Jie Yang,Jiangdong Dai,Lulu Wang,Wenna Ge,Atian Xie,Jinsong He,Yongsheng Yan
The problem of tetracycline (TC) antibiotic pollution in aquatic environment has attracted wide attention and research. It is still meaningful to develop high-efficiency separation materials and investigate their adsorption behavior and mechanism. In this research, porous carbons were prepared using the renewable willow branches as carbon source, via pre-carbonization and alkali activation. The activation temperature and alkali usage played important roles in the pore structure, which was mainly microporous. The WBAC-850-4 obtained at 850 °C and alkali/biochar ratio of 4:1 exhibited the largest specific surface area (3342 m 2 /g) and total pore volume (1.912 cm 3 /g), displaying the ultrahigh TC adsorption capacity of 1300 mg/g at 298 K. which was higher than that of the reported TC-adsorbents. WBAC-850-4 kept high adsorption ability with a minor impact in the broad pH range of 3.0–8.0. Thermodynamic analysis implied the physisorption dominated the spontaneous adsorption process. The structure-activity relationship between the TC adsorption capacity and porosity properties was established for the first time. Notably, the adsorption capacity of TC had a positive linear correlation with specific surface area, total pore volume, micropore surface area and micropore pore volume, and the correlation coefficient were higher than 0.97. It was first revealed that micropore filling was the main mechanism for porous carbons to bind TC, which meaningfully provided new insight for designing advanced TC-adsorbents in future.
Guanyi Chen,Chuanbin Wang,Jingnan Tian,Juping Liu,Qingjie Ma,Bin Liu,Xiangping Li
Removal of heavy metals from water by biochar is necessary and benefit for human life and environmental protection. In this study, biochar from sludge (SB), cow dung (DB), corn stalk (CB) and willow branches (WB) were synthesized and activated by potassium hydroxide (KOH), and these biochars were used as adsorbent to remove divalent cadmium ion (Cd(II)) from water. The materials were further characterized by using N 2 -sorption, scanning electron microscopy (SEM), elemental analysis, thermal gravity and differential thermal gravity (TG/DTG) and fourier transform infrared spectroscopy (FTIR). It found that external surface area of biochar had significant effect on the adsorption of Cd(II). Batch adsorption experiments were performed to investigate the effects of various parameters, including initial pH value, adsorbent dosage, concentration of Cd(II) and adsorption time. The results showed that CB had a better adsorption ability to remove Cd(II) from water than the other biochars. The pseudo-second-order and pseudo-first-order kinetics models were introduced to study the adsorption kinetics of Cd(II) by CB. The Freundlich model and Langmuir model were both fit for the experimental isotherm data. The maximum adsorption capacity of 40 mg/g was obtained by CB according to the experimental isotherm data by Langmuir model.
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