STUDY ON SORPTION ISOTHERMS OF SHRIMP BEADS

ABSTRACT

Sorption isotherms of shrimp heads ( adsorption and desorption ) were analyzed by the microclimate method as temperatures of 30, 45 and 60°C and conditions for shrimp heads conservation by drying were determined. Equilibrium time was reduced from normally 2–3 weeks to only 5–8 days by employing sulfuric acid at different concentrations and vacuum. The results were adjusted by Henderson and G.A.B. models and correlation coefficients were up to 0.9900 for the last model.     

WATER - CORN EQUILIBRIUM: TEMPERATURE DEPENDENCY OF THE G.A.B. MODEL PARAMETERS AND CALCULATION OF THE HEAT OF SORPTION

ABSTRACT

By using sorption data for com in the range of 4.4-60°C, the temperature (T) variations of the GAB. model parameters (M_m, C_B and k) were studied. As only the monolayer moisture (M_m) varied (decreased) with temperature, a generalized GAB equation of four total parameters was obtained. This, together with the Clapeyron equation allowed a method to calculate the heat of sorption (L_b) as a function of T and moisture content (M). For each temperature, Lb presented a maxinuin some 30% above the heat of vaporization of water (L_f), which occurred around the M_m, in congruence with the sorption theory. A similar behavior of L_b was found using the Othmer method. In contrast, the Gallaher equation predicted an ever increasing L_b up to 3 L_f at very low moistures. The GAB-Clapeyron method is then proposed to calculate L_b as a function of M and T.     

Hydrogen production through sorption enhanced steam reforming of natural gas: Thermodynamic plant assessment

A detailed and comprehensive simulation model of a H₂ production plant based on the Sorption Enhanced Reforming (SER) process of natural gas has been developed in this work. Besides thermodynamic advantages related to the shift of reforming equilibrium, SER technology features an intrinsic CO₂ capture that can be of interest in environmentally constrained economies. The model comprises natural gas treatment, H₂ and CO₂ compression, as well as H₂ purification with an adsorption unit that has been integrated within the SER process by using the off-gas for sorbent regeneration. A complete thermal integration has been also performed between the available hot gas streams in the plant, so that high pressure steam is generated and used to generate power in a steam cycle.     

Competitive Sorption of Pesticides onto Treated Wood Charcoal and the Effect of Organic and Inorganic Parameters on Adsorption Capacity

This paper presents competitive sorption of coexisting pesticides onto treated wood charcoal and describes the effect of various water quality parameters, viz., pH, ionic strength, chloride concentration, presence of calcium and magnesium, fertilizers, humic acid, polyacrylic acid, and also the effect of coexisting pesticides on the sorption of endosulfan onto treated wood charcoal. The coexisting pesticides were found to hinder the performance of wood charcoal in removing endosulfan. Competitive uptake study revealed that endosulfan occupies more sites followed by atrazine and monocrotophos. Solubility in water could be one of the major reasons for this preferential order. The presence of humic acid was found to show much more significant influence on the performance of wood charcoal than the presence of polyacrylic acid. Among fertilizers, single superphosphate was found more influential. Most of it, among the other reasons, could be due to the competition of the coexisting molecules for the available adsorption sites on wood charcoal. Other parameters have resulted in some fluctuations in performance, but the effects are not significant. Endosulfan removal efficiency faltered at higher pH values, and ionic species did not affect the sorption as endosulfan is nonionic under neutral conditions.     

Coupled Consolidation and Contaminant Transport in Compressible Porous Media

This paper presents an experimental and numerical investigation of coupled consolidation and contaminant transport in compressible porous media. Numerical simulations were performed using the CST2 computational model, in which a dual-Lagrangian framework is used to separately follow the motions of fluid and solid phases during consolidation. Diffusion and large strain consolidation-induced transport tests were conducted on composite specimens of kaolinite slurry consisting of an upper uncontaminated layer and a lower layer contaminated with potassium bromide. Assessment of the importance of the consolidation process on solute transport is based on measured and simulated solute breakthrough curves and final contaminant concentration profiles. CST2 simulations closely match the experimental data for three different loading conditions. Diffusion and consolidation-induced advection made important contributions to solute transport and mass outflow in this study. Additional simulations indicate that consolidation-induced contaminant transport may also be affected by specimen boundary drainage and initial concentration conditions.     

Experimental study on a combined double-way chemisorption refrigeration system

A combined double-way chemisorption refrigeration system was described and investigated, and the experimental test unit was built, which consists of two adsorption beds: one high-temperature salt bed (HTS bed), which is filled with manganese chloride; and one low-temperature salt bed (LTS bed), which is filled with barium chloride. Moreover, the working performance of double-way chemisorption refrigeration cycle was studied. This cycle uses only one heat input to get two cold outputs, one of which comes from the evaporation heat produced by the refrigerant during the adsorption process, and another of which is from decomposition reaction heat consumed by LTS during the resorption process. The experimental results showed that the coefficient of performance (COP) and specific cooling power (SCP) were 0.703 and 225 W kg⁻¹ respectively at the refrigeration temperature of 15 °C, regeneration temperature of 160 °C and heat sink temperature of 30 °C. Also, the relation between the average global conversion and the COP value were found and analyzed. And the choice of salts and optimum reaction time were discussed either.     

Sorption of P(V), As(V), and Sb(V) Oxyanions on Goethite and Hematite During their Thermal Transformation

Sorption of pentavalent oxyanions P(V), As(V), and Sb(V) was studied on goethite and hematite prepared by its thermal transformation. The surface properties of goethite and products of its thermal modification at different temperatures were studied by BET method, FT-IR, XRD, and DTA-TGA. Amounts of immobilized ions reached their maxima on sorbent prepared at 250°C. Changes of the specific surface area (32.5 m².g^?1 at 150°C, 82.3 m².g^?1 at 250°C and 34.8 m².g^?1 at 350°C) during the thermal transformation at different temperatures were observed. Further analysis confirmed the complete transformation of goethite to hematite at temperatures 200 ? 250°C accompanied with the disappearance of hydroxyl absorption bands at ～800 and ～900 cm^?1 in FT-IR spectrum and significant loss of weight observed on TGA curve. The study of adsorption isoterms revealed that antimony has higher affinity for all studied sorbents.     

Effect of Regeneration Temperature on the Composition and Carbon Dioxide Sorption Ability of a K2CO3/Al2O3 Solid Sorbent in a Bubbling Fluidized Bed Reactor

The effect of the regeneration temperature (150°, 250°, and 350°C) during multiple CO₂ cyclic sorption-regeneration cycles of a K₂CO₃/Al₂O₃ solid sorbent in a bubbling fluidized bed reactor was evaluated in terms of the CO₂ capture capacity and chemical composition of the solid sorbent. The CO₂ capture capacity after regeneration at 150° and 250°C decreased with increasing cycle numbers, reaching approximately 57 and 78%, respectively, and 19.0 and 39.3%, respectively, of the original capacity after one and five regeneration cycles. This decline in the CO₂ capture capacity was due to the accumulation of KHCO₃ (at 150°C) and KAl(CO₃)₂(OH)₂ (150° and 250°C) from their incomplete degradation back to the K₂CO₃/Al₂O₃ solid sorbent. When regenerated at 350°C, the CO₂ capture capacity remained essentially constant in each cycle number because of complete desorption (no residual KHCO₃ and KAl(CO₃)₂(OH)₂). The formation mechanism of complex structure occurred similar to the one in a fixed bed reactor/thermogravimetric analyzer with lower regeneration temperature. The general operation conditions for K₂CO₃/Al₂O₃ solid sorbents are summarized.     

Application of nitroso-R-salt in modification of strongly basic anion-exchangers Amberlite IRA-402 and Amberlite IRA-958

The batch method was applied in order to determine the influence of phase contact time, solution pH and temperature as well as HCl concentration on nitroso-R-salt (NRS) deposition on the strongly basic anion-exchangers Amberlite IRA-402 and Amberlite IRA-958. The equilibrium sorption of NRS from 1 × 10^− 4 mol/dm³ solution was achieved after 60 min. The amount of NRS adsorbed decreased with increasing hydrochloric acid concentration. A significant increase of NRS uptake is observed with the increase of initial solution pH up to 3 for Amberlite IRA-402. Amberlite IRA-402 and Amberlite IRA-958 in chloride form as well as modified by means of NRS were used for recovery of Pd(II) ions from 0.1, 0.5 and 1.0 mol/dm³ HCl solutions.The studied anion-exchangers in NRS form as far as their application in removal of Pd(II) chlorocomplexes is concerned can be presented in the order: Amberlite IRA-402 > Amberlite IRA-958.     

Ion-exchanged and salt hydrates-encapsulated zeolites for solar refrigeration

Solar refrigeration is the best method of utilization of solar energy due to the in-phase relationship between the availability of the solar radiation and the refrigeration requirements. Zeolites with their water content and ion-exchange capability can be used as the material for solar refrigeration. This study aims at further enhancement in the adsorption refrigeration capacity of zeolite by salt hydrate encapsulation. Ion-exchanged and salt hydrate encapsulated zeolites are prepared and characterized for their application as potential candidates in solar refrigeration. A sorption machine has been constructed with the salt-encapsulated zeolite and the results highlight the enhanced suitability of the salt-encapsulated zeolites for solar refrigeration.