Adsorption Capacity Of Zn Research Articles

Synthesis of amidoxime adsorbent prepared by radiation grafting on upcycled low-density polyethylene sheet for removal of heavy metals from wastewater

The issue of discharging waste, especially heavy metals from industrial activities into the environment, not only adversely impacts environmental quality but also has impacts on communities and human health. Removal and reduction of heavy metal contamination in rivers and wastewater are, therefore, critical initiatives that require significant attention. This work studied the removal of heavy metals, including Zn(II), Cu(II), As(III), and Pb(II) by utilizing an upcycled amidoxime low-density polyethylene sheet (AO-sheet). The synthesized AO-sheet was analyzed for various physical properties, including scanning electron microscope, energy-dispersive x-ray spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. For the batch adsorption experiment, parameters affecting adsorption capacity were studied: initial concentration, submerging time, and pH. Adsorption isotherms were also studied. The results of the heavy metal adsorption study showed that the initial concentration was the most significant parameter; the higher the initial concentration, the greater the adsorption capacity. The adsorption capacity of Zn(II) and Pb(II) increased with submersion time, which achieved 21.07 and 0.855 mg/g-adsorbent, respectively, after four weeks of submersion under the highest initial concentration studied. The adsorption capacity of Cu(II) was 7.98 mg/g-adsorbent after two weeks of optimal adsorption duration under the highest initial concentration studied. The adsorption capacity of As(II) was 1.07 mg/g-adsorbent after one week of optimal submersion time under the highest initial concentration studied. Moreover, the appropriate pH range for effective adsorption of Zn(II), Cu(II), and Pb(II) was identified as 8–9, while for As(III), it was 6–8, with an adsorption duration of 0.43 weeks (3 days). From the Langmuir isotherm, it was found that the adsorption of this work was characterized by monolayer adsorption. The results demonstrate that the AO-sheet can be effectively used to remove heavy metals from wastewater. Its potential for reusability was up to 8 cycles, with the Zn(II) adsorption capacity being reduced to about 20.37%.

Understanding Zinc Transport in Estuarine Environments: Insights from Sediment Composition

Sediments are sources and sinks of heavy metals in water, and estuaries are heavily influenced by human production and life. Therefore, it is of great significance to study the composition of estuarine sediments and the relationship between their components to understand the transport and transformation pathways of heavy metals in the environment. In this research, we investigated the characteristics and patterns of Zn adsorption by organic–inorganic composites, organic–clay mineral composites, and iron oxide–clay mineral composites in eight estuarine sediment samples from Dianchi Lake. The results show that both Langmuir and Freundlich isothermal models can describe the adsorption behaviour of the adsorbent better. The order of the adsorption capacity of the three groups of samples for zinc was organic–inorganic composites > organic–clay mineral composites > iron oxide–clay mineral composites. Through FTIR and XRD analyses, the adsorption of Zn2+ on the three groups of samples was dominated by electrostatic attraction and coordination adsorption, accompanied by the occurrence of ion exchange and co-precipitation. After FTIR semi-quantitative analysis, it was found that the source of the differences in the high and low Zn adsorption of the three types of samples may be mainly due to the content of phenolic functional groups in the organic matter. This may be related to the low redox site of the phenolic hydroxyl group, which, as an electron donor, is susceptible to electrostatic attraction and complexation with heavy metal cations. The organic–inorganic composite has a higher adsorption capacity for Zn when the ratio of the active fraction of organic matter to the free iron oxide content is 0.65–0.70. In this range, the organic matter can provide enough negative charge without making the sample surface too dense. Iron oxides can also activate the sample by providing sufficient contact between the clay minerals and the organic matter. When this ratio is too high or too low, it will be unfavourable for Zn adsorption.

Adsorption performance of bentonite and clay for Zn(II) in landfill leachate

BackgroundThe increasing prevalence of the Galvanized and dry battery industries has led to a rise in zinc proportions in landfills, posing environmental risks. This study explores the potential of bentonite, renowned for its metal adsorption capability, as a landfill barrier material.MethodsAdsorption characteristics of Zn(II) in natural bentonite and Shanghai clay were investigated. Various factors affecting Zn(II) adsorption, including pH, Na ion strength, contact time, initial Zn(II) concentration, and adsorption temperature, were analyzed through batch-type adsorption tests.ResultsThe change in pH and Na strength demonstrates no significant impact on the adsorption of Zn(II) onto bentonite, highlighting the strong selectivity of bentonite for Zn(II). Conversely, the equilibrium adsorption capacity of Zn(II) onto clay increases with rising pH or decreasing ion strength. The Zn(II) adsorption onto bentonite is well-described by the pseudo-second-order, intra-particle diffusion, and Elovih models, each achieving an R2 value exceeding 0.9. While both physical and chemical adsorption coexist in Zn(II) adsorption onto bentonite or clay, the primary determinant of the adsorption rate is chemical adsorption. The adsorption onto bentonite is spontaneous, whereas onto clay it is not. The mechanism involves van der Waals forces, ion exchange, and chemical actions such as inner-sphere complexation for Zn(II) adsorption onto both bentonite and clay.

Zinc speciation in highly weathered tropical soils affected by large scale vegetable production

Agriculture in highly weathered tropical soils often requires considerable application of lime and fertilizers to ensure satisfactory plant nutrient levels. The consequences of these continue long-term applications is not well understood may induce changes in soil chemical properties, the abundance, and speciation of potentially toxic trace element and as well as of micronutrients in agriculture soils. In this study, we evaluated the adsorption (at pH 5) and speciation of Zn in tropical soils (both agricultural and native vegetation) as a function of fertilization and contact time using chemical fractionation analyses and X-ray absorption spectroscopy. The soils overall had high Zn adsorption capacities (∼ 700 mg kg-1), but the agricultural soil was approximately 30 % higher than of the soil under native vegetation, and the proportion of Zn in the mobile fraction was 35 % in native vegetation and 21 % in agricultural soils. Zn speciation via linear combination analysis showed a strong relationship with soil mineralogical composition and reveled that Zn associated with organic matter decreased while Zn associated with P increased after the conversion of soils from native vegetation to highly fertilized soil. Aluminosilicate soil minerals were identified as major sinks of soil Zn, accounting for 34 % of total Zn retention regardless of soil origin and land use. Association of Zn with phosphate (i.e., hopeite) was observed in the agricultural soil samples, which might be an unexpected Zn-bearing mineral in highly weathered tropical soils and could have impacts on Zn plant nutrition.

Application of CO2-loaded geopolymer in Zn removal from water: A multi-win strategy for coal fly ash disposal, CO2 emission reduction, and heavy metal-contaminated water treatment

Coal fly ash accumulation, global warming, and heavy metal-contaminated water environments are three primary environmental concerns. Porous geopolymers are economical porous adsorbents that can be produced using coal fly ash as a raw material and employed for heavy metal removal from water. However, residual alkalis on the geopolymer can lead to extreme increases in pH and cause environmental stresses, which limits the large-scale production and application of geopolymers in industries and environments. A green approach to alleviating the high basicity of geopolymers through CO2 exposure is proposed, with CO2 adsorption experiments as well as Zn removal batch and column experiments conducted to evaluate the practicality of the synergistic strategy. CO2 adsorption experiments show the CO2 capture capacity of fresh geopolymer (F@PG) is 0.80 mmol g−1, greater than that of the conventionally washed geopolymer (W@PG, 0.26 mmol g−1), with the pH of the geopolymer decreasing after both washing and CO2 exposure. Batch experiments suggest neither washing nor CO2 exposure cause a significant change in the Zn adsorption capacity of the geopolymer; column experiments show the CO2-exposed geopolymer (C@PG) has a pH < 9.5 and a satisfactory Zn removal performance similar to W@PG, but F@PG with a pH ∼12 results in a conversion of Zn to anionic forms and a decrease in Zn removal efficiency. These results indicate CO2 exposure is a practical method to decrease the pH of geopolymers for applications related to heavy metal-contaminated water treatment and provide a large-scale industrial option for coal fly ash consumption and CO2 emission reduction.

Enhanced termination of zinc and cadmium ions from wastewater employing plain and chitosan-modified mxenes: synthesis, characterization, and adsorption performance

Zinc and cadmium pollutants cause a significant environmental effect that cannot be ignored. Due to their considerable amount in an aqueous environment, industries are seeking suitable adsorbents that are environmentally friendly and inexpensive for removing metals from wastewater before disposing of them in surface waters. This research employed original MXene (MX) and chitosan-modified MXene (CSMX) to extract zinc (Zn(II)) and cadmium (Cd(II)) metal ions from water-based solutions. The composite material produced was analyzed using techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). The effects of contact duration, pH of the solution, and initial concentration of metal ions on the adsorption process of Zn(II) and Cd(II) onto both MX and CSMX composites were investigated. MX and prepared CSMX composite presented a high adsorption capacity for both studied heavy metals, which were 91.55 and 73.82 mg/g for Zn(II) and Cd(II) onto MX, 106.84 and 93.07 mg/g for Cd(II) and Zn(II) onto CSMX composite, respectively. Furthermore, the maximum competitive adsorption capacities for Zn(II) onto MX and CSMX composites are 77.29 and 93.47 mg/g, and for are Cd(II) 60.30 and 79.66 mg/g, respectively. Hence, the removal capacities for both single and competitive metal ions were superior to CSMX composite. However, the adsorption capacities after five successive regeneration sequences were only dropped by 13.2% for Zn(II) and 17.4% for Cd(II) onto the CSMX composite compared to the first cycle. These results confirm that both metals could be efficiently terminated from wastewater, which makes the prepared CSMX composite a favorable candidate adsorbent in practical applications.

A Bifunctional Chitosan/Alginate Nanoparticles (CANPs) for Trace Metals Adsorption as well as Antibacterial Polyelectrolyte Complex (PEC) Materials

Chitosan/Alginate Nanoparticles (CANPs) were produced via microemulsion method. SEM images captured that CANPs has rough, irregular, and porous surfaces. The particle sizes were in the range of 1-15 nm with an average diameter of 8.31 nm. CANPs were applied for trace metals removal. Optimum adsorption capacity of Zn(II) and Cu(II) were 8.144 and 5.582 mg g-1, respectively. Kinetic studies show that the adsorption of Zn(II) and Cu(II) onto CANPs fitted pseudo second order model. Isotherm studies determined that the sorption followed Dubinin-radushkevich model. Zn(II) adsorbed CANPs (Zn/CANPs) and Cu(II) adsorbed CANPs (Cu/CANPs) were investigate their antibacterial activity againts E. coli and S. aureus. Zone of Inhibition (ZOI) of Zn/CANPs were 19.3 mm (E. coli) and 17.5 mm (S. aureus). ZOI of Cu/CANPs were 14.17 mm (E. coli) and 10.75 mm (S. aureus). The results revealed that CANPs were a promising bifunctional material for metals removal and has good antibacterial activity.

Preparation of Activated Boron Nitride and Its Adsorption Characteristics for Zn, Cu, and Cd in Flue Gas.

Developing non-carbon-based adsorbents is essential for removing heavy metals from post-incineration flue gas. In this study, a new high-temperature-resistant adsorbent-activated boron nitride (BN) was prepared using precursors combined with a high-temperature activation method. The adsorption characteristics of BN for Zn, Cu, and Cd in simulated flue gas and sludge incineration flue gas were investigated using gas-phase heavy metal adsorption experiments. The results showed that BN prepared at 1350 °C for 4 h had defect structures, abundant pores, functional groups, and a high specific surface area of 658 m2/g. The adsorption capacity of BN in simulated flue gases decreases with increasing adsorption temperature, whereas it is always higher than that of activated carbon (AC). The total adsorption capacities for Zn, Cu, and Cd were the highest at 50 °C with 48.3 mg/g. BN had strong adsorption selectivity for Zn, with a maximum adsorption capacity of 54.45 mg/g, and its adsorption process occurred mainly on the surface. Cu and Cd inhibited Zn adsorption, leading to a decrease in the Zn adsorption capacity. In sludge incineration flue gas, BN can quickly reach adsorption equilibrium. The BN had a synergistic disposal capacity for heavy metals and fine particulate matter. The maximum adsorption capacity was reduced compared to the simulated flue gas adsorption capacity, which was 5.1 mg/g. However, BN still exhibited a strong adsorption selectivity for Zn, and its adsorption capacity was always greater than that of AC. The rich functional groups and high specific surface area enable BN to physically and chemically double-adsorb heavy metals.

Investigation of performance and mechanism of zinc removal from polluted water by concrete fines derived from aggregate recycling: From problematic byproducts to effective adsorbent

Concrete fines are byproducts produced from aggregate recycling. Because of their properties, they cannot be directly recycled for use in concrete manufacturing, which is problematic to move the cement and concrete industry toward sustainable development goals and reduce its environmental impact. Taking advantage of concrete fines unique properties was regarded as a possible research direction. The hydrated cement fraction was expected to provide alkalinity to neutralize the acidic solutions, while calcium related compounds were expected to provide the function of heavy metals removal. In this research, concrete fines were used to remove Zn from acid mine drainage as an active treatment. The removal performance was comprehensively investigated. The maximum capacity of Zn-adsorption is 111.9 mg/g, and almost 100% Zn can be removed for an initial Zn concentration of 20 mg/L. The dominant reaction mechanism of Zn adsorption to concrete fines was determined to be ion-exchange reaction with surface complexation and precipitation. The Zn2+ ions in solution can exchange with the Ca2+ ions in calcium silicates and calcium silicate hydrates in concrete fines and replace the protons released by ionization of the silanol group for complexation, and thus Zn removal is not limited to an alkaline environment or high initial Zn concentration. The acidity was alkalized by hydration reaction, mainly consuming calcium hydroxide. Based on these mechanisms, concrete fines are effective adsorbent to remove Zn without the need for the synergistic reactions of other metals and for making the aqueous solution strongly alkaline, even in the strongly acidic environments and in effluents with high Zn concentration. Through evaluation and comparison of Zn adsorption capacity with other materials, concrete fines were regarded as promising alternative adsorbent for Zn removal.

Steel slag base geopolymer for efficient removal of Zn and Ni ions from aqueous solutions: Preparation and characterization

Geopolymer was successfully prepared by using the steel slag and sodium hydroxide. The changes in morphology, functional groups, specific surface area and crystal structure during geopolymerization were observed by SEM-EDS, FTIR, BET, XRD, VSM and other techniques. The results showed that the specific surface area of the geopolymer is nearly 3 times higher than that of the steel slag, which enhanced the adsorption capacity of the geopolymer. Steel slag base geopolymer easily achieved the maximum adsorption capacities of Zn (145.43 mg/g) and Ni ions (69.97 mg/g). These findings imply that the steel slag base geopolymer is a promising material for removing Zn and Ni.

Tailored graphene/silica functional composite as signaling and adsorbent material: A sequential excimer probe with a fluoro-switching response with zinc and adenosine triphosphate

Graphene as a sensory platform with luminescent tags faces agglomeration and fluorescence quenching challenges. Therefore, composite materials derived from graphene and mesoporous silica are studied to address the issues with their cooperative actions. However, such materials are rare and are never explored for simultaneous sensing and adsorption studies. Therefore, in this work, a modified approach was made to produce better quality graphene oxide, which was subsequently used for preparing reduced graphene oxide/silica composite (rGOmSiO2) and further functionalized with quinoline-based ligand to create a functional composite (rGOmSiO2@BIQINOL) for specificity. This material shows very selective TURN-ON fluorescence sensing of zinc-ion among various cations and anions through a coordination-driven excimer formation (rGOmSiO2@BIQINOL@Zn). Subsequently, the above Zn-adduct shows a TURN-OFF fluorescence emission with ATP (adenosine triphosphate) via coordination-driven excimer breakdown (rGOmSiO2@BIQINOL@Zn@ATP). A sequential probing of Zn2+ and ATP with a very sensitive limit of detection (27 nM & 157 nM, respectively) was demonstrated. The adsorption studies show high adsorption capacities for Zn (595 mg g−1) and ATP (445 mg g−1) with the material's recyclability. Also, the materials were used precisely for real sample quantification of Zinc & ATP. The simultaneous detection and adsorption of Zn and ATP with material recyclability is advantageous compared to literature reports.

Distinct responses of Chlorella vulgaris upon combined exposure to microplastics and bivalent zinc

Microplastics (MPs) and heavy metals are ubiquitous pollutants in the aquatic environment. In this study, the sorption behavior of two typical MPs (PVC and PE) to bivalent zinc ions (Zn(II)) and their combined toxic effects on Chlorella vulgaris were systemically studied. The growth inhibition rate, the activities of photosynthesis and antioxidant enzymes (SOD and CAT), the cell membrane integrity and the cell apoptosis rate were employed to evaluate the toxicity. Our result showed that PVC and PE have different adsorption capacities for Zn(II), and the combined exposure to Zn(II) and MPs had distinct patterns on the inhibition of the cell growth and induction of oxidative stress. Under our experimental concentrations, PE and Zn(II) showed a synergistic effect, while PVC and Zn(II) exhibited an antagonistic effect. Finally, an action mechanism was proposed to explain the experimental phenomena. This study demonstrated that flow cytometry can be a powerful tool to study the toxic effect of MP composites, and MPs can not only allow a free ride for the water contaminants, but also remarkably alter their toxic effects on phytoplankton. These effects deserve further consideration during evaluation of ecological risks of MPs in the water environment.

Development of the concept of environmentally friendly CHPP and TPP with the active use of photosynthetic processes

The article considers the possibility of applying the concept of a “transition link” from hydrocarbon to “green” energy. The entire world industry uses hydrocarbons as fuel. The share of “green” energy is growing, but it cannot completely replace oil, gas and coal at this stage. In many production processes, due to technology, a significant amount of heat is lost. Thus, the anthropogenic impact is doubled both due to fuel combustion and due to heat losses into the environment. Traditional methods of reducing harmful emissions, as a rule, are focused only on a specific type of treatment and are capital treatment facilities. The authors' approach to the problem differs from the generally accepted one. The developed method makes it possible to obtain an additional product due to waste heat, while reducing emissions of carbon monoxide into the atmosphere. The authors have chosen Combined heat power plant (CHPP), thermal power plant (TPP) as the object of research. Their role as a source of heat, light and hot water supply can hardly be overestimated. But thermal power plants and thermal power plants are also sources of greenhouse gases generated during fuel combustion, sources of heat loss with exhaust gases and thermal pollution of water bodies with cooling liquid. Thermal pollution of water bodies leads to their overgrowth with algae, and as a result, deterioration of water quality. The method presented by the authors is based on the integrated use of waste heat generated in large volumes in algae cooling ponds and the production of bioethanol. Studies were carried out on a mass spectrometer of the chemical composition of algae formed in various media (sea, tap and purified water). During the experiments, legumes were grown on purified water, tap water, and distilled water. According to the calculations, the cost of 1 L of the resulting bioethanol will be about 28 rubles/l, which is 3 times cheaper than what is currently produced. It is concluded that the polluted water of a thermal power plant or thermal power plant has a negligible effect on the bioethanol yield. A 17.8-fold decrease in sodium was shown due to the use of biofilters. During the experiments, legumes were grown on purified water, tap water, and distilled water.The conclusion is made about the significant adsorption capacity of Zn, Mg, Fe, Al, Si, Pb ions. The resulting water after passing through the algae was tested according to SanPiN 2.1.4.1074-01, and fully complied with the standard, which allows it to be used for technological and technical purposes and, moreover, to be returned to the natural environment without consequences.The work is planned within the framework of an international project to create devices and industrial technology that provides for the production of synthesis gas in a fuel processor and hydrogen for generating electrical energy using a fuel cell.

Study on the Pyrolysis and Adsorption Behavior of Activated Carbon Derived from Waste Polyester Textiles with Different Metal Salts.

In this study, the effects of the catalysis of heavy metals on the pyrolysis of waste polyester textiles (WPTs) and the adsorption behaviors of the pyrolysis products of WPTs for Cr(VI) were explored. TG−DTG analysis indicated that the metal ions catalyzed the pyrolysis process by reducing the temperature of the decomposition of WPTs. The surface morphology and pore structure of the carbons were analyzed using SEM and BET. The results demonstrated that Zn−AC possessed the largest specific surface area of 847.87 m2/g. The abundant acidic functional groups on the surface of the activated carbons were proved to be involved in the Cr(VI) adsorption process via FTIR analysis. Cr(VI) adsorption experiments indicated that the adsorption process was more favorable at low pH conditions, and the maximum adsorption capacities of Zn−AC, Fe−AC, and Cu−AC for Cr(VI) were 199.07, 136.25, and 84.47 mg/g, respectively. The FTIR and XPS analyses of the carbons after Cr(VI) adsorption, combined with the adsorption kinetics and isotherm simulations, demonstrated that the adsorption mechanism includes pore filling, an electrostatic effect, a reduction reaction, and complexation. This study showed that metal salts catalyze the pyrolysis processes of WPTs, and the activated carbons derived from waste polyester textiles are promising adsorbents for Cr(VI) removal.

Optimization of coal fly ash-based porous geopolymer synthesis and application for zinc removal from water

Coal fly ash-based porous geopolymer (CFAPG) is a potential adsorbent for heavy metal-contaminated water remediation and can also mitigate the accumulation of coal fly ash from thermal power plants. Production parameters influence the physicochemical properties (e.g., adsorption capacity) of CFAPG. Ten potential factors involved in the CFAPG production process were examined using a Plackett-Burman design (PBD) and then an orthogonal experimental design (OED). The results show the alkali activator modulus (MS), alkali-ash mass ratio (AA), foaming agent-ash mass ratio (FAR), and sodium dodecyl sulfate-ash mass ratio (SDSA) were the most important factors influencing the Zn adsorption capacity of CFAPG. Ternary plots confirm the interaction between these four factors, with the role of FAR being easily masked by other factors and MS being the least influenced by other factors. Furthermore, Zn adsorption on the CFAPG created with optimal parameters was best described by the Bi_Langmuir model, indicating two different sorption site classes on the surface of CFAPG with a total maximum Zn adsorption capacity of 13.42 mg g−1. These results provide key parameters for the production of geopolymers as heavy metal adsorbents.

Comparison of microscopic adsorption characteristics of Zn(II), Pb(II), and Cu(II) on kaolinite

In this research, kaolinite was used to investigate the comparative adsorption of copper, lead, and zinc ions through batch control experiments and first principles calculations. Different adsorption conditions were considered as the effect of solution acidity, initial concentration of ions, and contact shaking time. The adsorption system isotherms and kinetic studies were better agreed with the Langmuir and pseudo-second-order kinetic models. They reached adsorption equilibrium within two hours and maximum adsorption capacities of Zn(II), Pb(II), and Cu(II) on kaolinite were 15.515, 61.523, and 44.659 mg/g, respectively. In addition, the microscopic adsorption changes of Zn(II), Pb(II), and Cu(II) on kaolinite were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The results showed that Zn(II), Pb(II), and Cu(II) were most likely to be adsorbed on the kaolinite surface. Furthermore, the adsorption mechanism of [Zn(OH)]+, [Pb(OH)]+, and [Cu(OH)]+ on the kaolinite (001) surface was systematically studied through first-principles density functional calculations. The adsorption characteristics of different ions were evaluated by calculating the adsorption energy of the equilibrium adsorption configuration, state density, and electron density. The adsorption energy of [Zn(OH)]+, [Pb(OH)]+, and [Cu(OH)]+ were − 0.49, − 1.17, and − 1.64 eV, respectively. The simulation results indicated that new hybrid orbitals were formed between the metal ions and O atoms on the kaolinite surface, with electron transfer occurring the adsorption processes. The charge transfer direction for [Pb(OH)]+ was opposite those for [Zn(OH)]+ and [Cu(OH)]+. [Zn(OH)]+ was more likely to form polydentate complexes with hydroxyl groups on the kaolinite surface than [Cu(OH)]+ and [Pb(OH)]+. This work further elucidated the interaction mechanism between the adsorption systems and provided fundamental theoretical support for the structural modification and optimization of kaolinite, such as increasing the layer spacing of kaolinite and introducing other active groups on its surface to improve the adsorption capacity of heavy metal ions in water treatment and soil remediation.

Biochar-graphene oxide composite is efficient to adsorb and deliver copper and zinc in tropical soil

Highly weathered soils have low micronutrient availability and very low efficiency for most soluble fertilizers . In this article the effect of poultry litter biochar-graphene oxide composite (PLB-GO) as a novel adsorbent for copper (Cu) and zinc (Zn) was evaluated, as well as its fertilizing effects on plant growth, nutrient use efficiency and soil fertility . In order to do so, poultry litter biochar (PLB) and PLB-GO were produced, characterized and evaluated by isotherm adsorption and kinetics studies regarding their Cu and Zn sorption and desorption properties. Cu and Zn loaded on PLB and PLB-GO as biochar-based fertilizers (BBF) were also evaluated. PLB-GO showed 16.2% and 17.7% higher Cu and Zn adsorption capacity , respectively, than pristine PLB, and in both cases <0.5% of the sorbed metal content was released in water. Plant effects on growth and nutrient uptake were, in general, higher or similar to the results obtained for sulfates . The application of PLB increased Cu availability while PLB-GO increased Zn availability after cultivation, even after increasing nutrient uptake and being little soluble in water. Addition of small amounts (≤0.5%) of GO in biochar has potential to increase its properties to retain micronutrients and enhance the fertilizer use effectiveness in highly weathered soils. • Biochar enrichment with graphene oxide increased metals adsorption from 16.2% to 17.7%. • Copper and zinc adsorbed by graphene oxide-biochar showed low water solubility (<0.5%). • Biochar-based micronutrient fertilizer increased grain production from 8% to 17%. • Biochar-based micronutrient fertilizer showed enhanced efficiency in highly weathered soil.

Proposition of critical thresholds for copper and zinc transfer to solution in soils.

Several studies have reported increased copper (Cu) and zinc (Zn) levels in agricultural soils worldwide, mainly due to organic waste and successive leaf fungicide applications in crops. However, the critical transfer thresholds in soils, which can indicate the real risk of environmental contamination and toxicity to plants, remain poorly understood. This study aimed to define the maximum Cu and Zn adsorption capacity (MAC) and threshold (T-Cu and T-Zn) in different soils in Southern Brazil, which present different clay and organic matter (OM) levels. Bw (Oxisol) and A horizon (Inceptisol) samples were used to obtain soils with clay and OM contents ranging from 4 to 70% and from 0.5 to 9.5%, respectively. Cu and Zn adsorption curves were plotted for MAC determination purposes. Based on Cu and Zn MAC values, different concentrations of these elements were applied to the soils for subsequent quantification of available Cu and Zn levels (Mehlich-1 and water). T-Cu in soils with different clay contents ranged from 81 to 595mg Cu kg-1, whereas T-Zn, from 195 to 378mg Zn kg-1. T-Cu in soils with different OM levels ranged from 97 to 667mg Cu kg-1, whereas T-Zn, from 226 to 495mg Zn kg-1. T-Cu can be calculated through the equation: T-Cu = 75 × (%CL0.34) × (%OM0.39), whereas T-Zn: T-Zn = 2.7 × (CL) + 126 (by taking into consideration the clay content) and T-Zn = - 9.3 × (%OM)2 + 92.4 × (%OM) + 66 (by taking into consideration OM content). T-Cu and T-Zn can be used by researchers, inspection bodies, technical assistance institutions, and farmers as safe indicators to monitor the potential for environmental contamination.

Citric and Tartaric Acids Effect on Zn&lt;sup&gt;2+&lt;/sup&gt; Desorption in the Soil around Textile Industry Area-Yogyakarta

Study of physico-chemical properties, adsorption and desorption of Zn using citric acid and tartaric acid on the textile industrial area has been carried out. This study aims to analyze the physico-chemical character of the soil and the content of heavy metals around the textile industry which is suspected of being contaminated by waste, the adsorption isotherm and capacity of Zn, the desorption kinetics of Zn using citric acid and tartaric acid solutions. Soil samples were divided into three sample points based on the location where they were taken, namely sample points I, II and III. The physical and chemical properties of soil were measured, included pH, ash content, electrical conductivity, total organic carbon, cation exchange capacity and content of heavy metals The adsorption capacity was studied by the adsorption of Zn on the soil. Meanwhile, the desorption was studied by using both citric and tartaric acid solution. The results showed that sample I had the highest total organic carbon content of 692.3 mg g-1, and a cation exchange capacity of 42.0 cmol+ kg-1 with a metal content of 735.0 mg kg-1. The maximum adsorption capacity of Zn is 708.7 mg kg-1. The optimum desorption using citric acid occurs at a concentration of 0.6 mol L-1, pH 3 and a time of 7 h, while tartaric acid occurs at a concentration of 0.8 mol L-1, pH 3 and a time of 7 h. Keywords: citric acid, tartaric acid, physico-chemical properties, zinc

Effects of Chelating Surfactants on Competitive Adsorption of Lead and Zinc on Loess Soil

The study of competitive adsorption of heavy metals on soil is important for heavy metals contaminated soil remediation. However, there have been few studies on the impact of desorption reagents on heavy metal adsorption in soil. Batch adsorption studies were used to investigate the competitive adsorption mechanism of two heavy metals, Pb and Zn, on a loess soil in the presence of a new chelating surfactant, sodium N-lauroyl ethylenediamine triacetate (LED3A). Results showed that competitive adsorption equilibria of Pb and Zn were reached at 3 and 10 h, respectively. The maximum equilibrium adsorption capacities were 19.55 and 18.35 g.kg-1, respectively. LED3A affected the competitive adsorption kinetics of Pb and Zn by increasing the change in external mass transfer and reducing the change in internal mass transfer. LED3A reduced Pb and Zn adsorption capacities onto the soil through competitive chelation of the heavy metals. The heavy metal chelating ability of LED3A was higher for Zn than for Pb. When its concentration was larger than 5 g.L-1, LED3A showed a significant effect on the competitive adsorption of Pb and Zn. In the competitive system, the effect of Pb concentration on the Zn adsorption capacity was greater than the effect of Zn concentration on the Pb adsorption capacity. LED3A weakened the effect of Pb concentration and enhanced the effect of Zn concentration. LED3A showed a significant potential for efficiently leaching remediation of Pb and Zn co-contaminated soil.