Cadmium Sorption Research Articles

Applicability of disulfide-polymer particles surface embedded on alginate beads for cadmium removal from airport derived stormwater

Stormwater runoff derived from airports causes severe cadmium contamination in excess of the maximum limit level and is difficult to treat due to the irregular contamination levels from scattered rainfall. To overcome this and remove cadmium from runoff, a new reactive filtration column is introduced. Sulfur functionalized polymer particles were successfully embedded onto the surface of alginate bead (DiS-algi) and simulated a real stormwater treatment filtration column. The DiS-algi shows 22.3 mg/g of batch and 877 μg/g of continuous flow sorption capacity. Also, the results for the new sorption material show that within 6 mins half of the cadmium was removed with 31 L/mg of Langmuir sorption affinity, outperforming an activated carbon filter. From a breakthrough test the reactive column shows complete uptake of cadmium from a contaminated flow, lasting two hours until reaching the breakthrough point. Furthermore, regeneration tests of the column verified its reusability. DiS-algi appears to be a viable new cadmium sorption material for airport derived stormwater runoff filtration systems.

Cadmium sorption and extractability in tropical soils with variable charge.

The availability of cadmium (Cd) for plants and its impact in the environment depends on Cd sorption in soil colloids. The study of Cd sorption in soil and its fractionation is an interesting tool for the evaluation of Cd affinity with soil pools. The objective with this study was to evaluate Cd sorption and desorption in tropical soils with variable charge (three Oxisols), in a Mollisol and in two Entisols with diverse physical, chemical, and mineralogical attributes. We used a thermodynamic approach to evaluate Cd sorption and performed a chemical fractionation of Cd in the six soils. Data from Cd sorption fit the Langmuir model (r > 0.94), and the sorption capacity ranged from 0.33 to 11.5mmolkg-1. The Gibbs standard free energy was positively correlated to Cd sorption capacity (r = 0.74, except for the Quartzipsamments), and it was more favorable in soils with great sorption capacity. Distribution of Cd among fractions was not affected (t test, α = 0.05) by initial concentration, and there was a predominance of Cd extractable in 0.1molL-1 CaCl2.

Effects of chemical oxidation on surface oxygen-containing functional groups and adsorption behavior of biochar

Biochar is a beneficial soil amendment but the changes in its surface properties during the aging process, especially the oxygen-containing functional groups and the associated adsorption behaviors, are not well documented. In this paper, the aged wheat straw biochar was simulated by chemical oxidation with HNO3-H2SO4 and NaOH-H2O2 systems. Characterization results showed that carbon loss and oxygen incorporation ran throughout the aging process. Surface oxygen-containing functional groups were found to be increased in all treated biochars, especially for carboxyl. Much more developed mesopores were observed in aging biochar, specific surface area was increased by 126% for biochar treated with NaOH-H2O2, and 226% for biochar treated with 40% of HNO3-H2SO4. Thermogravimetric analysis showed that the increasing oxygen-containing functional groups led to 14% and 30% mass loss by treating biochar with alkali and acid, respectively. The improved biochar surface through the increase of oxygen-containing functional groups enhanced the cadmium sorption capacity, and the sorption capacity increased by 21.2% in maximum. Roughed surface from oxidation was another reason for increasing cadmium adsorption. Results indicated that the adsorption performance of biochar on pollutant would be changed during aging process along with the changing surface properties.

CONCENTRATION OF THORIUM (IV) BY CHELATING SORBENT

The paper analyses complexation of thorium(IV) with 2,3,4-trihydroxy-4’-fluoroazobenzene. A complex is formed immediately after mixing the components. Their molar ratio (1:2) was established using the methods of Starik–Barbanel relative yield, equilibrium shift and isomolar series. The maximum light absorption of the complex is observed at 440 nm, with the molar absorption coefficient being equal to 1.80×10 4 . In this work, we synthesised a new sorbent containing fragments of para-aminosalicylic acid. Identification of sorbents was carried out using IR spectroscopy. Sorption was studied in static and dynamic modes. The optimal conditions for concentration were investigated. The magnitude of the sorption and the degree of metal extraction was calculated from its residual concentration in the solution using a spectrophotometric method. Our results show that the maximum sorption is observed at pH = 4. In the course of preliminary kinetic experiments, it was found that the maximum sorption of cadmium is attained within 2 hours, remaining practically at the same level thereafter. The effect of the ionic strength of the solution was studied using the photometric method. Thorium(IV) was sorbed from solutions having an ionic strength of 0.1–1.4. It is shown that a significant decrease in the sorption of thorium(IV) occurs in solutions with an ionic strength of more than 0.2 M. The effect of metal concentration on sorption was also investigated. An isotherm of thorium sorption by the synthesised sorbent was constructed. An increased concentration of thorium(IV) in the solution leads to an increase in the amount of sorbed metal, with the maximum concentration being reached at 1856 mg/l. We also studied the effect of various acids (HClО 4 , H2SО 4 , HNО 3 , HCl) on the desorption of thorium(IV) from the sorbent: thorium(IV) was quantitatively desorbed by 2 M nitric acid. The degree of extraction of thorium ions (IV) under optimal conditions exceeds 95%. The study has revealed the possibility of using the matrix of a copolymer of maleic anhydride and styrene modified by para-aminosalicylic acid for sorption-photometric determination of thorium(IV). Following regeneration, this sorbent can be reused.

Cadmium removal from aqueous solution by low-cost native and surface modified Sorghum x drummondii (Sudangrass)

In an attempt to find inexpensive and effective biosorbents and modification methods, cadmium sorption ability of native Sorghum x drummondii, commonly called sudangrass, and its modified biomass was studied for the first time. From several modified biosorbents, 0.05 M NaOH-modified sudangrass performed the best and hence was used for further experiments. Both sorbents were characterized and various parameters were investigated on their sorption performance. Equilibrium time was reduced from 90 to 20 min after modification. Intra-particle diffusion and pseudo-second order kinetic models were found as best-fitting models for sudangrass and NaOH-modified sudangrass, respectively. Langmuir isotherm model described equilibrium data with the highest accuracy. Maximum monolayer adsorption capacity of cadmium onto sudangrass and NaOH-modified sudangrass was obtained as 1.52 and 7.76 mg g−1, respectively, showing a five-fold improvement for cadmium sorption. Sorption mechanism and thermodynamic investigations suggested that cadmium removal by modified sudangrass is a chemisorption and endothermic process, while cadmium removal by sudangrass is predominantly physisorption and exothermic. This study indicated that both native and modified sudangrass sorbents are capable of removing cadmium ions from aqueous solution with modified biosorbent having a much higher potential for this application.

Effect of feed source and pyrolysis conditions on properties and metal sorption by sugarcane biochar

Abstract Sugarcane biomass from different feed sources of sugar mill operation were used in producing biochar at different temperatures (350, 500, 650, and 800 °C) with/out steam activation at 800 °C. Feed sources included fresh cane-trash, fresh bagasse, and old bagasse collected from a pile left outside the plant for several years. Biochar yield and composition were determined and metal sorption capacity evaluated. Pyrolysis more than doubled biochar ash content which was 2 to 3 times higher for fresh cane trash and old bagasse than for fresh bagasse biochars. On the other hand, surface area of fresh bagasse activated biochars (493 m2 g−1) nearly doubled that of the old bagasse (262 m2 g−1), or fresh cane trash (204 m2 g−1) biochars. Cadmium sorption capacity increased upon activation and was an order of magnitude higher for old bagasse biochars than for fresh bagasse or fresh cane trash biochars across production temperatures (ranging from 43.4 mg g−1 to 63.8 mg g−1 compared to 0.35 mg g−1 to 0.47 mg g−1, or 4.35 mg g−1 to 6.29 mg g−1, respectively). Maximum sorption capacity for Cd and Cu was highly correlated with biochar ash content, while that of Pb correlated with biochar surface area and total sulfur content. Cu sorption capacity inversely correlated with O/C ratio and reduced significantly upon acid washing of activated 500 °C old bagasse biochar (from 32.2 mg g−1 to 14.3 mg g−1). Ash content seemed to play a decisive role in metal sorption capacity of sugarcane bagasse biochars. Overall, old sugarcane bagasse feedstock demonstrated best performance in producing biochars of higher metal sorption capacity compared to fresh cane-trash or fresh bagasse.

Derived and thiourea-functionalized silica for cadmium removal: isotherm, kinetic and thermodynamic studies

The present study explored the feasibility of using derived and thiourea-functionalized silica as adsorbent for the removal of cadmium under different experimental conditions. Effects of various parameters such as function of point of zero charge (pHPZC), solution pH, sorbent-sorbate resident time and ratio, concentration and temperature were investigated. The sorption of cadmium followed the pseudo-second-order rate kinetics. Thermodynamic studies revealed that the sorption of cadmium was endothermic and spontaneous, with good affinity toward the sorbent. Various isotherm models, viz. Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Harkins–Jura, and Halsey isotherms were used to analyze the equilibrium data at different temperatures. The Freundlich, Halsey, Langmuir, and Temkin models were found to be in good agreement with the experimental data with high R2, low RMSE, and low χ2 values. The results show that the sorption capacity increases with an increase in solution temperature from 28 to 65 °C. The maximum sorption capacity calculated from Langmuir isotherm was 27.55 and 28.41 mg g−1 for derived and thiourea-functionalized silica, respectively, at optimum condition of pH 5 and contact time of 120 min.

Metal sorption to Spodosol Bs horizons: Organic matter complexes predominate

While metal sorption mechanisms have been studied extensively for soil surface horizons, little information exists for subsoils, for example Spodosol Bs horizons. Here the sorption of cadmium(II), copper(II) and lead(II) to seven Bs horizons from five sites was studied. Extended X-ray absorption fine structure (EXAFS) spectroscopy showed that cadmium(II) and lead(II) were bound as inner-sphere complexes to organic matter. Addition of o-phosphate (to 1 μmol l−1) did not result in any significant enhancement of metal sorption, nor did it influence EXAFS speciation. An assemblage model using the SHM and CD-MUSIC models overestimated metal sorption for six out of seven soil samples. To agree with experimental results, substantial decreases (up to 8-fold) had to be made for the fraction ‘active organic matter’, fHS, while the point-of-zero charge (PZC) of ferrihydrite had to be increased. The largest decreases of fHS were found for the soils with the lowest ratio of pyrophosphate-to oxalate-extractable Al (Alpyp/Alox), suggesting that in these soils, humic and fulvic acids were to a large extent inaccessible for metal sorption. The low reactivity of ferrihydrite towards lead(II) can be explained by potential spillover effects from co-existing allophane, but other factors such as ferrihydrite crystallisation could not be ruled out. In conclusion, organic matter was the predominant sorbent for cadmium(II), copper(II) and lead(II). However, for lead(II) the optimised model suggests additional, but minor, contributions from Fe (hydr)oxide surface complexes. These results will be important to correctly model metal sorption in spodic materials.

Correction to: Biosolids application affects the competitive sorption and lability of cadmium, copper, nickel, lead, and zinc in fluvial and calcareous soils.

Unfortunately, in the original publication of the article, Prof. Yong Sik Ok's affiliation was incorrectly published.

Starch coated titanium dioxide nanoparticles as a challenging sorbent to separate and preconcentrate some heavy metals using graphite furnace atomic absorption spectrometry

ABSTRACTIn this study, a challenging nanosorbent was described for preconcentration/separation method based on the sorption of cadmium, cobalt, copper, nickel, lead on starch coated titanium dioxide nanoparticles and its analysis by graphite furnace atomic absorption spectrometry. Optimum conditions were investigated for quantitative sorption. By using the proposed technique, the analyte elements were determined in spiked tap-water samples in the range of 95% confidence level. Limit of detection (3δ) was 0.05, 0.28, 1.90, 3.10 and 0.11 µg/L (3σ, N = 10) for cadmium, cobalt, copper, nickel and lead, respectively. The optimised technique is fast, easy handled, simple and environmental friendly.

The kinetics of cadmium sorption by polyelectrolyte-coated fly ash from aqueous solution

The kinetics of cadmium sorption by polyelectrolyte-coated fly ash from aqueous solution

Simultaneous control of cadmium release and acidic pH neutralization in excavated sedimentary rock with concurrent oxidation of pyrite using steel slag

The aim of this study was to determine whether steel slag potentially could be utilized as an amendment for the reuse of excavated sedimentary rock naturally containing pyrite and the toxic metal cadmium. For this purpose, this study elucidated the mechanisms for simultaneous pH neutralization and cadmium immobilization of excavated sedimentary rock using steel slag under conditions of concurrent pyrite oxidation. A batch leaching test was conducted using excavated sedimentary rock (mudstone) that was well mixed with steel slag in combinations ranging from 0 to 50 %wt to evaluate the relationship between the dosage of steel slag and both cadmium release and the pH value after 30 days of the treated rock. Another batch leaching test was performed using excavated sedimentary rock combined with steel slag from 0 to 1.5 %wt to monitor cadmium release and the pH as pyrite oxidation proceeded. Cadmium was sorbed onto the steel slag to evaluate cadmium sorption ability at pH values of 6.5 and 9.0. Using the cadmium-sorbed steel slag, the crystalline structure and the level of cadmium release from the steel slag at different pH values were determined. The pH of excavated sedimentary rock without steel slag decreased, while that with more than 0.5 %wt steel slag remained within a neutral to alkaline pH range after 90 days, when potential pyrite oxidation was complete. The presence of steel slag did not inhibit the process of pyrite oxidation. These findings demonstrate that both pyrite oxidation and pH neutralization independently occurred in the excavated sedimentary rock, even in the presence of steel slag. The addition of more than 0.5 %wt steel slag maintained the level of cadmium released at less than 0.1 mg kg−1 throughout the 90-day period. The cadmium sorption test and X-ray diffraction analysis showed that cadmium immobilization using the steel slag was mainly governed by the (co)precipitation of carbonate minerals. This study indicates that an addition of 0.5 %wt steel slag to the excavated sedimentary rock can achieve pH neutralization and suppress cadmium release simultaneously, even with the occurrence of pyrite oxidation. Thus, this study suggests that steel slag potentially could be utilized as an amendment to allow the reuse of excavated sedimentary rock.

Binary Component Sorption of Cadmium, and Copper Ions onto Yangtze River Sediments with Different Particle Sizes

Sorption is a crucial process that influences immobilization and migration of heavy metals in an aqueous environment. Sediments represent one of the ultimate sinks for heavy metals discharged into water body. Moreover, the particle size of sediments plays an extremely important role in the immobilization of heavy metals. In this study, the sorption and desorption of cadmium (Cd) and copper (Cu) onto sediments with different particle sizes were investigated to predict the rate and capacity of sorption, to understand their environmental behaviors in an aqueous environment. Batch sorption and kinetic experiments were conducted to obtain the retained amount and rate of Cd and Cu in a binary system. Experimental data were simulated using sorption models to ascertain the sorption capacity and the kinetic rate. Results of European Communities Bureau of Reference (BCR) sequential extraction showed the highest concentration of Cd (0.344 mg kg−1), and its distribution varied with sediment particle size and site. Furthermore, most of Cu (approximately 57% to 84%) existed as a residual fraction. The sorption of Cu onto six sediments followed a pseudo-first order reaction, whereas that of Cd followed a pseudo-second order reaction. Additionally, the competitive Langmuir model fitted the batch sorption experimental data extremely well. The highest sorption capacities of Cd and Cu reach 0.641 mmol kg−1 and 62.3 mmol kg−1, respectively, on the smallest submerged sediment particles. The amounts of Cu and Cd desorbed (mmol kg−1) increased linearly with the initial concentration increasing. Thus, sediment texture is an important factor that influences the sorption of heavy metal onto sediments.

Biochar Types from Latrine Waste and Sewage Sludge Differ in Physico-Chemical Properties and Cadmium Adsorption

Pyrolysis of latrine fecal waste could produce valuable products for minimizing environmental contamination with heavy metals. The objective of this study was to determine yields, characteristics and cadmium (Cd) sorption of biochar from latrine fecal waste and sewage sludge, as affected by pyrolysis temperature. Slow pyrolysis at 350, 550 and 650°C, was used to produce the biochar. In addition to proximate and ultimate analysis, surface area, porosity and functional groups were analyzed. A batch sorption study was conducted to determine the cadmium sorption capacity of the biochar. Biochar from latrine waste had higher yield, ash content, surface area and pore volume and lower total and fixed carbon (C) and volatile matter than from sewage sludge. Yield, volatile matter, total C, nitrogen (N) and hydrogen (H) decreased with pyrolysis temperature, while ash content, surface area and porosity increased. Surface functional groups of the biochar also varied with feedstock and pyrolysis temperature. The Cd sorption capacities were higher for biochar from latrine waste than from sewage sludge. The findings indicated that characteristics of biochar from latrine waste differ from that of sewage sludge origin and has greater potential as an adsorbent for removal of Cd from wastewater.

Competitive sorption of nickel, copper, lead and cadmium on okra leaves (Abelmoschus esculentus)

In this study, potential of okra leaves for the removal of Ni(II), Cu(II), Pb(II) and Cd(II) from the mixed metal aqueous solution were evaluated. The data were analyzed by Freundlich, Langmuir, D-R, Flory-Huggins and Halsey adsorption models. Pseudo first order rate, Pseudo second order rate, Morris-Weber and Elovich equations were employed to understand the kinetics of the reaction. The characterization of the adsorbent was carried out by EDX and FTIR techniques. The order of maximum metal uptake calculated by D-R isotherm was Cu(II) > Pb(II) > Cd(II) and Ni(II), 453 mg g-1, 81 mg g-1, 13.82 mg g-1 and 1 mg g-1 respectively, with the energy of adsorption in the range of 9-15 for Ni(II) and Cd(II) expected for the ion exchange nature of adsorption and 7-8 for Cu(II) and Pb(II) showing the physical nature of adsorption. The calculated thermodynamic parameters like Gibbs free energy and enthalpy change demonstrate that adsorption process was spontaneous and endothermic in nature. Further it was observed that all four metal ions could be adsorbed at pH 6 with detection limits of 0.04-0.1 µg L-1. The method was successfully applied for the removal of these metal ions from the ground water, tap water and wastewater samples collected from different areas of Pakistan.

Cadmium removal from aqueous solution by biochar obtained by co-pyrolysis of sewage sludge with tea waste

Resource utilization is a critical pathway for sustainable solid waste treatment. Biochar was prepared from the co-pyrolysis of sewage sludge and tea waste. Brunauer–Emmett–Teller measurement, scanning electron microscopy and Fourier transform infrared analysis were employed to characterize the biochar. Then, the interface behavior between biochar and Cd from aqueous solution was investigated. The effect of adsorbent dose and pH on Cd adsorption was evaluated. Adsorption kinetics and the adsorption isotherm were studied, and the adsorption mechanism was explored. The results showed that the suitable adsorbent dose was 4 g L−1 and the optimal pH of the Cd solution remained at 6.0. Cadmium sorption on the biochar could be well described by the pseudo-second order kinetic model (R 2 > 0.98). The adsorption process was described using the Langmuir (R 2 > 0.86), Freundlich (R 2 > 0.86), Temkin (R 2 > 0.84) and Dubinin–Radushkevich (R 2 > 0.86) isotherm models. The proportion of organic constituents in biochar was 69.2–72.4%. Minerals that originated in biochar played an important role during the Cd adsorption process, and the contribution of minerals accounted for 27.6–30.8% of the total adsorption. The main mechanism of the Cd adsorption process by biochar involved ion exchange, surface complexation, electrostatic interaction, surface co-precipitation, and other mechanisms. Therefore, biochar created by the co-pyrolysis of sewage sludge and tea waste could be used as an adsorbent for the removal of metal ions from contaminated water.

Growth characteristics and response of wheat to cadmium, nickel and magnesium sorption affected by zeolite in soil polluted with armaments

The presence of large heavy metal concentrations in soil polluted with chemical weapons causes serious operational restrictions against cultivation of agricultural crops like wheat. To solve this problem, the usage of zeolite has been proposed as one of the most efficient practical approaches. The main objective of this research is the investigation of the influence of natural Iranian zeolite on sorption of cadmium (Cd2+) and nickel (Ni2+) and the investigation of growth characteristics of wheat in soil polluted with chemical weapons. The experiments were carried out in factorial arrangement in a randomized complete design with three replications during 2015-2016 crop season. Treatments with four levels of zeolite included: a1) 0%; a2) 0.5%; a3) 1.5%; and a4) 2.5% of soil weight and two soil samples, one obtained from out of the war zone (without contamination) (b1) and other was from contaminated soil to weapons (b2). Results showed that the polluted soil led to a significant enhancement in amount of Cd2+ and Ni2+ in shoots and roots of wheat. In addition, the findings revealed that the application of zeolite caused a significant reduction in Cd2+ and Ni2+ concentrations in shoots and roots and significantly increased dry matter, chlorophyll index and magnesium (Mg2+) concentration in wheat. In general, results showed that zeolite released nutrients and stabilized heavy metals in polluted soil and the negative effect of soil polluted by toxic heavy metals was reduced in the plant, which lead to decontamination of soil and increase in safety of environment.

Sorption isotherms of metal ions onto an N-(2-sulfoethyl)chitosan-based material from single- and multi-component solutions

ABSTRACTThe scope of work is to study the mutual influence of metal ions during their sorption by sulfoethylated chitosan. The sorption isotherms of metal ions from single- and multi-component solutions are obtained. The sorption capacity of the sorbent towards Ag(I) and Cu(II) is revealed to be 1.63 and 1.41 mmol/g in single-, and 1.40 and 0.85 mmol/g in five-component solution. By comparing the affinity parameter and capacity of sulfoethylated chitosan towards ions in single- and multi-component solutions, it is concluded that Ag(I) and Cu(II) ions suppress the sorption of cobalt(II), nickel(II), zinc(II), cadmium(II), magnesium(II), calcium(II), strontium(II), barium(II), manganese(II) and lead(II).

Sorption and desorption of potentially toxic metals (Cd, Cu, Ni and Zn) by soil amended with bentonite, calcite and zeolite as a function of pH

Sorption and desorption studies of cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) were carried out at the pH range of 2 to 9 by a soil amended with three sorbents including bentonite, calcite and zeolite. A geochemical computer model was used to simulate the sorption of metals by control and amended soils as influenced by pH. Metals sorption on control and amended soils was dependent on pH, and increased with increasing equilibrium pH. Furthermore, metals sorption on soil amended by sorbents was greater than control, indicating the increase of soil sorption capacity by adding sorbents, while their desorption decreased. The modeling results indicated that the sorption of metals was modeled successfully using the ion exchange and surface complexation reactions. In general, the maximum sorption of metals was observed by bentonite-amended soil and calcite-amended soil, whereas the maximum desorption of all metals obtained in zeolite-amended soil, suggesting that the sorption of metals on zeolite was based on the reversible mechanism. In general, the sequence of metals sorption at pH2 to 9 for all treatments was in order of Cu>Zn>Cd≥Ni. In addition, this sequence was observed mostly for metals activity and desorption (occasionally an exchange in the positions of Cd and Ni) but with an inverse trend. Results indicated that distribution coefficient (Kd) increased with increasing pH and, in particular, had a sharp increase at the neutral to alkaline pH.

Thermal stability of biochar and its effects on cadmium sorption capacity

In this study, the thermal stability of a wood shaving biochar (WS, 650°C), a chicken litter biochar (CL, 550°C) and an activated carbon (AC, 1100°C) were evaluated by combustion at 375°C for 24h to remove the labile non-carbonized organic matter. Results showed that WS and CL biochars were not thermally stable and can lose most of the organic C during combustion. The combusted WS and CL biochars retained considerable amounts of negative charge and displayed higher sorption for Cd (from 5.46 to 68.9mg/g for WS and from 48.5 to 60.9mg/g for CL). The AC retained 76.5% of its original C and became more negatively chargely after combustion, but its sorption for Cd slightly decreased (from 18.5 to 14.9mg/g). This study indicated that after potential burning in wildfires (200–500°C), biochars could have higher sorption capacity for metals by remaining minerals.