Preparation And Adsorption Performance Of Biochar Derived From Pomelo Peels

Biochar as an adsorbent has been widely used in water treatment owing to its wide source,simple synthetic method,low price and great properties.However,there is little coverage about the preparation of hydrophobic biochar and its application for the adsorption of organics.This paper,therefore,reported the fabrication and adsorption performance of the Ni²⁺ adsorbents and organics adsorbents with pomelo peels as the raw materials,respectively,which was quite significant for the design and application of biochar,even for the environmental protection.The main research contents and conclusions of this paper are listed as follows:1.Pomelo peels?PPs?and PPs-derived carbon?PPC?had been prepared and used to adsorb the Ni²⁺ from aqueous solution.The results showed that PPC had a better adsorption capacity for Ni²⁺ compared with PPs.By a set of batch experiments,optimum adsorption conditions for the removal of Ni²⁺ by PPs and PPC were obtained in our work.Their kinetics data were both in good agreement with the pseudo-second-order kinetic model with high R2 values.Moreover,their experimental equilibrium data were both well described by the Langmuir isotherm model,revealing that the adsorption processes involved the monolayer coverage of Ni²⁺ molecules onto the surface of adsorbents,and calculated qm values were 21.49 mg/g and 88.34 mg/g for PPs and PPC,respectively.2.With pomelo peels as the raw materials,a kind of porous and amorphous carbon aerogel?PPCA600,PPCA700 and PPCA800?was prepared via HTC,freeze-drying and pyrolysis process?600 oC,700 oC and 800 oC?.The results indicated that the as-prepared PPCA had a large specific surface area?466.0-759.7 m2/g?.The characteristics of the carbon materials from pomelo peels were closely related to the pyrolysis carbonization temperature.Specifically,the higher the pyrolysis carbonization temperature,the higher graphitization degree,less hydrophilic groups,more defect structure,smaller pore size,and larger specific surface area,etc.More importantly,the static sorption experiments revealed that PPCA had excellent sorption ability while it decreased slightly when the calcination temperature increased for all kinds of organic matters,for instance,the mass gain of PPCA600 ? PPCA700 and PPCA800 for DMF were 3425%,2718% and 2647%,respectively.Aafter five cycles,the absorbed mass of ethanol,acetone,soybean oil and sunflower oil on PPCA800 still kept high values of 98%,92%,89.35% and 72.15% of the initial uptake,respectively,showing the satisfactory recyclability of the sorbent.3.With PPCA600 as the matrix,the PPCA600/PVDF composites?PPCA600/1%PVDF,PPCA600/3%PVDF and PPCA600/5%PVDF?had been prepared by the steps such as soaking in PVDF solution at different concentrations?1%,3% and 5%?,solvent exchange and drying.On the one hand,SEM images showed that the composites had an interconnected 3D porous morphology,and with the increase of PVDF content,the granular morphology of PVDF gradually became the stacked morphology,which was beneficial to improve the mechanical strength of the materials.Additionally,the WCA value of PPCA600/PVDF composite was about 135.1o-144.7o that was larger than WCA value of PPCA600.On the other hand,the sorption studies revealed that PPCA600/PVDF had an excellent sorption ability while it decreased with the increase of PVDF content.On the whole,their sorption abilities were worse slightly compared with PPCA600.Besides,PPCA600/PVDF displayed a good recyclability for all kinds of organic matters in reusability test.In addition,the absorption process of phenol in aqueous solution on PPCA600/3%PVDF had been investigated.The kinetics data were in good agreement with the pseudo-second-order kinetic model and the equilibrium data were both well described by the Langmuir isotherm model with calculated qm value of 13.09 mg/g.