The study aims to determine the adsorption mechanism of reactive brilliant red X-3B (RBR) on a novel low-cost clay–biochar composite with different proportions of bagasse and natural attapulgite (ATP). Pure bagasse, pure ATP, and two mixtures with weight ratios of 1:5 and 1:3 were pyrolyzed at 700 °C for 4 h in a muffle furnace. Biochar samples were characterized with an element analyzer and by scanning electron microscopy, X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller method, and zeta potential measurement. Results of the batch and leaching experiments showed that the adsorption capacities followed the order of 1:3 clay–biochar > 1:5 clay–biochar > bagasse biochar > pure ATP. Furthermore, ATP and bagasse exerted a synergistic effect on the adsorption of RBR. The adsorption data showed good correlation with the Langmuir isotherm, and the kinetic data were fitted to the pseudo-second-order model. The adsorption of RBR on clay-biochar involved electrostatic interaction, hydrogen bond, π–π interactions, and surface participation. The modification of biochar by ATP improved the adsorption capacity by increasing functional groups and creating adsorption sites. Therefore, ATP-modified clay–biochar composites could be effective adsorbents for the removal of RBR from wastewater.
The process of ball milling and the materials that compose planetary ball mills are highly complex, and the existing research on the change in ball-milling energy is not mature. The theoretical model of a ball mill was established for the first time to simulate the motion, collision process, energy transfer, and temperature change of small balls during the ball-milling process. Furthermore, by comparing the information with the experimental data for a ball mill, the motion trajectory of the grinding ball, and the energy transfer between the balls and materials were studied, and the micro process during milling was discussed. This study provides a certain theoretical basis for the follow-up engineering application.
In this paper, the biochar prepared by pyrolysis biomass of Water Hyacinth were used as adsorption materials. The effects of initial concentration, adsorption temperature and electrolyte concentration on the adsorption process were analyzed. The adsorption effect of biochar prepared from the stem and root parts of biomass on Cd 2+ in solution was investigated, and the interaction between leaching rule of alkali (earth) metal K + , Mg 2+ , Ca 2+ and adsorption of heavy metal ions in the process of adsorption was studied. The results showed that the biochar prepared by pyrolysis of stem biomass (SBC) has a richer pore structure. Compared with the biochar prepared by root biomass (RBC), the specific surface area and pore volume of SBC increased by 25.85% and 27.91% respectively. This phenomenon indicated that SBC had a stronger adsorption effect than RBC. At 25ºC, the maximum adsorption capacity of RBC and SBC for Cd 2+ was 77.20 mg g -1 and 87.20 mg g -1 , respectively. Isothermal adsorption experiments and ionic strength experiments showed that the increase of temperature could promote the adsorption of Cd 2+ by biochar. The adsorption process has a high degree of fitting with the Langmiur model, as well as the pseudo-second-order model. The adsorption sites were normally on the inner and outer surfaces of biochar, and the adsorption process was multi-molecular layer adsorption. In addition, the adsorption of Cd 2+ by biochar had a correlation with the leaching of alkali (earth) metal in the system. In the adsorption process, the leaching of alkali (earth) metals was affected by the initial concentration of Cd 2+ in the solution, and SBC leached more alkali (earth) metals than RBC, which proved that SBC has more
Wetland emergent plants are considered a good source of biochar materials, which have proven to be an effective alternative to activated carbon for water treatment and soil amendment purposes. In this work, physicochemical properties of biochar made from the root, stem, and leaf of Zizania caduciflora (ZCR, ZCS, and ZCL) under the same pyrolysis condition were compared to evaluate their ability on adsorbing cadmium (Cd) in aqueous solutions. Batch experiments exhibited that the maximum adsorption capacities of Cd(II) by different organs were in the order of ZCL (59.8 mg/g) > ZCS (40.6 mg/g) > ZCR (36.2 mg/g), which have shown some advantages in relevant scientific researches. The adsorption trends at different temperatures were determined and fitted using Langmuir and Freundlich models. The best-fitted adsorption isotherm was found to be the Langmuir isotherm. Two different kinetic models, pseudo-first-order and pseudo-second-order, were used to fit the kinetics data, with the latter best describing the experimental data (R 2 > 0.989). Statistical analyses showed that ionic strength played an important role in controlling the sorption of Cd(II) onto the ZCR, ZCS, and ZCL. Concerning the mechanism, the adsorption of cadmium on biochar is recognized to be a chemical process as surface complexation and metal ions exchange, while it also exhibits some physisorption features due to the porous and defective structure.
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