Universal Journal of Green Chemistry

Design and Analysis of the Waste Heat Recovery System for Stenter Exhaust

2023-10-27T17:21:58+08:00

In this study, combined with the exhaust adsorption, desorption and catalytic combustion technology, a waste heat recovery scheme using stenter exhaust to heat desorbed air and preheat stenter suction air was proposed. Using Aspen Plus to design the waste heat recovery system, and using Aspen EDR to design the structure of heat exchangers. The energy utilization efficiency of waste heat recovery system was evaluated through the exergy analysis, and the influence of exhaust flow rate variation on exergy efficiency of heat exchanger under different exhaust temperatures were discussed. Moreover, the influence of fluid parameter variations on the heat transfer process was also analyzed. Finally, the economic calculation was carried out and the overall energy-saving effect of waste heat recovery system was demonstrated. The results showed that the utilization of this waste heat recovery system can recover 537 kW, the exergy efficiency of desorbed air heat exchanger and preheating air heat exchanger were 51% and 58.9% respectively. In terms of the economic evaluation, the annual energy-saving economic benefits was about $ 89,312, and the static investment payback period was 1.17 years.

A Factorial Design Assessment of Marine Exoskeleton-Based Bio-sorption of Relevant Electroplating Metals

2022-09-07T11:54:24+08:00

A preliminary assessment of the capacity of pulverized crab shells to function as bio-sorbents for the removal of selected metals, zinc, cadmium, and chromium was analyzed according to a factorial experimental design. These metals were chosen because they have little precedent in past sorption studies and represent metals discharged into receiving waters by the electroplating industry. The design was done to assess parameters that have the highest impact on adsorption capacity and removal efficiency. Validation with other heavy metal ion removals was performed for comparison followed by a factorial 33 DOE using JMP®. It was found that for zinc, adsorbent amount, pH, time and the interaction of adsorbent amount*time and pH*adsorbent amount have the highest significance. For cadmium, only adsorbent amount is significant. Finally, chromium uptake was strongly dependent on adsorbent amount and pH. According to ionic radius theory, the favorability for adsorption is according to the following trend: chromium > cadmium > zinc; however, under our set of experimental conditions, the order was: cadmium > zinc > chromium because the presence of calcium carbonate exerts a major role in their sequestration.

A Green Route for Sustainable Nanoporous Solid Acid Catalyst Synthesis Using Bio Template and Analysis of Its Progressive Transformation of CO2

2024-01-31T16:07:54+08:00

Green chemistry approach is a most important area in the modern chemical world. The nano (meso) porous materials have the specific application in separation, adsorption and catalysis. A green template (Egg white) is used as a bio template for the synthesis of nanoporous material to replace the hazardous templates. It is a bio-degradable template; it does not create any environmental issues. The synthesized material is characterized by various spectroscopic techniques to confirm its structural formation. Based on pore size, the catalyst named as AlSiO₄-14. The synthesized catalyst (AlSiO₄-14) is active at 175^oC. This low temperature activity will not produce coke formation at the same time it does not require any regeneration and the catalyst is continuously active for catalytic reactions. The catalytic activity of carbon dioxide decomposition is achieved at lower temperature. The complete carbon dioxide decomposition of AlSiO₄-14 is 43 % is a great impact of the material.

Usefulness of the Biomass of Tobacco (Nicotiana tabacum) for The Elimination of Chromium (VI) from Polluted Waters

2022-12-29T17:46:47+08:00

The tobacco plant is capable of accumulating heavy metals in its different parts, making it a good candidate for use in bioremediation, although there are few reports in which the biomass of this plant is used for the removal of heavy metals in solution. Also, cigarette residues are an environmental problem, so the use of these residues is an opportunity to obtain biomass for the removal of heavy metals from polluted environments. The objective of this work was to determine the removal capacity of Cr (VI) by commercial tobacco biomass, finding that 1 g of biomass removal 72 mg/L of the metal at 24 h, pH 2.0, 28 °C and 100 rpm, while at higher temperatures the removal is higher, and if the concentration of the metal is increased (1 g/L), its removal capacity is reduced, since 64.72% is removed at 24 h at 28 °C, although at 60 °C, 1 g/L is removal at 8 hours. If the concentration of the bioadsorbent is increased, the metal removal does not increase. Finally, 5 g of biomass eliminates 66.1% and 74% of Cr (VI) present in naturally contaminated soil (100 mg/g) and water (100 mg/L), respectively.