Reaction mechanism of thermal decomposition of Phosphogypsum.

Phosphogypsum (PG) is a co-product of the phosphoric acid industry. To reduce the environmental impact and land occupation caused by PG disposal, researchers are trying to integrate it into building materials, agriculture, etc. Herein, PG decomposition with carbon monoxide (CO) was studied with i) thermogravimetric analysis (TGA), ii) induction heated fluidized bed reactor (IHFBR), and iii) thermodynamically using FactSageTM. Experimentally, PG starts decomposing around 600 °C and produces mainly calcium sulfide (CaS) at high CO partial pressure, above 50 %, and mainly to calcium oxide (CaO) at lower CO partial pressure (<20 %). At 1000 °C and above, CaSO4 was completely converted to CaS, CaO, and minor co-products due to the presence of impurities in PG. Elemental and XRD analyses were adopted to understand the reaction mechanisms of PG decomposition. Thermodynamic simulations confirmed the full conversion of calcium sulfate (CaSO4) above 600 °C for a CO/CaSO4 ratio above 6.81 (mol/mol), whereas only 60 % conversion would be achieved at 1500 °C and lower ratio (<0.49 (mol/mol)). As a result, CaS and CaO may be produced, depending on the temperature and CO partial pressure.

Determination of prediction equations for apparent metabolizable energy corrected for nitrogen of corn gluten meal and canola meal in broilers.

The objectives of this experiment were to determine the AMEn content of different samples of corn gluten meal (CGM) and canola meal (CM) by a reference diet method and to develop prediction equations based on the chemical composition to estimate the AMEn value of CGM and CM in broilers. A total of 300 one-day-old male broiler chicks were randomly assigned to fifteen treatments (14 experimental diet and 1 reference diet) with 4 replicates of each with 5 birds per replicate. At first, birds were fed a starter diet from 0 to 10 d of age, and then, a grower diet from 11 to 23 d of age. To determine the AMEn content, the test diet consisted of 60% reference diet, 38% each test CGM or CM, and 2% minor ingredients. To adaptation, the broilers were fed experimental diets for 4 d, and then feces were collected on 28 d. The gross energy values and chemical compositions among the CGM and CM from different origins were significantly different. The AMEn values of the CGM samples varied from 3,123 to 3,918 kcal/kg, and for the CM, the range was from 1,578 to 2,109 kcal/kg. At the end of the experiment, data were analyzed with SPSS software, and a regression equation was obtained based on the chemical composition. The best equations were selected based on the standard of prediction and regression adjusted R2. The equation, AMEn = 49.196 × CP + 80.87 × EE (SEP 180.99; adjusted R2 0.97), was selected to predict the AMEn value of CGM, and the equation, AMEn = 631.55 × EE + 16.716 × CP (SEP 55.3; adjusted R2 0.94), was selected to predict the AMEn value of CM.

Membrane Surface Modification via In Situ Grafting of GO/Pt Nanoparticles for Nitrate Removal with Anti-Biofouling Properties.

Nanofiltration processes for the removal of emerging contaminants such as nitrate are a focus of attention of research works as an efficient technique for providing drinking water for people. Polysulfone (PSF) nanofiltration membranes containing graphene oxide (GO)/Pt (0, 0.25, 0.5, 0.75, 1 wt%) nanoparticles were generated with the phase inversion pathway. The as-synthesized samples were characterized by FTIR, SEM, AFM, and contact angle tests to study the effect of GO/Pt on hydrophilicity and antibacterial characteristics. The results conveyed that insertion of GO/Pt dramatically improved the biofouling resistance of the membranes. Permeation experiments indicated that PSF membrane embracing 0.75 wt% GO/Pt nanoparticles had the highest nitrate flux and rejection ability. The membrane's configuration was simulated using OPEN-MX simulating software indicating membranes maintaining 0.75 wt% of GO/Pt nanoparticles revealed the highest stability, which is well in accordance with experimental outcomes.

Microwave-responsive SiC foam@zeolite core-shell structured catalyst for catalytic pyrolysis of plastics.

Catalytic pyrolysis is a promising chemical recycling technology to supplement mechanical recycling since plastics can be broken down into monomers or converted to the required fuels and chemicals. In this study, a microwave (MW) -responsive SiC foam@zeoltie core-shell structured catalyst was proposed for the catalytic pyrolysis of polyolefins. Under microwave irradiation, the SiC foam core works as both microwave adsorber and catalyst support, thus concentrating the generated heat energy on the ZSM-5 zeolite shell, where the catalytic reaction takes place. SiC foam with an open cellular structure can also improve the global transport of mass and heat during plastics pyrolysis. In this work, the effects of the SiO2/Al2O3 ratio and alkaline treatment of ZSM-5 zeolite coated SiC foam under MW irradiation on the variations in product distribution from low-density polyethylene (LDPE) pyrolysis were investigated at 450 °C. The results indicated that the appropriate acidity and pore structure were crucial to upgrading gas and liquid products. Particularly, the creation of a mesoporous structure in ZSM-5 zeolite via alkaline treatment could improve the diffusion of large molecules and products, thus significantly increasing the selectivity of high-valued light olefins and aromatics while inhibiting the formation of unwanted alkanes, which are expected in the chemical industry. Concretely, the concentration of olefins in gas increased to 51.0 vol% for ZSM-5(50)-0.25AT, and 65.6 vol% for ZSM-5 (50)-0.50AT, compared with 45.2 vol% for the parent ZSM-5(50). The relative concentration of aromatics in liquid decreased from 96.6% for ZSM-5(50) to 75.9% for ZSM-5(50)-0.25AT, and 71.1% for ZSM-5(50)-0.50AT. Given the respective yield of gas and liquid, the total selectivity of C2-C4 olefins and aromatics for mesoporous ZSM-5 zeolites could reach 58.6-64.9% during LDPE pyrolysis, which were higher than that for the parent ZSM-5 zeolite.