Macro and micromechanics analysis of short fiber composites stiffness: The case of old newspaper fibers–polypropylene composites

Stiffness is one of the most relevant characteristics of composite materials. Natural wood fibers have demonstrated their ability to increase the Young’s moduli of composite materials, and old newspapers are a potential source of reinforcing fibers for composite materials. There are some micromechanic models to predict the Young’s modulus of composite materials, and one of the input data is the intrinsic modulus of their fibers. This intrinsic modulus is a value which is difficult or impossible to measure in the case of wood fibers, due to their measures. This paper evaluates the stiffening abilities of old newspaper fibers and the possibility to back calculate the value of the intrinsic Young’s modulus by means of micromechanic models. Different percentages of old newspaper fibers were compounded with polypropylene (PP). Micromechanics of the fibers were obtained using Hirsch model, Cox–Krenchel’s model, Tsai–Pagano model and Halpin–Tsai equations. The most important results were the average intrinsic Young’s modulus of the fibers, the mean orientation angle and the mean modulus efficiency factor.     

Kinetic study for phosphate removal from water by recycled date-palm wastes as agricultural by-products

The presence of excessive amounts of nutrients including phosphates in water is undesirable. They cause the deterioration of water quality and problems in many natural and engineering systems. The recycling of agricultural waste materials as biosorbents for contaminants removal provides a cheap and ecological means to reduce wastes. This study explored the use of date palm wastes for the effective removal of phosphate from aqueous solutions. Granular date stones (GDS) and palm surface fibres (PSF) as raw abundant waste materials were examined for PO₄ ^-3 removal from aqueous solution. The experimental work was performed in a batch mode to investigate the influence of initial phosphate concentration, contact time, and pH of solution on phosphate biosorption. The FT-IR spectra for the waste materials display many adsorption peaks, confirming the complex nature of the GDS and PSF. Phosphate percentage removal up to 87 and 85% were obtained at initial PO₄ ^-3 concentration of 50 mg as P/L using GDS and PSF, respectively. Due to their low cost and high capability, these types of waste can be used for cost-effective removal of phosphate from wastewater.     

Recycling of industrial wastes in ceramic manufacturing: State of art and glass case studies

Nowadays, ceramic tile are manufactured at zero emissions permitting to recycle all by-products and part of residues derived from depuration treatments (exhausted lime, glazing sludge and polishing sludge). In addition to this environmentally friendly tendency, in the last years an increasing number of scientific studies demonstrated the feasibility to use alternative raw materials in substitution of different component of the ternary clay-feldspar-quartz system. In the first part of the paper is reported the state of the art of industrial waste recycling in the ceramic sector, with the focus on review studies related to both ceramic tiles and bricks..In the second part of the work are reported two case studies conducted by the authors with the aim to formulate ceramic bodies using alternative raw materials. New tailored compositions were obtained replacing clays, flux and/or inert compounds (higher than 60 wt%) by scraps from packaging waste glass in tiles, and cathode ray tube glasses and packaging waste glass up to 20 wt% in the brick compositions.     

Fabrication of zirconium-pillared montmorillonite porous ceramic as adsorbents for Cr3+ removal and recycling

A novel zirconium-pillared montmorillonite (Zr-Mt) porous ceramic (P-ZMt) for Cr³⁺ removal was developed by gelcasting. P-ZMt was characterized by XRD, SEM, XPS, TEM, BET. The influence of pH value, contact time, temperature and initial concentration on the adsorption efficiency was investigated. The results revealed that the P-ZMt has a high removal efficiency of Cr³⁺ over a broad range of pH value. The pseudo-second-order kinetic model fitted our acquired Cr³⁺ adsorption data best, in comparison with the pseudo-first-order kinetic model. The Langmuir model was applied to fit the adsorption process better than that of the Freundlich model. The thermodynamic parameters (∆H, ∆G and ∆S) were also determined, which revealed that the Cr³⁺ adsorption process was spontaneous in nature. The present developed P-ZMt could be recovered and reused for more than 6 times. The novel developed P-ZMt is an inexpensive, effective and long-life-cycle adsorbent for Cr³⁺ removal from water solution.     

不锈钢粉尘综合利用现状及研究进展

介绍了国内外不锈钢粉尘的处理工艺,对等离子工艺、Inmetco工艺、Fastmet/Fastmelt工艺、STAR工艺等几种代表性工艺的优缺点做了对比,并重点阐述了一步还原直接回收工艺,对该工艺所面临的问题展开了讨论。     

电厂循环水杀菌灭藻处理探讨

介绍了电厂循环水处理方法，并对各种方法进行了优缺点比较，对电厂循环水处理有一定的指导意义。     

Klärschlammverbrennung in einer stationären Wirbelschicht mit integrierter Phosphor-Rückgewinnung

Currently, wet-chemical and thermochemical processes in particular are being discussed for the future obligatory recovery of phosphorus from sewage sludge. The coupling of phosphorus recovery with incineration in stationary fluidized bed incinerators, the dominant mono-incineration technology, offers potential advantages in terms of aftertreatment costs and economic efficiency. Tests have shown that by adjusting the incineration conditions and adding additives, an ash could be produced that corresponds to the fertilizer ordinance (DüMV) and can, therefore, potentially be used as phosphorus recyclate.     

转炉钢渣在农业生产中的再利用

对转炉钢渣的理化特性进行了简要的介绍,详细论述了其在农业生产上的资源化再利用技术以及施用转炉钢渣肥料后对土壤环境的影响。转炉钢渣应用于农业生产可以使其含有的有益元素得到充分利用,不会对农产品及土壤环境造成危害,而且通过在转炉钢渣中加入添加剂合成新型农业肥料可以有效地提高转炉钢渣肥料的附加值,更好地满足农业生产的高产和优质的需求。     

Transport of cobalt(II) through a hollow fiber supported liquid membrane containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier

This work presents experimental, modeling and simulation studies for Co²⁺ ion extraction using hollow fiber supported liquid membrane (HFSLM) operated in a recycling mode. Extractant di-(2-ethylhexyl) phosphoric acid (D2EHPA) diluted with kerosene has been used as the membrane phase. The Co²⁺ ion concentration in the aqueous feed phase was varied in the range of 1–3 mM. Also, D2EHPA concentration was varied in the range of 10–30% (v/v). A mass transfer model has been developed considering the complexation and de-complexation reactions to be fast and at equilibrium. Equations for extractant mass balance and counter-ion (H⁺) transport have also been incorporated in the model. Extraction equilibrium constant (K_ex) for cobalt–D2EHPA system has been estimated from equilibration experiments and found to be 3.48 × 10⁻⁶. It was observed that the model results are in good agreement with the experimental data when diffusivity of metal-complex (D_m) through the membrane phase is 1.5 × 10⁻¹⁰ m²/s. Feed phase pH and strip phase acidity had negligible effect on the extraction profiles of Co²⁺ ions. An increase in D2EHPA concentration increased extraction rates of Co²⁺ ions. The membrane phase diffusion step was found to be the controlling resistance to mass transfer.     

用废聚苯乙烯泡沫塑料制备胶粘剂的研究

利用废弃聚苯乙烯泡沫塑料(EPC),加入甲苯、丙酮和乙酸乙酯作溶剂,溶质(EPS)与溶剂之比为0.357时,测得胶粘剂的强度较高;用邻苯二甲酸二丁酯作为改性剂,改性剂加入量体积为7%时,胶液强度达到最高,可加入甘油调整胶液的强度和粘度.