Biodiesel production by esterification of oleic acid over zeolite Y prepared from kaolin

Zeolite Y, with a Si/Al ratio 3.1, was prepared using Iraqi kaolin and tested as a catalyst in the liquid-phase esterification of oleic acid (a simulated free fatty acid frequently used as a model reaction for biodiesel production). XRD confirmed the presence of the characteristic faujasite structure of zeolite Y, and further analysis was conducted using BET adsorption, FTIR spectroscopy, XRF, DLS particle size and SEM. A range of experimental conditions were employed to study the reaction; alcohol/oleic acid molar ratio, temperature, and catalyst mass loading. The optimum conditions for the reaction were observed at 70 °C, 5 wt% catalyst loading and 6:1 ethanol to oleic acid molar ratio. The oleic acid conversion using the zeolite prepared from kaolin was 85% after 60 min, while the corresponding value for a commercial sample of HY zeolite was 76%. Our findings show that low Si/Al ratio zeolite Y is a suitable catalyst for esterification, which is in contrast to the widespread view of the unsuitability of zeolites, in general, for such applications

Shape-Selective Adsorption of Substituted Aniline Pollutants from Wastewater

ZSM-5 zeolite was used to treat wastewater containing aniline, 2-nitroaniline (2-NA), 3-nitroaniline (3-NA) and 4-nitroaniline (4-NA). Each molecule was removed from aqueous solution by Type I Langmuir adsorption onto ZSM-5. The quantities adsorbed varied greatly due to their shape-selective adsorption within the pores of ZSM-5. Aniline and 4-NA had maximum adsorption amounts of 161 and 265 mg g −1 , respectively, while the maximum amounts of 3-NA and 2-NA were 94.3 and 37.2 mg g −1 , corresponding to reductions of 64% and 86%, respectively, relative to 4-NA. This outcome was caused by the increase in the effective diameter for adsorption when the nitro group was located at the 2- and 3- positions of the molecule. This significantly reduced their ability to enter into, and diffuse through, the pores of ZSM-5. These findings underpin the importance of choosing the correct substrate when using such materials for water purification

Formic Acid Dehydrogenation Using Noble-Metal Nanoheterogeneous Catalysts: Towards Sustainable Hydrogen-Based Energy

The need for sustainable energy sources is now more urgent than ever, and hydrogen is significant in the future of energy. However, several obstacles remain in the way of widespread hydrogen use, most of which are related to transport and storage. Dilute formic acid (FA) is recognized asa a safe fuel for low-temperature fuel cells. This review examines FA as a potential hydrogen storage molecule that can be dehydrogenated to yield highly pure hydrogen (H2) and carbon dioxide (CO2) with very little carbon monoxide (CO) gas produced via nanoheterogeneous catalysts. It also present the use of Au and Pd as nanoheterogeneous catalysts for formic acid liquid phase decomposition, focusing on the influence of noble metals in monometallic, bimetallic, and trimetallic compositions on the catalytic dehydrogenation of FA under mild temperatures (20–50 °C). The review shows that FA production from CO2 without a base by direct catalytic carbon dioxide hydrogenation is far more sustainable than existing techniques. Finally, using FA as an energy carrier to selectively release hydrogen for fuel cell power generation appears to be a potential technique

Adsorption of aniline from aqueous solutions onto a nanoporous material adsorbent: isotherms, kinetics, and mass transfer mechanisms

MCM-48, which is particulate and nanoporous, was formulated to actively remove aniline (AN) (i.e., benzenamine) from wastewater. MCM-48 was characterized by several methods. It was found that the MCM-48 was highly active in adsorbing aniline from wastewater. The Langmuir, Freundlich, and Temkin isotherms were employed to evaluate the adsorption equilibrium. At 100 and 94 mg g−1, the maximum theoretical and experimental absorption of aniline, respectively, fit with a Type I Langmuir isotherm. The Langmuir model was optimal in comparison to the Freundlich model for the adsorption of AN onto the mesoporous material MCM-48. The results of these kinetics adsorption models were investigated using model kinetics that employed both pseudo-first- and pseudo-second-order models as well as models utilized intraparticle diffusion. The kinetics adsorption models demonstrated that the absorption was rapid and most closely agreed with the pseudo-first-order model. The kinetic studies and the adsorption isotherms revealed the presence of both physical adsorption and chemisorption. The potential adsorption mechanisms include the following: (1) hydrogen bonding, (2) π-π interactions, (3) electrostatic interaction, and (4) hydrophobic interactions. The solution's pH, ionic strength, and ambient temperature also played essential roles in the adsorption. HIGHLIGHTS The mesoporous silica MCM-48 was very successful to remove aniline.; A maximum aniline adsorption 94 mg/g was achieved on MCM48 adsorbent.; MCM-48 was found very active for the removal of aniline compounds from wastewater.; Aniline adsorption mechanism is a chemisorption and physical adsorption process.; The MCM-48 was regenerated and reused efficiently in a batch adsorption.

Attapulgite as an eco-friendly adsorbent in the treatment of real radioactive wastewater

Operators cannot ignore the radiation hazards arising from nuclear weapons. In this study, batch adsorption experiments were investigated to remove the radioactive isotope Cs-137 from the real radioactive wastewater. The attapulgite natural clay mineral was characterized and adopted as an adsorbent in a batch adsorption system. Equilibrium was reached after 2 h with a Cs-137 removal efficiency of 97% for attapulgite. The kinetics of Cs-137 adsorption on the attapulgite clay surface were evaluated. The pseudo-second-order kinetic model produced an excellent fit with the experimental kinetic data. HIGHLIGHTS Very cheap attapulgite clay was used in a batch adsorption system.; Iraqi attapulgite natural clay proved as an efficient adsorbent for the removal of Cs-137.; Natural clay was modified and manufactured from a locally available material.; The real samples of radioactive wastewater containing 137Cs have been treated.

Modification of FAU zeolite as an active heterogeneous catalyst for biodiesel production and theoretical considerations for kinetic modeling

In this work, a high purity FAU-type zeolite catalyst was prepared from shale rock and modified as a heterogeneous efficient catalyst for biodiesel production from sunflower oil. The characterization properties for both of the prepared catalysts were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), Brunauer–Emmett–Teller (BET), and Fourier-transform infrared spectroscopy (FTIR). The incipient wetness impregnation method was adopted for loading the catalyst with three base precursors: NaOH, KOH, and Ca(OH)3. Different factors affecting transesterification reaction onto modified Na-K-Ca-FAU zeolite were investigated such as; temperature (35, 45, 55, and 65 °C), catalyst concentrations (2, 3,4, 5, and 6 wt%) and the molar ratio of methanol to sunflower oil (3:1, 6:1, 9:1 and 12:1). The optimum conditions of transesterification reactions were obtained for reaction time (4 h) and agitation rate (700 rpm) in a batch reactor at 65 °C reaction temperature, 5% catalyst concentration, and a 9:1 M ratio of methanol to oil. The experimental results showed that the conversion of triglyceride in sunflower oil to fatty acid methyl ester (FIME) increased from 48.62 to 91.6% when the FAU zeolite was loaded with 15 wt% of the three bases. The properties of the produced biodiesel were evaluated within the standard performance ASTM D-6751. This study shows that the three base precursors (i.e., NaOH, KOH, and Ca(OH)3) were successfully loaded onto support FAU zeolite and functioned as excellent catalysts for biodiesel production. Theoretical considerations for kinetic modeling in the heterogeneous transesterification reaction were investigated using MATLAB programming. The experimental and theoretical considerations for kinetic modeling were fitted well

Anaerobic Digestion of Blood from Slaughtered Livestock: A Review

Blood from livestock slaughtering imposes a high organic pollution load and risks. If it is discharged untreated to sewer systems, it increases the organic pollution load on wastewater treatment plants by 35–50%. This paper reviews blood anaerobic digestion. It analyzes the quantities, composition, methane potential reported, microbiology, biochemical pathways of blood protein degradation, environmental and health issues, and strategies suggested to manage them during livestock blood anaerobic digestion. Although challenging, anaerobic digestion of blood as a mono-substrate is possible if the culture-reactor system is controlled based on a complete characterization and understanding of the microbial community and its metabolic activities. Co-digestion of blood and other feedstock proceeds well if the mixtures are well designed. Generally, the specific methane yield from digesting blood alone ranges between zero and 0.45 m3 kg−1 protein, whereas for co-digesting blood and other substrates, the yield varies between 0.1 and 0.7 m3 kg−1 volatile solids. More research is required for microbiology and kinetics, the role of adsorbents, reactor configuration, and culture adaptation during anaerobic digestion of blood to better control the process