Efficient removal of cadmium by salts modified-biochar: Performance assessment, theoretical calculation, and quantitative mechanism analysis.

Modified biochar is a feasible adsorbent to solve cadmium pollution in water. However, few studies could elucidate the mechanism of cadmium adsorption by biochar from a molecular perspective. Furthermore, traditional modification methods are costly and have the risk of secondary contamination. Hence, several environmentally friendly sodium salts were used to modify the water chestnut shell-based biochar and employ it in the Cd2+ adsorption in this work. The modification of sodium salt could effectively improve the specific surface area and aromaticity of biochar. Na3PO4 modified biochar exhibited the highest Cd2+ adsorption capacity (112.78 mg/g). The adsorption of Cd2+ onto biochar was an endothermic, monolayer, chemisorption process accompanied by intraparticle diffusion. Microscopically, the enhancement of aromatization after modification made Cd2+ more likely to interact with the regions rich in π electrons and lone pair electrons. This study provided a new research perspective and application guidance for heavy metal adsorption on biochar.

Spleen Stiffness Performance in the Noninvasive Assessment of Gastroesophageal Varices after Transjugular Intrahepatic Portosystemic Shunts.

OBJECTIVES: To investigate the performance of spleen stiffness (SS) by using two-dimensional shear-wave elastography (2D-SWE) for assessing the severity of gastroesophageal varices (GEVs) after transjugular intrahepatic portosystemic shunt (TIPS). METHODS: 102 eligible patients were categorized as in the post-TIPS short-term (n = 69) and long-term (n = 38) follow-up groups. The performance of SS by using 2D-SWE for evaluating the severity of GEVs was compared with liver stiffness (LS), spleen stiffness-to-liver stiffness ratio (SS/LS), liver stiffness spleen-diameter-to-platelet-ratio score (LSPS), portal hypertension (PH) risk score, platelet count-to-spleen diameter ratio (PSR), and varices risk score by using receiver operating characteristic (ROC) curve and DeLong test. RESULTS: In the post-TIPS short-term follow-up group, area under the receiver operating characteristic curves (AUCs) of SS were 0.585 for mild (cutoff value = 30.3 kPa), 0.655 for moderate (cutoff value = 30.6 kPa), and 0.739 for severe (cutoff value = 31.9 kPa) GEVs, which were higher than other parameters for severe GEVs. AUCs of SS were lower than other parameters for mild and moderate GEVs, but no difference was found (p > 0.05). In the post-TIPS long-term follow-up group, AUCs of SS were 0.778 for mild (cutoff value = 28.9 kPa), 0.82 for moderate (cutoff value = 29.9 kPa), and 0.824 for severe (cutoff value = 37.7 kPa) GEVs, which were higher than other parameters except for severe GEVs. AUC of SS was lower than other parameters for severe GEVs, but no significant difference was found (p > 0.05). CONCLUSION: SS is an effective noninvasive tool to predict GEV severity during the post-TIPS follow-up.

Novel sodium bicarbonate activation of cassava ethanol sludge derived biochar for removing tetracycline from aqueous solution: Performance assessment and mechanism insight.

NaHCO3 was used as a novel activator to produce cassava ethanol sludge-based biochar. The NaHCO3-activated biochar showed superior adsorption capacity for tetracycline (154.45 mg/g) than raw biochar (34.04 mg/g). Orthogonal experiments confirmed the optimal preparation conditions of biochar. Increasing adsorbent dosage and temperature facilitated tetracycline removal. The maximum removal was 92.60% at pH = 3.0. Calcium ions and alkalinity decreased tetracycline removal. The time for attaining equilibrium was extended with increasing tetracycline concentration, but the equilibrium could be completed within 24 h. Langmuir model fitted the equilibrium data well. Kinetics process followed the Elovich model. The adsorption rate was controlled by both intraparticle and liquid film diffusion and the process was endothermic and spontaneous. The electrostatic attraction, hydrogen bonding, π-π interactions, and pore-filling were involved in the adsorption mechanism. The findings may provide an underlying guide for sludge disposal and removal of tetracycline from wastewater in practical application.