Study On Removal Of Phosphorus From Water By Lignin Sulfonate-derived Carbon

High phosphorus concentration in water will have a great negative impact on many natural water bodies,leading to serious agricultural pollution,eutrophication and other environmental problems,which greatly inhibits the effective use of water resources.In this work,calcium lignosulfonate（CL）was used to produce biochar at 400℃and800℃).The CL derived carbon（CLDC）samples of CLDC400,CLDC800,Fe-CLDC400,Fe-CLDC800,Mg-CLDC400 and Mg-CLDC800 were prepared by magnesium（Mg）or iron（Fe）modification for removing phosphorus from water,which provided theoretical direction for the industrial application of biochar in the fields of phosphorus removal and recovery from wastewater.The morphologies of CLDC400,CLLDC800,Fe-CLDC400,Fe-CLDC800,Mg-CLDC400 and Mg-CLDC800 were analyzed by scanning electron microscope,surface area analyzer,X-ray diffraction and X-ray photoelectron spectroscopy.The results showed that the Feelement in Fe-CLDC mainly existed in the form of FeCl₂ and Fe³⁺before adsorption,and in the form of Fe³⁺and FePO₄/Fe₂（SO₄）₃ after adsorption.The Mg in Mg-CLDC mainly existed in the form of Mg O and MgCl₂ before adsorption,and then as Mg₃（PO₄）₂ and Mg HPO₄.To compare the phosphorus adsorption properties of the carbon materials,a series of batch sorption tests were performed in phosphorus microcondition.The main properties of CLDC400,CLLDC800,Fe-CLDC400,Fe-CLDC800,Mg-CLDC400 and Mg-CLDC800 before and after sorption were evaluated according to the following factors such as initial solution pH（2-12）,phosphorus concentration（0-50 mg/L）,adsorbent dosage（0-6 g/L）and temperature（30 and 50℃）.The results showed that the phosphorus removal followed by Freundlich sorption and pseudo-second-order kinetic models.According to Langmuir model,the highest sorption capacities of CLDC400 and CLDC800（50℃）were 53.22 mg/g and 17.77mg/g.The highest sorption capacities of Fe-CLDC400 and Fe-CLDC800 were 37.12mg/g and 93.40 mg/g,respectively.The highest sorption capacity of Mg-CLDC400 and Mg-CLDC800 were 89.40 and 117.60 mg/g respectively.The phosphorus adsorption mechanisms of CLDC materials were likely as follows:adsorption,complex reaction,ion exchange,chemical precipitation and electrostatic attraction.