Performance and dynamic modelling of biochar and kaolin packed bed adsorption column for aqueous phase methylene blue (MB) dye removal.

A practical continuous adsorption study in a packed-bed column was conducted by using two separate layers of kaolin and pine cone based biochar packed bed adsorbents for the removal of methylene blue (MB) dye from its aqueous solution. A series of column experiments were performed to determine the breakthrough curves (BTCs) by varying bed height (3-7 cm), inlet flow rate (13-17 ml/min) and initial dye concentration (50-150 mg/L). The Thomas, Yoon-Nelson, Bed Depth Service Time (BDST) and Dose response (DR) dynamic models were applied to column experimental data under various operational conditions to predict the column breakthrough curves (BTC) using both nonlinear regression and linear regression and to determine various characteristic parameters such as percentage removal of dye, breakthrough time, used bed length, mass transfer zone (MTZ) and dye adsorption density q(total) that are useful for process design. The MB dye adsorption was found to be most favourable under low flow rate, high adsorbent bed height and high initial dye concentrations. The experimental column breakthrough data were in good agreement with the various dynamic models and the results of various model characteristic parameters could be used to scale up the process to an actual industrial column operation. Also, this column study revealed the feasibility of pine cone biochar and kaolin adsorbents as alternative sustainable adsorbents for dye-bearing wastewater treatment.

Synthesis and characterization of slow pyrolysis pine cone bio-char in the removal of organic and inorganic pollutants from aqueous solution by adsorption: Kinetic, equilibrium, mechanism and thermodynamic.

Pine cone bio-char was synthesized through slow pyrolysis at 500°C, characterized and used as an effective adsorbent in the removal of organic Methylene Blue (MB) dye and inorganic nickel metal (Ni(II) ions from aqueous phase. Batch adsorption kinetic study was carried out by varying solution pH, dye concentration, temperature, adsorbent dose and contact time. Kinetic and isotherm models indicates that the adsorption of both adsorbates onto pine cone bio-char were mainly by chemisorption. Langmuir maximum adsorption capability was found to be 106.4 and 117.7mg/g for Methylene Blue (MB) and nickel ions (NI(II) respectively. Thermodynamic parameters suggested that the adsorption was an endothermic and spontaneous. These results indicate the applicability of pine cone as a cheap precursor for the sustainable production of cost-effective and environmental friendly bio-char adsorbent.

Removal of anionic dye Congo red from aqueous solution by raw pine and acid-treated pine cone powder as adsorbent: equilibrium, thermodynamic, kinetics, mechanism and process design.

Pine cone a natural, low-cost agricultural by-product in Australia has been studied for its potential application as an adsorbent in its raw and hydrochloric acid modified form. Surface study of pine cone and treated pine cone was investigated using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The modification process leads to increases in the specific surface area and decreases mean particle sizes of acid-treated pine cone when compared to raw pine cone biomass. Batch adsorption experiments were performed to remove anionic dye Congo red from aqueous solution. It was found that the extent of Congo red adsorption by both raw pine cone biomass and acid-treated biomass increased with initial dye concentration, contact time, temperature but decreased with increasing solution pH and amount of adsorbent of the system. Overall, kinetic studies showed that the dye adsorption process followed pseudo-second-order kinetics based on pseudo-first-order and intra-particle diffusion models. The different kinetic parameters including rate constant, half-adsorption time, and diffusion coefficient were determined at different physico-chemical conditions. Equilibrium data were best represented by Freundlich isotherm model among Langmuir and Freundlich adsorption isotherm models. It was observed that the adsorption was pH dependent and the maximum adsorption of 32.65 mg/g occurred at pH of 3.55 for an initial dye concentration of 20 ppm by raw pine cone, whereas for acid-treated pine cone the maximum adsorption of 40.19 mg/g for the same experimental conditions. Freundlich constant 'n' also indicated favourable adsorption. Thermodynamic parameters such as ∆G(0), ∆H(0), and ∆S(0) were calculated. A single-stage batch absorber design for the Congo red adsorption onto pine cone biomass also presented based on the Freundlich isotherm model equation.