Heavy metal removal from aqueous systems using hydroxyapatite nanocrystals derived from clam shells

Hydroxyapatite (HA) was synthesized by wet chemical precipitation, using clam shell (CS) waste as feedstock. SEM and TEM observation of the produced hydroxyapatite revealed the presence of rod-shaped nanocrystals, while XRD and EDS analyses confirmed the characteristic patterns of hydroxyapatite molecules. This material was subsequently employed as a sorbent for heavy metal removal from aqueous solutions, both in batch and column equilibrium procedures. In batch studies, higher sorption efficiencies were obtained at pH 5, with the highest adsorption capacities of 265, 64, and 55 mg g⁻¹ for Pb(ii), Cd(ii), and Cu(ii), respectively. In addition, an adsorption capacity of 42.5 mg g⁻¹ was determined using a CS-HA packed bed column fed with a solution of Pb(ii). Finally, the breakthrough curve was fitted with Thomas model in order to predict column behavior and scaling up.

Removal of Pb(ii), Cu(ii) and Cd(ii) was attained using hydroxyapatite nanocrystals derived from clam shells, in batch and column experiments.     

Mesoporous adsorbent for competitive adsorption of fluoride ions in zinc sulfate solution

Al–La hybrid gel was constructed using an innovative acid-catalyzed and calcination free sol–gel formation process which only included a sol–gel process lasting for 30 min and a drying procedure at 150 °C. This novel material was used as an adsorbent for competitive adsorption of fluoride ions in zinc sulfate solution. The properties, optimal adsorption conditions, synthetic principle and adsorption mechanism of the material were systemically investigated. The results showed that γ-AlO(OH) composed the skeleton of the Al–La hybrid gel and La(CH₃COO)₃ was embedded in the framework, which formed large amounts of ink-bottle type mesopores. A high fluoride ion adsorption rate with the removal rate reaching 50.88% within 1 min at 50 °C, 3 g L⁻¹ was obtained. Analysis of the adsorption data has demonstrated that the adsorption of fluoride ions by the Al–La hybrid gel followed pseudo-second-order kinetics. Moreover, both Langmuir and Freundlich models can describe the adsorption process well. The maximum adsorption capacity of the Al–La hybrid adsorbent was 28.383 mg g⁻¹. Furthermore, the mechanism analysis results indicated that the fluoride ions were mainly removed by the electrostatic adsorption on the AlO(OH), and a small amount of fluoride ions was also adsorbed by the complexation of lanthanum and fluoride ions. Since both AlO(OH) and La(CH₃COO)₃ had a large number of fluoride ion adsorption sites, the Al–La hybrid gel obtained an ideal adsorption capacity. In addition, the adsorption rate was greatly enhanced by the capillary action existing from the initial to the final stage of adsorption.

Al–La hybrid gel was prepared using an innovative acid-catalyzed and calcination free sol–gel process, and showed excellent adsorption performance for fluoride ions in zinc sulfate solution.     

Isolation and characterisation of lactoferrin separated from human whey by adsorption chromatography using Cibacron Blue F3G-A linked affinity adsorbent

A new one-step procedure for isolating lactoferrin from human whey using Cibacron Blue affinity chromatography is described. Characteristics of the isolated lactoferrin include pI 5.5-6.1 and differential migration on SDS-polyacrylamide gel electrophoresis of apo and iron saturated lactoferrin. The concentration of lactoferrin in breast milk varies with time after parturition but the iron saturation remains relatively constant with time.     

Heavy metal toxicity,part ii: lead and metal fume fever

This review is the second of a two-part review of heavy metal toxicity. This part will identify the salient features of the toxicopathophysiology, clinical presentation, and emergency department management of lead toxicity and metal fume fever.     

Oral solid gentamicin preparation using emulsifier and adsorbent.

Oral gentamicin (GM) therapy has been challenged by formulating GM in oral solid preparation. GM was dispersed with a surfactant used for the self-microemulsifying drug delivery system (SMEDDS), PEG-8 caprylic/capric glycerides (Labrasol), and the mixture was solidified with several kinds of adsorbents. The used adsorbents were microporous calcium silicate (Florite RE), magnesium alminometa silicate (Neusilin US2), and silicon dioxide (Sylysia 320). In vitro release study showed that the percentage released of GM from each preparation per 2 h was 99.8+/-0.06% for Florite RE 10 mg, 96.7+/-1.16% for Florite RE 20 mg, 98.3+/-0.32% for Neusilin US2, and 94.4+/-0.23% for Sylysia 320. The T50% values were 0.35+/-0.05 h for Florite RE 10 mg, 0.34+/-0.03 h for Florite RE 20 mg, 0.26+/-0.03 h for Neusilin US2, and 0.15+/-0.01 h for Sylysia 320. The in vivo rat absorption study showed that Florite RE 10 mg preparation had the highest C(max) (2.14+/-0.67 microg/ml) and AUC (4.74+/-1.21 microg h/ml). Other preparations had C(max) and AUC of 0.69+/-0.10 microg/ml and 1.56+/-0.43 microg h/ml for Florite RE 20 mg, 1.07+/-0.31 microg/ml and 1.80+/-0.33 microg h/ml for Neusilin US2, and 0.99+/-0.21 microg/ml and 1.77+/-0.50 micorg h/ml for Sylysia 320, respectively. The bioavailability (BA) of GM from the microporous calcium silicate preparation, Florite RE 10 mg, was 14.1% in rats, derived by comparing the AUC obtained after intravenous injection of GM, 1.0 mg/kg, to another group of rats. The microporous calcium silicate preparation using Florite RE 10 mg was evaluated in dogs after oral administration in an enteric capsule, Eudragit S100 (50 mg/dog). High plasma GM levels were obtained (i.e., the C(max) was 1.26+/-0.20 microg/ml and the AUC was 2.59+/-0.33 microg h/ml). These results suggest that an adsorbent system is useful as an oral solid delivery system of poorly absorbable drugs such as GM.     

Heavy metal levels in patients with ineffective erythropoiesis

Objectives

Iron is taken into enterocytes at the duodenum via apical divalent metal-ion transporter 1 protein. Besides iron, divalent metal-ion transporter 1 also transports other divalent metals. We aimed to investigate blood heavy metal levels in patients with ineffective erythropoiesis.

Heavy metal poisoning: clinical presentations and pathophysiology

Humans have had a long and tumultuous relationship with heavy metals. Their ubiquitous nature and our reliance on them for manufacturing have resulted at times in exposures sufficient to cause systemic toxicity. Their easy acquisition and potent toxicity have also made them popular choices for criminal poisonings. This article examines the clinical manifestation and pathophysiology of poisoning from lead, mercury, arsenic, and thallium.     

Heavy metal music and drug abuse in adolescents

A large number of adolescents in a psychiatric population, particularly those who are chemically dependent, prefer to listen to heavy metal music. Young people who do not identify with traditional values may find simple but unconventional answers to complex problems in the lyrics of this type of music. While a clearcut relationship cannot be established between heavy metal music and destructive behavior, evidence shows that such music promotes and supports patterns of drug abuse, promiscuous sexual activity, and violence.     

Experimental study using heparin-immobilized adsorbent of EDA(+)fibronectin.

EDA(+)fibronectin, which might participate in the pathogenesis and/or progress of immune diseases, is efficiently removed from plasma by cryofiltration; however, cryofiltration removes not only EDA(+)fibronectin, but also other proteins. We thus developed a new adsorbent by using its high affinity with heparin. The purpose of this study was to evaluate the efficacy of the adsorbent of EDA(+)fibronectin (OHC-20) in experimental arthritis. The experimental arthritis was induced by injection of 0.5 mg of Mycobacterium butyricum in Lewis rats. Rats were divided into 4 groups; 1 nontreatment group, and 3 treatment groups. Adsorption therapy in treatment groups was performed three times: on Days 1, 3, and 5 in Group A; Days 7, 9, and 11 in Group B; and Days 13, 15, and 17 in Group C. The walking postures of rats improved from dragging to walking on tiptoe, and the increase of hind-foot volume was suppressed in Groups B and C. We conclude that heparin-immobilized adsorbent might be promising for immune diseases.     

Study on the applicability of pressurized physically activated carbon as an adsorbent in adsorption heat pumps

Activated carbon is a suitable adsorbent for adsorption heat pumps (AHPs) with ethanol refrigerants. Although chemically activated carbon with highly developed pore structures exhibits good ethanol adsorption, the associated high production costs inhibit its practical application as an AHP adsorbent. Moreover, although physical activation can produce inexpensive activated carbon, the limited pore development limits the ethanol uptake. Recently, we developed a pressurized physical activation method that can produce activated carbon with a well-developed pore structure and characteristic pore size distribution. In this study, we investigated the applicability of the pressurized physically activated carbon as an adsorbent in activated carbon–ethanol AHP systems. Because of the large number of pressurization-induced pores of appropriate size, the pressurized physically activated carbon showed effective ethanol uptake comparable with that of chemically activated carbon on a weight basis. Furthermore, on a volume basis, the pressurized physically activated carbon, with a high bulk density, showed much higher effective ethanol uptake than chemically activated carbon. These results confirm the potential of the pressurized physically activated carbon as a relatively inexpensive high-performance adsorbent for AHP systems with ethanol refrigerants.

Thanks to the large number of pressurization-induced pores of appropriate size and the high bulk density, the pressurized physically activated carbon showed much higher effective ethanol uptake than chemically activated carbon.     

Phosphorylated cellulose paper as highly efficient adsorbent for cadmium heavy metal ion removal in aqueous solutions

In search for more effective and eco-friendly adsorbent materials, this study comprehensively investigated Cd²⁺ adsorption onto phosphorylated cellulose paper (PCP). For this, cellulose microfibers (CMF) was extracted from Alfa fibers and phosphorylated using the solid-state phosphorylation approach. Then, the prepared PCP samples were characterized by SEM, EDX, XRD, FTIR, TGA, conductometric titration and zeta potential measurement. The adsorption of cadmium ions, the effect of time, pH and Cd²⁺ initial concentration were systematically studied in batch experiments. Based on the results, the highest adsorption capacity achieved was 479 mg of Cd²⁺ per g of PCP, which was remarkable compared to other modified cellulose capacities cited in the literature. Furthermore, the Cd²⁺ removal mechanism was investigated based on characterization results before and after adsorption and also based on the kinetics results. It was concluded that cation exchange and electrostatic attraction between phosphorylated cellulose and the cadmium ion mainly dominated the adsorption process. These findings highlighted that the phosphorylated cellulose paper has a broad application prospect in removal of divalent metal from aquatic solution.

In search for more effective and eco-friendly adsorbent materials, this study comprehensively investigated Cd²⁺ adsorption onto phosphorylated cellulose paper (PCP).     

Heavy metal induced stress on wheat: phytotoxicity and microbiological management

Among many soil problems, heavy metal accumulation is one of the major agronomic challenges that has seriously threatened food safety. Due to these problems, soil biologists/agronomists in recent times have also raised concerns over heavy metal pollution, which indeed are unpleasantly affecting agro-ecosystems and crop production. The toxic heavy metals once deposited beyond certain permissible limits, obnoxiously affect the density, composition and physiological activities of microbiota, dynamics and fertility of soil leading eventually to reduction in wheat production and via food chain, human and animal health. Therefore, the metal induced phytotoxicity problems warrant urgent and immediate attention so that the physiological activities of microbes, nutrient pool of soils and concurrently the production of wheat are preserved and maintained in a constantly deteriorating environment. To mitigate the magnitude of metal induced changes, certain microorganisms have been identified, especially those belonging to the plant growth promoting rhizobacteria (PGPR) group endowed with the distinctive property of heavy metal tolerance and exhibiting unique plant growth promoting potentials. When applied, such metal-tolerant PGPR have shown variable positive impact on wheat production, even in soils contaminated with metals, by supplying macro and micro nutrients and secreting active biomolecules like EPS, melanins and metallothionein (MTs). Despite some reports here and there, the phytotoxicity of metals to wheat and how wheat production in metal-stressed soil can be enhanced is poorly explained. Thus, an attempt is made in this review to better understand the mechanistic basis of metal toxicity to wheat, and how such phytotoxicity can be mitigated by incorporating microbiological remediation strategies in wheat cultivation practices. The information provided here is likely to benefit wheat growers and consequently optimize wheat production inexpensively under stressed soils.

Among many soil problems, heavy metal accumulation is one of the major agronomic challenges that has seriously threatened food safety.     

Rapid acyclovir radioimmunoassay, using charcoal adsorption.

Charcoal adsorption of unbound acyclovir rather than ammonium sulfate precipitation of bound acyclovir to facilitate the separation of bound antigen from free antigen gave rise to a radioimmunoassay which was quicker yet still as sensitive and accurate as that previously used.     

ABO-incompatible kidney transplantation using regenerative selective immunoglobulin adsorption

Background: ABO‐incompatible (ABOi) kidney transplantation is an established procedure relying on the removal of donor‐specific isoagglutinine antibodies as part of the recipient preconditioning. At present, current protocols using immunoadsorption apply a single‐use selective carbohydrate isoagglutinine adsorber. A regenerative and selective immunoglobulin immunoadsorption could be an alternative but has not been reported for ABOi transplantation. Methods: Eight patients were treated with the commonly used isoagglutinine carbohydrate epitope adsorber and seven with a regenerative polyclonal sheep anti‐immunoglobulin adsorber as part of the preconditioning for ABOi kidney transplantation. An IgG‐isoagglutinine titer of less or equal 1:4 qualified for transplantation. Treatment safety, efficiency, length of desensitization, number of postoperative immunoadsorptions, and allograft outcome were retrospectively compared. Results: With the use of the immunoglobulin adsorber the median initial isoagglutinine IgG titers of 1:64 (range 1:32–1:256) were lowered to the target of 1:4 preoperatively with a mean of 6.2 immunoadsorptions (range 5–11). Mean IgG/IgM titer step reduction per IA was 1.98/1.21 for (range 0–4/0–4) and mean titer step rebound 1.31/0.82 (range 0–4/0–3), respectively. The number of immunoadsorptions and length of desensitization was not different from the use of the specific isoagglutinine adsorbers. After transplantation, no rejection occurred and only one postoperative immunoadsorption was necessary. No adverse events in relation to immunoadsorption were observed. Graft function was comparable to the isoagglutinine adsorber group. Conclusion: These data suggest that ABOi kidney transplantation can be performed safely and effectively with a selective regenerative immunoglobulin immunoadsorber. J. Clin. Apheresis, 2012. © 2012 Wiley Periodicals, Inc.     

Heavy metal and trace element concentrations in patients with idiopathic dilated cardiomyopathy

Blood, serum and urine concentrations (24 hour samples) of cadmium, lead, magnesium, calcium, zinc, copper and iron were determined by means of atomic absorption spectrophotometry in 54 patients with dilated cardiomyopathy (CMP). These data were compared with the values in 17 healthy controls. CMP patients showed higher blood cadmium concentrations (+173%, p less than 0.001), higher serum calcium concentrations (+4%, p less than 0.01) and lower serum magnesium levels (-11%, p less than 0.01). In urine samples CMP patients had higher cadmium levels and lower concentrations of calcium (-43%, p less than 0.05) and magnesium (-36%, p less than 0.05). Correlations with clinical data revealed no definite reason for the abnormal laboratory findings in CMP patients. In individual cases, however, the high cadmium concentrations could be of aetiological importance.     

Removal of hexavalent chromium ions using micellar modified adsorbent: isothermal and kinetic investigations

Hexavalent chromium is a very poisonous oxyanion and has had a negative impact on human health. This study assessed the viability of removing chromium(vi) using micellar modified adsorbents. In this study, chromium(vi) was removed from locally accessible wheat bran using separate applications of anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants. The initial chromium content (5–12 ppm), pH (2–12), adsorbent dose (1–6 g/100 mL), agitation time (15–240 min), agitation speed (50–300 rpm), and temperature (15–50 °C) were all varied in the adsorption investigation. Pseudo first-order and second-order kinetic models were utilized to analyze the kinetic investigation. To determine thermodynamic parameters, the van''t Hoff relationship was used. The maximum result for chromium(vi) uptake was obtained as 87.7%, 83.5% and 98.9% for WB, SDS-mWB, and CTAB-mWB, respectively, at an agitation time of 240 min (i.e., 4 h), temperature (i.e., 25–30 °C), agitation speed (150 rpm). However, both WB and CTAB-mWB derives metal ion removal at lower pH levels (2–4), whereas SDS-mWB requires a pH between 4 and 6 for maximum percentage removal of Cr(vi). The equilibrium data of WB and SDS-mWB were modeled by the Langmuir adsorption isotherm, while the data of CTAB-mWB fitted well in the Freundlich isotherm model. The kinetic analysis of WB, SDS-mWB, and CTAB-mWB revealed that the pseudo-second-order kinetic model provides a thorough explanation for each of these adsorbents. It was found that CTAB-mWB can preferably be used for the removal of chromium(vi) due to its high affinity with adsorbate molecules and adsorption capacity.

In this investigation, anionic sodium dodecyl (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants were separately applied to locally accessible wheat bran to remove chromium(vi).     

Synthesis,characterization, and CO2 adsorption properties of metal organic framework Fe-BDC

The iron-containing Metal–Organic Frameworks (MOFs) have attracted a great deal of attention in the areas of gas separation, catalytic conversion, and drug delivery, due to their high surface area and activity, as well as the non-toxicity of iron. In this study, Fe-based MOFs using BDC ligands, MIL-101(Fe), MIL-53(Fe) and Amino-MIL-101(Fe) are synthesized by a solvothermal method and characterized by conventional methods such as BET, SEM, and TGA. Afterwards, the synthesized MOFs are investigated from the point of view of the adsorbing capability of carbon dioxide at different pressures and temperatures, and also their resistance to water and solvent. The results showed that Amino-MIL-101(Fe) achieved more CO₂ adsorption than MIL-101(Fe) and MIL-53(Fe), equal to 13 mmol g⁻¹ at 4 MP. Although MIL-53(Fe) has the best temperature resistance, around 350 °C, Amino-MIL-101(Fe) is more stable against water and ethanol and its surface area is increased from 670 to 915 m² g⁻¹ after washing with ethanol. The adsorption study reveals that CO₂ is adsorbed not only by a physical adsorption mechanism, but also by chemisorption of acidic carbon dioxide by basic NH₂ agent in the structure of Amino-MIL-101(Fe).

The adsorption isotherm of MIL-101(Fe)-NH₂ was independent of temperature and the heat of adsorption was considered equal to the activation energy of CO₂ chemisorption by NH₂ agent.