langmuir maximum adsorption capacity was found to be 62.5 mg.g−1. The experimental values of ΔH°, ΔG° and ΔS° revealed that the adsorption process was spontaneous and endothermic.

Insights about the formation of secondary char during HTC processes

This investigation aims to get insight about the extent of formation of secondary char (SC) during the hydrothermal carbonization (HTC) of lignocellulosic biomass (walnut shell) by introducing a new role on the system; a porous solid able to partially adsorb chemicals from the process water.In this way, the potential migration of the feedstock degradation products from process water was followed along different time conditions at constant temperature, by adding a porous activated carbon (AC) into the HTC reaction media; two types of adsorbents were tested, differing on their pore size distribution. It was found that the addition of AC decreased the adsorption of decomposition products on the primary char, what had a significant effect on its solid yield, decreasing it from the beginning of the process (a decrease of about 30% of final HC mass was observed) and affecting the kinetics and the capture of chemicals on the HC surface.At the same time, AC gained in mass, up to a value neat 40%, which was associated to its saturation, as confirmed by the pore volume characterization of the adsorbent, and also because SC microspheres were found on its surface with increasing number and size for runs performed for longer periods.The physicochemical properties of both HC and ACs, were influenced by the change introduced in the system; these modifications were followed by elemental and calorific value analyses, thermal degradation profiles, surface chemistry analyses by FT-IR spectroscopy, and SEM-EDX imaging.

MXene/Cellulose Hydrogel Composites: Preparation and Adsorption Properties of Pb2.

In this work, acrylic cellulose hydrogel, a typical natural polymer adsorbent, was modified using MXene through in situ polymerization to create a synthetic inorganic-polymer composite known as MXene/cellulose hydrogel. FTIR, XRD, SEM, and thermogravimetric analyses were applied to characterize the chemical structure and micromorphology. The MXene/cellulose hydrogel was utilized for the removal of Pb2+ from wastewater. Under optimal experimental conditions (initial Pb2+ concentration of 0.04 mol/L, adsorption time of 150 min, pH = 5.5, and MXene doping content of 50% at 30 °C), a maximum adsorption capacity of 410.57 mg/g was achieved. The MXene/cellulose hydrogel corresponded with the pseudo-second-order kinetic equation model and exhibited a better fit with the Freundlich isotherm model.

Efficacy of Mg-Al-layered double hydroxide nano-adsorbents for a multi-anionic mixed dye solution

Through this work, we show the efficacy of Mg-Al layered double hydroxide (LDH) as an efficient multi-anionic toxic dye adsorbent. Contrary to typical dye adsorption experiments where a single dye is usually tested for checking the potency of a particular adsorbent, eight different (anionic) dyes (comprising of anionic, reactive, azo, and acid dyes) were blended into one dye solution so that it can closely mimic a wastewater effluent of anionic dyes. With LDH adsorbent, the dye adsorption experiments depicted ∼ 100 % dye removal for all eight individual dye solutions along with the mixed dye solution in just two minutes.

Activated Carbons and Chitosan Adsorbents in Removing Contaminants from Water

Being more and more widely used for a variety of water treatments, chitosan and activated carbons are playing an increasingly significant part nowadays. Activated carbons purify water through the pore structure and adsorb ions or other particles. Chitosan also adsorb a large amount of metallic ions and purifies water through the reactions by the functional groups. This paper discusses the different features of the two substances and then gives a comparison between the two types of adsorbents by comparing their characteristics, conditions and applications. Specifically, the suitable temperatures, the specific modifications and solubility are discussed, together with other factors. The difference in their physical and chemical properties plays an important role in the comparison. For physical properties, the activated carbons have strong mechanical strength and are soluble in many types of solvents. By contrast, chitosan is generally soluble in an acidic solution. There are also some differences in the adsorption abilities and ways to purify solutions. Next, chitosan is more easily dissolved in solution with low PH and at room temperature. However, the activated carbons require lower PH and lower temperature to be dissolved. Then, activated carbons are more likely to cause secondary pollution due to the impurities in the activated carbons. The two substances require different modifications to increase the rate of adsorption. As a result, the firms should consider the features of the two types of adsorbents and choose the better one. They should also understand the suitable conditions for each adsorbent.

A Prussian blue analog-based copper-aluminum layered double hydroxide for cesium removal from water: fabrication, density functional theory-based molecular modeling, and the adsorption mechanism.

A new type of adsorbent, a Prussian blue analog-based copper-aluminum layered double hydroxide (PBA@CuAl-LDH), was successfully synthesized using a one-step method for the removal of radioactive Cs+ from wastewater. The adsorption performance, characteristics and the underlying adsorption mechanism of PBA@CuAl-LDH were systematically examined. The results showed that PBA@CuAl-LDH exhibited excellent adsorption performance, with a maximum adsorption capacity of 109.2 mg g-1. Over 85% of PBA@CuAl-LDH can be recycled, and the material exhibited only a 6.6% loss in adsorption performance. The adsorption process was well-fitted using the pseudo-second-order kinetic model and the Freundlich isotherm model, revealing the surface heterogeneity of the composite adsorbent. A molecular model of PBA@CuAl-LDH was constructed by combining density functional theory and multiple instrumental characterization techniques. Our results indicate that PBA crystals can be generated between layers and on the surface. Ion exchange was revealed as the main adsorption mechanism of Cs+ by PBA@CuAl-LDH. Specifically, the interstitial spaces of the PBA crystals generated between the layers and on the surface played an important role in ion exchange. These findings provide concrete theoretical support for radioactive pollution control and have significant value in directing the fabrication of cesium removal materials and their future engineering application.

Cellulose acetate/metal-organic framework composite beads with macroporous adsorption channels as a novel hemoadsorbent for effective virus capture.

Due to their rapid spread, high variability, and drug-resistant strains, new viral infections are continuously emerging. A lack of effective antiviral drugs and vaccines, resulting in disease and death, has significant socioeconomic consequences. Hemoperfusion can effectively adsorb and remove toxins from the blood, thus purifying the blood and serving as an acute treatment. Therefore, the aim of this study was to construct adsorbents to selectively remove viruses from the blood to quickly treat pathogen infection. We reported on new metal-organic framework (MOF)-polymer beads based on MIL-53(Al) and cellulose acetate (CNC), which were prepared by a one-step phase inversion method and applied as a viral hemo-adsorbent for the first time. The characterization results demonstrated that MIL-53(Al) was well dispersed in the CNC matrix. The adsorption results demonstrated that the capture efficiency of the human immunodeficiency virus (HIV) could exceed 99.93%, and the corresponding infectious titer decreased by approximately 103 times in clinical application. Moreover, CNC/MIL-53 exhibited low hemolysis ratios and good anticoagulant properties. Furthermore, molecular dynamics simulations revealed that the interplay of hydrogen bonding was the governing physisorption mechanism. Overall, CNC/MIL-53 could serve as a new type of hemoperfusion adsorbent for virus removal from blood and provide a new treatment pathway to mitigate epidemics.

Progress of research on purification of CH4 from a CH4/CO2/N2 mixture by pressure swing adsorption

This review primarily addresses the types of adsorbents, molecular simulation, and process optimization involved in the purification of CH4 by variable pressure adsorption.

Removal of lead from aqueous solution using modified dewatered sewage sludge as adsorbent

The increasing demand for clean water also increases sewage and its sludge by-products. Current challenges of disposing and treating sewage sludge necessitates the development and modification of the material into valuables. The composition and structure of sewage sludge give it the potential to be used as an adsorbent for heavy metal ions removal. This study investigated the performance of three different types of dewatered sludge-based adsorbents prepared with varying methods of activation, consisting of CS (carbonized sludge at 600 oC), CS-NaOH (CS activated with NaOH), and CS-KOH (CS activated with KOH) to remove lead (Pb) from aqueous solution. Adsorption experiments were carried out using synthetic Pb wastewater in a batch system. Several experimental parameters were evaluated, including adsorbent types, contact time, adsorbent dose, pollutant concentration, pH, and competing adsorbates. Adsorption data were analysed using isotherms and kinetics model equations and were found to fit Langmuir and pseudo-second-order models, which suggests that the adsorptive behaviour of CS-NaOH is monolayer chemical sorption and depends on the active surface sites. The study revealed that the highest Pb removal, achieving a 100% removal efficiency, was observed with CS-NaOH adsorbent dose of 1 g/L, initial Pb (II) concentration of 10 mg/L, and a contact time of 120 minutes at pH 6. The presence of cadmium (Cd) and methyl orange (MO) in synthetic wastewater inhibited Pb(II) adsorption efficiency using CS-NaOH, which indicates potential competition between adsorbates. In conclusion, CS-NaOH was revealed as a promising adsorbent for lead removal from water.

Development of new effective activated carbon supported alkaline adsorbent used for removal phenolic compounds

Phenolic (phenol) compounds are the major contaminates in wastewater, which can have a considerable negative influence on the environment and health of human. Adsorption is an efficient process that is widely applied in order to eliminate phenol in wastewater. In recent, Adsorption process has acquired a lot of attentiveness owing to its relative moderate operating conditions. However, adsorption process needs considerable ameliorations in terms of adsorbent modification, process type, productivity, and conversion rate. This work studies the development of a fast and effective adsorption process in a fixed bed adsorption column (FBAC) in order to reach safe and continuous elimination of phenolic compounds. Several adsorption parameters (reaction temperature, adsorbent bed height, feed flow rate and kind of adsorbent) were studied to achieve the highest removal of phenolic compounds. The adsorption process was conducted in the presence of two type of adsorbents (activated carbon (AC), and KOH/AC), 73% and 94% of phenol elimination were attained, respectively, at 10 cm bed height, 1 ml/s feed flow rate, and 75 °C reaction temperature. The adsorbents activity was investigated after six consecutive adsorption cycles at the best process conditions, and the adsorbents show high stability in terms of phenolic compounds adsorption. After that, the spent adsorbents were regenerated by utilizing various solvents (methanol, ethanol and iso-octane), and the results show that iso- octane achieved highest regeneration efficiency. The adsorption process was implemented in the adsorption column that the performance is possibly to be adjusted at an industrial scale since it can be scaled up predictably.

Sorption of methylene orange on biocarbon sorbent, obtained by pyroly-sis of wastewater sludge

Water pollution and deterioration of air and water quality is a rapidly growing problem directly related to the generation of waste water and the accumulation of significant amounts of wastewater sludge (WWS). One of the methods for recycling WWS is their pyrolytic processing into biochar adsorbents for purification from various pollutants. The type of adsorbent and its properties play a key role in the efficiency of the purification process, which explains the relevance of the search for alternative materials for water treatment processes. The purpose of the study was to create a biocarbon sorbent during the pyrolysis of wastewater sludge and determine its sorption capacity for the methylene orange dye. To obtain samples of biocarbon sorbent, dried and crushed samples of wastewater sludge were exposed to a temperature of 500 °C for 1.5 hours in a vacuum chamber with a heating rate to a given temperature of 5°C/min. Elemental analysis of the resulting sorbent allowed to establish a decrease in the content of carbon, oxygen, and sulphur: for C by 2.50 at.%, for O by 9.91 at.%, for S by 0.4 at.%, relative to WWS. Scanning electron microscopy confirmed a significant reduction in the particle size of biochar compared to the original WWS sample. In the initial WWS sample, after the sample preparation stage, the dispersion of particle sizes was 10-70 µm, and after pyrolysis of the sediment, the dispersion decreased to the range of 10-45 µm. The percentage of biochar yield was calculated, constituting 42% of the weight of the initial WWS and studies on the sorption of methylene orange were carried out. The sorption capacity of biochar for the anionic dye methylene orange after 120 min of sorption was 4.9 mg/g, the degree of solution purification reached 82%. The kinetics of dye sorption was correctly described by a pseudo-second-order equation and indicated the polymolecular nature of sorption.

Efficient removal of aqueous Pb(II) ions by magnetic alginate composite microcapsules containing canola straw‐derived biochar as the reinforcing fillers

AbstractWith the rapid development of industry, water pollution caused by lead has caused great harm to human health. In this study, alginate is used as a base and blended with biochar to form calcium alginate hydrogel beads with high mechanical properties through ionic cross‐linking. Besides, the material (BC/MCAC) is prepared by the material (C‐γ‐Fe2O3) as a magnetizing agent and to remove lead. Then, a series of batch experiments and material characterizations are performed to evaluate the adsorption process of the material. The results show that the maximum adsorption capacity of BC/MCAC to Pb(II) is 211.6 mg g−1 at pH = 7. The adsorption process is well described by the Langmuir adsorption isotherm and pseudo‐second‐order kinetic model. This indicates that the lead adsorbed by BC/MCAC is a monolayer chemisorption that occurs on a uniform surface. After three regeneration cycles, BC/MCAC is found to retain 82.37% of the lead adsorption capacity and has good regeneration ability. Lead is removed by BC/MCAC mainly through the complexation of oxygen‐containing functional groups, electrostatic interaction, and ion exchange. BC/MCAC allows for more sustainable use of the wastes and is expected to be a new type of lead adsorbent for industrial wastewater.

Exploration adsorption characteristics of zeolite 13X depending on humidity and flow rate in sorption thermal energy storage applications

Sorption thermal energy storage (STES) systems utilizing zeolite 13X present a promising solution to pressing global energy challenges. In this study, we explore the influence of absolute humidity and flow rate on the heat release process within a STES system, with a focus on local and overall performance considering temperature profile, degree of adsorption reaction, and average thermal power. A numerical model has been developed to investigate the adsorption kinetics of zeolite 13X and water, which is validated through experiments on pressure drop and transient temperature changes. In this study, we introduce P(%), a novel factor providing a holistic perspective of the adsorption process throughout the reactor. Through the analysis of P(%), we elucidate the link between the adsorption reaction, local heat transfer characteristics, and average thermal power within the reactor. Our findings reveal that increasing absolute humidity and flow rate accelerates the adsorption reaction of zeolite, leading to reduced discharge time. Our findings indicate that the adsorption reaction rate significantly decreases when P(%) approaches 95%. It is noteworthy, however, that the specific threshold of P(%) can vary based on the adsorbent type or reactor design. Despite this, P(%) can be utilized as a factor to establish the criteria for optimal control of STES. This research provides a guideline for optimum operational control and reactor design of STES systems.

Sintering study of digital light process printed zeolite by positron, thermogravimetric and x-ray techniques

This study examined the sintering of digital light process (DLP)-printed zeolite 13X with two different phyllosilicate binders—bentonite and kaolin. DLP printing offers the potential for developing a robust additively manufactured zeolite structure that can improve upon typical adsorption column configurations by employing additively manufactured triply periodic minimal surface (TPMS) structures. Zeolite 13X is a crystalline alumina silicate material with applications in pressure swing adsorption (PSA) for CO2 and N2 gas refinement and for adsorption cooling systems. The present study developed a process to fabricate zeolite parts by DLP printing where the TPMS structures were found to hold together much better than the printed discs. Thermogravimetric analysis was used to develop debinding and sintering curves and x-ray diffraction was performed to confirm the crystalline structure of the zeolite was preserved. The micropore structure and distribution were characterized with positron annihilation lifetime spectroscopy (PALS) to investigate the effects of sintering on pore size and density. From the PALS analysis, it is concluded that DLP printing produces samples with a high surface area; however, the sintering process destroys a regular nanostructure into less regular, less crystalline, and more amorphous structure pores, which is visible by more trapping and less positronium formation with sintering in the PALS parameters.

A method for the efficient removal of Pb(II) by D001 resin in a rotating packed bed

The treatment of Pb(II) is a challenging problem. In this study, a new approach for removal of Pb(II) using D001 resin in a rotating packed bed (RPB) is proposed, and the adsorption behaviors and mechanisms are investigated. The results reveal that under optimal conditions (initial Pb(II) concentration c0 = 100 mg L−1, high-gravity factor β = 36.33, liquid flow rate QL = 60 L h−1, initial solution pH = 5.0, and temperature T = 303 K), the removal rate of Pb(II) in RPB is 95.54 % at 120 min, which is 12.18 % and 9.81 % higher than that in thermostatic shaker (TS) and stirred tank reactor (STR). The adsorption of Pb(II) by D001 resin can be well described by the Langmuir adsorption isotherm and the adsorption heat is 13.24 kJ mol−1, and it is a typical monomolecular layer adsorption. It is also found that the adsorption mechanism of Pb(II) by D001 resin in RPB follows the pseudo-first-order kinetics, and the rate constant k1 is 1.72 and 1.64 times that in TS and STR. The R-SO3Na is the dominant group and Na+ undergoes ion exchange with Pb (II) on the surface of D001 resin. This study provides a new method for the treatment of Pb(II).

Insights into chromium removal mechanism by Ca-based sorbents from flue gas

Chromium is a typical toxic pollution in sewage sludge incineration flue gas. Cr removal from flue gas is a challenge due to the high toxicity and valence variability of chromium. Ca-based sorbents, including CG-CaO, CA-CaO, and CCi-CaO, were developed for Cr capture by calcining calcium D-gluconate monohydrate, calcium acetate hydrate, and calcium citrate tetrahydrate, respectively. CG-CaO, CA-CaO, and CCi-CaO exhibit better Cr removal performance than traditional CaO. CA-CaO shows superior Cr adsorption ability due to the large BET surface area and pore volume. The Cr adsorption efficiency of CA-CaO is up to 94.79 % at 1000 °C. XRD and XPS results reveal that the adsorbed Cr contains Cr(III) and Cr(VI), and exists in the form of CaCr2O4 and CaCrO4. Cr adsorption on Ca-based sorbents is mainly controlled by adsorption and oxidation mechanism. The adsorption process of Cr on different Ca-based sorbents was described by four typical adsorption kinetic models. For CaO and CG-CaO, pseudo-first order model and Elovich model are suitable for the description of Cr adsorption. For CA-CaO and CCi-CaO, pseudo-second order model, Elovich model and Weber and Morris model fit well with the experimental values of Cr adsorption, suggesting that Cr adsorption on CA-CaO and CCi-CaO is controlled by a combined mechanism of chemisorption and intraparticle diffusion. The saturated adsorption capacity of CaO, CG-CaO, CA-CaO and CCi-CaO are evaluated to be 39.77, 48.98, 102.22 and 104.52 mg/g, respectively. The effects of incineration flue gas components on Cr adsorption were also explored. O2 shows no obvious influence on Cr adsorption over CA-CaO. HCl, SO2, NO and CO2 can inhibit Cr adsorption because of the competitive adsorption, and the inhibitory effect of SO2 is the strongest.

Surface Characterization of the Adsorbent Derived from Activated East Kalimantan’s Low Rank Coal (LRC) Yuli Patmawati

Adsorption process has several applications today particularly for the treatment of wastewater. Consequently, the creation and enhancement of adsorbent materials is an important subject of research. When a novel adsorbent is offered, adequate material properties is necessary to understand its characteristics, encourage the utilization of it as well as comprehend Its effectiveness in the intended technique. The objective of this inquiry is to figure out the structure and surface area of the adsorbent derived from East Kalimantan’s activated LRC utilizing Brunauer Emmett Teller (BET) analyses. Before conducting BET analysis, the adsorbent is degassed and vacuumed. After that, it gets exposed to N2 gas at constant temperature of 77 Kelvin. From this paper reported an adsorbent derived from East Kalimantan's activated LRC has surface areas of 321.26 m2/g, many micropores with the average pore size of 1.41 nm and 0.23 cm3/g total volume of pore. Furthermore, based upon the isotherms of N2 gas adsorption and desorption, the adsorbent derived from East Kalimantan's activated low rank coal follows a combination of IUPAC types I and IV. It possesses microporous and mesoporous characteristics, as well as monolayer and multilayer adsorption processes. Identifying the surface characteristics of the adsorbent makes it feasible to evaluate the effectiveness of utilizing the adsorbent derived from East Kalimantan’s activated LRC in the adsorption process as compared to different types of adsorbents.

Graphene quantum dots based fluorescent biosensor for nitrogen detection of urea fertilizer

A simple and fast fabrication of fluorescent biosensor based on graphene quantum dots (GQDs) for agricultural application is presented. Graphene oxide was used as a starting material for GQDs synthesis by hydrothermal method. Optical properties and morphology of the synthesized GQDs were characterized by UV-Vis, photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM). The results showed that the synthesized GQDs exhibited spherical shape with their average diameter of 5.70 nm. The UV-Vis and PL spectra showed typical adsorption peak and maximum emission peak of the synthesized GQDs at 330 nm and 472 nm, respectively. To study sensing performance of fluorescent biosensor for nitrogen detection, aqueous solution of GQDs was mixed with different concentrations of nitrogen solution. According to PL spectra result, it is found that PL intensity of GQDs solution significantly increased corresponding to higher concentrations of nitrogen solution. This result suggests that fluorescent biosensor based on GQDs may be an alternative technique for primary nutrient detection in soils.