Batch Equilibrium Experiments Research Articles

Analysis of influencing factors of phenanthrene adsorption by different soils in Guanzhong basin based on response surface method

Adsorption desorption is an important behavior affecting the migration of phenanthrene in soil. In this study, three typical soils of loess, silts and silty sand in Guanzhong Basin, Shaanxi Province, China were used as adsorbents. Batch equilibrium experiments were carried out to study the adsorption desorption kinetics and isotherm of phenanthrene in different soils. Response surface method (RSM) was used to study the effects of temperature, pH, phenanthrene concentration and organic matter content on soil adsorption of phenanthrene. The results showed that after adsorption, the outline of soil particles became more blurred and the degree of cementation increased. The kinetic adsorption of phenanthrene by soil conforms to the quasi second-order kinetic model, and the adsorption desorption isotherm is nonlinear and conforms to the Freundlich model. Due to the difference of soil properties, the adsorption amount of phenanthrene by soil is loess > silty sand > silts. The thermodynamic results show that the adsorption of phenanthrene by soil is spontaneous and endothermic, and the desorption is spontaneous and exothermic. Through RSM, the interaction between phenanthrene concentration and soil organic matter in Loess and silts is significant, and the interaction between temperature and soil organic matter in silty sand is significant. Among the four factors affecting the adsorption rate of loess, silts and silty sand, soil organic matter is the most significant. The theoretical optimum adsorption rates of loess, silts and silty sand are 98.89%, 96.59% and 93.37% respectively.

Enhanced biosorption of europium and cesium ions from aqueous solution onto phalaris seed peel as environmental friendly biosorbent: Equilibrium and kinetic studies

The sorption characteristics of Eu(III) and Cs(I) removal from aqueous solution were estimated using phalaris seeds peel powder (PSP), a novel biosorbent that is economical and low-cost. Batch equilibrium experiments were carried out to investigate the effects of contact time, initial metal concentration, media pH, and interference ions on the sorption of Eu(III) and Cs(I). PSP powder characterization via Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG/DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM) revealed some changes before and after the adsorption process. This indicates that most likely, adsorption has taken place between the metal ions and the adsorbents in the aqueous solution. The obtained results show that Eu(III) has a higher selectivity than Cs(I). The kinetics of the adsorption of Eu3+ and Cs+ have been discussed. It was shown that the second-order kinetic equation could describe the sorption and was found to be the best fitted model (R2 = 0.999) for two metal ions. Langmuir and, Dubinin–Radushkevich (D–R), isotherm were found to best fit (R2 = 0.99) in this study. The separation factor (RL) value of less than 1.0 indicates that the biosorption of both metal ions on PSP is favorable. Thermodynamic parameters, such as ΔHo, ΔGo, and ΔSo, have been calculated by using the thermodynamic equilibrium coefficient obtained at different temperatures. The obtained results indicated the endothermic nature of the sorption process for both metal ions onto PSP. PSP powder has the potential to be used as a low-cost biosorbent for the removal of Eu(III) and Cs(I) from wastewater, according to the findings.

An Insight into the Sorption Behavior of 2,3,7,8-Tetrachlorodibenzothiophene on the Sediments and Paddy Soil from Chaohu Lake Basin.

Considering the frequent detection of polychlorinated dibenzothiophenes (PCDTs) in various environmental matrices and the potential ecological health risks, the environmental behavior of such compounds needs to be elucidated further. In this work, the sorption behavior of 2,3,7,8-tetrachlorodibenzothiophene (2,3,7,8-TCDT) onto three sediments and paddy soil from Chaohu Lake were investigated via batch equilibration experiments. From the perspective of sorption kinetics and isotherms, the sorption characteristics and mechanism of 2,3,7,8-TCDT on the above four carriers were compared, and the relationship between their structural characteristics and soil sorption capacity was discussed. Results suggested that rapid sorption played the primary role during the sorption process of 2,3,7,8-TCDT and the corresponding sorption isotherms were well fitted using the Freundlich logarithmic model. Moreover, the effects of pH and dissolved organic matter (DOM) on the sorption of 2,3,7,8-TCDT were investigated. The maximum sorption capacity of 2,3,7,8-TCDT on sediment was under acidic pH condition (pH = 4.0). Meanwhile, DOM at a low level promoted the sorption capacity of sediment toward 2,3,7,8-TCDT, while the high concentration of DOM inhibited this effect. In addition, the values of logKoc were obtained using high-performance liquid chromatography (HPLC) and did not show any significant correlation with organic carbon (OC) contents, thereby indicating that the partition effect was the dominating influencing factor for the sorption of 2,3,7,8-TCDT both on sediments and soil. This work provides useful data to understand the sorption behavior of 2,3,7,8-TCDT on sediments and soil and assess its potential environmental risk.

High concentration of nitrogen recovery from anaerobic digested slurry (ADS) using biochars: adsorption and improvement.

Biochar produced from biomass has been increasingly used as an environmentally friendly and low-cost adsorbent. This study systemically evaluated the effects of raw materials including corn straw (CS), cattle manure (CM), and cherry woods (CW) as well as pyrolysis temperature (400, 500, and 600 °C) on the physicochemical properties, such as morphological structure, element content, and surface functionality of biochars. The batch experiments of NH4+-N adsorption using anaerobic digested slurry (ADS) confirmed that CM600 (biochar derived from CM at 600 °C) had the highest adsorption capacity of 18.16 mg·g-1. The effects of coexisting ions in ADS, biochar dosage, adsorption time and initial concentration on NH4+-N adsorption from ADS by the biochars were evaluated. The results of the batch equilibrium and kinetics experiments showed that Langmuir isotherm model and pseudo-second-order kinetic model well described NH4+-N adsorption by the biochars, indicating that physical and chemical adsorption occurred simultaneously. Furthermore, compared to the biochar-modified method, the raw material-modified biochar (CM600-modified biochar) showed excellent adsorption capacity with a maximum of 69.82 mg·g-1 (284% increase) for the high NH4+-N concentration (4,000 mg·L-1) from ADS. Therefore, it was concluded that high-concentration nitrogen recovery from ADS using modified biochar was an effective method.

Predicting Langmuir model parameters for tungsten adsorption in heterogeneous soils using compositional signatures

• Soil taxonomic designations were statistically discriminated by compositional data. • Stacked ensemble models showed greater accuracies than unstacked models. • Multiple W chemical interactions evident across diverse range of soil “types”. Metallic tungsten (W) is a highly dense material of increasing importance to the U.S. Army as a strategic, non-radioactive replacement for depleted uranium. While there is a growing body of evidence regarding the mechanistic behavior of ionic W (formed after the spontaneous oxidation of metal) in the environment, predicting its environmental fate remains challenging, owing to the widespread geochemical heterogeneity of soils. Therefore, we developed W adsorption prediction models by creating different functional “compositions” of the chemical and physical characteristics for different soil “types” (a non-specific yet commonly used to term to designate different soils). A relatively small dataset consisting of twenty soils (possessing six different soil “types” from across the U.S.) were evaluated for W adsorption behavior. Physical and chemical soil data were separated into water-extracted (WE), bulk, and particle-size distribution (PSD) compositions, and center log-ratio (clr) transformed. Classification models built using extremely randomized trees (ERT) showed that the compositions' accuracies were WE > Bulk > PSD at the Order and Suborder levels. W's adsorption isotherms were constructed using batch equilibrium experiments and modeled against the Langmuir model, where S max = calculated adsorption maximum, K 1/L = inverse Langmuir affinity coefficient. Afterward, both the ERT and ensemble, or stacked, ERT models (by addition of Order and/or Suborder taxonomic labels as ensemble classifiers) were developed for predicting the S max and K 1/L parameters based on the different compositions. In general, model accuracies were substantially increased by the addition of the labels (stacked models). Feature importance calculations pointed to a wide range of potential chemical mechanisms simultaneously controlling W adsorption, laying the groundwork for more detailed in-situ elemental speciation studies. Overall, this work showcased a new technological capability allowing for accurately predicting W adsorption on a wide variety of morphological soil designations. Capsule: This work found that soil morphological designations greatly improved the accuracy of Langmuir adsorption predictions of CoDA-transformed characterization data.

Direct Production of Ni–Co–Mn Mixtures for Cathode Precursors from Cobalt-Rich Lithium-Ion Battery Leachates by Solvent Extraction

A novel solvent extraction scheme was developed for the processing of Co-rich lithium-ion battery (LIB) leachate to a Ni–Co–Mn (NCM) sulfate mixture that can be directly used in the precursor synthesis of LIB cathodes. Conventional hydrometallurgical recycling of spent LIBs usually aims at separation of Li, Ni, Co, and Mn into pure fractions, which is simplified here. Operating pH and the number of extraction stages for each separation were evaluated from batch equilibrium experiments. Two continuous countercurrent extractions with bis(2-ethylhexyl) hydrogen phosphate (D2EHPA) and one with Cyanex 272 were studied in bench-scale mixer-settler equipment, and a Ni–Co–Mn solution with n(Ni):n(Co) = 14.16 and n(Ni):n(Mn) = 8.06 was obtained. The Ni:Co:Mn molar ratio in the NCM mixture can be adjusted to, for example, 8:1:1 using a Co-rich raffinate from the same process, and no additional transition metal salts are required for tuning the composition. Stripping raffinate containing 102.7 g L−1 Co at 99.8% relative purity was obtained from Cyanex 272 extraction. The main benefit of the process concept is that the solvent extraction separations can be operated with less stringent requirements than when producing pure metal salts.

Adsorption behaviour of tetrabromobisphenol A on sediments in Weihe River Basin in Northwest China

Tetrabromobisphenol A (TBBPA) is adsorbed on sediments in river environments, and various environmental factors have distinct effects on its adsorption behaviour. Investigating the adsorption behaviour of TBBPA on the sediments in Weihe River Basin is critical for protecting the water environment and providing a theoretical basis for the prevention and control of brominated flame retardant pollution. In this study, the adsorption behaviour of TBBPA on Weihe River sediment was investigated by conducting batch equilibrium experiments, and the effects of pH, dissolved organic matter, and ionic strength on the adsorption of TBBPA were discussed. The obtained results revealed that rapid adsorption was the main mechanism of the TBBPA kinetic adsorption process. The isothermal adsorption behaviour of TBBPA was well fitted by Freundlich model (R2 99.21%) than Langmuir model (R2 98.59%). The adsorption capacity for TBBPA is 34.13 mg/kg. The thermodynamic results revealed that the adsorption process of TBBPA by the sediment was a spontaneous endothermic reaction. The increase in pH and ionic strength inhibited the adsorption of sediments on TBBPA. With the increase in the humic acid concentration, the adsorption of TBBPA initially increased and subsequently decreased. Synchrotron radiation-Fourier transform infrared spectroscopy indicated that the adsorption mechanism of TBBPA on the surface of sediment was mainly π–π and hydrogen bonds. The obtained results are useful for understanding of TBBPA migration and transformation in river water bodies.

Recycling of Waste Toner Powder as Adsorbent to Remove Aqueous Heavy Metals.

The removal of Cd2+, Zn2+ and Ni2+ from metal solutions onto waste toner power (WTP) was investigated. The influence of parameters such as pH, contact time, initial metal concentration and adsorbent dosage was studied in batch adsorption experiments. Batch equilibrium experiments showed that the highest removal efficiency for Zn2+ and Cd2+ occurs at pH 7, while pH 5 is the most suitable for Ni2+ removal. The amount of metal removed (mg/g) improved when increasing the initial concentration, and sorption of heavy metals reached equilibrium in 24 h. Metals’ uptake increased with increasing adsorbent dosage. The adsorption isotherms of Zn2+, Cd2+ and Ni2+ onto WTP fit the Langmuir better than the Freundlich model with correlation coefficient R2 values ranging from 0.998 to 0.968 and 0.989 to 0.881, respectively. The data showed that the maximum adsorption capacity of heavy metals, amax, ranged from 2.42 to 1.61 mg/g, from 6.22 to 2.01 mg/g and from 3.49 to 2.56 mg/g for Ni2+, Zn2+ and Cd2+, respectively, with the three WTPs used in this study. This adsorbent can potentially be used to remove metal ions from wastewater.

Synthesis, Characterization of Novel cross linked BETH resin and its application in treatment of industrial waste water

Green chemistry emphasizes the importance of developing unique, eco-friendly solutions to protect humanhealth and ecosystems. In order to examine this concept for minimizing industrial waste and lessening theenvironmental impact of hazardous chemicals, new greener procedures for heavy metal extraction fromindustrial waste must be implemented. Because of their low cost and ease of synthesis, plant based resinsare increasingly being used in the treatment of water resources in accordance with the goals and objectivesof green chemistry. To remediate harmful industrial effluents, cross linked Bajra Epoxy TryptophanHydroxamate (BE-TH) resin were produced in the current study. The FT-IR spectroscopy and Scanningelectron microscopy were used to determine the BE-TH resin’s characterization. The uptake of metal ionsby the BE-TH resin was studied by batch equilibrium experiment. The adsorption of different metal ionssuch as Cd(II), Zn(II) and Fe(II) take place successfully on the BE-TH resin. The maximum percentageremoval Cd (II) and Zn (II) occurred at the pH range of 7-7.5. The results have established good potentialityfor the BE-TH resin to be used as an adsorbent for the removal of toxic metals from industrial waste water.

Effect of Humic Acid on the Adsorption/Desorption Behaviors of Trivalent Chromium on Calcium Modified Montmorillonite and Kaolinite

AbstractThe interactions between Cr(III) and calcium ion modified montmorillonite or kaolinite (Ca−Mt or Ca−Kaol) in the absence and presence of humic acid (HA) were investigated by batch equilibrium experiments under different pH values. A linear additive model was introduced to extrapolate the solid‐liquid distribution of Cr(III) in ternary systems by using Kd values obtained from binary systems among clay mineral, Cr, and HA. The different affinity of Cr(III) between HA and clay minerals had great effects on the Cr(III) adsorption in the ultimate ternary system. Ca−Mt showed a better adsorption ability for Cr(III) due to the superior physicochemical properties compared to Ca−Kaol. The adsorption‐desorption isotherms were used to study the reversibility of Cr(III) sorption in the binary and ternary systems, and the physicochemical characterization explored the main mechanism of Cr(III) immobilization by clay minerals including cation exchange and surface complex.

Amending a tropical Arenosol: increasing shares of biochar and clay improve the nutrient sorption capacity

Tropical Arenosols may be challenging for agricultural use, particularly in semi-arid regions. The aim of this study was to evaluate the impact of the addition of increasing shares of biochar and clay on the nutrient sorption capacity of a tropical Arenosol. In batch equilibrium experiments, the sorption of ammonium-N (hbox {NH}_{4}^{+}{text{-N}}), nitrate-N (text {NO}_{3}^{-}{text{-N}}), potassium (text {K}^{+}), and phosphate-P (text {PO}_{4}^{3-}{text{-P}}) was quantified for mixtures of an Arenosol with increasing shares of biochar and clay (1%, 2.5%, 5%, 10%, 100%) and the unmixed Arenosol, biochar, and clay. The mid-temperature biochar was produced from Prosopis juliflora feedstock; the clayey material was taken from the sedimentary parent material of a temporarily dry lake. Only the Arenosol–biochar mixture with 10% biochar addition and the biochar increased the text {NH}_{4}^{+}{text{-N}} maximum sorption capacity (q_{max}) of the Arenosol, by 34% and 130%, respectively. The q_{max} of text {PO}_{4}^{3-}{text{-P}} slightly increased with ascending biochar shares (1–10%) by 14%, 30%, 26%, and 42%, whereas the undiluted biochar released text {PO}_{4}^{3-}{text{-P}}. Biochar addition slightly reduced text {NO}_{3}^{-}{text{-N}} release from the Arenosol but strongly induced text {K}^{+} release. On the other hand, clay addition of 10% and clay itself augmented q_{max} of text {NH}_{4}^{+}{text{-N}} by 30% and 162%; ascending clay rates (1–100%) increased q_{max} for text {PO}_{4}^{3-}{text{-P}} by 78%, 130%, 180%, 268%, and 712%. Clay rates above 5% improved text {K}^{+} sorption; however, no q_{max} values could be derived. Sorption of text {NO}_{3}^{-}{text{-N}} remained unaffected by clay amendment. Overall, clay addition proved to enhance the nutrient sorption capacity of the Arenosol more effectively than biochar; nonetheless, both materials may be promising amendments to meliorate sandy soils for agricultural use in the semi-arid tropics.

Sorption properties and mechanisms of erythromycin and ampicillin in loess soil: Roles of pH, ionic strength, and temperature

The concern over veterinary antibiotic (VA) pollution has significantly increased. To understand the sorption properties and mechanisms of macrolides and β-lactam antibiotics in loess soil, batch equilibrium experiment was adopted to explore the sorption kinetics, sorption thermodynamics, and factors that influence erythromycin (ERY) and ampicillin (AMP) in loess soil. The equilibrium time of ERY and AMP sorption by loess soil was about 9 h and 2 h, respectively, and the sorption process was in line with a pseudo-second-order model. A linear sorption model can well describe the sorption of ERY in loess soil, while AMP was more consistent with the Freundlich model. The sorption affinity (Kd) of AMP on loess soil was 95.3–276.6L/kg and the Kd of ERY was only 8.3–9.7L/kg. The sorption capacity (Cs) of ERY first increased and then decreased, whereas the Cs of AMP gradually decreased with an increase in temperatures. A weak acid condition was favorable for the sorption of ERY, whereas an alkaline condition was favorable for the sorption of AMP. With the enhance of ionic concentration, the Cs of target pollutants was more effective, but ionic strengths too high inhibited the sorption of ERY. The Cs of the two pollutants increased with an increase in initial concentration. The results indicated that ERY is mainly adsorbed to loess soil by electrostatic sorption and cation exchange, whereas AMP depended on complexation, cationic bridging, and hydrogen bonding. Overall, AMP indicated the higher sorption expected in loess, whereas ERY displayed a high migration potential. Data presented in this study reveal aspects of the transport of macrolide and β-lactam antibiotics in soil–aqueous systems.

Removal of Nickel Ions from Aqueous Solutions by 2-Hydroxyethyl Acrylate/Itaconic Acid Hydrogels Optimized with Response Surface Methodology.

The adsorption of Ni2+ ions from water solutions by using hydrogels based on 2-hydroxyethyl acrylate (HEA) and itaconic acid (IA) was studied. Hydrogel synthesis was optimized with response surface methodology (RSM). The hydrogel with the best adsorption capacity towards Ni2+ ions was chosen for further experiments. The hydrogel was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis before and after the adsorption of Ni2+ ions. Batch equilibrium experiments were conducted to investigate the influence of solution pH, hydrogel weight, ionic strength, adsorption time, temperature and initial concentration of nickel ions on the adsorption. Time-dependent adsorption fitted the best to the pseudo-second-order kinetic model. A thermodynamic study revealed that the adsorption was an exothermic and non-spontaneous process. Five isotherm models were studied, and the best fit was obtained with the Redlich–Peterson model. Consecutive adsorption/desorption studies indicated that the HEA/IA hydrogel can be efficiently used as a sorbent for the removal of Ni2+ ions from the water solution. This study develops a potential adsorbent for the effective removal of trace nickel ions.

Comparing conventional and emerging adsorbents for per‐ and polyfluoroalkyl substances: Kinetic, equilibrium, and column experiments

AbstractAn expanding list of states have established enforceable drinking water regulations and/or advisories for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid. Additionally, many state regulations extend to shorter chain per‐ and polyfluoroalkyl substances (PFAS) compounds not currently addressed by the United States Environmental Protection Agency (USEPA). This current work presents batch equilibrium and continuous column (rapid small‐scale column test) bench‐scale experiments conducted on drinking water sources with similar PFAS composition but varying background water quality (namely dissolved organic carbon). Adsorption of PFOA was evaluated using activated carbon and an emerging modified clay as adsorbents. Both batch equilibrium and continuous column experiments demonstrated that modified clay has a greater adsorptive capacity and faster adsorption kinetics compared to activated carbon for both long‐ and short‐chain compounds studied, as represented by PFOA and perfluorobutanesulfonic acid, respectively.

Drinking water treatment residual as a ballast to sink Microcystis cyanobacteria and inactivate phosphorus in tropical lake water

The combination of a low dose of coagulant with a ballast that can inactive phosphorus (P) in lake sediment—a technique known as “flock and lock”—is one method for restoration of eutrophic lakes. The effectiveness of a drinking water treatment residual (DWTR) as a ballast in flock and lock was assessed using assays of eutrophic lake water from Thailand dominated by Microcystis aeruginosa cyanobacteria colonies by measuring changes in chlorophyll-a, pH, and zeta potential. P sorption isotherms were developed from long-term batch equilibrium experiments; desorption of nutrients and metals was assessed via leaching experiments; and morphological changes to cellular structure were assessed using scanning electron microscopy. Results showed that combining DWTR with a low dose of aluminum sulfate (0.6-4.0 mg Al/L) effectively sank 74-96% of Microcystis, with DWTR dose (50-400 mg/L), initial chlorophyll-a concentration (92-976 µg/L), pH (7.4-9.3), and alkalinity (99-108 ppm CaCO3) identified as factors significantly associated with sinking efficacy. P sorption capacity of the DWTR (7.12 mg/g) was significantly higher than a local soil (0.33 mg/g), enabling the DWTR to inactivate P in lake sediment. Desorption of Al, Fe, Ca and N from the DWTR was estimated to contribute to a marginal increase in concentrations of those compounds in the water column of a small shallow lake (1.2, 0.66, 53.4, and 0.07 µg/L, respectively) following a simulated application. Therefore, pre-treated DWTRs may be a viable alternative ballast in the flock and lock approach to lake restoration, supplementing or replacing modified local soils or lanthanum modified clays.

Synthesis of calcium–aluminum-layered double hydroxide and a polypyrrole decorated product for efficient removal of high concentrations of aqueous hexavalent chromium

To efficiently remove high concentrations of hexavalent chromium (Cr(VI)), calcium–aluminum-layered double hydroxide (CaAl-LDH, denoted as CAL), and polypyrrole-modified CAL (CAL-PPy) were prepared by hydrothermal and in situ polymerization methods, respectively. The chemical structure, morphology, and elemental results indicated that the chain-like polypyrrole was decorated with hexagonal CAL. The specific surface area of CAL-PPy increased from 8.746 m2/g to 24.24 m2/g. The adsorption performances of CAL and CAL-PPy for aqueous Cr(VI) were investigated using batch equilibrium experiments. The decontamination process of aqueous Cr(VI) (100 mg/L) reached the equilibrium state within 50 min, and the kinetic data met the pseudo-second-order kinetic equation. The Langmuir model described the isothermal data properly, and the obtained theoretical adsorption capacity of CAL for Cr(VI) at 318 K was 34.06 mg/g, while that of CAL-PPy was 66.14 mg/g. The removal mechanisms involved electrostatic attraction, surface complexation, anion exchange, and reduction to low-toxicity Cr(III). Therefore, CAL and CAL-PPy have underlying applications in treating real wastewater containing Cr(VI).

Atrazine behavior in an agricultural soil: adsorption–desorption, leaching, and bioaugmentation with Arthrobacter sp. strain AAC22

PurposeTo evaluate atrazine behavior in an agricultural soil (adsorption–desorption, leaching) and the effects of bioaugmentation with the Arthrobacter sp. strain AAC22, as a soil remediating strategy.Material and methodsAn agricultural soil with a history of atrazine application was used. Equilibrium batch experiments allowed the investigation of the adsorption–desorption of atrazine at different soil depths, while the atrazine leaching potential was assessed using disturbed soil columns. Arthrobacter sp. strain AAC22 was selected for bioaugmentation, to remove atrazine in soil microcosms. Removal efficiency was determined by a bioassay with oat seeds.Results and discussionAdsorption and desorption isotherms of atrazine at different soil depths were well described by the Freundlich equation (R2 > 0.99 and R2 > 0.98, respectively). The Freundlich constant (Kf) and desorption coefficient (Kfd1–3) decreased and increased, respectively, as soil depth increased. The Kf and Kfd1–3 values were correlated positively to organic carbon (r = 0.97) and negatively to pH (r = − 0.93). In this soil, 70.2% of atrazine applied (2.5 kg ha−1) was recovered in the leachate and 7.6% remained in the soil column. The higher atrazine concentration leached can be explained by the negative hysteresis of adsorption–desorption in this soil. Bioaugmentation with AAC22 enhanced atrazine removal being nearly 70% after 2 days of treatment, and it was almost complete (> 99%) after 8 days. A bioassay demonstrated that bioaugmentation was successful and toxic by-products were not detected.ConclusionThe adsorption–desorption and leaching experiments demonstrated the high mobility of the atrazine in the study soil. The bioaugmentation using the AAC22 strain is an effective strategy for atrazine removal in polluted soils.

Study of the sorption/desorption behavior of chlortetracycline on sediments in the upper reaches of the Yellow River

The presence of antibiotic in aquatic environments has become a topic of great concern with respect to both environment and global public health. However, to date, only a few studies have been carried out on the sorption behavior of antibiotics in aquatic environments. In this study, batch equilibrium experiments were conducted to explore the sorption/desorption behavior of Chlortetracycline (CTC) on the sediments in the Lanzhou section of the Yellow River. The results showed multilayer chemisorption on heterogeneous surfaces dominated by hydrophobic distribution and an obvious hysteresis phenomenon was observed. In addition, the sorption was found to be influenced by factors such as a continuous increase in the temperature, reduction in the initial concentration of CTC, and the increasing particle size of the sediments. The pH was found to affect the dissociation degree of CTC, and the sorptive amount was found to decrease with the increase in the pH value. The presence of other ions which with high valence state and concentration presenting an obvious inhibitory effect in the sorption process. Additionally, the large sorptive amount of antibiotics in the sediments due to the high Cation exchange capacity (CEC), organic matter, and clay particles indicated the influence of the physicochemical properties of sediments on the sorption behavior of antibiotics. This study preliminarily grasps the trend of CTC sorption/desorption on sediments, which is helpful in understanding the fate of CTC and assessing its ecological risks in the upper reaches of the Yellow River.

Oil Sorption Performance of Sorbent Materials Examined Under Static and Dynamic Conditions

Oil spill cleanup and subsequent restoration of the environment is majorly a function of spill cleanup methods applied. Some of these methods, though efficient, are, however, very expensive and require more personnel for their application and relative deployment in the field. The study was aimed at examining the efficiency of a locally and readily available, eco-friendly and low cost agricultural waste (coconut husk coir) as sorbent materials for spilled engine oil cleanup under static and dynamic marine water conditions. The sorbent material was prepared and used in three forms: raw coconut husk coir (CHC), modified coconut husk coir (MCHC), and reused coconut husk coir (RCHC). Under static and dynamic marine water conditions, oil sorption batch equilibrium experiments were used to study the engine oil sorption capacity and efficiency of the sorbent. Effects of sorbent dosage and sorption times on the oil sorption and efficiency of CHC, MCHC, and RCHC were studied and determined. At a constant sorption time of 60 minutes and varying sorbent dosages of 2-8 /320 ml of engine oil-marine water concentration, MCHC exhibited the highest oil sorption efficiency of 61.18% and 44.33% for dynamic and static conditions, CHC had 55.61% and 38.50% for dynamic and static conditions, whereas RCHC had 41.66% and 26.04% for dynamic and static conditions, respectively. It is statistically deduced from the results that sorption times and sorbent dosages have significant effects on the sorption efficiency of experimental coir for spilled engine oil removal. Though there is a need for proper blending or modifications of the sorbent material to enhance its affinity to oil and hydrophobicity, there are enough potentials in the materials for mild marine water current spilled engine oil cleanup.

Oil Sorption Performance of Sorbent Materials Examined Under Static and Dynamic Conditions

Oil spill cleanup and subsequent restoration of the environment is majorly a function of spill cleanup methods applied. Some of these methods, though efficient, are, however, very expensive and require more personnel for their application and relative deployment in the field. The study was aimed at examining the efficiency of a locally and readily available, eco-friendly and low cost agricultural waste (coconut husk coir) as sorbent materials for spilled engine oil cleanup under static and dynamic marine water conditions. The sorbent material was prepared and used in three forms: raw coconut husk coir (CHC), modified coconut husk coir (MCHC), and reused coconut husk coir (RCHC). Under static and dynamic marine water conditions, oil sorption batch equilibrium experiments were used to study the engine oil sorption capacity and efficiency of the sorbent. Effects of sorbent dosage and sorption times on the oil sorption and efficiency of CHC, MCHC, and RCHC were studied and determined. At a constant sorption time of 60 minutes and varying sorbent dosages of 2-8 /320 ml of engine oil-marine water concentration, MCHC exhibited the highest oil sorption efficiency of 61.18% and 44.33% for dynamic and static conditions, CHC had 55.61% and 38.50% for dynamic and static conditions, whereas RCHC had 41.66% and 26.04% for dynamic and static conditions, respectively. It is statistically deduced from the results that sorption times and sorbent dosages have significant effects on the sorption efficiency of experimental coir for spilled engine oil removal. Though there is a need for proper blending or modifications of the sorbent material to enhance its affinity to oil and hydrophobicity, there are enough potentials in the materials for mild marine water current spilled engine oil cleanup.