Role of Combined Na2HPO4 and ZnCl2 in the Unprecedented Catalysis of the Sequential Pretreatment of Sustainable Agricultural and Agro-Industrial Wastes in Boosting Bioethanol Production

Improper lignocellulosic waste disposal causes severe environmental pollution and health damage. Corn Stover (CS), agricultural, and aseptic packaging, Tetra Pak (TP) cartons, agro-industrial, are two examples of sustainable wastes that are rich in carbohydrate materials and may be used to produce valuable by-products. In addition, attempts were made to enhance cellulose fractionation and improve enzymatic saccharification. In this regard, these two wastes were efficiently employed as substrates for bioethanol production. This research demonstrates the effect of disodium hydrogen phosphate (Na₂HPO₄) and zinc chloride (ZnCl₂) (NZ) as a new catalyst on the development of the sequential pretreatment strategy in the noticeable enzymatic hydrolysis. Physico-chemical changes of the native and the pretreated sustainable wastes were evaluated by compositional analysis, scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). These investigations showed major structural changes after the optimized sequential pretreatment. This pretreatment not only influences the delignification process, but also affects the functionalization of cellulose chemical structure. NZ released a higher glucose concentration (328.8 and 996.8 mg/dl) than that of ZnCl₂ (Z), which released 203.8 and 846.8 mg/dl from CS and TP, respectively. This work led to the production of about 500 mg/dl of ethanol, which is promising and a competitor to other studies. These findings contribute to increasing the versatility in the reuse of agricultural and agro-industrial wastes to promote interaction areas of pollution prevention, industrialization, and clean energy production, to attain the keys of sustainable development goals.     

Preparation and characterization of polyurethane–organoclay nanocomposites

Nanocomposite polyurethane (PU)–organoclay materials have been synthesized via in‐situ polymerization. The organoclay is first prepared by intercalation of tyramine into montmorillonite (MMT)‐clay through ion exchange process. The syntheses of polyurethane–organoclay hybrid films containing different ratios of clay were carried out by swelling the organoclay into diol and diamine followed by addition of diisocyanate and then cured. The nanocomposites with dispersed and exfoliated structure of MMT were obtained as evidenced by X‐ray diffraction and scanning electron microscope. X‐ray diffraction showed that there is no peak corresponding to d₀₀₁ spacing in organoclay with the ratios up to 20 wt%. SEM images confirmed the dispersion of nanometer silicate layers in the polyurethane matrix. Also, it was found that the presence of organoclay leads to improvement in the mechanical properties. The tensile strength was increased with increasing the organoclay contents to 20 wt% by 221% in comparision to the PU with 0% organoclay. POLYM. COMPOS. 28:108–115, 2007. © 2007 Society of Plastics Engineers     

Catalytic activity of polymer–montmorillonite composites in chemical reactions

Polymer–clay composite material has been prepared by intercalation of polymeric ammonium salt onto the montmorillonite (Na–MMT) followed by grafted polymerization of hydroxyethyl methacrylate onto amine‐terminated poly(butadiene‐co‐acrylonitrile)–montmorillonite (ATBN–MMT) intercalate. The hydroxyl groups were modified to chloromethyl groups followed by conversion to onium salts, which are suitable as phase transfer catalysis. The catalytic activities of the supported catalysts were investigated in nucleophilic reactions of thiocyanate and cyanate ions with alkyl and aryl halides. The rates of the reactions have been investigated under different factors such as the nature and structure of the support, the amount of catalyst, the solvent, and the temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1121–1129, 2006     

Polymer–organoclay hybrids by polymerization into montmorillonite‐vinyl monomer interlayers

A different series of polymer–clay hybrid materials have been prepared by modification of the clay with different vinyl monomers, followed by polymerization of different ratios of vinyl monomers–clay with the monomers, such as methyl methacrylate, hydroxyethyl methacrylate, and styrene‐maleic anhydride. The materials were investigated by IR, which confirmed the intercalation of vinyl‐cation within the clay interlayers, and by TGA, which illustrated that phosphonium cation has high thermal stability than ammonium cation. Swelling studies of these materials in different organic solvents showed that the swelling degree increases as clay ratio decrease, and also showed higher swelling relative to vinyl–clay. X‐ray diffraction illustrated that the nanocomposites were exfoliated up to a 25 wt % content of organoclay relative to the amount of polymer. SEM and TEM examined the micrograph, which showed a good dispersion of the polymers into clay galleries, and formation of nanosize particles ranged 150–300 Å. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Polystyrene nanocomposite materials by in situ polymerization into montmorillonite–vinyl monomer interlayers

A different series of new polystyrene–clay nanocomposites have been prepared by grafting polymerization of styrene with vinyl‐montmorillonite (MMT) clay. The synthesis was achieved through two steps. The first step is the modification of clay with the vinyl monomers, such as N,N‐dimethyl‐n‐octadecyl‐4‐vinylbenzyl‐ammonium chloride, n‐octadecyl‐4‐vinylbenzyl‐ammonium chloride, triphenyl‐4‐vinylbenzyl‐phosphonium chloride, and tri‐n‐butyl‐4‐vinylbenzyl‐phosphonium chloride. The second step is the polymerization of styrene with different ratios of vinyl‐MMT clay. The materials produced were characterized by different physical and chemical methods: (1) IR spectra, confirming the intercalation of the vinyl‐cation within the clay interlayers; (2) thermogravimetric analysis (TGA), showing higher thermal stability for PS–nanocomposites than polystyrene (PS) and higher thermal stability of nanocomposites with of phosphonium moieties than nanocomposites with ammonium moieties; (3) swelling measurements in different organic solvents, showing that the swelling degree in hydrophobic solvents increases as the clay ratio decreases; (4) X‐ray diffraction (XRD), illustrating that the nanocomposites were exfoliated at up to a 25 wt % of organoclay content; and (5) scanning electron microscopy (SEM), showing a complete dispersion of PS into clay galleries. Also, transmission electron microscopy (TEM) showed nanosize spherical particles of ～ 150–400 nm appearing in the images. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3739–3750, 2007     

Preparation and properties of elastomeric polyurethane/organically modified montmorillonite nanocomposites

Elastomeric polyurethane (PU) was mixed with 1, 3, 5, 7, and 10 wt% of Cloisite 30B to obtain PU-based nanocomposites. The thermal stabilities of the obtained products were characterized by thermal analysis using a thermogravimetric analyzer (TGA), which showed that the addition of 5 wt% of organoclay to the PU increased its stability, whereas thermal stabilization was less efficient at 10 wt%. The electrical conductivities of these composites were studied as a function of temperature, and it was found that the conductivity of PU was enhanced upon using 5 wt% of organoclay. The tensile strength, elongation (%), and Young’s modulus were considerably enhanced upon increasing the organoclay content to 5 wt%, but were then decreased to some extent upon further increasing the nanoparticle loading to 10 wt%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study these nanocomposite structures, and it was found that the PU molecular chains were intercalated into the galleries of the silicate layers in all of the nanocomposites, and that this reached a maximum when 5 wt% of Cloisite 30B was used.     

Novel Nonionic Polyurethane Surfactants and Ag Nanohybrids: Influence of Nonionic Polymeric Chains

Five novel nonionic surfactants were prepared by the reaction of polyethylene glycol of different molecular weights with toluene diisocyanate. The obtained polyurethane polymers were reacted with oleic acid to obtain the nonionic polyurethane surfactants. The structures of the synthesized compounds were determined by using: Fourier Transform Infrared Spectroscopy (FTIR) and their average molecular weights by means of GC analysis. Silver nanohybrids of the nonionic polyurethane surfactants were prepared via physical combination by chemically prepared silver nanoparticles. The silver nanohybrids were determined using: UV, TEM, and DLS spectroscopy. The influence of the nonionic chain length (polyethylene glycol chains) on the surface activity of the synthesized nonionic polyurethane oleate surface active agents and their silver nanohybrids was studied. The results of surface activity of the nonionic polyurethanes oleate and their nanohybrids showed an increase in the critical micelle concentration by decreasing the polyethylene glycol chain lengths. The nanohybrids were also more surface active. Longer polyethylene glycol chains provide good protection for the formed silver nanoparticles than the shorter chains.     

Assessment of the nutritional status of preschool-age children during the second Intifada in Palestine

BACKGROUND: The Palestinian economy has dramatically deteriorated at all levels since the Al-Aqsa Intifada (uprising) began in 2000, resulting in an unprecedented catastrophe to the livelihoods of the Palestinians residing in the West Bank and Gaza. It was also marked by lack of household physical and financial access to food and health care, which placed children at increased risk of malnutrition and poor health. This prompted a significant increase in food aid from 2002 until the summer of 2003. OBJECTIVES: To assess the nutritional status of children 6 to 59 months of age after 1 year of food assistance. METHODS: In the West Bank and Gaza, a nationally representative sample of children 6 to 59 months of age was randomly selected with a validated multistage clustered design, with the Health Survey 1999 sample used as the sampling frame. The sample was stratified according to governorate, place of residence (urban, nonurban, or refugee camp), locality, and size of locality (number of households). A cross-sectional survey of nutritional status was carried out. Data were collected by interviews with the primary caregivers of the children. Measurements were made of children's weight and height or length. Food-intake data were collected by the 24-hour food-recall method with the use of a booklet of photographs of foods commonly eaten in Palestine. RESULTS: A total of 3,089 children were assessed, of whom 3.1% in the West Bank and 3.9% in the Gaza Strip were suffering from acute malnutrition; the prevalence of chronic malnutrition was 9.2% in the West Bank and 12.7% in the Gaza Strip (p = .02). Sex, refugee status, locality, and maternal education were not significantly associated with acute malnutrition by logistic regression analysis, whereas infants 6 to 23 months of age were significantly at risk. Calorie and protein intakes were generally lower than recommended dietary allowances. CONCLUSIONS: The prevalence rates of both acute and chronic malnutrition among children in the West Bank and Gaza are significantly higher than the national Palestinian averages. There is a need to establish nutritional surveillance systems to monitor the nutritional status of children in conflict areas.