Lead Extraction from Contaminated Soil Using Water-Soluble Polymers

The applicability of water-soluble polymers as extractants for the remediation of heavy metal-contaminated soils has been explored using a lead-contaminated Superfund soil as a sample system. Polyethylenimine (PEI) was functionalized with bromo- or chloroacetic acid to give an aminocarboxylate chelating group, which effectively binds lead. The resulting polymer, PEIC, has extraction properties similar to the molecular chelator ethylenediaminetetraacetic acid. A series of studies was done to probe optimum conditions for lead extraction from soils obtained from the Cal-West Superfund site in New Mexico that contained approximately 10,000 ppm of Pb. In batch extraction experiments using polymer functionalized at two different levels, the polymers removed greater than 97% of the lead from the soils. Subsequent experiments demonstrated that the selective extraction of lead could be controlled by varying polymer functionalization levels. Concentration and regeneration of the polymers using ultrafiltration was also demonstrated. Release of lead from the polymer was accomplished by acidification to pH 1 with HCl. Subsequent ultrafiltration allowed recovery of the extractant polymer for reuse.     

珠江三角洲典型区域土壤重金属污染探查研究

以珠江三角洲典型区域研究高强度经济开发下土壤环境中重金属污染的状况。测定了84份样品中铜、锌、镉、铬、铅的含量水平。土壤中镉、铬、铅、镍、铜、锌的含量分别在0.166～0.433mgkg-1、2.28～94.28mgkg-1、20.36～143.3mgkg-1、2.29～63.55mgkg-1、4.8～65.1mgkg-1、10.06～131mgkg-1之间。从分析结果可以看出,镍、铅等元素在有些地方普遍偏高,且有的极为明显,已高出背景值108.3mgkg-1。其他元素也存在不同水平的富集,普遍高出背景值。     

福建沿海地区不同用地土壤重金属污染及其评价

对福建沿海地区4种不同用地类型的8种重金属元素进行了检测和评价,结果表明:水田污染最严重是Pb,菜园地是Hg,果园是As,旱地是As。在多项综合指数评价中,菜园土污染最严重,综合污染指数(P)达到1.18,其余依次为水田0.64,果园0.59,旱地0.47。在单项污染综合指数中,Hg和Cd污染最严重,其污染指数(I)分别达到0.86和0.61,其余依次为Cr、Pb、Cu、As、Zn、Ni。评价结果为进一步的土壤污染与治理提供了科学依据。     

Effects of titanium dioxide nanoparticles on the efficiency of surfactant flooding of heavy oil in a glass micromodel

Nanotechnology has the potential to profoundly change enhanced oil recovery and to improve mechanism of recovery, and it is chosen as an alternative method to unlock the remaining oil resources and applied as a new enhanced oil recovery method in last decade. The objective of this research is identification of potential of nanotitanium dioxide as an appropriate agent for improving the efficiency of surfactant flooding in five-spot glass micromodels. In this work a series of solvent injection experiments was conducted on horizontal glass micromodels at same conditions. Surfactant solutions and newly developed nanosurfactant solutions with 1600–2000 ppm sodium dodecyl sulfate were tested. Observations showed that nanotitanium dioxide has appropriate performance in enhancing the oil recovery at surfactant solution, near critical micelle concentration conditions. Also The results of experiments illustrated improvement of heavy oil recovery in micromodel test with nanotitanium dioxide (51.0%).     

A process mineralogy approach to geometallurgical model refinement for the Namakwa Sands heavy minerals operations,west coast of South Africa

The original geometallurgical model for the Namakwa Sands deposit was modified to accommodate ore blends in addition to the various single ore types. A process mineralogy approach was followed in a structured and systematic manner to evaluate the integrity of the adjusted model, particularly for ilmenite and zircon, the minerals of highest intrinsic value. This study reproduced recovery relationships predicted by the geometallurgical model for each of the key process functions, and as a result the integrity of the geometallurgical model is validated. Overall, the recovery potential determined for ilmenite and zircon are well adjusted to model estimates. Poor mineral liberation, an anomalously high abundance of garnet and pyroxene and variation in particle chemistry are recognized as the key recovery penalties. The gangue content is the most significant constraint to ilmenite recovery, whereas zircon chemistry is the most important negative factor in the production of a premium quality zircon product. Results of this study contributed to the refinement of the current geometallurgical model and also identified opportunities to optimise mineral resource utilisation in the future.     

Development and validation of an analytical method for the determination of arsenic,cadmium and lead content in powdered infant formula by means of quadrupole Inductively Coupled Plasma Mass Spectrometry

Cadmium (Cd), lead (Pb) and arsenic (As) can enter the food chain through the environment and/or as a consequence of the manufacturing process making foodstuffs the main human exposure route to these chemical elements. The risk associated with this exposure is of such a big concern for human health that the European Food Safety Agency recommends to reduce the exposure to Cd and Pb so as to protect especially vulnerable subgroups of population (e.g., infants). Therefore, the setting of new maximum levels (MLs) for chemical elements in infant formulae (e.g., for Cd) or the reconsideration of the existing ML for Pb is under discussion. On this basis, the availability of analytical methods, precise, accurate and sensitive enough to quantify low concentration values, is a key point especially for official control laboratories that have to state the sample compliance using a fully validated method with an associated uncertainty compliant with the requirements specified in the pertinent regulations. This work describes the development and validation of an analytical method to quantify As, Cd and Pb in powdered infant formulae based on animal protein at values of concentration close to the MLs that are likely to be set. The results obtained make the method suitable for a precise and accurate determination of these chemical elements at these low concentration values. In particular, the results for limit of quantification (LoQ) were respectively (μg kg⁻¹): As 6.2, Cd 1.2 and Pb 4.5. While for the recovery rates the following percentages were obtained: As 105%, Cd 98% and Pb 108%. The expanded uncertainties were found extremely satisfactory (Cd 13% and Pb 19%). The LoQ and the uncertainty for Pb meet the requirements set in Commission Regulation (EC) No. 333/2007 and following amendments being lower than the maximum values allowed. Even for Cd the expanded uncertainty resulted adequate in relation with the low concentration considered.     

Novel approach for attapulgite/poly(acrylic acid) (ATP/PAA) nanocomposite microgels as selective adsorbent for Pb(II) Ion

A novel approach was developed for the preparation of the attapulgite/poly(acrylic acid) (ATP/PAA) nanocomposite microgels via the “one-pot” inverse suspension radical polymerization of acrylic acid (AA) with the multi-functionalized attapulgite nanorods (org-ATP) as the sole crosslinker. The parameters of the feeding ratio of the functional attapulgite (org-ATP) nanorods and AA (org-ATP/AA), oil (liquid paraffin)–water ratio, and feeding ratios of dispersing agent (sodium dodecyl benzene sulfonate (SDBS)) and initiator (ammonium persulfate (APS)) were optimized via 4-Variable 3-Level Orthogonal experiments. Under the optimized preparation condition, more than 85% of the monomer AA had been grafted onto the org-ATP nanorods to form the 3-dimensional network of the ATP/PAA nanocomposite microgel. The ATP/PAA nanocomposite microgel exhibited better mechanical stabilities (resistance to pressure and resistance to agitation) and selective adsorption to heavy metal ions, especially to Pb²⁺. The adsorbed Pb²⁺ ion could be completely eluted with HCl solution. The better mechanical stability and regeneration make it potential adsorbent for the heavy metal contaminated water.     

Effect study of hexagonal mesoporous silica/polyaniline nanocomposite on the structural properties of polysulfone membranes and its heavy metal removal efficiency

New mixed matrix membranes of polysulfone were synthesized by different content of hexagonal mesoporous silica coated by polyaniline and used for nickel and lead ion removal. The membranes were characterized by FESEM, XRD, BET, TGA, and FTIR, and zeta potential measurements. The results showed that PANi/HMS particles enhanced the membrane porosity and permeability. These effects were explained according to an increase of the membrane hydrophilicity due to the formation of new functional groups during membrane casting. The results showed that metal ion rejection was performed by a filtration–adsorption mechanism, resulting in fixation of metal ions on the active sites of membranes.     

Viscosity Reduction of Heavy Oil during Slurry‐Phase Hydrocracking

The saturates, aromatics, and resins fractions of maltenes from upgraded oils obtained by slurry‐phase hydrocracking (SPH) under low‐severity reaction conditions using analytical‐grade and mineral catalysts were obtained by chromatographic separation. The reactions in the SPH at low severity with the catalysts used occur by free radicals, and their subsequent hydrogenation is from heavier fractions (asphaltenes and resins) to lighter fractions (aromatics, saturates, and light cuts). The degree of conversion depends on the type of catalyst used (Mo > Fe) and is also proportional to the active metal content of the catalyst. The enhanced conversion of aromatics and resins towards the saturates fraction depends on the hydrogenation capacity of the catalyst. The better flow properties of the maltenes are due to the conversion of heavier to lighter fractions and to the upgrading of the resins fraction properties.