Kinetics and Mechanisms of Phosphorus Adsorption in Soils from Diverse Ecological Zones in the Source Area of a Drinking-Water Reservoir

Abstract

On-site soils are increasingly used in the treatment and restoration of ecosystems to harmonize with the local landscape and minimize costs. Eight natural soils from diverse ecological zones in the source area of a drinking-water reservoir in central China are used as adsorbents for the uptake of phosphorus from aqueous solutions. The X-ray fluorescence (XRF) spectrometric and BET (Brunauer-Emmett-Teller) tests and the Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectral analyses are carried out to investigate the soils’ chemical properties and their potential changes with adsorbed phosphorous from aqueous solutions. The intra-particle diffusion, pseudo-first-order, and pseudo-second-order kinetic models describe the adsorption kinetic processes. Our results indicate that the adsorption processes of phosphorus in soils occurred in three stages and that the rate-controlling steps are not solely dependent on intra-particle diffusion. A quantitative comparison of two kinetics models based on their linear and non-linear representations, and using the chi-square (χ2) test and the coefficient of determination (r2), indicates that the adsorptive properties of the soils are best described by the non-linear pseudo-second-order kinetic model. The adsorption characteristics of aqueous phosphorous are determined along with the essential kinetic parameters.

Core–shell TiO2@C ultralong nanotubes with enhanced adsorption of antibiotics

“…The pseudo-rst-order model was based on the assumption that the adsorption was controlled by diffusion. 29 The pseudo-rst-order dynamic model is as follows: 30 ln(q e À q t ) ¼ ln q e À K 1 t (3) Fig. 4 (a) The N 2 adsorption-desorption isotherm and (b) pore diameter distribution of the TiO 2 @C nanotubes.…”

Mg-Modified Sugarcane Bagasse Biochar for Dual Removal of Ammonium and Phosphate Ions from Aqueous Solutions

“…Kinetic models: The model expressed in Equation (3) was used to describe the intra-particle diffusion as the controlling step for the adsorption process (Weber and Morris, 1963;Zhang et al, 2015)…”

“…The conversion process includes drying and grinding of biomass, pyrolysis and then separation (Pan et al, 2010). Factors affecting the characteristics of generated biochar include the type of feedstock, reaction time and conditions of thermochemical conversion (Zhang et al, 2015;Li et al 2016;Sizmur et al, 2017;Tan et al 2017). While the alkaline nature of biochar is determined by the metal alkalinity content of ash, cation exchange capacity is related to the surface area, surface functional groups (mainly carboxyl groups), type of feedstock and temperature of pyrolysis (Jiang et al, 2013;Luo et al, 2015;El-Gamal et al, 2017).…”

Kinetics, thermodynamics and mechanisms of phosphate sorption onto bottle gourd biomass modified by (3-chloro-2-hydroxypropyl) trimethylammonium chloride

“…The analysis of sorption kinetics is very important considering that it clarifies the pathway of the reaction and the control mechanism of the sorption process. 22 In the case of anionic pollutants, the sorption process can be described by surface sorption analysis, that is, type of interaction (pseudo first-order and pseudo second-order) and diffusion models (Chrastil and Weber-Morris models). [23][24][25] The selected models are typical for defining the sorption kinetics in the fluid-solid system and have been used in most studies dealing with this problem.…”