Adsorptive removal of petroleum hydrocarbons from aqueous solutions by novel zinc oxide nanoparticles grafted with polymers

Zinc oxide nanoparticles were synthesized and modified by a three-stage method. Elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning and transmission electron microscopy, and Brunauer–Emmett–Teller method were applied to characterize the nanoparticles. These nanoparticles were evaluated for toluene adsorption from aqueous solutions as a representative of petroleum hydrocarbon removal. The optimum adsorption condition achieved at pH of 6 and contact time of 30 min. The adsorption isotherms were fitted to the Langmuir model. The measured adsorption capacity was 12.8 mg g^?1. This study demonstrated that these nanoparticles could be used as an effective adsorbent for petroleum hydrocarbon removal.     

Polythiophene modified chitosan/magnetite nanocomposites for heavy metals and selective mercury removal

Multi-functional nanocomposites were prepared based on magnetite nanoparticles, chitosan nanoparticles and polythiophene for efficient and selective mercury (II) removal from its aqueous solution. The prepared materials combine several functionalities; hydroxyl, amino, sulphur and phosphate groups in addition to the magnetite property of magnetite nanoparticles. The produced nanocomposites not only show a complete removal of mercury (II) ions but also a higher selectivity was recorded in presence of other metal ions over a wider pH range.     

Utilization of sulfide-caustic pyrolysis wastes for the removal of heavy metals from waste waters

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 10, pp. 5–6, October, 1990.     

Biogas production as affected by heavy metals in the anaerobic digestion of sludge

Biogas production can be generated by sludge digestion process in the form of methane which in some plants is collected and used as a source of energy. Sewage which is collected from mixed industrial and domestic population may be contaminated with metals and industrial chemicals. The aim of the present study is to investigate the effect of heavy metals on the biogas production in the anaerobic digestion process for the treatment of sewage sludge. The selected metals are Hg, Cd and Cr III. The toxic effect and the inhibitory impact of the digestion process are among the objective of the study. The fate and toxic effects of heavy metals on the biogas production was determined.The sewage sludge samples were separated from the sewage water of the pilot plant at the National Research Centre, TDC site. The effect of heavy metals on the biogas production of the anaerobic digester was studied. The inhibitory effect on the biogas production and toxic level of metals was determined in this study. The general ranking of heavy metal toxicity appears to be Hg > Cd > Cr (III). The present investigation reveals that heavy metals in addition to the anaerobic digester decreased the biogas production as an indication of efficiency of the process. A significant decrease in gas production and volatile organic matter removal was obtained. It was also noted that an accumulation of organic acid intermediates was obtained as a result of methanogenic bacterial inhibition. This accumulation was limited during the pulse feed of metals. This is due to the rapid poisoning of the active bacterial forms in the digester.     

O-Acylation of chitosan by l-arginine to remove the heavy metals and total organic carbon (TOC) from wastewater

Chitosan has acylated with l-arginine in the presence of H₂SO₄ as a catalyst to the aim of increasing the adsorption efficiency. Chitosan (CS) and chitosan-O-arginine (CS-Arg) were characterized and investigated by elemental analysis, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The results obtained from elemental analysis exhibited presence of sulfur content, indicate that sulfuric acid still a crosslinker between CS-Arg chains, also the degree of substitution (DS) of l arginine in CS backbone was 1.83, indicate the acylation process has took place in both C3-OH and C6-OH of CS. XRD results exhibited that CS-Arg is more crystalline than CS, due to the formation of intra and inter molecular hydrogen bonds between amino and hydroxyl groups. The removal of heavy metals (Mn²⁺, Pb²⁺and Al³⁺) and total organic carbon (TOC) from wastewater by CS and CS-Arg in batch mode has been studied at different adsorbent dosages, temperatures and contact times. The maximum removal efficiency for three metal ions using CS achieved 99.6%, 99.1% and 98.9%, respectively, while by using CS-Arg were 97.1%, 94.3% and 99%. However, the maximum adsorption capacity of TOC by CS achieved 50 mg/g and 40.35 mg/g by CS-Arg. The total maximum adsorption capacity of CS-Arg is lower than CS.     

Adsorption of heavy metal ion from aqueous solution by nickel oxide nano catalyst prepared by different methods

Environmental pollution by heavy metal is arising as the most endangering tasks to both water sources and atmosphere quality today. The treatment of heavy metals is of special concern due to their recalcitrance and persistence in the environment. To limit the spread of the heavy metals within water sources, nickel oxide nanoparticles adsorbents were synthesized and characterized with the aim of removal of one of the aggressive heavy elements, namely; lead ions. Nano nickel oxide adsorbents were prepared using NaOH and oxalic acid dissolved in ethanol as precursors. The results indicated that adsorption capacity of Pb(II) ion by NiO-org catalyst is favored than that prepared using NaOH as a precipitant. Nickel oxide nanoparticles prepared by the two methods were characterized structurally and chemically through XRD, DTA, TGA, BET and FT-IR. Affinity and efficiency sorption parameters of the solid nano NiO particles, such as; contact time, initial concentration of lead ions and the dosage of NiO nano catalyst and competitive adsorption behaviors were studied. The results showed that the first-order reaction law fit the reduction of lead ion, also showed good linear relationship with a correlation coefficient (R²) larger than 0.9.     

Study the adsorption properties of magnetite nanoparticles in the presence of different synthesized surfactants for heavy metal ions removal

Co-precipitation method is used to prepare magnetite nanoparticles (Fe₃O₄) which stabilized by two nonionic and one cationic surfactant. ¹H NMR used to confirm the chemical structure of the synthesized surfactants. The prepared magnetite nanoparticles characterized by size distribution (DLS), Fourier transform infrared spectroscopy (FTIR), and magnetic properties (magnetic susceptibility analysis). X-ray diffraction (XRD) illustrated a cubic crystalline structure of the prepared magnetite nanoparticles. Transmission electron microscope (TEM) images showed that the magnetite nanoparticles had uniformly dispersed. The adsorption efficiency of the prepared nanoparticles toward lead, zinc, and cadmium, metal ions was estimated by using atomic absorption spectroscopy (AAS). There are several factors controlling the uptake enhancement studies of the synthesized nanoparticles such as the pH of the metal ion solutions and adsorbent doses.     

Concentration of heavy metals in the food chain components of the nearshore coastal waters of Kalpakkam,southeast coast of India

Kalpakkam, located on the southeast coast of India, has witnessed intense nuclear power plant activities resulting in a substantial increase in social and industrial development. This has prompted the study of the concentrations of heavy metals in water, sediment, zooplankton and fish in the coastal waters of Kalpakkam to understand their pattern of distribution and bioaccumulation. The concentrations of metals were in the order Fe > Zn > Pb > Cr > Mn > Ni > Cu > Cd > Co in water, Fe > Zn > Mn > Pb > Cr > Cu > Ni > Cd > Co in zooplankton, Fe > Zn > Cu > Mn > Cr > Pb in fish and Fe > Cu > Zn > Pb > Cr > Ni > Cd in sediment. Metal concentrations in plankton were much higher than those in water, sediment and fish. The results showed wide variations in heavy metal concentrations in four food web components. The major sources of metals on the Kalpakkam coast are land-based anthropogenic ones. The coastal sediment is moderately polluted with Cu & Cd. Relatively low dissolved metal concentrations were observed when compared to other coastal waters. However, the results indicated that dermal absorption (CDIdermal) of Fe might be a matter of concern due to its carcinogenicity. The summer season had higher Metal Pollution Index (MPI) values, than the rest of the year. Metal pollution indices indicated that southwest monsoon (SWM) and northeast monsoon (NEM) periods had lower contamination (MPI: 1.0–2.0; Class-III) than the summer season (MPI: 2.0–4.0; Class-IV). The bioaccumulation of metal is faster and the content is much higher in zooplankton than in fish. Bioconcentration factors (BCF) were significantly different for different metals. Amongst the toxic metals the BCF was highest for Cr for both zooplankton and fish tissue. The metal concentrations in the fish species studied were sufficiently low that the fish tissue was safe for human consumption.     

Determination of heavy metals in selected black sea fish species

Heavy metals can be accumulated by marine organisms thought a variety of pathways, including respiration, adsorption and ingestion. The levels of heavy metals are known to increase drastically in marine environment through mainly anthropogenic activities. Fish are good indicators for the long term monitoring of metal accumulation in the marine environment. The aim of this study was to determine the levels of Cd, As, Hg, Pb, Zn and Cu in edible part and gill of seven most consumed Bulgarian fish species collected from north-east coast of Black Sea. These fish species are sprat (Sprattus sprattus sulinus), Mediterranean horse mackerel (Trachurus mediterraneus ponticus), Black sea gobies (Neogobius melanostromus), shad (Alosa pontica), Atlantic bonito (Sarda sarda), bluefish (Pomatomus saltatrix) and grey mullet (Mugil cephalus). The fish samples were collected during 2010. The analytical determination of As, Cd, Pb, Zn and Cu were performed by using flame and graphite furnace atomic absorption spectrometry after microwave digestion procedure. The total mercury determination was determined using a direct mercury analyzer (DMA-80). The metal concentration of analyzed elements was highest in the gill for all fish species. The maximum metal concentration was measured for Cu (1.40 mg kg⁻¹ w.w), Zn (11 mg kg⁻¹ w.w) and Pb (0.08 mg kg⁻¹ w.w) in muscle tissues of shad and sprat. The edible part of horse mackerel has the maximum value for Hg (0.12 mg kg⁻¹ w.w) while Atlantic bonito predominantly accumulates As (1.10 mg kg⁻¹ w.w). The analytical results obtained from this study were compared within acceptable limits for human consumption set by various health institutions.     

Seasonal investigation of heavy metals in marine fishes captured from the Bay of Bengal and the implications for human health risk assessment

To investigate the seasonal contamination levels and to evaluate the potential human health risks, ten heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, and Zn) were measured in ten different marine fish species from the Bay of Bengal during four seasons. The metal concentrations varied significantly (p < 0.05) among the fish species with maximum and minimum accumulation of Zn (46.47 μg/g) and Cd (0.25 μg/g), respectively. The fishes captured during summer accumulated a higher amount of metals relative to other seasons, which was attributed to a higher influx of agricultural waste, sewage and sludge by heavy rainfall and floods. According to estimated daily intake (EDI), target hazard quotient (THQ), total target hazard quotient (TTHQ), and the permissible safety limits prescribed by various agencies, consumption of the examined fish species should be considered as safe for human health. However, the estimation of carcinogenic risk (CR > 10⁻⁵) due to exposure to arsenic indicated that consumers remain at risk of cancer.     

Antimicrobial efficacy of clove essential oil infused into chemically modified LLDPE film for chicken meat packaging

Linear low-density polyethylene (LLDPE) is one of the most commercially successful packaging materials; however, to be used for active packaging purpose functionality must be crafted. In this work, LLDPE surface was chemically modified by chromic acid (CA) treatment and coated with clove essential oil (CLO); afterwards, the films were tested for antimicrobial properties. The optical, mechanical, barrier, thermal, and morphological properties of the films were characterized. FTIR spectroscopy confirmed the infusion of CLO in the film, and coating of CLO influenced the yellow color value of the films. The tensile stress and elongation at break of acid-treated and CLO coated films differed significantly from the control sample. CLO coating improved the UV-barrier property of LLDPE film. The melting point, T_m of the composite films dropped significantly from 122 to 117 °C when CLO was coated on the etched film surfaces. The morphology of the LLDPE/CA films exhibited pitting and roughness of the surface. LLDPE/CA/CLO films exhibited strong antimicrobial activity against Salmonella Typhimurium and Listeria monocytogenes in a packed chicken sample for 21 days of refrigerated storage. Thus, the developed film could be used as active packaging for fresh chicken.     

Kinetics and thermodynamics of Mn(II) removal from aqueous solutions onto Mg-Zn-Al LDH/montmorillonite nanocomposite

This study deals with the removal of Mn(II) from aqueous solutions by Mg-Zn-Al LDH/montmorillonite nanocomposite. LDH adsorbent was prepared by co-precipitation method and the composite was prepared by physical mixing of LDH and MMT using high-shear action. The data revealed that the maximum adsorption efficiency were 24.5, 26.4 and 28.9?mg/g at adsorbent mass of 0.25?g/L, pH of 6.0, initial Mn(II) concentration of 80?mg/L, stirring rate of 160?rpm, contact time of 75?min and different temperatures of 298, 308 and 318?K, respectively. Langmuir and Freundlich models were used to optimize the adsorption process and pseudo-first order and pseudo-second order models were used to evaluate the adsorption kinetics of Mn(II) ions onto Mg-Zn-Al (LDH)/MMT nanocomposite. The data indicated that Langmuir model fits the experimental data better than Freundlich model and pseudo-second order model is sufficient to depict the kinetics of Mn(II) onto Mg-Zn-Al (LDH)/MMT composite. Also, the data obtained from thermodynamics study; Gibbs free energy (ΔG°), Enthalpy change (ΔH°), and Entropy change (ΔS°) revealed that the adsorption process is spontaneous, endothermic and randomness at the solid-solution interface during the process of adsorption.     

Removal of Ni (II), Mn (II) and Zn (II) from crude yellow cake aqueous solution by cross-linked chitosan and polyvinyl alcohol

The removal of Ni (II), Mn (II) and Zn (II) from crude yellow cake onto chitosan cross-linked by Epichlorohydrin (CS-ECH) and polyvinyl alcohol (PVA) were investigated in nitrate solutions. The influence of contact time, pH, temperature and initial metal concentrations on the adsorption processes were investigated using batch modes. Langmuir and Fruindlish models were used for investigation of adsorption isotherm. The results showed that the equilibrium adsorption behavior of metal ions onto CS-ECH and PVA could be fitted to Langmuir model. The total maximum adsorption capacity of CS-ECH and PVA were calculated, and the results indicate the higher values of CS-ECH than PVA, due to the properties of chemical structure of CS-ECH. The adsorption kinetics parameters were also tested using pseudo-first-order, pseudo-second-order models, and interparticle diffusion models. The results indicate the adsorption processes of metal ions on both CS-ECH and PVA followed the pseudo-first-order and the pseudo-second-order models which meaning the mixed adsorption, except the adsorption of Mn (II) on PVA is only described by the pseudo-second-order equation. The results indicate the adsorption processes of metal ions followed the pseudo-second-order models for both CS-ECH and PVA. Otherwise, the values of thermodynamic parameters (ΔH^o_ads, ΔS^o_ads, and ΔG^o_ads) of metal ions removal by CS-ECH and PVA exhibit the spontaneity, and exothermicity of adsorption processes.     

硅胶表面聚酰胺-胺的合成及其对Ni2+的吸附

用硅烷偶联剂对硅胶表面进行氨基功能化,利用氨基与丙烯酸甲酯发生的Michael加成反应和乙二胺与酯进行的交换反应在硅胶表面合成了聚酰胺-胺树状大分子(PAMAM-SG);利用红外光谱对PAMAM-SG的结构进行了表征,研究了溶液pH值、ρ(Ni2 )和温度对PAMAM-SG吸附Ni2 能力的影响。结果表明,带有氨基和酯基的PAMAM-SG吸附Ni2 的能力均受到溶液酸碱性的影响,确定的其溶液最佳pH值为4.0~7.0;PAMAM-SG吸附Ni2 的量随ρ(Ni2 )的增大而增加直至平衡,吸附速率随时间的延长而逐渐降低,随温度的升高而增大。在30℃时具有较好的吸附性能,吸附量最大值为38.54 mg/g,各代PAMAM-SG的吸附能力从大到小依次为1.0 G,2.0 G,1.5 G,0.5 G,0 G,-0.5 G。