Study On The Preparation Of Activated Carbon From Domestic Waste And Its Adsorption Desulfurization Performance

Due to its characteristics of large surface area,huge porosity and a large mount of oxygen-containing surface functionnal groups,activated carbons have a wide range of applicatgions in a variety of liquids and gases adsorption areas.With the growing shortage of energy and the development of people's consciousness to protect environment,the raw materials for actvated carbons developed to the re-utilization of wastes,such as plant waste cantaining lignin and cellulose,wrapping waste,and sludge,and so on.The biggest advantage for activated carbons is that reuse the daily-life waste.The preparation and applications of activated carbons will incrasingly draw attention widespread.With the increasing awareness of environmental protection,the environmental regulations have been more and more stringent and the production of low-sulfur or sulfur-free gasoline has become the general trend of the world's clean energy.In China,environmental legislations have been imposed to restrict the sulfur content in motor gasoline to less than 50 ppm by 2014,and less than 10 ppm by 2016.Hence,it is of great practical significance to research and develop the efficient desulfurization method.In this work,we used sawdust,coir fiber,packing paper,palm leaves,oil cake,and com stalks as raw matrials for preparaing activated carbons.We used KOH,H3PO4,and H2SO4 as actvating ahent.The process for preparing activated carbons including one-step method or two-step method.The effect of preparation method,activating agent,the dose of actviting agent,actvation temperature,and actvation time on the activated carbons desulfurization were studied.The sawdust prepared with one-step method,KOH as activating agent,with KOH/sawdust ratio of 3,as well as activated at 700? for 1h exbibited the best performance.The adsorption capacity for best activated carbon was achieved 24.5mg/g after ambient temperature adsorbed at for 24h.The content of lignin and cellulose in sawdust,coir fiber,packing paper,palm leaves,oil cake,and com stalks were determined.The oxygen-containing functional groups on the surface of activated carbons were determined with Boehm titration.The activated carbons were charaterized by the specific area measurements(BET),Scanning electron microscopy techniques(SEM),and Fourier transform infrared(FT-IR).The adsorptive desulfurization properties of the activated carbons were evaluated with static adsorption xeperiments through model oil.The model oil was made up of n-octane solution and along with a certain amount of Dibenzothiophene.The experiment results showed that the more lignin a raw matrial contains,the larger adsorption capacity.KOH-activation activated carbons present plentiful cavity construction and higher surface area.The sawdust prepared with one-step method,KOH as activating agent,with the best conditions contains most carbonyl groups.The carbonyl group as a good electron acceptor can form electron donor-acceptor complexes with the unpaired electrons in the molecular structure of DBT.The DBT adsorption capacity increased as the increase of the carbonyl group.The activated carbons made with sawdust adsorpted DBT were investigated by Langmuir?Freundlich?Dubinin-Radushkevich(D-R)adsorption isotherm.The adsorptions kinetic of activated carbons were studied with the pseudo-first-order dynamic equation,pseudo-second-order dynamic equation,and Langmuir model.The study found that the isothermal equilibrium of the adsoprtion of activated carbons can be represented by Langmuir model.And the adsorption process can be described by the pseudo-first-order model.The largest adsorption capacity for best activated carbon was 93.5mg/g.The adsorption of activated carbons was spontaneous and exothermic.