Manganese dioxide decorated kiwi peel powder for efficient removal of lead from aqueous solutions, blood and Traditional Chinese Medicine extracts.

For human health and environment safety, it is of great significance to develop novel materials with high effectiveness for removal of lead from not only aqueous solutions but also human body and traditional Chinese medicines. Here, functional kiwi peel composite, manganese dioxide decorated kiwi peel powder (MKPP), is proposed for the removal of Pb2+ effectively. The adsorption of Pb2+ in aqueous solution is a highly selective and endothermic process and kinetically follows a pseudo-second-order model, which can reach equilibrium with the capacity of 192.7 mg/g within 10 min. Comprehensive factors of hydration energy, charge-to-radius ratio and softness of Pb2+ make a stronger affinity between MKPP and Pb2+. The possible adsorption mechanism involves covalent bond, electrostatic force and chelation, etc. MKPP can be efficiently regenerated and reused with high adsorption efficiency after five cycles. Besides, MKPP can remove over 97% of Pb2+ from real water samples. MKPP can also alleviate lead poisoning to a certain extent and make the Pb level of TCM extract meet the safety standard. This work highlights that MKPP is a promising adsorbent for the removal of Pb2+ and provides an efficient strategy for reusing kiwi peel as well as dealing with the problem of Pb pollution.

Preparation of pectin/poly(m-phenylenediamine) microsphere and its application for Pb2+ removal.

Novel pectin/poly(m-phenylenediamine) (P/PmPDA) microspheres with different content of PmPDA were prepared by assembling PmPDA on the surface of pectin microsphere. The successful preparation was confirmed by the results of Fourier Transform Infrared spectra (FTIR), scanning electron microscopy (SEM) and elemental analysis. Compared with pectin microsphere, the Pb2+ adsorption performance of P/PmPDA microspheres was significantly improved. The results of batch adsorption experiments were in good agreement with the Langmuir isotherm model for Pb2+ adsorption, indicating the adsorption was monolayer. The maximum adsorption capacity of Pb2+ was found to be 390.9 mg/g. The kinetic adsorption process was well described by the pseudo-second-order model and chemical adsorption dominated the adsorption process. The potential mechanisms of Pb2+ adsorption were speculated as ion exchange and chelation, which were supported by X-ray photoelectron spectroscopy (XPS). The P/PmPDA microspheres showed good recyclability after five adsorption/desorption cycles. All these results indicated the potential of P/PmPDA microspheres for removing Pb2+.

Removing Pb2+ with a pectin-rich fiber from sisal waste.

A pectin-rich dietary fiber from sisal waste (P-SF), containing 11.8% pectin, was produced by a sequential enzymatic-ultrasonic process. P-SF was effective in adsorbing Pb2+ from aqueous solution with a maximum adsorption amount of 184 mg g-1. Adsorption isotherms were fitted well by the Langmuir equation, and the adsorption kinetics could be described by a pseudo-second-order model. X-ray photoelectron spectroscopy and energy dispersive spectroscopy suggested that Pb2+ was adsorbed by P-SF via ion exchange, complexation and mineral precipitation. Dietary supplementation with 10% (w/w) P-SF in basal feed led to a significant decrease in Pb2+ in the brain, liver and kidney. P-SF has greater in vivo efficacy of Pb2+ removal as compared to commercial soybean dietary fiber. The reduction of brain Pb2+ level by P-SF was as effective as by a Pb2+ excretion drug. These findings suggested that P-SF has a great potential to be used as a dietary supplement to cope with Pb2+ poisoning.

Harnessing Peptides against lead pollution and poisoning: Achievements and prospects.

Among the broad applicability of peptides in numerous aspects of life and technologies, their interactions with lead (Pb), one of the most harmful substances to the environment and health, are constantly explored. So far, peptides were developed for environmental remediation of Pb-contaminations by various strategies such as hydrogelation and surface display. They were also designed for Pb detection and sensing by electrochemical and fluorescent methods and for modeling natural proteins that involve in mechanisms by which Pb is toxic. This review aims at summarizing selected examples of these applications, manifesting the enormous potential of peptides in the combat against Pb pollution. Nevertheless, the absence of new medicinal treatments against Pb poisoning that are based on peptides is noticeable. An overview of previous achievements utilizing Pb-peptide interactions towards various goals is presented and can be therefore leveraged to construct a useful toolbox for the design of smart peptides as next-generation therapeutics against Pb.

Novel derived pectin hydrogel from mandarin peel based metal-organic frameworks composite for enhanced Cr(VI) and Pb(II) ions removal.

The hydrogels-metal organic frameworks hybrid materials have received increasing attentions in recent years. The pectin hydrogel (PH) was derived from mandarin orange peels by-products and calcium chloride was applied as a cross-linker for incorporation with Fe-TAC metal organic frameworks (MOFs) for the formation of PHM composite on in situ synthesis method. The synthesized PHM composite was characterized by SEM, FT-IR, XRD and N2 adsorption-desorption and investigated for the adsorption of anionic species, Cr(VI) as well as cationic species, Pb(II) ions from aqueous solution. The adsorption kinetics for Cr(VI)/Pb(II) ions removal followed the pseudo-second order kinetic model and the equilibrium adsorption data were well fitted by Langmuir model. The maximum adsorption capacities of Cr(VI)/Pb(II) ions were 825.97 and 913.88 mg g-1, respectively. High swelling capacity (1500.0%) was also characterized for PHM composite after only 400 min and excellent stability for eight cycles with respect to regeneration with 0.1 mol L-1 HCl. The validity of PHM composite for simultaneous removal from real water matrices were confirmed as Cr(VI) (99.73, 99.87 and 99.87%) and Pb(II) (99.02, 98.55 and 98.55%) from tap water, sea water and industrial wastewater samples, respectively.

Rapid removal of lead(II) ions from water using iron oxide-tea waste nanocomposite - a kinetic study.

Lead (Pb) ions are a major concern to the environment and human health as they are contemplated cumulative poisons. In this study, facile synthesis of magnetic iron oxide-tea waste nanocomposite is reported for adsorptive removal of lead ions from aqueous solutions and easy magnetic separation of the adsorbent afterwards. The samples were characterised by scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray diffraction, and Braunner-Emmet-Teller nitrogen adsorption study. Adsorptive removal of Pb(II) ions from aqueous solution was followed by ultraviolet-visible (UV-Vis) spectrophotometry. About 95% Pb(II) ion removal is achieved with the magnetic tea waste within 10 min. A coefficient of regression R2 ≃ 0.99 and adsorption density of 18.83 mg g-1 was found when Pb(II) ions were removed from aqueous solution using magnetic tea waste. The removal of Pb(II) ions follows the pseudo-second-order rate kinetics. External mass transfer principally regulates the rate-limiting phenomena of adsorption of Pb(II) ions on iron oxide-tea waste surface. The results strongly imply that magnetic tea waste has promising potential as an economic and excellent adsorbent for the removal of Pb(II) from water.

Nanoadsorbents preparing from oligoethylene glycol dendron and citric acid: Enhanced adsorption effect for the removal of heavy metal ions.

Poly(methacrylate oligoethylene glycol dendron-co-citric acid) (PGCA) that is based on citric acid and oligoethylene glycol (OEG) dendrons is utilized as a nanomaterial for the removal of heavy metal ions from aqueous solution. PGCA shows excellent solubility in aqueous solution and realizes satisfactory removal efficacy for Pb2+ ions; the removal rate exceeds 95 %. In addition, PGCA can be utilized in Chinese herbal decoctions; the removal rate of Pb2+ ions in the ligusticum wallichii decoction exceeds 90 %, meanwhile the concentration of the active ingredient, namely, ferulic acid, is maintained. In this nanoadsorbent, citric acid provides the active site for the chelation of heavy metal ions, and OEG dendron serves as a protective layer that reduces the opportunity for carboxyl groups to be occupied by other ingredients. In summary, nanomaterial PGCA is designed and synthesized successfully that can be applied as a nanoadsorbent for the removal of Pb2+ ions from aqueous solution, especially in Chinese herbal decoctions that have acidic compounds as active ingredients.

Bacterial and heavy metal contamination in selected commonly sold herbal medicine in Blantyre, Malawi.

Background: There has been an increase in use of herbal medicine worldwide. It is either used as a stand-alone or complementary therapy to conventional medicine due to past good experience, poverty and family traditions. In Malawi, there are no regulations governing the supply, acquisition, marketing and quality enforcement of herbal medicine. This compromises its safety thereby exposing consumers to avoidable bacteria and heavy metals leading to various adverse health effects. Methods: Cross-sectional laboratory experiments were conducted to determine bacterial and heavy metal contamination of herbal medicine commonly sold in Blantyre, Malawi. A total of 47 samples which were in three formulations namely liquid, powder and tablet were used in the experiments. 29 samples were used for bacterial limit tests and 18 samples were used for heavy metal analysis. Bacterial contamination was determined by streak plate method and biochemical tests while heavy metals were determined by atomic absorption spectroscopy. Descriptive statistics and t-tests were calculated using Microsoft excel and SPSS software programs. Results: Twenty out of the 29 samples (68.9%) were contaminated with Bacillus, coagulase negative Staphylococcus, Klebsiella, Enterobacter, Citrobacter and other-Coliform bacterial species. Most isolated microorganism was Citrobacter spp. (30%), followed by Bacillus spp. (25%). Out of 20 contaminated samples, 75% were contaminated with coliforms. From these 75% which were contaminated with coliforms, 93.3% of them exceeded WHO regulatory limit (103 CFU/g for enterobacteria). Although liquid samples had the highest level of bacterial contaminants, the count was not statistically different from other formulations (P = 0.058). For heavy metals, lead and cadmium were detected and 67% of the samples had lead levels exceeding regulatory limits. Conclusion: Levels of bacterial and lead contamination in herbal medicine from Blantyre markets are far above acceptable limits set by WHO and Canadian guidelines. The use of these herbal medicines is a major risk to the health of consumers.

Removal of lead, zinc and cadmium from contaminated soils with two plant extracts: Mechanism and potential risks.

Screening appropriate washing agents to remediate soils contaminated with heavy metals is crucial for decreasing metal hazards posing to environment and human health. In this study, two plant washing agents-water-extracted from Fagopyrum esculentum and Fordiophyton faberi, were applied to remove soil Pb, Zn, and Cd by washing. Results indicated that metal removals augmented with increase of washing solution concentrations, decreased with increasing pH values of the solution and followed the pseudo-second-order model depending on contact duration. At concentration of 50 g/L, pH 3 and contact duration of 120 min, F. esculentum had higher removals of Pb (5.98-6.83%), Zn (21.82-27.94%), and Cd (39.90-40.74%) than those of F. faberi. And metal ions could be removed by binding with carboxyl, hydroxyl, amide, amine and aromatic groups in washing solutions. The potential risks of residual metals declined by 51.35-52.12% for mine soil and 48.51-49.96% for farmland soil with exchangeable and carbonate-bound fractions obviously extracted after a single washing (P < 0.05). And soil organic carbon and nutrients increased to some extent except for total phosphorus and available potassium. Moreover, soil phytotoxicity lowered except that some adverse effects on seed germination existed. Therefore, the water extract from F. esculentum is a promising washing agent for heavy metal removal.

Ultrasound-assisted extraction of Pb, Cd, Cr, Mn, Fe, Cu, Zn from edible oils with tetramethylammonium hydroxide and EDTA followed by determination using graphite furnace atomic absorption spectrometer.

A new method for extraction and determination of trace and ultratrace impurities from edible oils via an ultrasound-assisted extraction using tetramethylammonium hydroxide (TMAH) and ethylenediaminetetraacetic acid (EDTA) has been described. Method is simple and sensitive. Extraction variables like pH, concentrations of TMAH and EDTA, ultrasonication and centrifugation times were all optimised for analytes using engine-oil. Under optimised conditions, extraction of spiked analytes from all the edible oils into aqueous-medium were investigated and found to be quantitative (89-101%). Using this method, concentrations of impurities in edible-oils were determined by graphite furnace atomic absorption spectrometer (GFAAS) using standard-addition calibration method and validated with microwave-digestion method. The method was successfully applied to edible oils extracted from various seeds such as mustard oil, sun flower oil, sesame oil, ground nut oil, coconut oil, rice bran oil and corn oil containing ultratrace impurities. Accuracy of developed method for edible-oils was checked with corresponding results obtained by microwave digestion method.

Characteristics and performance of Cd, Ni, and Pb bio-adsorption using Callinectes sapidus biomass: real wastewater treatment.

In the current study, the bio-adsorption potential of Callinectes sapidus biomass for control of cadmium, nickel, and lead from the aqueous stream was assessed. Spectrum analysis of FTIR, AFM, EDAX, mapping, SEM, TEM, and XRF was used to study the properties of the C. sapidus biomass. The XRF analysis revealed that C. sapidus bio-adsorbent has various effective metal oxides that can be useful to adsorb pollutants. The best model to describe the equilibrium data was Freundlich isotherm. The Langmuir bio-adsorption capacity was reported at 31.44 mg g-1, 29.23 mg g-1, and 29.15 mg g-1 for lead, cadmium, and nickel ions, respectively. Pseudo-first-order and pseudo-second-order kinetic models were studied to test the kinetic behavior of the process. An intra-particle diffusion model was used to determine the effective mechanisms involved in the bio-adsorption. Based on t1/2, it can be concluded that the equilibrium speed of the bio-adsorption process is high. The thermodynamic study showed that the metal bio-adsorption process using C. sapidus biomass is exothermic and spontaneous. The field applicability of the crab bio-adsorbent for eliminating concurrently several contaminants (metal ions, antibiotics, sulfate, nitrate, and ammonium) from an actual wastewater was successfully examined.

Lead and copper removal from groundwater by spherical agglomeration using a biosurfactant extracted from Yucca decipiens Trel.

The spherical agglomeration technique (SAT) has emerged as an innovative alternative for the removal of heavy metals from water at optimum levels of surfactant addition. This technique has achieved high removal efficiencies. In the present study, Yucca decipiens extracts were applied as the biosurfactant for the removal of heavy metals from groundwater of a mining community using SAT. Aqueous models were generated to explain the removal of copper and lead in solutions. It was possible to remove 99.96% and 99.62% respectively. The highest concentrations of copper and lead 209.5 and 2 mg L-1, respectively, were observed at a waterhole in the mining community. This sample was used to test the efficiency of SAT, using optimal conditions of the models. It was possible to remove 99.22% of copper and 91.50% of lead present in the groundwater. High concentrations of sodium and calcium were found. To reduce the residual sodium concentration, the pH was decreased from 11 to 9.5. 99.84% of copper and only 93.49% of lead were removed; the remaining concentrations did not exceed the limit of Mexican regulations (NOM-001-SEMARNAT-1996, 1996). It was demonstrated that the Yucca extracts are effective or the treatment of water with high concentrations of heavy metals under the conditions of SAT.

Ultrasound-assisted surfactant-enhanced emulsification microextraction using a magnetic ionic liquid coupled with micro-solid phase extraction for the determination of cadmium and lead in edible vegetable oils.

A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) using a magnetic ionic liquid (MIL) coupled with micro-solid phase extraction was developed for the preconcentration of cadmium and lead in edible vegetable oils prior to analysis by graphite furnace atomic absorption spectrometry. MIL [C4mim] [FeCl4] was used as the extractant, non-ionic surfactant Triton X-100 as the emulsifier and Fe3O4 nanoparticles as the sorbent, while ultrasound was applied to assist the dispersion of the extractant and accelerate the mass transfer process. By mixing Fe3O4 nanoparticles with the MIL after UASEME, the phase separation time was shortened and the separation can be simplified by applying an external magnetic field. Under the optimized conditions, the proposed method was validated and the results demonstrated that the method can produce satisfactory linearity, sensitivity, reproducibility and recovery for the analytes. Finally, the method was successfully applied for the determination of Cd and Pb in edible vegetable oil samples.

Remediation of lead-contaminated sediment by biochar-supported nano-chlorapatite: Accompanied with the change of available phosphorus and organic matters.

Some rivers in China have been seriously contaminated due to the discharge of lead (Pb) smelting wastewater. In this study, biochar-supported nano-chlorapatite (BC-nClAP) was synthesized to immobilize Pb in contaminated sediment. The remediation effect of BC-nClAP on Pb-contaminated sediment was evaluated through batch experiments and the materials were characterized by x-ray diffraction, scanning electron microscope, Brunner-Emmet-Teller and electronic differential system. It was found that BC-nClAP can transform Pb effectively from labile fraction into stable fraction with a maximum transformation efficiency increasing to 94.1% after 30 days of treatment, and the stabilization efficiency of toxicity characteristic leaching procedure reached 100% only after 16 days of treatment. The content of available phosphorus (AP) in the sediments treated by BC-nClAP was much less than that treated by nClAP, which indicated a lower risk of eutrophication and suggested the dissolution-precipitation mechanism involved in Pb immobilization. BC-nClAP presented the best immobilization efficiency of Pb and the content of organic matters in BC-nClAP treated samples increased the most, thus the OM might play an important role during the Pb immobilization.

Reduction of heavy metal (Pb2+) biosorption in zebrafish model using alginic acid purified from Ecklonia cava and two of its synthetic derivatives.

Heavy metal contamination has become a major problem that causes severe environmental and health issues due to their biosorption, bioaccumulation, and toxicity. This study was designed to evaluate heavy metal chelating abilities of alginic acid (AA) extracted from the brown seaweed Ecklonia cava and two of its derivatives prepared by the partial oxidation of the 2° OH groups (OAA) and partial carboxylation of the monomeric units (CAA) upon reducing the heavy metal biosorption in zebrafish (Danio rerio) modal. Metal ions were quantified using ICP-OES and biopolymers were characterized by FTIR and XRD analysis. All investigated biopolymers indicated potential ability for chelating Pb2+, Cu2+, Cd2+, As3+, and Ag+. The sorption capacities were in the order of CAA>OAA>AA. All biopolymers indicated a comparatively higher chelation towards Pb2+. AA, OAA, and CAA could effectively reduce Pb2+ induced toxicity and Pb2+ stress-induced ROS production in zebrafish embryos. Besides, they could reduce the biosorption of Pb2+ in adult zebrafish which could lead to bioaccumulation. Since alginic acid purified from E. cava and its derivatives could be utilized as seaweed derived biopolymers to purify heavy metals contaminated water and as a dietary supplement to reduce heavy metal biosorption in organisms.

Phytochelatin 2 accumulates in roots of the seagrass Enhalus acoroides collected from sediment highly contaminated with lead.

Phytochelatins (PCs), the heavy metal-binding peptides of plants, play a main function in heavy metal detoxification. In this study, Enhalus acoroides samples collected at six distinct seagrass beds from the coast of Khanh Hoa province, Viet Nam, were evaluated for their PCs. The contents of different PCs in each organ including leaf, rhizome, and root were determined by using HPLC analysis. Significant differences of PC2 contents among specific organs and their relation were tested by ANOVA, Tukey test, and Pearson's correlation. The results showed that higher PC2, appearance of PC3 and a strong correlation between PC2 and Pb concentration were found in the root organ collected from a Pb contaminated area. We conclude that high Pb in the sediment induce high PC2 and PC3 production in the root. This first report on in situ detection of PCs of seagrass encourages future investigation on the ability to use seagrass for phytoremediation and as a bioindicator of heavy metals based on PC contents.

Lead-binding capacity of calcium pectates with different molecular weight.

Nowadays, heavy metal contamination of environment is considered as a serious threat to public health because of toxicity of these pollutants and the lack of effective materials with metal-binding properties. Some biopolymers such as pectins were proposed for removal of metal ions from industrial water disposals. Chemical structure of pectins is quite variable and substantially affects their metal binding properties. In this work, relationship between molecular weight and Pb(II)-binding capacity of calcium pectates was investigated in a batch sorption system. The results showed that all pectate samples are able to form complexes with Pb(II) ions. The effects of contact time, pH of the media and equilibrium metal concentration on metal-binding process were tested in experiments. The equilibrium time min required for uptake of Pb(II) by pectate compounds was found to be 60min. Langmuir and Freundlich models were applied for description of interactions between pectates and metal ions. Binding capacity of low molecular pectate was highest among all the samples tested. Langmuir model was figured out to be the best fit within the whole range of pH values. These results demonstrate that calcium pectate with low molecular weight is more promising agent for elimination of Pb(II) ions from contaminated wastewaters.

Utilization of phosphorus loaded alkaline residue to immobilize lead in a shooting range soil.

The alkaline residue generated from the production of soda ash using the ammonia-soda method has been successfully used in removing phosphorus (P) from aqueous solution. But the accumulation of P-containing solid after P removal is an undesirable menace to the environment. To achieve the goal of recycling, this study explored the feasibility of reusing the P loaded alkaline residue as an amendment for immobilization of lead (Pb) in a shooting range soil. The main crystalline phase and micromorphology of amendments were determined using X-ray diffraction (XRD) and scanning electron microscopy-electron dispersion spectroscopy (SEM-EDS) methods. The toxicity characteristic leaching procedure (TCLP), sequential extraction procedure, and physiologically based extraction test (PBET) were employed to evaluate the effectiveness of Pb immobilization in soil after 45 d incubation. Treatment with P loaded alkaline residue was significantly effective in reducing the TCLP and PBET extractable Pb concentrations in contrast to the untreated soil. Moreover, a positive change in the distribution of Pb fractions was observed in the treated soil, i.e., more than 60% of soil-Pb was transformed to the residual fraction compared to the original soil. On the other hand, P loaded amendments also resulted in a drastic reduction in phytoavailable Pb to the winter wheat and a mild release of P as a nutrient in treated soil, which also confirmed the improvement of soil quality.

Assessment of Pb and Cd in seed oils and meals and methodology of their extraction.

Oil seed, which is a secondary product in phytoremediation, contaminated with heavy metals should be disposed of in an appropriate fashion. In this study, heavy metal concentrations found in oilseed rape and peanut oils were below 0.1 mg kg(-1) after extractions, being found most of the heavy metals in meals rather in oils. Extraction experiments were carried out to determine the optimum methodology for the removal of Pb and Cd from seed meals using K3C6H5O7, K2C4H4O6 and (NH4)2EDTA. The highest extraction of the Pb and Cd in the seed meals was achieved using 30 mM extractant solutions at 30°C for 24 h and a three-step extraction procedure. K3C6H5O7 and K2C4H4O6 had less impact on the removal of nutrients than (NH4)2EDTA.

Effect of biochar on the extractability of heavy metals (Cd, Cu, Pb, and Zn) and enzyme activity in soil.

Biochar is a carbon-rich solid material derived from the pyrolysis of agricultural and forest residual biomass. Previous studies have shown that biochar is suitable as an adsorbent for soil contaminants such as heavy metals and consequently reduces their bioavailability. However, the long-term effect of different biochars on metal extractability or soil health has not been assessed. Therefore, a 1-year incubation experiment was carried out to investigate the effect of biochar produced from bamboo and rice straw (at temperatures ≥500 °C) on the heavy metal (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) extractability and enzyme activity (urease, catalase, and acid phosphatase) in a contaminated sandy loam paddy soil. Three rates (0, 1, and 5%) and two mesh sizes (<0.25 and <1 mm) of biochar applications were investigated. After incubation, the physicochemical properties, extractable heavy metals, available phosphorus, and enzyme activity of soil samples were analyzed. The results demonstrated that rice straw biochar significantly (P < 0.05) increased the pH, electrical conductivity, and cation exchange capacity of the soil, especially at the 5% application rate. Both bamboo and rice straw biochar significantly (P < 0.05) decreased the concentration of CaCl2-extractable heavy metals as biochar application rate increased. The heavy metal extractability was significantly (P < 0.01) correlated with pH, water-soluble organic carbon, and available phosphorus in soil. The 5% application rate of fine rice straw biochar resulted in the greatest reductions of extractable Cu and Zn, 97.3 and 62.2%, respectively. Both bamboo and rice straw biochar were more effective at decreasing extractable Cu and Pb than removing extractable Cd and Zn from the soil. Urease activity increased by 143 and 107% after the addition of 5% coarse and fine rice straw biochars, respectively. Both bamboo and rice straw biochars significantly (P < 0.05) increased catalase activity but had no significant impact on acid phosphatase activity. In conclusion, the rice straw biochar had greater potential as an amendment for reducing the bioavailability of heavy metals in soil than that of the bamboo biochar. The impact of biochar treatment on heavy metal extractability and enzyme activity varied with the biochar type, application rate, and particle size.