The potential to remove chromium(VI) from aqueous solutions through biosorption using coffee husk was investigated. The effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(VI) were studied. The data obeyed Langmuir and Freundlich adsorption isotherms. The Langmuir adsorption capacity was found to be 44.95 mg/g. The Freundlich constants Kf and n were 1...

The flexibility and structure transition behaviour of ZIF-8 in a series of samples with different particle size has been studied using a combination of high-resolution N2 gas adsorption isotherms and, for the first time, a broad in situ PXRD and Rietveld analysis. During the stepped adsorption process, large particles showed a narrow adsorption/desorption pressure range with a shorter equilibri...

The performance of two phenol-formaldehyde resin-based activated carbons prepared in our laboratory, as potential adsorbents for precombustion CO2 capture has been evaluated under static (adsorption isotherms) and dynamic (adsorption-desorption cycles conducted in a fixed bed) conditions. Most of the literature on CO2 capture with solid sorbents is based on equilibrium CO2 adsorption capacities...

hydrothermal synthesis of nickel-chitosan hybrid  has  been accomplished using ni(ch3coo)2,4h2o, chitosan and water as starting material, template and solvent respectively, followed by calcination at 800 and 900˚c to provide nanoporous nio800  and nio900. the solid products were characterized by x-ray diffraction (xrd), nitrogen adsorption-desorption, scanning electron microscopy (sem) and four...

the aim of the present work is to prepare an adsorption package to simulate adsorption / desorption operation for both single and multi-component systems in an isothermal condition by different mechanisms such as; local adsorption theory and mass transfer resistance (rigorous and approximated methods). different mass transfer resistance mechanisms of pore, solid and bidispersed diffusion, toget...

In the present study seven synthetic polymers were used as adsorbents for the removal of Cd(II) from aqueous solution. The equilibrium studies were systematically carried out in a batch process, covering various process parameters that include agitation time, adsorbent dosage, and pH of the aqueous solution. The analyzing system was an atomic absorption spectrometer (Perkin-Analyst 100). It was...

The adsorption and desorption properties of SQD-85 resin for Cu(II) had been investigated. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, contact time and temperature. The results show that the optimal pH for the adsorption was 5.99 in the HAc-NaAc system, and the maximum adsorption capacity was estimated to 324 mg/g a...

A new model of time-dependent sorption-desorption hysteresis is presented. This type of hysteresis is not related to transitions between metastable adsorption states, which are a common cause of capillary condensation hysteresis in mesoporous materials. We show that time-dependent hysteresis is a consequence of slow kinetics and failure to reach equilibrium at given experimental conditions. The...

the role of calcite as related to the chemical behavior of boron (b) in calcareous soils was investigated through an assessment of b adsorption and desorption reactions on and from calcite in four ratios of solid to solution rate, three levels of ionic strength, and within a ph range of 7.5 to 11.5. experimental data indicated that b adsorption is increased by an increase in the solid to soluti...

A continuous-flow adsorption/desorption process for the recovery of phenolic compounds (PCs) from olive mill wastewaters (OMWs) was developed in a 0.53 m packed column, using a previously selected resin (Amberlite XAD16) and an actual OMW. The goals of the study were (i) to optimize the OMW pre-treatment step, (ii) to optimize the resin packing procedure, (iii) to evaluate the PC adsorption/des...