Objectives:Heavy metals caused by industrialization have affected human society for several decades. Because of their toxicity for humans, lots of heavy metal treatments have been developed. However, many of those treatments have economic considerations and environmental disadvantages. This work explored an experimental assessment of adsorption of heavy metals using starfish (SF) biochar through quantitative and qualitative characterization and batch-tests.Methods:Biochar (NACSF) was produced at 300℃ for 2 h in anaerobic conditions. The NACSF was characterized with XRD, XRF, FT-IR, SEM-EDX and elemental analyses. Moreover, batch-tests for each heavy metal using NACSF were conducted with ICP-OES analyses in order to evaluate the adsorption characteristics.Results and Discussion:Based on the characterization results, the NACSF consisted of carbon and CaCO₃ mainly. The adsorption rates of Pb, Cu, Zn and Cd decreased in the following order: Pb≫Cu>Zn≥Cd. Moreover, the Langmuir equation fit all adsorption data better than the Freundlich equation. Also, due to the alkalinity of NACSF, the measured pH values of all experimental groups were approximately 7~8.Conclusions:The NACSF treatment was the most effective for Pb removal and it was determined that precipitation and surface adsorption were the most likely mechanisms for Pb removal. Thus, NACSF derived from starfish could be an cost-effective and eco-friendly treatment for heavy metal contaminated wastewater.

Objectives : Heavy metal contamination and accumulation have a harmful effect on the health of humans and animals and are serious problems worldwide. Currently, various technologies have been used for the treatment of contaminated wastewater, of which adsorption is the most commonly known and economically feasible technology. Many researchers are making attempts to find an effective and easily available adsorbent in terms of cost. In this study, starfish (<i>Asterina pectinifera</i>, SF) derived biochar was prepared and its characteristics were evaluated through various device analyses. After the biochar evaluation, the adsorption capacity was evaluated by conducting batch experiments.Methods : Biochar (Pyrolyzed Starfish at 500℃, PSF500) was produced by pyrolysis at 500℃ for 2 h in anaerobic conditions. Moreover, the characteristics of the surface were evaluated through SEM, TGA, XRD, elemental analysis and FT-IR analysis. In addition, batch experiments using heavy metal contaminated wastewater were conducted.Result and Discussion : In PSF500, CaCO3, Ca(OH)2 and CaCO3 were identified as the main phases by XRD analyses and various functional groups and pores that affect adsorption were observed on the surface of the sample. The batch experiment confirmed that the maximum adsorption was 153.8, 270.3, 434.8, and 147.1 mg/g for Cu, Zn, Pb and Cd, respectively. Also, it was confirmed that all heavy metals fit the similar Pseudo-second-order kinetic model and Langmuir model, which are the most suitable models for analyses of inorganic pollutants. After the sorption experiment, XRD and SEM analyses were conducted using the residue of PSF500, and in each sample CuO, Zn5(CO3)2(OH)6, Pb3(OH)2(CO3)2, Cd(OH)2 and CdCO3 were confirmed to be deposited on the surface of the sample.Conclusions : It was confirmed that PSF500 follows the complex mechanism of adsorption and precipitation with respect to heavy metals. Based on the experimental results, PSF500 could be used as an eco-friendly sorbent with CaCO3 as its main ingredient.

One of biopolymer, β-glucan (BG) chains were crosslinked by citric acid under the heating condition for the adsorption of Pb and Cu ions in the aqueous solution. The variation of functional groups on BG itself and crosslinked β-glucan (CBG) with their surface adsorption characteristics were investigated by FTIR and SEM-EDX. Adsorption kinetic results showed that adsorption of Pb and Cu onto the CBG followed the pseudo-second-order kinetic model and intra-particle diffusion model. The Langmuir adsorption model was depicted better adsorption characteristics than the Freundlich model. The adsorption capacities of Pb and Cu onto the CBG estimated by the Langmuir model were 59.70 and 23.44 mg/g, respectively. This study suggested that CBG may act as an eco-friendly adsorbent for the adsorption of Pb and Cu in the aqueous solution.

One byproduct of brewing beer is Brewer's spent grain (BSG), which is reused in animal feed. However, BSG has valuable potential for other products such as biochar because of its high protein and ber content. Radioactive waste is one of the biggest concerns in Korea because of the permanent shutdown of the Gori nuclear power plant. In this study, we aimed to used BSG-850, a biochar originating from BSG after pyrolysis, for the adsorption of cobalt (Co) and strontium (Sr), which are two radionuclides that contribute to radioactive waste. At 298 K, BSG-850 exhibited adsorption capacities of 3.304 and 1.462 mg/g for Co and Sr, respectively. At 308 K, BSG-850 exhibited adsorption capacities of 4.659 and 2.54 mg/g for Co and Sr, respectively. At 318 K, BSG-850 exhibited adsorption capacities of 5.516 and 3.036 mg/g for Co and Sr, respectively. The reusability of BSG-850 capacity was 75.3, 47.8, 43.6, and 36.2% for Co after 1, 2, 3, and 4 cycles, respectively. For Sr adsorption, the capacity was 93.6, 84.2, 57.2, and 32.7% after 1, 2, 3, and 4 cycles, respectively. In the presence of other competitive ions, the adsorption capacity decreased. Through this research, the adsorption capacity and adsorption properties of BSG-origin biochar for Co and Sr were con rmed. Thus, BSG may be a desirable option for solving radioactive waste problems.