Development of a new compound based on low-density polyethylene degraded with zeolite waste for the removal of diesel from water.

A new adsorbent composite has been developed based on low-density polyethylene and zeolite. This material was used to remove diesel as pollutant in an aqueous system. In the synthesis of the composite and diesel removal were combined these effects: capacity of the zeolite to degrade polyethylene, partial filling of the zeolite with the polyethylene degradation products, favorable thermodynamic interactions between composite-diesel and porosity of the composite (imbibition effect). The term composite is used in the sense that partially degraded-polyethylene oligomers (waxes) are introduced into the zeolite pores in intergranular positions, insuring a good cohesion of waxes and zeolite. The material was synthetized easily by mixing low-density polyethylene and zeolite (1:1) and degraded at 200 °C at three different times: 2, 4 and 6 h. Several techniques as Differential Scanning Calorimeter, Thermogravimetric analysis, Size Exclusion Chromatography and X-Ray Diffraction are combined to study the steps of synthesis and the mechanism of diesel adsorption. The molecular weight obtained at different degradation time varied between 8470 and 99,100, while the molecular weight of the original LDPE was 136,300 g/mol. Diesel removal capacity was determined by TGA through the difference of weight loss at diesel evaporation temperatures (115-275 °C). All the prepared materials presented buoyancy in water and swelling of diesel. Highlighting among them the material prepared at 2 h with a weight loss of 39%, meanwhile the materials prepared for 4 and 6 h presented a weight loss of 29% and 23% respectively, that corresponded to the diesel removed from the water.

Synthesis and Characterization of a Lignin-Styrene-Butyl Acrylate Based Composite.

In recent years, the pursuit of new polymer materials based on renewable raw materials has been intensified with the aim of reusing waste materials in sustainable processes. The synthesis of a lignin, styrene, and butyl acrylate based composite was carried out by a mass polymerization process. A series of four composites were prepared by varying the amount of lignin in 5, 10, 15, and 20 wt.% keeping the content of butyl acrylate constant (14 wt.%). FTIR and SEM revealed that the -OH functional groups of lignin reacted with styrene, which was observed by the incorporation of lignin in the copolymer. Additionally, DSC analysis showed that the increment in lignin loading in the composite had a positive influence on thermal stability. Likewise, Shore D hardness assays exhibited an increase from 25 to 69 when 5 and 20 wt.% lignin was used respectively. In this same sense, the contact angle (water) measurement showed that the LEBA15 and LEBA20 composites presented hydrophobic properties (whit contact angle above 90°) despite having the highest amount of lignin, demonstrating that the interaction of the polymer chains with the -OH groups of lignin was the main mechanism in the composites interaction.

N,N'-Bis(2-amino-benz-yl)ethane-1,2-diaminium dinitrate.

In the title salt, C16H24N4 (2+)·2NO3 (-), both the cation and anion are placed in general positions, although the cation displays non-crystallographic inversion symmetry, with the aliphatic chain extended in an all-trans conformation. The benzene rings are almost parallel, with a dihedral angle between their mean planes of 3.3 (6)°. The nitrate ions are placed in the vicinity of the protonated amine groups, forming efficient N-H⋯O inter-ion hydrogen bonds. Each nitrate ion in the asymmetric unit bridges two symmetry-related cations, forming an R 4 (4)(18) ring, a common motif in organic ammonium nitrate salts. This results in the formation of chains along [010] with alternating cations and anions. The neutral amine groups are involved in slightly weaker N-H⋯O hydrogen bonds with the nitrate O atoms, and there are also a number of C-H⋯O hydrogen bonds present. The resulting supra-molecular structure is based on a two-dimensional network extending in the ab plane.

Tris[2-(2H-indazol-2-yl)eth-yl]amine.

The title tertiary amine, C(27)H(27)N(7), a potential tripodal ligand for coordination chemistry, crystallizes with the central N atom located on a threefold axis of a trigonal cell. The gauche conformation of the N(amime)-CH(2)-CH(2)-N(indazole) chain [torsion angle = -64.2 (2)°] places the pendant 2H-indazole heterocycles surrounding the symmetry axis, affording a claw-like shaped mol-ecule. Two symmetry-related indazole planes in the mol-ecule make an acute angle of 60.39 (4)°. The lone pair of the tertiary N atom is located inside the cavity, and should thus be inactive (as a ligand). In the crystal, neither significant π-π nor C-H⋯π inter-actions between molecules are found.

N,N'-Bis(2-amino-benz-yl)ethane-1,2-diaminium bis-(4-methyl-benzene-sulfonate).

The title salt, C(16)H(24)N(4) (2+)·2C(7)H(7)O(3)S(-), crystallizes with the dication situated on an inversion center and the anion in a general position. The cation contains two ammonium and two free amine groups, and the observed conformation for the chain linking the benzene rings is different from that found in the free tetra-amine and in the fully protonated tetra-amine. All amine and ammonium H atoms of the cation form hydrogen bonds with eight symmetry-related anions, using the sulfonate O atoms as acceptors. This arrangement for the ions precludes any π-π contacts between benzene rings in the crystal.

N,N'-Bis(2-aza-niumylbenz-yl)ethane-1,2-diaminium tetra-chloride.

The title compound, C(16)H(26)N(4) (4+)·4Cl(-), is based on a fully protonated tetra-amine. In the cation, both benzene rings are connected by an all-trans chain, and the rings are almost parallel, with an angle between the mean planes of 8.34 (12)°. The benzene rings are arranged in such a way that the NH(3) (+) substituents are oriented cis with respect to the central chain. This arrangement is a consequence of multiple N-H⋯Cl hydrogen bonds, involving all N-H groups in the cation and the four independent Cl(-) anions. These contacts have strengths ranging from weak to strong (based on H⋯Cl separations), and generate a complex three-dimensional crystal structure with no preferential crystallographic orientation for the contacts.

2,2'-(Propane-1,3-di-yl)bis-(2H-indazole).

The title mol-ecule, C(17)H(16)N(4), is a bis-indazole crystallized in the rare 2H-tautomeric form. Indazole heterocycles are connected by a propane C(3) chain, and the mol-ecule is placed on a general position, in contrast to the analogous compound with a central C(2) ethane bridge, which was previously found to be placed on an inversion center in the same space group. In the title mol-ecule, indazole rings make a dihedral angle of 60.11 (7)°, and the bridging alkyl chain displays a trans conformation, resulting in a W-shaped mol-ecule. In the crystal, mol-ecules inter-act weakly through π-π contacts between inversion-related pyrazole rings, with a centroid-centroid separation of 3.746 (2) Å.

Contamination and chemical fractionation of heavy metals in street dust from the metropolitan area of Monterrey, Mexico.

The prevalence of heavy metal pollution and mobility of both Pb and Cd was investigated in street dust samples from the Metropolitan Area of Monterrey (MAM) in northern Mexico. Street dust samples from 30 selected sites were analysed for their content of Zn, Cd, Pb, Cr and Ni after digestion according to U.S. EPA Method 3051. Multivariate analysis including correlation coefficient analysis, Principal Component Analysis and Cluster Analysis was used to analyse the data and identify possible sources of these heavy metals. Compared with background values, elevated concentrations of Pb (300 mg kg(-1)), Cd (7.6 mg kg(-1)) and Cr (78 mg kg(-1)) were observed in street dust of MAM. Based on multivariate statistical approaches, the studied elements were classified in three main sources: (1) Cr, Ni and Zn mainly derived from industrial activities; (2) Cd originating from traffic-related activities; and (3) Pb associated with vehicular emissions. A sequential extraction procedure using the Tessier method was applied to evaluate the mobility of Pb and Cd in street dust. The majority of Pb was associated with the residual fraction followed by the carbonate fraction. The majority of Cd was associated with the residual fraction. These results indicated that the mobility was higher in Pb (26%) compared with Cd (11%), posing a potential risk to the environment.

2,2'-(2,6-Pyridinedi-yl)diquinoline.

The title mol-ecule, C(23)H(15)N(3), is a terpyridine derivative resulting from the Friedländer annulation between 2,6-diacetyl-pyridine and N,N'-bis-(2-amino-benz-yl)ethyl-ene-di-amine. The asymmetric unit contains one half-mol-ecule, the complete mol-ecule being generated by a mirror plane (one N atom and one C atom lie on the plane). The mol-ecule, although aromatic, is deformed from planarity as a result of crystal packing forces: mol-ecules are stacked along the short c axis, with a short separation of 3.605 (1) Šbetween the mean planes. The bent mol-ecular shape is reflected in the dihedral angle of 16.10 (5)° between the essentially planar quinoline groups. In addition to π⋯π inter-actions, the crystal structure features weak inter-stack C-H⋯N contacts involving atoms of the central pyridine rings which lie in a common crystallographic m plane.

Tris{2-[(2-amino-benzyl-idene)amino]-ethyl}amine.

The title Schiff base, C(27)H(33)N(7), is a tripodal amine displaying C(3) symmetry, with the central tertiary N atom lying on the threefold crystallographic axis. The N-CH(2)-CH(2)-N conformation of the pendant arms is gauche [torsion angle = 76.1 (3)°], which results in a claw-like mol-ecule, with the terminal aniline groups wrapped around the symmetry axis. The lone pair of the apical N atom is clearly oriented inwards towards the cavity, and should thus be chemically inactive. The amine NH(2) substituents lie in the plane of the benzene ring to which they are bonded. With such an arrangement, one amine H atom forms an S(6) motif through a weak N-H⋯N hydrogen bond with the imine N atom, while the other is engaged in an inter-molecular N-H⋯π contact involving the benzene ring of a neighbouring mol-ecule related by inversion. The benzene rings also participate in an intra-molecular C-H⋯π contact of similar strength. In the crystal structure, mol-ecules are separated by empty voids (ca 5% of the crystal volume), although the crystal seems to be unsolvated.

N,N'-Bis(2-ammonio-benz-yl)ethane-1,2-diammonium-nitrate-perchlorate (1/1.5/2.5).

The title compound, C(16)H(26)N(4) (4+)·2.5ClO(4) (-)·1.5NO(3) (-), is an organic salt in which the cation is a fully protonated tetra-mine. The cation lies on an inversion center and, as a consequence, both benzene rings are parallel. The central chain is found in an all-trans arrangement, a conformation different from that observed in the crystal structure of the non-protonated mol-ecule. The charges are balanced by a mixture of nitrate and perchlorate ions. One site is occupied by an ordered perchlorate ion, while the other contains both nitrate and perchlorate ions, with occupancies of 0.75 and 0.25, respectively. In the crystal, the NH(2) (+) groups of the cation form N-H⋯O hydrogen bonds with the anions. The NH(3) (+) groups also behave as donor groups, allowing the building of chains along [100], alternating cations and disordered anions being connected via N-H⋯O hydrogen bonds.