Influence of dissolved organic matter from corn straw on Zn andCusorption to Chinese loess

The interaction of Zn and Cu with dissolved organic matter (DOM) is a significant physicochemical process affecting their sorption as well as mobility in soil. The objective of this study was to examine the influence of DOM from corn straw on the sorption of Zn and Cu by loess through batch adsorption technique. The sorption isotherms of Zn and Cu could be well described by the Freundlich equation, and the partition distribution coefficient (k) in the presence of DOM was reduced by 86% for Zn and 58% for Cu, as compared to the control receiving no DOM, suggesting that DOM had a stronger inhibitory effect on Zn sorption than that of Cu. In addition, the sorption of metal increased with an increase in pH for loess, with maximum inhibition on metal sorption observed at pH > 7.6 for Zn and pH > 5.5 for Cu in the absence ofDOM but Cu sorption of DOM was suddenly decreased with an increase of pH at pH > 7.9 in the presence of DOM. At a DOM concentration of <200 mg L^?1, sorption of Zn and Cu was reduced by 46% for Zn and 32% for Cu with an increase in DOM concentration.     

富磷污泥生物炭去除水中Pb(Ⅱ)的特性研究

以城市污水厂富磷剩余污泥为研究对象,考察高温热解制备生物炭吸附剂对水中Pb(Ⅱ)的去除效果.研究表明,随着热解温度升高,制备的生物炭对Pb(Ⅱ)的吸附能力增强;在相同热解温度下,生污泥生物炭对Pb(Ⅱ)的吸附能力比消化污泥生物炭大.采用700℃热解1 h制备生污泥生物炭以研究对Pb(Ⅱ)吸附的影响因素,结果显示:吸附180 min达到吸附平衡;富磷污泥生物炭对Pb(Ⅱ)的去除率随pH增加而升高;生物炭投加量增加,对Pb(Ⅱ)去除率上升,而单位吸附容量迅速减小.污泥生物炭对Pb(Ⅱ)的吸附符合准二级反应动力学,Langmuir模型比Freundlich模型能更好地拟合等温吸附线.在pH 5.0、吸附时间3 h、生物炭投加量20 g.L-1条件下,对Pb(Ⅱ)的最大吸附量为34.5 mg.g-1,表明富磷污泥生物炭可以作为一种廉价的吸附剂.     

海泡石黏土矿物对Cu2+的吸附动力学研究

研究分析了海泡石黏土矿物对铜离子的吸附性能和动力学特征,结果表明,海泡石黏土矿物对Cu~(2 )吸附的最佳pH值为6.0左右,随着pH值的增大,吸附作用减弱;在[Cu~(2 )]=100mg·l~(-1),溶液pH值为6,吸附时间为2h时,添加0.1 g海泡石,海泡石对Cu~(2 )的吸附去除率仅为39.5%,当海泡石用量提高至0.4 g时,其对Cu~(2 )的吸附去除率提高到94.8%;实验结果同样显示,18min内有90%的Cu~(2 )被海泡石吸附,随着吸附时间的增加,吸附作用趋于稳定,2h可达到吸附平衡。该吸附过程符合Langmuir和Freundlich等温吸附方程.同时,分别采用拟一级模型和拟二级模型考察了吸附动力学,并计算了这些动力学模型的速率常数.实验数据和拟二级模型计算结果之间有较好的相关性.     

Heavy metals uptake from aqueous solutions using marine algae (Colpomenia sinuosa): kinetics and isotherms

The adsorption of copper, zinc, cobalt, lead and cadmium ions onto Colpomenia sinuosa was studied as a function of contact time, initial metal ion concentration and initial pH. In addition, desorption studies were performed. Characterisation of this adsorbent was also confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Batch adsorption experimental data were analysed using Langmuir, Freundlich and Dubinin–Raduschkevich (D–R) adsorption isotherms. The results indicated that the biosorption equilibrium was well described by both the Freudlich and D–R isotherms. Moreover, sorption kinetics was performed and it was observed that equilibrium was reached in<60 min, which could be described by the pseudo-second-order kinetic model for all heavy metals. The sorption of heavy metals onto the biomass was largely dependent on the initial solution pH. The elution efficiency for heavy metal ions desorption from C. sinuosa was determined for 0.1 M HCl, 1.0 M HCl and 1.0 M HNO₃. Desorption efficiency and also adsorption capacity were highest for Pb(II). The results indicate that C. sinuosa has great potential for the removal of heavy metals in an ecofriendly process.     

Efficient removal of heavy metals from electroplating wastewater using polymer ligands

Poly(hydroxamic acid)-poly(amidoxime) chelating ligands were synthesized from poly(methyl acrylate-co-acrylonitrile) grafted acacia cellulose for removing toxic metal ions from industrial wastewaters. These ligands showed higher adsorption capacity to copper (2.80 mmol?g⁻¹) at pH 6. In addition, sorption capacities to other metal ions such as iron, zinc, chromium, and nickel were also found high at pH 6. The metal ions sorption rate (t_1/2) was very fast. The rate of adsorption of copper, iron, zinc, chromium, nickel, cobalt, cadmium and lead were 4, 5, 7, 5, 5, 8, 9 and 11 min, respectively. Therefore, these ligands have an advantage to the metal ions removal using the column technique. We have successfully investigated the known concentration of metal ions using various parameters, which is essential for designing a fixed bed column with ligands. The wastewater from electroplating plants used in this study, having chromium, zinc, nickel, copper and iron, etc. For chromium wastewater, ICP analysis showed that the Cr removal was 99.8% and other metal ions such as Cu, Ni, Fe, Zn, Cd, Pb, Co and Mn removal were 94.7%, 99.2%, 99.9%, 99.9%, 99.5%, 99.9%, 95.6% and 97.6%, respectively. In case of cyanide wastewater, the metal removal, especially Ni and Zn removal were 96.5 and 95.2% at higher initial concentration. For acid/alkali wastewater, metal ions removing for Cd, Cr and Fe were 99.2%, 99.5% and 99.9%, respectively. Overall, these ligands are useful for metal removal by column method from industrial wastewater especially plating wastewater.     

Investigation of acetaminophen adsorption with a biosorbent as a purification method of aqueous solution

ABSTRACT

Pharmaceutical compounds are considered emerging environmental pollutants that have a potential harmful impact on environment and human health. In this study, the spiky green horse-chestnut shell was used for the biosorption and removal of acetaminophen from aqueous solution. It was analysed how the parameters, like contact time, pH, mass of biosorbent and temperature, influence the effectiveness of acetaminophen removal from aqueous solutions. The equilibrium was quickly achieved after 10?min (～60%). The amount of acetaminophen adsorption slightly increased with the increase of the mass of biosorbent, and for example for an aqueous solution containing 10?mg/L of acetaminophen adsorption was increased from 62% to 81%. The promising results obtained at pH ranged between 2 and 9, which shows that the adsorption of acetaminophen did not depend on the pH and it may be a consequence of the predominant microporous sorbent and its surface charge. The result is better correlated to a pseudo-second-order kinetic model of type 2 (r ²?=?0.9992) than pseudo-first-order. A sorption mechanism of acetaminophen on biosorbent was also proposed. The sorption of acetaminophen over biosorbent is mainly preceded by hydrophilic interactions between hydroxyl and carbonyl groups in pharmaceutical molecules and hydroxyl and carboxyl groups on the surface of biosorbent.     

Pomegranate husk as an adsorbent in the removal of toxic chromium from wastewater

The use of a new sorbent developed from the husk of pomegranate, a famous fruit in Egypt, for the removal of toxic chromium from aqueous solution has been investigated. The batch experiment was conducted to determine the adsorption capacity of the pomegranate husk. The effects of initial metal concentration (25 and 50 mg l^-1), pH, contact time, and sorbent concentration (2-6 g l^-1) have been studied at room temperature. A strong dependence of the adsorption capacity on pH was observed, the capacity increased as the pH decreased, and the optimum pH value was pH 1.0. Adsorption equilibrium and kinetics were studied with different sorbent and metal concentrations. The adsorption process was fast, and equilibrium was reached within 3 h. The maximum removal was 100% for 25 mg l^-1 of Cr⁶⁺ concentration on 5 g l^-1 pomegranate husk concentration, and the maximum adsorption capacity was 10.59 mg g^-1. The kinetic data were analysed using various kinetic models—pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion equations—and the equilibrium data were tested using several isotherm models, Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich, and Generalized isotherm equations. The Elovich and pseudo-second-order equations provided the greatest accuracy for the kinetic data, while Langmuir and Generalized isotherm models were the closest fit for the equilibrium data. The activation energy of sorption has also been evaluated as 0.236 and 0.707 kJ mol^-1 for 25 and 50 mg l^-1 chromium concentration, respectively.     

Modelling the kinetics and equilibrium properties of cadmium biosorption by river green alga and water hyacinth weed

Cadmium biosorption properties of non-living, dried river green alga from a river source, and water hyacinth weed, Eichhornia crassipes from a lake in Zimbabwe have been investigated. The cadmium uptake was found to depend on initial pH, uptake being apparently minimal at low pH values and increasing with an increase in pH. Cadmium biosorption kinetics by both samples is fast, with 80% of total uptake occurring within 60?min. The effect of initial solution pH and initial cadmium concentration on cadmium biosorption from a cadmium solution has been studied. The data for algal biomass fitted the Langmuir monolayer adsorption isotherm, while the biosorption of the metal by water hyacinth weed fitted the Freundlich adsorption isotherm with 1/n values all less than 1. Maximum metal uptake capacities were recorded using 0.35?g of biomass and a 250?mg?L^?1 cadmium solution at pH 6.5 and at 25°C and these were about 85 and 50?mg?L^?1 for water hyacinth weed and green alga, respectively, showing that water hyacinth weed offered a greater potential for cadmium uptake. The absorption was described by pseudo-second order rate model and the rate constant and equilibrium sorption capacity are reported.     

Biochars derived from carp residues: characteristics and copper immobilization performance in water environments

● P-rich carp residues-derived biochars presented excellent Cu sorption capacity. ● Sorption mechanisms of Cu on CRBs were mainly precipitation and surface complexation. ● CRBs could immobilize Cu and reduce its bioavailability in aquatic environment. Heavy metal pollution has attracted worldwide attention because of its adverse impact on the aquatic environment and human health. The production of biochar from biowaste has become a promising strategy for managing animal carcasses and remediating heavy metal pollution in the aquatic environment. However, the sorption and remediation performance of carp residue-derived biochar (CRB) in Cu-polluted water is poorly understood. Herein, batches of CRB were prepared from carp residues at 450–650 °C (CRB450–650) to investigate their physicochemical characteristics and performance in the sorption and remediation of Cu-polluted water. Compared with a relatively low-temperature CRB (e.g., CRB450), the high-temperature biochar (CRB650) possessed a large surface area and thermodynamic stability. CRB650 contained higher oxygen-containing functional groups and P-associated minerals, such as hydroxyapatite. As the pyrolytic temperature increased from 450 to 650°C, the maximum sorption capacity of the CRBs increased from 26.5 to 62.5 mg/g. The adsorption process was a type of monolayer adsorption onto homogenous materials, and the sorption of Cu²⁺ on the CRB was mainly based on chemical adsorption. The most effective potential adsorption mechanisms were in order of electrostatic attraction and cation-π interaction > surface complexation and precipitation > pore-filling and cation exchange. Accordingly, the CRBs efficiently immobilized Cu²⁺ and reduced its bioavailability in water. These results provide a promising strategy to remediate heavy metal-polluted water using designer biochars derived from biowastes, particularly animal carcasses.     

Pomegranate husk as an adsorbent in the removal of toxic chromium from wastewater

The use of a new sorbent developed from the husk of pomegranate, a famous fruit in Egypt, for the removal of toxic chromium from aqueous solution has been investigated. The batch experiment was conducted to determine the adsorption capacity of the pomegranate husk. The effects of initial metal concentration (25 and 50 mg l^?1), pH, contact time, and sorbent concentration (2–6 g l^?1) have been studied at room temperature. A strong dependence of the adsorption capacity on pH was observed, the capacity increased as the pH decreased, and the optimum pH value was pH 1.0. Adsorption equilibrium and kinetics were studied with different sorbent and metal concentrations. The adsorption process was fast, and equilibrium was reached within 3 h. The maximum removal was 100% for 25 mg l^?1 of Cr⁶⁺ concentration on 5 g l^?1 pomegranate husk concentration, and the maximum adsorption capacity was 10.59 mg g^?1. The kinetic data were analysed using various kinetic models—pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion equations—and the equilibrium data were tested using several isotherm models, Langmuir, Freundlich, Tempkin, Dubinin–Radushkevich, and Generalized isotherm equations. The Elovich and pseudo-second-order equations provided the greatest accuracy for the kinetic data, while Langmuir and Generalized isotherm models were the closest fit for the equilibrium data. The activation energy of sorption has also been evaluated as 0.236 and 0.707 kJ mol^?1 for 25 and 50 mg l^?1 chromium concentration, respectively.     

焙烧态镁铝铁类水滑石对磷酸根离子的吸附

用共沉淀法制备了镁铝铁三元类水滑石(LDH),在不同温度下对其焙烧4 h,得到焙烧态类水滑石(CLDH).采用XRD、FT-IR对材料进行分析,研究其对水中磷酸根的吸附性能和机制.结果表明,铁的掺杂量过大会破坏类水滑石的层状结构,且随着铁含量的增大,类水滑石对磷酸根的吸附量逐渐减小.当Mg/Al/Fe物质的量之比为2∶0.9∶0.1,在300℃下焙烧时,CLDH吸附磷酸根能力最好,吸附容量约27.03 mg.g-1,为焙烧前的1.32倍.在pH 4—11范围内,在竞争离子存在的条件下,CLDH-0.1-300都能表现出较好的吸附性能,对实际废水中的磷也有较强的吸附能力.CLDH-0.1-300对磷酸根的吸附符合二级反应动力学模型,吸附等温线符合Langmuir等温式.用浓度为0.5 mol.L-1的NaOH溶液可以对吸附磷酸根后的类水滑石CLDH-0.1-300实现解吸再生,"吸附-再生-再吸附"循环3次后吸附容量仍接近初始值的60%.     

Kinetic and mechanism studies of the adsorption of lead onto waste cow bone powder (WCBP) surfaces

This study examines the adsorption isotherms, kinetics and mechanisms of Pb2(+) sorption onto waste cow bone powder (WCBP) surfaces. The concentrations of Pb2(+) in the study range from 10 to 90 mg/L. Although the sorption data follow the Langmuir and Freundlich isotherm, a detailed examination reveals that surface sorption or complexation and co-precipitation are the most important mechanisms, along with possibly ion exchange and solid diffusion also contributing to the overall sorption process. The co-precipitation of Pb2(+) with the calcium hydroxyapatite (Ca-HAP) is implied by significant changes in Ca2(+) and PO?3? concentrations during the metal sorption processes. The Pb2(+) sorption onto the WCBP surface by metal complexation with surface functional groups such as ≡ POH. The major metal surface species are likely to be ≡ POPb(+). The sorption isotherm results indicated that Pb2(+) sorption onto the Langmuir and Freundlich constant q(max) and K( F ) is 9.52 and 8.18 mg g?1, respectively. Sorption kinetics results indicated that Pb2(+) sorption onto WCBP was pseudo-second-order rate constants K? was 1.12 g mg?1 h?1. The main mechanism is adsorption or surface complexation (≡POPb(+): 61.6%), co-precipitation or ion exchange [Ca?(.)?? Pb?(.)?? (PO?)? (OH): 21.4%] and other precipitation [Pb 50 mg L?1 and natural pH: 17%). Sorption isotherms showed that WCBP has a much higher Pb2(+) removal rate in an aqueous solution; the greater capability of WCBP to remove aqueous Pb2(+) indicates its potential as another promising way to remediate Pb2(+)-contaminated media.     

Lead(II) and cadmium(II) removal from aqueous solution using processed walnut shell: kinetic and equilibrium study

The biosorption potential of processed walnut shell for Pb(II) and Cd(II) ions from aqueous solutions was explored. The effects of pH, contact time, initial ion concentration, and amount of dried adsorbent were studied in batch experiments. The maximum adsorption was achieved within the pH range 4.0–6.0. The equilibrium data were well fitted by the Langmuir isotherm model. The maximum monolayer adsorption capacities were found to be 32?g?kg^?1 and 11.6?g?kg^?1 for Pb(II) and Cd(II) ions, respectively. Kinetic data were best described by the pseudo-second-order model. The structural features of the adsorbent were characterized by Fourier transform infrared spectroscopy, which confirmed the involvement of hydroxyl (–OH), carboxyl (–COO^–), and carbonyl (C=O) groups in metal sorption. This readily available adsorbent is efficient in the uptake of Pb(II) and Cd(II) ions from an aqueous solution and could be used for the treatment of wastewater streams bearing these metal ions.     

Sorption of cadmium(II) and copper(II) by soil humic acids: temperature effects and sorption heterogeneity

Sorption by humic acids is known to modify the bioavailability and toxicity of metals in soils and aquatic systems. The sorption of cadmium(II) and copper(II) to two soil humic acids was measured at pH 6.0 using ion-selective electrode potentiometric titration at different temperatures. Sorption reactions were studied with all components in aqueous solution, or with the humates in suspension. Adsorption reactions were described using a multiple site-binding model, and a model assuming a continuous log-normal distribution of adsorption constants. Adsorption of Cu²⁺ was more favourable than adsorption of Cd²⁺. The log-normal distribution model provided the closest fit to observations and allowed parameterisation of adsorption data using a mean adsorption constant (log K _μ). Sorption of Cd²⁺ to dissolved humic acids increased slightly in extent and sorption affinity with increasing temperature, but the effect was small (log K _μ 2.96–3.15). A slightly greater temperature effect occurred for sorption of Cd²⁺ to solid-phase humic acids (log K _μ 1.30–2.08). Sorption of copper(II) to both aqueous- and colloidal-phase humates showed more pronounced temperature dependence, with extent of sorption, and sorption affinity, increasing with increasing temperature (log K _μ 3.4–4.9 in solution and 1.4–4.5 in suspension). The weaker adsorption of Cd²⁺ than Cu²⁺, and smaller temperature effects for dissolved humates than suspended humates, suggested that the observed temperature effects had a kinetic, rather than thermodynamic, origin. For any metal-to-ligand ratio, free metal ion concentration, and by inference metal bioavailability, decreased with increasing temperature. The consistency of the data with kinetic rather than thermodynamic control of metal bioavailability suggests that equilibrium modelling approaches to estimating bioavailability may be insufficient.     

生物源提取液与工业废水对土壤中Ni、Co的活化研究

研究了酢浆草提取液(OX)、猪粪提取液(PM)以及味精厂废水(MGW)对土壤中Ni、Co的作用。结果表明，OX提取液原液对土壤中的Ni、Co有较好的活化作用，其活化比例分别达到4．8％和14．6％，但稀释后效果大幅度下降；MGW原液可活化土壤中的1．6％的Ni，但对Co的活化效果较差；PM提取液则对土壤中的重金属起到一定的固定作用。OX提取液的pH值与Ni、Co总活化比例之间呈显著幂相关，可能是由于受到多种酸性活性成分的影响所致。     

Contribution of black carbon to nonlinearity of sorption and desorption of acetochlor on sediment

In order to investigate the contribution of various black carbon (BC) contents to nonlinearity of sorption and desorption isotherms for acetochlor on sediment, equilibrium sorption and desorption isotherms were determined to measure sorption and desorption of acetochlor in sediment amended with various amounts of BC. In this paper, two types of BC referred to as BC400 and BC500 were prepared at 400°C and 500°C, respectively. Higher preparation temperature facilitated the formation of micropores on BC to enhance its sorption capacity. Increase of the BC content obviously increased the sorption amount and reduced the desorption amount for acetochlor. When the BC500 contents in total organic carbon (TOC) increased from 0 to 60%, Freundlich sorption coefficient (K _f) increased from 4.07 to 35.74, and desorption hysteresis became gradually obvious.When the content of BC in TOC was lower than 23%, the sorption isotherm had a significant linear correlation (p = 50.05). In case of desorption, a significant nonlinear change could be observed when the content of BC was up to 13%. Increase of BC content in the sediment would result in shifting the sorption-desorption isotherms from linearity to nonlinearity, which indicated that contribution of BC to nonlinear adsorption fraction became gradually remarkable.     

Phenanthrene adsorption by soils treated with humic substances under different pH and temperature conditions

The mobility of phenanthrene (PHE) in soils depends on its sorption and is influenced by either the existing soil humus or exogenous humic substances. Exogenous humic acids (HAs) were added to soil to enhance the amount of soil organic carbon (SOC) by 2.5, 5.0, and 10.0 g kg⁻¹. PHE desorption of the treated soils was determined at two pH levels (3.0 and 6.0) and temperatures (15 and 25 °C). Soil PHE adsorption was related to pH and the type and quantity of added HAs. Humic acid (HA) and fulvic acid (FA) derived from peat had different effects on adsorption of PHE. Adsorption increased at first and then decreased with increasing quantity of exogenous FA. When the soil solution pH (in 0.005 M CaCl₂) was 4.5 or 3.0, the turning points were 2.5 g FA kg⁻¹ at pH 3.0 and 5 g FA kg⁻¹ at pH 4.5. When soil solution pH was 6, the amount of adsorbed PHE was enhanced with increasing exogenous HAs (HA or FA) and amount of adsorption by soil treated with FA was higher than with HA. Adsorption of PHE in the FA treatment at 10.0 g kg⁻¹ was lower than the controls (untreated soil or treatment with HAs at 0 g kg⁻¹) when the soil solution pH was 3.0. This suggests that FA adsorbed by soil was desorbed at low pH and would then increase PHE solubility, and PHE then combined with FA. PHE adsorption was usually higher under lower pH and/or lower temperature conditions. PHE sorption fitted the Freundlich isotherm, indicating that exogenous humic substances influenced adsorption of phenanthrene, which in turn was affected by environmental conditions such as pH and temperature. Thus, exogenous humic substances can be used to control the mobility of soil PAHs under appropriate conditions to decrease PAH contamination.     

石英砂负载氧化铁吸附除锑的研究

考察了石英砂负载氧化铁(IOCS)在不同的实验条件下(无机阴离子种类及其离子强度、 pH值、IOCS投加量、温度等)对水溶液中锑的去除效果.结果表明:三种无机阴离子(NO-3,Cl-,SO2-4)对IOCS吸附锑的去除率、吸附容量以及反应速率几乎没有影响;在pH3-9范围内,锑的去除率达到90%.二级反应动力学模型及Langmuir等温吸附模型可分别较好地描述锑的吸附动力学及吸附等温线实验结果.随着温度的增加,反应速率以及吸附容量也随之增加.     

Removal of toxic chromium(VI) from aqueous solution by activated carbon using Casuarina equisetifolia

Highly activated carbon from the seed husk of Casuarina Casuarinas equisetifolia, a worldwide famous plant, have been prepared and tested for the removal of toxic Cr(VI) from its aqueous solution. The adsorbent was investigated for influences of initial chromium concentration (75, 100, 125, and 150 mg l^-1), pH, contact time, and quantity of carbon on removal of Cr(VI) from aqueous solution at room temperature (25±2 °C). The adsorption kinetic of Cr(VI) was studied, and the rates of sorption were found to conform to pseudo-second-order kinetics with a good correlation (R²≥0.99). The Langmuir and Freundlich models fit the isotherm data well. Furthermore, the Gibbs free energy was obtained for each system and was found to be-5.29 kJ mol^-1 for removal of Cr(IV). The negative value of Δ G° indicates the feasibility and spontaneous nature of adsorption. The results indicate that acidic pH (1.05) supported the adsorption of Cr(IV) on activated carbon. The maximum adsorption capacity of Cr(VI) on activated carbon was about 172.4 mg g^-1 at pH 1.05.     

Sorption of Isoproturon and Dimetomorph on lignocellulose from wheat

The adsorption of toxic chemicals on solid substates is a potential means to clean polluted waters. Here, the adsorption of two pesticides, isoproturon and dimetomorph, on lignocellulose extracted from wheat straw is investigated at 20 °C using batch adsorption experiments. Here, we show that the sorption of both pesticides is independent of pH. The sorption capacity of lignocellulose is evaluated. We show that the presence of metallic cations has no influence on the retention capacity of lignocellulose towards pesticides.