Use of silica-immobilized humin for heavy metal removal from aqueous solution under flow conditions

Humin extracted from Sphagnum peat moss was immobilized in a silica matrix and column experiments were performed in order to evaluate the removal and recovery of metal ions from aqueous solution under flow conditions. These experiments also allowed testing the recycling capacity of the column. Single-element solutions of Cu(II) and Pb(II), and a multi-metal solution containing Cd(II), Cu(II), Pb(II), Ni(II), and Cr(III) were passed through the columns at a flow rate of 2 ml/min. A 0.5 M sodium citrate solution was used as the stripping agent in the metal-ion recovery process. Humin immobilized in the silica matrix exhibited a similar, and in some cases, even a higher capacity than other biosorbents for the removal of metal ions from aqueous solutions under flow conditions. The sodium citrate was effective in removing Cu(II), Pb(II), Cd(II), and Ni(II) from the metal saturated column. The selectivity of the immobilized biomass was as follows: Cr(III)>Pb(II)>Cu(II)>Cd(II)>Ni(II). This investigation provides a new, environmentally friendly and cost-effective possibility to clean up heavy-metal contaminated wastewaters by using the new silica-immobilized humin material.     

Comparative study of biosorption of heavy metals using different types of algae

Sorption capacity of six different algae (green, red and brown) was evaluated in the recovery of cadmium, nickel, zinc, copper and lead from aqueous solutions. The optimum sorption conditions were studied for each monometallic system. The optimum pH was 6 for the recovery of Cd, Ni and Zn, and less than 5 for Cu and Pb. The best results were obtained with the lowest biomass concentration used (0.5 g/L). Experimental data fitted a Langmuir model very well according to the following sequence of the sorption values: Pb>Cd> or =Cu>Zn>Ni. The brown algae achieved the lowest metal concentration levels in solution; the best results were obtained with Fucus spiralis. Finally, a software computer program was used to simulate the process by comparison of theoretical with experimental results and show minimum differences between both types of data.     

Biosorption of Cu2+, Cd2+, Pb2+, and Zn2+ using dried marine green macroalga Caulerpa lentillifera

The sorption of Cu2+, Cd2+, Pb2+, and Zn2+ by a dried green macroalga Caulerpa lentillifera was investigated. The removal efficiency increased with pH. The analysis with FT-IR indicated that possible functional groups involved in metal sorption by this alga were O-H bending, N-H bending, N-H stretching, C-N stretching, C-O, SO stretching, and S-O stretching. The sorption of all metal ions rapidly reached equilibrium within 20min. The sorption kinetics of these metals were governed by external mass transfer and intraparticle diffusion processes. The sorption isotherm followed the Langmuir isotherm where the maximum sorption capacities was Pb2+>Cu2+>Cd2+>Zn2+.     

Equilibrium and kinetic studies on biosorption potential of charophyte biomass to remove heavy metals from synthetic metal solution and municipal wastewater

The risk of heavy metal contamination in domestic water causes serious health and environmental problems. Biosorption has been considered as an efficient and alternative way for treatment of heavy metal–contaminated wastewater. The potentials of dried charophytes, Chara aculeolata and Nitella opaca, to biosorb lead (Pb), cadmium (Cd), and zinc (Zn) from synthetic solutions and municipal wastewater were investigated. The efficiency of metal removal was studied under varied conditions in different sorbent dosages, pH, and contact times. Biosorption isotherm and kinetics were used to clarify heavy metal preference and biosorption mechanism. C. aculeolata and N. opaca performed well in the biosorption of all three metal ions, with preference towards Pb, followed by Cd and Zn, in the single-metal solutions. Pb adsorption onto algal biomass followed first-order rate kinetics (N. opaca) and intraparticle diffusion (C. aculeolata and N. opaca). These results indicated physical adsorption process between Pb ions and both algal biomasses. Cd and Zn biosorption kinetics fitted the second-order rate model, indicating chemical adsorption between metal ions and both algae. The experimental data of three-metal biosorption fitted well to Langmuir isotherm model, suggesting that the metal ion adsorption occurred in a monolayer pattern on a homogeneous surface. C. aculeolata exhibited slightly higher maximum uptake of Pb, Cd, and Zn (105.3 mgPb/g, 23.0 mgCd/g, 15.2 mgZn/g) than did N. opaca (104.2 mgPb/g, 20.5 mgCd/g, 13.4 mgZn/g). In multi-metal solutions, antagonistic effect by metal competition was observed. The ability of charophytes to remove Pb and Zn was high in real municipal water (81–100%). Thus, the charophytic biomass may be considered for the treatment of metal contamination in municipal wastewater.     

Batch and column studies of biosorption of heavy metals by Caulerpa lentillifera

The biosorption of Cu(II), Cd(II), and Pb(II) by a dried green macroalga Caulerpa lentillifera was investigated. The sorption kinetic data could be fitted to the pseudo second order kinetic model. The governing transport mechanisms in the sorption process were both external mass transfer and intra-particle diffusion. Isotherm data followed the Sips isotherm model with the exponent of approximately unity suggesting that these biosorption could be described reasonably well with the Langmuir isotherm. The maximum sorption capacities of the various metal components on C. lentillifera biomass could be prioritized in order from high to low as: Pb(II)>Cu(II)>Cd(II). The sorption energies obtained from the Dubinin-Radushkevich model for all sorption systems were in the range of 4-6 kJ mol(-1) indicating that a physical electrostatic force was potentially involved in the sorption process. Thomas model could well describe the breakthrough data from column experiments. Ca(II), Mg(II), and Mn(II) were the major ions released from the algal biomass during the sorption which revealed that ion exchange was one of the main sorption mechanisms.     

Petiolar felt-sheath of palm: a new biosorbent for the removal of heavy metals from contaminated water.

Biosorption of heavy metals such as Pb2+, Ni2+, Cd2+, Cu2+, Cr3+ and Zn2+ by petiolar felt-sheath of palm (PFP) from contaminated water was examined. PFP was found to efficiently remove all the toxic metal ions with selectivity order of Pb2+ > Cd2+ > Cu2+ > Zn2+ > Ni2+ > Cr3+. The uptake was rapid, with more than 70% completed within 15 min. The bound metal ions were successfully desorbed and the PFP fibrous-biomass remained effective after several adsorption-desorption cycles.     

The Adsorption Properties of Agricultural and Forest Soils Towards Heavy Metal Ions (Ni,Cu, Zn,and Cd)

Adsorption of Cu, Cd, Ni, and Zn in single and multi-metal solutions by agricultural and forest soils was investigated in batch sorption experiments. The results showed significant differences in sorption capacities of the studied soils. The selectivity order was as follows: agricultural soil? top forest soil > bottom forest soil. The adsorption sequence Cu > Zn > Ni > Cd was established for the agricultural and bottom forest soil, while the order for the top forest soil was Cu > Ni > Zn > Cd. The experimental isotherms for the metal sorption were described satisfactorily by the Freundlich and Langmuir models. The competitive adsorption experiment indicated a reduction in the amount of metals adsorbed by the soils from the multi-metal solution compared to the single metal solution. Properties of the soils, such as pH, content of clay and organic matter, exchangeable bases and hydrolytic acidity, showed a significant influence on adsorption capacities of the studied soils.     

Role of the Ca-pectates on the accumulation of heavy metals in the root apoplasm

In order to better understand the processes that regulate the accumulation in the apoplasm of heavy metals and their mobilization by the plant metabolites it is essential to study the mechanisms that regulate the interactions between metal ions and pectins. In such a context, the sorption of Cd(II), Zn(II), Cu(II) and Pb(II) from single and multi-metal solutions, by a Ca-polygalacturonate gel with a degree of esterification of 18.0 (PGAM₁) and 65.5% (PGAM₂) was studied in the 3.0–6.0 pH range in the presence of CaCl₂ 2.5 mM. The sorption of Cr(III) from single metal solution was also considered. The results show that the amount of each metal ion sorbed increases with increasing the initial metal ion concentration and pH. The data from the single metal solution tests show that at pH 6.0 the affinity of the metal ions towards the PGAM₁ matrix follows the order: Cr(III) > Cu(II) ? Pb(II) ? Zn(II) ? Cd(II). The simultaneous sorption of the bivalent metal ions by the PGAM₁ gels indicates that Pb(II) is selectively sorbed. The FT-IR spectra show that the carboxylate groups are mainly responsible for the metal ion coordination. The ability of PGAM₂ to accumulate Cr(III), Cu(II), and Pb(II) was lower than that found in the PGAM₁ systems whereas the sorption of Zn(II) and Cd(II) was negligible.     

Removal of lead from aqueous solutions by Penicillium biomass

The removal of lead ions from aqueous solutions by adsorption on nonliving Penicillium chrysogenum biomass was studied. Biosorption of the Pb(+2) ion was strongly affected by pH. Within a pH range of 4 to 5, the saturated sorption uptake of Pb(+2) was 116 mg/g dry biomass, higher than that of activated charcoal and some other microorganisms. At pH 4.5, P. chrysogenum biomass exhibited selectivity for Pb(+2) over other metal ions such as Cd(+2), Cu(+2), Zn(+2), and As(+3) Sorption preference for metals decreased in the following order: Pb > Cd > Cu > Zn > As. The sorption uptake of Pb(+2) remained unchanged in the presence of Cu(+2) and As(+3), it decreased in the presence of Zn(+2), and increased in the presence of Cd(+2). (c) 1993 John Wiley & Sons, Inc.     

Description of two-metal biosorption equilibria by Langmuir-type models

A biosorbent prepared from Ascophyllum nodosum seaweed biomass, FCAN2, was examined for its sorption capacity. Equilibrium batch sorption studies were performed using two-matal systems containing either (Cu + Zn), (Cu + Cd), or (Zn + Cd). In the evaluation of the two-metal sorption system performance, simple isotherm curves had to be replaced by three-dimensional sorption isotherm surfaces. In order to describe the isotherm surfaces mathematically, three Langmuir-type models were evaluated. The apparent one-parameter Langmuir constant (b) was used to quantify FCAN2 "affinity" for one metal in the presence of another one. The uptake of Zn decreased drastically when Cu or Cd were present. The uptake of Cd wasmuch more sensitive to the presence of Cu than to that of Zn. The presence of Cd and Zn alter the "affinity" of FCAN2 for Cu the least at high Cu equilibrium concentrations. The mathematical model of the two-metal sorption system enabled quantitative estimation of one-metal (bio)sorption inhibition due to the influence of a second metal. (c) 1995 John Wiley & Sons Inc.     

Mineral and chemical characteristics,textural parameters,and the mobility of the selected elements of flotation waste,originating from the Polish copper-mining industry

This article discusses the mineralogy and geochemical characteristics of the fresh copper-flotation waste samples. The mobility of As, Cd, Cr, Cu, Ni, Pb, Tl, Zn was investigated by leaching tests. The main mineral phases identified concerned dolomite, quartz, clay minerals, feldspars, and copper-bearing minerals. Chemically, CaO and silica were dominating, along with a significant concentration of precious (Cu), refractory (Cr, Ti, V, Zr), and toxic (As, Cd, Pb) metals. Elements were bound mainly to the residual fraction and sulphides in the following order: Pb > Cu ≈ Tl > As ≈ Zn > Ni ≈ Cr > Cd. The metal mobility patterns expressed as a percentage of total concentrations, were as follows: Cd (42%) > Cr (26%)> Ni (24%) > Zn (23%) > As (22%) > Tl (20%) > Cu (18%) > Pb (2%). Those constituents were released earlier in lower pH values, although Cu, Cr, and Pb were also released in higher alkaline pH values. However, Zn release was not dependent on pH. When L/S values decreased, elements like As, Cr, Cu, Pb, and Tl were released. That process caused decrease of Cd, Ni, and Zn release.     

Fingernails as biological indices of metal exposure

Metal determination in human tissues is the most common application of biological monitoring for screening, diagnosis and assessment of metal exposures and their risks. Various biopsy-materials may be used. This paper deals with the quantitative determination of Cd, Pb, Cr, Mn, Fe, Ni, Cu, and Zn concentrations in nails of male subjects exposed to these metals alongwith their respective controls, while working in locomotive, carriage and roadways workshops, and lead battery factories. The levels of Cd, Pb, Cr, Mn, Fe, Ni, Cu and Zn in fingernails, assayed by atomic absorption spectrophotometry, were compared with their respective controls by student ‘t’ test. All the obtained values were correlated to the personal and medical history of the subjects under study. Significantly high levels of Cd, Pb, Cr, Fe, Ni, Cu and Zn were present in smokers, compared to nonsmokers. The concentrations of Cd, Pb, Cr, Mn and Fe were not significantly high in vegetarian subjects. It was also observed that there is no contribution of liquor towards nail-metal concentration. Significant correlations were observed between skin disease and Cr, Mn, Fe, Cu; hypertension and Cd, Mn, Cu; mental stress and Cd, Pb, Mn, Ni, Cu, Zn; diabetes and Cr, Mn, Ni; chest pain and Pb; respiratory trouble and Cr, Mn, Fe, Ni, Zn; tuberculosis and Zn; acidity and Cd; and ophthalmic problems and Mn, Fe, Ni, and Zn     

浙江油茶产地土壤和果实金属元素含量特征

为探讨油茶(Camellia oleifera)产地土壤和油茶果实中金属元素分布和富集特征,在油茶果实成熟期,对浙江5个油茶产地土壤及油茶果实中金属元素进行污染分析和富集能力评价.结果表明,浙江油茶产地土壤中Pb、Cr、Cd、As、Hg、Ni、Cu和Zn含量低于农用地土壤污染风险筛选值,综合污染等级为安全.个别产区常山...     

Improvement of heavy metal biosorption by mycelial dead biomasses (Rhizopus arrhizus, Mucor miehei and Penicillium chrysogenum): pH control and cationic activation

Abstract: Fungal mycelial by-products from fermentation industries present a considerable affinity for soluble metal ions (e.g. Zn, Cd, Ni, Pb, Cr, Ag) and could be used in biosorption processes for purification of contaminated effluents. In this work the influence of pH on sorption parameters is characterized by measuring the isotherms of five heavy metals (Ni, Zn, Cd, Ag and Pb) with Rhizopus arrhizus biomass under pH-controlled conditions. The maximum sorption capacity for lead was observed at pH 7.0 (200 mg g^-l), while silver uptake was weakly affected. The stability of metal-biosorbent complexes is regularly enhanced by pH neutralization, except for lead. A transition in sorption mechanism was observed above pH 6.0. In addition, comparison of various industrial fungal biomasses ( R. arrhizus, Mucor miehei and Penicillium chrysogenum indicated important variations in zinc-binding and buffering properties (0.24, 0.08 and 0.05 mmol g^−l, respectively). Without control, the equilibrium pH (5.8, 3.9 and 4.0) is shown to be related to the initial calcium content of the biosorbent, pH neutralization during metal adsorption increases zinc sorption in all fungi (0.57, 0.52 and 0.33 mmol g-l) but an improvement was also obtained (0.34, 0.33 and 0.10 mmol g⁻¹) by calcium saturation of the biomass before heavy metal accumulation. Breakthrough curves of fixed bed biosorbent columns demonstrated the capacity of the biosorbent process to purify zinc and lead solutions in continuous-flow systems, and confirmed the necessity for cationic activation of the biosorbent before contact with the heavy-metal solution.     

Biosorption of nickel and cadmium by metal resistant bacterial isolates from agricultural soil irrigated with industrial wastewater

Agricultural soil irrigated with industrial wastewater (more than two decades) analysed for heavy metals revealed high levels of Fe, Cr, Cu, Zn, Ni and Cd. Out of a total of 40 bacterial isolates obtained from these soils, 17 belonged to the family enterobacteriaceae and 10 were Pseudomonas spp. A maximum MIC of 200 for Cd, 400 for Zn and Cu, 800 for Ni, and 1600 microg/ml for Pb was observed. Biosorption of Ni and Cd studies over a range of metal ion concentrations with Escherichia coli WS11 both in single and bi-metal systems showed that the adsorption of Cd and Ni was dependent on the concentrations and followed the Freundlich adsorption isotherm. The biosorption of Ni increased from 6.96 to 55.31 mg/g of cells, and Cd from 4.96 to 45.37 mg/g of cells at a concentration ranging from 50 to 400 microg/ml after 2h of incubation in a single metal solution. A further increase in incubation time had no significant effect on the biosorption of metals.     

Heavy metal removal in a biosorption column by immobilized M. rouxii biomass

Mucor rouxii biomass was immobilized in a polysulfone matrix. The spherical immobilized biomass beads were packed in a column. The biosorption column was able to remove metal ions such as Pb, Cd, Ni and Zn not only from single-component metal solutions but also from multi-component metal solutions. Column kinetics for metal removal were described by the Thomas model. For single-component metal solutions, the metal removal capacities of the beads for Pb, Cd, Ni and Zn were 4.06, 3.76, 0.36 and 1.36 mg/g, respectively. For a multi-component metal solution containing Cd, Ni and Zn, the capacities were 0.36, 0.31 and 0.40 mg/g for Cd, Ni and Zn, respectively. The adsorbed metal ions were easily desorbed from the beads with 0.05N HNO3 solution. After acid desorption and regeneration with deionized water, the beads could be reused to adsorb metal ions at a comparable capacity.     

Solid-Phase Chemical Fractionation of Selected Trace Metals in Some Northern Kentucky Soils

The fractionation and distribution with depth of Cd, Cr, Cu, Ni, Pb, and Zn in 26 soils of Northern Kentucky were determined through a sequential extraction procedure in response to environmental concerns about increasing anthropogenic inputs in a fast-paced, urbanizing area. The selected sites have not received any biosolid- or industrial-waste applications. Average total concentrations per metal in soil profiles derived from alluvial, glacial till, and residual materials ranged from 0.43 to 56.00 mg kg^?1 in the sequence Zn > Ni > Pb > Cr > Cu > Cd, suggesting relatively small anthropogenic inputs. The distribution of Cu, Cr, Ni, and Zn increased with soil depth, whereas Cd and Pb remained stable, indicating a strong geological or pedogenic influence. Residual forms were most important for the retention of Cu, Zn, and Ni. Cadmium and Pb exhibited a strong affinity for the Fe-Mn oxide fraction, while Cr showed the strongest association with the organic fraction. In terms of metal mobility and toxicity potential inferred from metal concentrations in labile fractions, Cd posed the greatest risk, followed by Cr ～ Pb > Ni > Zn > Cu. Soil pH, OM, and clay content were the most important parameters explaining the partitioning of metals in labile and residual fractions, emphasizing the importance of metal fractionation in soil management decisions. Alluvial soils generally contained the highest total and labile metal concentrations, suggesting potential metal enrichment through anthropogenic additions and depositional processes. These environments exhibit the highest risk for metal mobilization due to drastic changes in redox conditions, which can destabilize existing metal retention pools.     

刺楸年轮中重金属含量动态变化及富集特性

为探索刺楸对受污染土壤重金属的富集和修复效应, 以南京栖霞山的乡土树种刺楸及其根际周边土壤为研究对象, 截取其根基部年轮盘及根际土壤样本, 采用ICP-AES法测定年轮及土壤样本中重金属(Cu、Cd、Cr、Mn、Ni、Pb、Zn)元素含量。结果表明: 栖霞山样地中的土壤受Mn、Pb和Zn污染最为严重, 存在Cu、Cd、Mn、Pb、Zn元素的高度复合污染, Cd、Cr、Cu、Ni、Zn在土壤和年轮中存在相关性, Mn和Pb则没有表现出明显的相关性; 刺楸修复受Cd、Mn、Pb、Zn污染的土壤效果并不显著, 更适用于Cr、Cu、Ni污染的土壤修复; 鉴于Cu元素含量变化特征, 刺楸也可以作为反映当地污染历史的记录载体; 刺楸年轮中的重金属元素之间存在交互作用, 其中Cd与Zn元素含量高度相关(r=0.984, p<0.01), 在刺楸年轮吸收重金属元素的过程中, Cu与Cd、Cr、Mn、Zn元素具有协同作用, Mn元素对其他元素有一定的拮抗作用。     

Simultaneous production of pullulan and biosorption of metals by Aureobasidium pullulans strain CH-1 on peat hydrolysate

It was demonstrated that during the growth of Aureobasidium pullulans strain CH-1 on the acid hydrolysate of peat from the Vlasina Lake, the content of metals (Cu, Fe, Zn, Mn, Pb, Cd, Ni and Cr) decreased due to biosorption. The reduction in the metal content was found to be in the range (%): 38.2-62.2, 67.7-97.3, 0.02-62.05, 0.05-23.97, 0.16-4.24, 3.45-51.72, 1.18-35.82, 0.86-44.44, for Cu, Fe, Zn, Mn, Pb, Cd, Ni and Cr, respectively. During this process, the metals were accumulated in the biomass, while pullulan, an extracellular polysaccharide produced by Aureobasidium pullulans strain CH-1, was found not to bind the above-mentioned metals.     

Heavy metal contamination in vegetables grown around peri-urban and urban-industrial clusters in Ghaziabad,India

Heavy metal contamination of agricultural soils resulting from rapid industrialization and urbanization is of great concern because of potential health risk due to dietary intake of contaminated vegetables. The present study aims to evaluate the status of heavy metals contamination of agricultural soils and food crops around an urban-industrial region in India. Transfer factor values of Cu, Cr, Pb, Cd, Zn, and Ni from soil to vegetable was estimated. The mean heavy metal concentrations (mg/kg) in agricultural soils (Cu: 17.8, Cr: 27.3, Pb: 29.8, Cd: 0.43, Zn: 87, Mn: 306.6, Fe: 16984, and Ni: 53.8) were within allowable concentrations for Indian agricultural soil. The concentrations of Pb, Cd, Zn, and Ni in crops/vegetables exceeded the World Health Organization/Food and Agriculture Organization safe limits. Relative orders of transfer of metals from soil to edible parts of the crops/vegetables were Cd > Pb > Ni > Zn > Cu > Cr. The enrichment factors of heavy metals in soil indicated minor to moderately severe enrichment for Pb, Cd, and Ni; minor to moderate enrichment for Zn; no enrichment to minor enrichment for Mn; and no enrichment to moderate enrichment for Cu at different sites. Ecological risk index of soil showed considerable contamination in one of the wastewater irrigated sites.