Preparation Of Amino-functionalized Cellulose And Its Adsorption Properties For Organophosphorus And Heavy Metal Ions

With the continuous development of social economy and the continuous advancement of urbanization,a large amount of waste water containing refractory organic pollutants and heavy metal ions produced by industrial and agricultural production and social life is discharged into the environment,bringing to human health and the ecosystem great threat.The adsorption method is considered to be one of the most ideal pollutant removal technologies due to its simple operation and low cost.However,the existing adsorption materials often have problems such as single function,slow adsorption rate and low capacity.Cellulose is the most abundant renewable resource in nature.It has the advantages of a wide range of sources,biodegradability,and easy functional modification.It has significant advantages in the removal of wastewater pollutants.Therefore,using cellulose as a raw material and molecular structure design to prepare green and efficient cellulose-based adsorption materials and achieve simultaneous removal of organic pollutants and heavy metal ions in complex system wastewater has important scientific significance and application value.In this thesis,cellulose is used as a raw material,through molecular structure design,polyethyleneimine(PEI)is grafted onto cellulose by sodium periodate oxidation to produce amino-functionalized cellulose(AFC)containing a large number of active groups.Furthermore,organophosphorus(phytic acid)and heavy metal ions Cu²⁺,Ni²⁺and Co²⁺are used as model pollutants to systematically study the adsorption and removal effect of AFC on organophosphorus and heavy metal ions in a single system and a multiple system.Discuss its adsorption kinetics,isotherm model,adsorption thermodynamics and adsorption mechanism.The specific research work is as follows:(1)Preparation of amino-functionalized cellulose and its adsorption performance for organophosphorus:amino-functionalized cellulose containing a large number of active groups was successfully prepared by oxidative grafting technology,and its surface amino group content was 2.6 mmol/g.Using phytic acid as an organophosphorus pollutant model,the effects of AFC dosage,initial concentration of organophosphorus,contact time,solution p H,and temperature on the adsorption performance of organophosphorus were systematically investigated.The study found that AFC can quickly and efficiently remove organics from water.Phosphorus can reach adsorption equilibrium within 60 min,and its maximum adsorption capacity is 178.6 mg P/g.The adsorption performance of ACF on organophosphorus under the coexistence of anions Cl^-,CO₃^2-,SO₄^2-,NO₃^-and organophosphorus was further investigated.The results showed that coexisting anions had almost no effect on the adsorption of organophosphorus.Indicate that AFC has strong anti-interference ability to adsorption organophosphorus.The study of adsorption mechanism found that the rapid and efficient adsorption of AFC on organophosphorus is mainly due to the electrostatic interaction and hydrogen bond interaction between a large number of active amino groups on the surface of AFC and organophosphorus.(2)Study on the adsorption performance of amino-functionalized cellulose on heavy metal ions:the effect of AFC on the adsorption performance of Cu²⁺,Ni²⁺and Co²⁺under different contact time,initial concentration,temperature,and p H of the solution was systematically studied.The results showed that AFC within 10 min the adsorption equilibrium of Cu²⁺,Ni²⁺and Co²⁺ions is reached,and its removal capacity is Cu²⁺(89.29 mg/g)>Ni²⁺(79.37 mg/g)>Co²⁺(52.91 mg/g).The study of adsorption mechanism found that the high adsorption capacity of AFC for three metal ions is caused by the complex and electrostatic attraction between a large number of highly active amino groups on the surface of AFC and metal ions.The binary and ternary mixed system with Cu²⁺/Ni²⁺,Cu²⁺/Co²⁺,Ni²⁺/Co²⁺and Cu²⁺/Ni²⁺/Co²⁺ions coexisting was constructed to study the competitive adsorption relationship between heavy metal ions.Due to the stronger affinity and complexation between amino groups and Cu²⁺ions,Cu²⁺ions showed excellent competitiveness,and it's adsorption capacity has maintained a growth of more than 20%in the binary and ternary mixed system.The binary system of heavy metals and organophosphorus coexisting Cu²⁺/phytic acid,Ni²⁺/phytic acid,Co²⁺/phytic acid was constructed,and the simultaneous removal performance of AFC on heavy metals and organophosphorus was studied.The results showed that there is a mutual promotion effect between Cu²⁺ions and organophosphorus,compared with the one-component system,the adsorption capacity increased by 21.59%and 9.90%,while Ni²⁺and Co²⁺ions showed mutual inhibition.This may be because the amino group on the AFC is easy to complex with Cu²⁺ions,and at the same time,the negatively charged organophosphorus and Cu²⁺ions can be further combined through electrostatic interaction,so they promote each other.The amino-functionalized cellulose prepared in this paper can quickly and efficiently remove organophosphorus and heavy metals Cu²⁺,Ni²⁺and Co²⁺in water,and can synergistically remove organophosphorus and Cu²⁺.Solves the problem of slow adsorption rate,small adsorption capacity,and single adsorption function of traditional adsorbents.This paper clarified the adsorption mechanism of AFC on heavy metals and organophosphorus,and provided a theoretical reference for the treatment of organic pollutants and heavy metal ions in the system wastewater.