Vertical profile and assessment of soil pollution from a typical coking plant by suspect screening and non-target screening using GC/QTOF-MS.

A comprehensive workflow for suspect screening and non-target screening with gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC/QTOF-MS) was used to characterize the pollution characteristics of soil samples in a typical coking plant in China. Suspect screening confirmed 57 chemicals including PAHs, alkyl PAHs, and phthalates contained in high-resolution personal compound database and library (PCDL). Non-target screening detected 88 chemicals from soil samples in the NIST 17 library. A total of 122 chemicals were screened in soil samples, and many of them were of emerging concern. Their presence in the soil obtained from coking operations has been underestimated, such as the oxygenated PAHs (naphtho[2,1-b]furan and 9H-fluoren-9-one), and the alkyl biphenyls compounds (4,4'-dimethylbiphenyl, 3,3'-dimethylbiphenyl, 4-methyl-1,1'-biphenyl and 2,2',5,5'-tetramethyl-1,1'-biphenyl). Toxicity assays by luminescent bacteria proved that the extracts from soil samples at different depths showed varying toxicity to V. qinghaiensis sp.-Q67. Soil extracts from a depth of 20-40 cm exhibited the greatest toxicity to luminescent bacteria compared with the other six-layered soil samples, which was correlated with the number of detectable pollutants and total organic carbon content. This study provided a screening method for suspect and non-target contaminants in urban industrial soil sites, which was important in identifying localized contamination sources.

Using Polychlorinated Naphthalene Concentrations in the Soil from a Southeast China E-Waste Recycling Area in a Novel Screening-Level Multipathway Human Cancer Risk Assessment.

Polychlorinated naphthalene (PCN) concentrations in the soil at an e-waste recycling area in Guiyu, China, were measured and the associated human cancer risk due to e-waste-related exposures was investigated. We quantified PCNs in the agricultural soil and used these concentrations with predictive equations to calculate theoretical concentrations in outdoor air. We then calculated theoretical concentrations in indoor air using an attenuation factor and in the local diet using previously published models for contaminant uptake in plants and fruits. Potential human cancer risks of PCNs were assessed for multiple exposure pathways, including soil ingestion, inhalation, dermal contact, and dietary ingestion. Our calculations indicated that local residents had a high cancer risk from exposure to PCNs and that the diet was the primary pathway of PCN exposure, followed by dermal contact as the secondary pathway. We next repeated the risk assessment using concentrations for other carcinogenic contaminants reported in the literature at the same site. We found that polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and PCNs caused the highest potential cancer risks to the residents, followed by polychlorinated biphenyls (PCBs). The relative importance of different exposure pathways depended on the physicochemical properties of specific chemicals.

Determination of polyhalogenated carbazoles in soil using gas chromatography-triple quadrupole tandem mass spectrometry.

Polyhalogenated carbazoles (PHCZs) are emerging environmental contaminants that have caused wide concerns due to their dioxin-like toxicity and environmental persistence. It would be desirable to determine all of these chemicals using a simple analytical method. Within this study, a simple and sensitive method combining accelerated solvent extraction (ASE) with gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS) was established to simultaneously analyze eleven frequently detected PHCZs in soil, including CCZ-3, CCZ-36, CCZ-1368, CCZ-2367, BCZ-3, BCZ-27, BCZ-36, BCZ-136, BCZ-1368, 1-B-36-CCZ, 18-B-36-CCZ. The calibration curves of the target analytes showed good linearity (R2 > 0.99, level = 6), and method detection limits (MDLs) ranging from 1.5 to 14.6 pg g-1. The average recoveries of the analytes in soil samples ranged from 64% to 126% with the RSD ranging from 2.0% to 10%. The developed method was successfully used for determination of these eleven PHCZs in soil samples from a tie-dye area in southwest China. Total concentrations of these eleven PHCZs ranging up to 46.3 ng g-1 dw. CCZ-36, BCZ-3, CCZ-3, 1-B-36-CCZ, 18-B-36-CCZ, and BCZ-1368 were the most abundant compounds in soil.

Emission characteristics of polychlorinated, polybrominated and mixed polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, PBDD/Fs, and PBCDD/Fs) from waste incineration and metallurgical processes in China.

Typical thermal processes are common sources of polychlorinated, polybrominated and mixed polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, PBDD/Fs, and PBCDD/Fs); however, very few reports have investigated their coemission. To clarify the emission characteristics of these DD/Fs, two municipal waste incinerators (MWIs), three hazardous waste incinerators (HWIs), one cement kiln coprocessing municipal waste incinerator (CMWI), one secondary copper smelter (SCu), and one iron and steel sintering smelter (ISS) in China were investigated. In total, 17 congeners of PCDD/Fs, 14 congeners of PBDD/Fs, and 12 congeners of PBCDDs in stack flue gases from these thermal processes were analyzed using a high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) in this study. PCDD/Fs, PBDD/Fs and PBCDD/Fs were detectable in all samples, with total concentrations of 911-5.15 × 103 pg/Nm3 (80.2-414 pg TEQ/Nm3). The concentrations of each DD/F were similar within the same type of facility and varied among different types of facilities. The contributions of PBDD/Fs and PBCDD/Fs to the total concentrations exceeded that of PCDD/Fs in some cases, such as in HWIs and SCu. In general, the ∑Cl4-7 CDFs and ∑Cl7-8 CDDs, 1,2,3,4,6,7,8-HpBDF, and 1-B-2,3,7,8-TeCDD and 2-B-1,3,7,8-TeCDD were the dominant congeners in the PCDD/F, PBDD/F, and PBCDD/F mass concentrations, respectively. Several other congeners present at low mass concentrations, such as 1,2,3,4,7,8-HxBDF, have potential as major contributors to the TEQs due to their high toxic equivalency factors. These results reveal the necessity of synergistically inhibiting the occurrences of PCDD/Fs, PBDD/Fs, and PBCDD/Fs from these sources and provide valuable information for use in the source identification of these pollutants in the environment.

Temporal variations of PM2.5-bound organophosphate flame retardants in different microenvironments in Beijing, China, and implications for human exposure.

In the present study, the temporal distribution of PM2.5-bound organophosphate flame retardants (OPFRs) was comprehensively investigated in various indoor environments as well as outdoor air in Beijing, China over a one-year period. The mean concentrations of Σ9OPFRs were 22.7 ng m-3 and 1.40 ng m-3 in paired indoor and outdoor PM2.5, respectively. The concentrations of tri-n-butyl phosphate (TNBP), tris (2-chloroethyl) phosphate (TCEP) and tris (2-chloroisopropyl) phosphate (TCIPP) in indoor PM2.5 were significantly correlated with those in outdoor PM2.5. For different indoor microenvironments, mean concentrations of Σ9OPFRs were in the order of office (29.0 ±â€¯11.7 ng m-3) > home (24.0 ±â€¯9.4 ng m-3) > dormitory (19.4 ±â€¯4.9 ng m-3) > activity room (14.4 ±â€¯3.1 ng m-3). TCIPP was the most abundant compound in the indoor PM2.5, followed by TCEP. Significantly higher concentrations of OPFRs were observed in indoor environments with more furnishing, electronics or other materials (p < 0.05). Moreover, lower levels of OPFRs in indoor air were observed at well-ventilated (with higher air exchange rate) indoor sampling sites. Concentrations of Σ9OPFRs in the activity room, dormitory, homes and outdoor sites generally increased in summer and heating seasons (November 2016 to February 2017). Significant correlations (p < 0.05) were observed between temperatures and mass concentrations of OPFRs with higher vapor pressures, i.e. TNBP, TCEP and TCIPP in all indoor and outdoor samples. Seasonal differences in human exposure were observed and the highest daily exposure dose occurred in summer. Toddlers may suffer the highest exposure risk of PM2.5-bound OPFRs via inhalation among all age groups. This is one of the very few studies that have revealed the seasonal variation and human exposure of PM2.5-bound OPFRs in different microenvironments, which shed light on emission sources and fate of OPFRs and potential human exposure pathway.

Distribution of polybrominated diphenyl ethers (PBDEs) in feather and muscle of the birds of prey from Beijing, China.

Polybrominated diphenyl ethers (PBDEs) in the feather and muscle of common kestrels (Falco tinnunculus), eagle owls (Bubo bubo) and little owls (Athene noctua) collected from Beijing, China were investigated. The concentrations of ∑23PBDEs in the muscle and feather of all the birds of prey ranged from 46 to 7.77 × 104 ng/g lipid weight (lw; median 241 ng/g lw) and 1.50-191 ng/g dry weight (dw; median 21.1 ng/g dw), respectively. Higher brominated congeners, e.g., BDE-209, -153, -207 and -196 were the dominant congeners in both feather and muscle. However, the concentrations of lower brominated congeners in feather were significantly correlated with those in muscle (p < 0.05), which suggested that feather could efficiently reflect lower brominated BDEs in the internal tissue of birds of prey. The calculated hazard quotients (HQs) > 10 in common kestrel and little owl suggested that the high levels of PBDEs posed potentially high risk to some birds of prey living in Beijing area.

Trophic transfer of hexabromocyclododecane in the terrestrial and aquatic food webs from an e-waste dismantling region in East China.

Trophic transfer of hexabromocyclododecane (HBCD) was investigated in both the terrestrial and aquatic food webs from an e-waste dismantling region in East China. The mean Σ3HBCD concentrations in the terrestrial species varied from 0.91 (0.16-1.85) ng g-1 lipid weight (lw) in dragonflies (Pantala flavescens) to 40.3 (22.1-51.1) ng g-1 lw in rats (Rattus norvegicus). The isomeric profile indicated that α-HBCD presented a decreasing trend along the trophic level (TL) (from 97.2% to 16.3% of Σ3HBCDs), while γ-HBCD showed a reverse trend (from 2.8% to 73.6% of Σ3HBCDs). The trophic magnification factor (TMF) derived from the slope of the regression line between TLs and ln-transferred Σ3HBCDs was 0.10, suggesting a trophic dilution of HBCD in the terrestrial food web. By contrast, in the aquatic species, Σ3HBCD concentrations varied from 5.02 (3.5-6.55) ng g-1 lw in apple snails (Ampullaria gigas spix) to 45.9 (14.9-67.8) ng g-1 lw in grass carps (Ctenopharyngodon idellus). α-HBCD was the dominant isomer, followed by γ-HBCD in the majority of species. A positive linear relationship was observed in the plots of ln Σ3HBCDs versus TLs (R2 = 0.81, p = 0.06). The TMF for Σ3HBCDs was 6.36, indicating a trophic magnification of HBCD in the aquatic food web. Although these results demonstrated the distinct trophic transfer of Σ3HBCDs in different ecosystems, further research is needed to eliminate the uncertainty of the tendencies, due to the non-significant relationship and limited species.

Temporal and spatial distribution, sources, and potential health risks of ambient polycyclic aromatic hydrocarbons in the Yangtze River Delta (YRD) of eastern China.

In this study, from July 2011 to June 2012, 31 sampling sites were identified in order to investigate the concentrations and sources of polycyclic aromatic hydrocarbons (PAHs), as well as to evaluate their potential health risks in the cities of Suzhou, Wuxi, and Nantong, which are located in the Yangtze River Delta (YRD). The samples were collected by means of passive air sampling (PAS), and the contents of 15 PAHs were detected by gas chromatography-mass spectrometry. The ∑15PAHs concentrations were found to range from 6.48 to 154 ng m-3, with an average value of 56.8 ± 14.8 ng m-3. The pollution levels in Suzhou and Nantong were higher than those in Wuxi. Furthermore, the concentrations of the PAHs in the urban sites were determined to be higher than those in the suburban sites for ambient air. The seasonal average contents were found to be at a maximum in autumn, with concentrations reaching 74.1 ng m-3. Vehicle emissions and coal/biomass combustion were the dominant sources of the PAHs in the ambient air, with the contributions of 48% and 46%, respectively. The BaP TEQ (0.88 ng m-3) was found to have surpassed the Chinese and Japanese dioxin emission limit, and in doing so, may have caused a certain degree of risk to human health.

Occurrence of chiral organochlorine compounds in the environmental matrices from King George Island and Ardley Island, west Antarctica.

Chiral organochlorine compounds (OCs) were measured in various environmental matrices (air, soil and vegetation) from west Antarctica using high resolution gas chromatography coupled with high resolution mass spectrometry (HRGC/HRMS). They were generally detected at a global background level compared with the previous studies. α-HCH and PCB-183 was observed in all the matrices except PCB-183 in two soil samples, while PCB-95, -136, -149, -174, -176 and o,p'-DDT were detected in most air but only a few solid matrices. Enantiomeric fractions (EFs) indicated that nonracemic residues of chiral OCs occurred in all the matrices and a wide variation of the EF values was observed in the vegetation. There was significant discrepancy between the EF values of PCB-183 and the racemic values, indicating that stereoselective depletion of PCB-183 was probably associated with the water-air exchange. The EFs values of α-HCH were generally lower than the racemic values but no statistical difference was obtained in all the matrices except lichen, supporting the assumption that water-air exchange may make influence on long-range transport of α-HCH.

Occurrence of organochlorine pesticides in the environmental matrices from King George Island, west Antarctica.

Antarctica is considered as a final sink of many persistent organic pollutants (POPs). This work aims to investigate the levels, distributions and potential sources of organochlorine pesticides (OCPs) with HRGC/HRMS technique. Twenty-three OCPs were measured in various environmental matrices from King George Island, west Antarctica. The total concentrations (Σ23OCPs) were at quite low levels, ranging 93.6-1260 pg g(-1) dry weight (dw) in soil and sediment, 223-1053 pg g(-1) dw in moss and 373-812 pg g(-1) dw in lichen. Hexachlorobenzene (HCB), dichloro-diphenyl-trichloroethane (DDT) and its metabolites (especially p,p'-DDE) and hexachlorocyclohexanes (HCHs) were the main contaminants in all samples. Lower α-HCH/γ-HCH and higher p,p'-DDE/p,p'-DDT ratios compared with the technical products indicated long-range atmospheric transport (LRAT) of recent lindane and aged technical DDT. Significant dependence of many OCPs concentrations on total organic carbon (TOC) was observed. Apart from LRAT, local biotic activities could also contribute and influence the spatial distribution of the contaminants.

Polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs) in environmental samples from Ny-Ålesund and London Island, Svalbard, the Arctic.

Polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs) were determined in environmental samples collected from Ny-Ålesund and London Island, Svalbard, the Arctic. Total PCB concentrations (∑25PCBs) varied from 0.57 to 2.52 ng g(-1) dry weight (dw) in soil, 0.30 to 1.16 ng g(-1) dw in plants and 0.56 to 0.98 ng g(-1) dw in reindeer dung. The non-Aroclor congener of CB-11 was predominant in most samples compared to other congeners, accounting for 16.0±9.8% to the ∑25PCBs. The ∑13PBDEs concentrations were 1.7-416, 36.7-495 and 28.1-104 pg g(-1) dw in soil, plants and reindeer dung, respectively. The signature of enantioselective biotransformation was observed in all samples for chiral CB-95, whereas in parts of samples for other chiral PCBs. Bioaccumulation factors (BAFs) in six plant species varied within individual contaminant congeners and plant species, with BAFs less than 1 for ∑PCBs and higher than 1 for ∑PBDEs. BAF values decreased with increasing soil concentrations, suggesting that high background levels in soil restricted the accumulation of these contaminants by plants.

Bioconcentration and trophic transfer of polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins and dibenzofurans in aquatic animals from an e-waste dismantling area in East China.

Eight aquatic biota species were collected from an e-waste dismantling area in East China to investigate bioconcentration and trophic transfer of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The mean concentrations of PCBs varied widely from 6.01 × 10(4) to 2.27 × 10(6) pg per g dry weight (dw). The ∑25PCB concentrations in eels were significantly higher than those in other species. The levels of PCDD/Fs changed from 8.13 pg per g dw in toads to 617 pg per g dw in stone snails. World Health Organization-toxic equivalents (WHO2005-TEQs) ranged from 2.57 to 2352 pg WHO-TEQ per g dw with a geometric mean value of 64.7 pg WHO-TEQ per g dw, which greatly exceeded the maximum levels of 4 pg per g ww set by the European Commission. The log-transferred bioconcentration factors (BCFs) of 25 PCB congeners ranged from 1.0 to 6.6, with the highest value for CB-205 in crucian carp and the lowest value for CB-11 in frog. A parabolic correlation was observed between log BCF and log Kow (R(2) = 0.53, p < 0.001), where the maximum value occurred at a log Kow of approximately 7. A similar correlation was also found in the plot of log BCF against the number of chlorine atoms of PCBs (R(2) = 0.57, p < 0.001), indicating that medium-halogenated congeners of PCBs are more easily accumulated by aquatic biota species. There were no significant correlations between the log-transferred concentrations and trophic levels of aquatic species, suggesting that trophic magnification for PCBs and PCDD/Fs was not observed in this study.

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polybrominated diphenyl ethers in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda.

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) were analyzed in sediments and fish from the Murchison Bay of Lake Victoria by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Average concentrations of total (Σ) PCDD/Fs and ΣPBDEs in sediments ranged from 68.8 to 479 pg g(-1) dry weight (dw) and 60.8 to 179 pg g(-1) dw, respectively. Contamination levels of sedimentary PCDD/Fs and PBDEs were low to moderate compared to other urbanized regions worldwide. The concentrations in different fish species (Nile perch; Lates niloticus and Nile tilapia; Oreochromis niloticus) were 5.32 to 49.0 pg g(-1) wet weight (ww) for PCDD/Fs and 59.3 to 495 pg g(-1) ww for PBDEs. Higher concentrations of the pollutants were found in L. niloticus than O. niloticus, which could be attributed to species differences in feeding habits and lifestyles. World Health Organization-toxic equivalents (WHO2005-TEQs) for PCDD/Fs ranged from 0.08 to 0.33 pgTEQg(-1) dw and 0.001-0.14 pg TEQg(-1) ww in sediments and fish, respectively. The TEQ values were low compared to the data for fresh water fish reported in literature and within a permissible level of 3.5 pg g(-1) ww recommended by the European Commission. Based on the Commission set value and minimum risk level criteria formulated by the Agency for Toxic Substances and Disease Registry, the fish from the Murchison Bay was fit for human consumption.

Dioxins contamination in the feed additive (feed grade cupric sulfate) tied to chlorine industry.

The sources of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) found in animal feed additive (feed grade cupric sulfate, CuSO4) were investigated and traced back to the formation of chlorinated organic compounds in the chlor-alkali industry. PCDD/Fs could be transported through the supply chain: hydrochloric acid (HCl) by-produced during formation of chlorinated organic compounds in chlor-alkali industry → spent acid etching solution (acid-SES) generated in printed circuit board production → industrial cupric salt → CuSO4 in animal feed, and finally enter the food chain. The concentration ranges in HCl and acid-SES were similar, of which the level in acid-SES was also consistent with that in various cupric salt products including CuSO4 based on Cu element content. PCDD/Fs also showed very similar congener profiles in all the sample types. This indicates a probable direct transport pathway of PCDD/Fs into the food chain, which may eventually be exposed to humans through consumption. To date this is the first study in China that systematically reports on the PCDD/Fs transport from industrial pollution sources to industrial processes and finally enters the human food chain.

Polychlorinated biphenyls and hexachlorocyclohexanes in sediments and fish species from the Napoleon Gulf of Lake Victoria, Uganda.

Polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs) were analyzed in surface sediments (<30 cm depth) and two fish species: Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus). The samples were collected from the Napoleon Gulf on the northern shore of Lake Victoria. The analysis was done using a gas chromatograph (GC) coupled to a high resolution mass spectrometer for PCBs and a GC equipped with an electron capture detector for HCHs. Total (Σ) PCBs in the muscles of fish varied widely with mean values ranging from 41 to 670 pg g(-1) lipid weight (lw). The PCB levels in L. niloticus were significantly greater than those in O. niloticus. The large variability observed in the data was attributed to differences in feeding habits and trophic levels. While O. niloticus is a filter-eating fish species feeding mainly on phytoplankton and zooplankton, L. niloticus have predatory feeding behaviors and prefer a diet of live fish and, therefore, are more prone to bio-accumulate contaminants. The mean PCB concentrations in the sediments varied from 362 to 848 pg g(-1) dry weight. Variations in PCB levels were observed from one study site to another, this was attributed to the nature and particle size of the sediments. HCH isomers were detected in fish at mean concentrations of up to 45,900 pg g(-1) lw. The PCB and HCH concentrations were lower than those from previous studies elsewhere in literature and were below the maximum residue limits set by the European Commission and FAO/WHO Codex Alimentarius Commission, implying that the fish was fit for human consumption.

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda.

Polychlorinated biphenyls (PCBs) were determined in sediments and two fish species collected from the Murchison Bay in Lake Victoria, using high resolution gas chromatography coupled to a high resolution mass spectrometer. Total PCB concentrations (Σ18PCBs) varied widely with mean values ranging from 777 to 4325pg g(-1) dry weight (dw) for sediments and 80 to 779pg g(-1) wet weight (ww) for fish. The PCB levels in the sediments were significantly higher at the station closest to Nakivubo channel, presumably due to effluents discharged by the channel, which may contain domestically produced commercial PCB mixtures. For fish, the concentrations in Nile perch (Lates niloticus) were significantly greater than those in Nile tilapia (Oreochromis niloticus) at all study stations, possibly due to dietary differences among species. World Health Organization-toxic equivalents (WHO2005-TEQs) for the dioxin-like PCBs were 0.04-0.64pg g(-1) dw and 0.01-0.39pg g(-1) ww for sediments and fish, respectively. The non-ortho PCBs exhibited the highest contribution to the Σ12TEQs (>75%) compared to the mono-ortho PCBs in both fish species. The TEQs in the present study were lower than many reported worldwide in literature for fish and were within the permissible level recommended by the European Commission, implying that the fish did not pose health hazards related to PCBs to the consumers.

[Preparation and performance investigation of Trichoderma viride-modified corn stalk as sorbent materials for oil spills].

This work aims at preparing oil spill sorbent (TCS, Trichoderma viride-modified corn stalk) through solid-state fermentation of corn stalk by Trichoderma viride. Single-factor experiments, including the effect of modification time, solid-liquid ratio of modification and modification temperature, and adsorption experiments simulating oil spill condition, were carried out. The results indicated that the maximum oil adsorption of TCS, 13.84 g x g(-1), could be obtained under the conditions of 6 days of modification, with a solid-liquid ratio of 1:4 and a modification temperature of 25 degrees C. This oil absorption was 110.33% of that of the raw material (RCS, Raw Corn Stalk). Comparing RCS and TCS by means of Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Diffraction (XRD), the results separately showed that TCS had rougher surface, lower cellulose content and higher instability, which explains the increase of oil absorption. Also, the component analysis indicated that bio-modification could reduce the contents of celluloses and hemicelluloses from corn stalk. Besides, sorption kinetics and oil retention performance test showed that, TCS, which could reach adsorption equilibrium after 1 h of 80 r x min(-1) oscillating, had fast oil adsorption rate, and it also had good oil retention performance, which could keep 74. 87% of the initial adsorption rate when trickling 10 min after reaching adsorption equilibrium.

Preparation of cellulose derived from corn stalk and its application for cadmium ion adsorption from aqueous solution.

Cellulose was isolated from corn stalk and modified by graft copolymerization to produce an absorbent material (AGCS-cell), which was characterized by scanning electron microscope and energy disperse spectroscopy (SEM-EDS), X-ray diffraction (XRD) and solid-state CP/MAS (13)C NMR. The results showed that AGCS-cell had better adsorption potential for cadmium ion than unmodified cellulose because of the addition of functional groups (CN and OH groups) and the lower crystallinity. The Langmuir isotherms gave the best fit to the data and gave an adsorption capacity was 21.37 mg g(-1), which was close to unpurified cellulose (AGCS) and reflected the feasibility of using AGCS-cell as an adsorbent to remove cadmium ions.

Removal of cadmium(II) from aqueous solution by corn stalk graft copolymers.

Corn stalk was modified using graft copolymerization to produce absorbent (AGCS), which was characterized by elemental analysis, fourier transform infrared, X-ray diffraction, solid-state CP/MAS (13)C NMR spectra, thermogravimetric analysis and differential scanning calorimeter. AGCS, having cyano group (-CN) after grafted successfully, exhibits more high adsorption potential for Cd(II) than unmodified forms. The efficiency of AGCS for removal of cadmium ions was evaluated. Factors affecting Cd(II) adsorption such as pH value and adsorbent dosage were investigated. More than 90% removal was achieved at pH 3.0-7.0 and the adsorption increased from 16.0% to 99.2% with increase of adsorbent dose. In addition, two isotherm models, namely, Langmuir and Freunlich were also analyzed to determine the best fit equation for adsorption of Cd(II) on AGCS.