Effects of solvent,supersaturation ratio and silica template on morphology and polymorph evolution of vanillin during swift cooling crystallization

Swift cooling crystallization of vanillin was investigated in water,ethanol,isopropanol and ethyl acetate.Morphology and polymorph evolution of vanillin were discussed in terms of solvent,supersaturation ratio and silica template.PXRD,DSC,FTIR and microscope were used to identify polymorphs of vanillin.Results showed that the nucleated polymorphs of vanillin depended largely on the solvent,supersaturation ratio and silica template.Low supersaturation ratios favor the nucleation of stable form I in water,and high supersaturation ratio exceeds 7 generating 100%metastable form II.However,if the supersaturation ratio is too high(S>8),liquid-liquid phase separation will occur,and no crystals could be obtained.In other solvents such as ethanol,isopropanol and ethyl acetate,only form I was obtained.However,it should be noted that the morphology of form I prepared in ethanol,isopropanol and ethyl acetate is distinct from that obtained in water,the former is flake-like and the latter is rod-like.The nucleation of vanillin from different solution was also studied with the presence of SiO_(2),SiO_(2)-NH_(2)and SiO_(2)−COOH templates,which did not change the nucleated polymorph of vanillin,but changed the nucleation and growth rate of stable form I.

Adsorption removal of sulfamethoxazole from water using UiO-66 and UiO-66-BC composites

The adsorption removal of anti-inflammatory drugs from water by diverse materials has drawn great attention.This study investigated the adsorption of sulfamethoxazole(SMX)by two types of materials,UiO-66 and UiO-66-BC composites.Highly porous MOF composites with functional groups were synthesized by combining UiO-66 with corncob-based biochar at different molar ratios.SEM results showed that macroporosity of UiO-66-BC composites was increased by increasing the ratio of biochar.It was found that UiO-66-BC composites displayed highly improved adsorption performance of SMX relative to pristine UiO-66.UiO-66-BC(5%)had the highest SMX adsorption capacity,about 2.4 times those of pristine UiO-66.It was the high surface area of UiO-66 and redundant functional groups of biochar that increased the adsorption performance of composites.Moreover,UiO-66-BC can be reused and displayed the competitive adsorption efficiency after successive adsorption,which made it a potential adsorbent for the removal of SMX from water.