Preparation And Properties Of Nano-cellulose Montmorillonite Composite Aerogel Modified By Different Cross-linking Agents

At present,with the deepening of industrialization,the development of science and technology and the awakening of people’s awareness of environmental protection,more and more countries begin to pay attention to environmental protection,rather than continue to sacrifice the environment to accelerate national economic development.However,the impact of the damage to the ecological environment that has been caused is far-reaching,and it can only be gradually eliminated by time and money.Some serious ecological problems are even difficult to eradicate.At present,there are two main types of treatment methods for oil spills.One is chemical method:in-situ combustion and dispersant precipitation degradation;the other is physical method:mechanical oil skimming recovery and adsorbent adsorption.Relatively speaking,there are many treatment methods for industrial wastewater,such as chemical precipitation method,ion exchange method,membrane separation method,biological flocculation method and adsorbent adsorption method.Therefore,the adsorbent adsorption method is not only suitable for oil spills and industrial wastewater treatment,but also for domestic wastewater treatment.However,traditional adsorbents have many shortcomings,such as high cost,difficult to recycle,and low adsorption efficiency.Therefore,the study of more low-cost,green,efficient and recyclable new adsorption materials has become one of the current research hotspots in the field of materials.This article mainly studies how to efficiently and quickly deal with the pollution of oil in water,organic solvents and heavy metal ions.Using liquid nitrogen orientation and freeze-drying method,etc.,by compounding other organic and inorganic materials,successfully prepared a green and environmentally friendly nano-cellulose-based composite aerogel,and then subjected to different modification treatments on the nano-cellulose-based composite aerogel,To give it hydrophobic oil absorption performance,enhance its mechanical properties,etc.,focusing on the performance of the composite aerogel on oil spills in water,organic solvents and different types of heavy metal ions.The main research results are as follows:（1）Using bamboo powder as the raw material,through a series of treatment methods such as benzene alcohol extraction,acid-base treatment and grinding and homogenization,nano cellulose with a diameter range of about 20-30 nm was successfully prepared with high crystallinity.,In line with the requirements of subsequent experiments.（2）The acid modified montmorillonite was successfully prepared by the method of sulfuric acid modification and activation,using montmorillonite K10 as the raw material.After strong acid treatment,the montmorillonite lamella structure was destroyed,and the metal cations Ca⁺,Na⁺and Mg²⁺between the montmorillonite lamellas were replaced.At the same time,the specific surface area of montmorillonite has also increased from 167.45 m²/g to208.87 m²/g.（3）Using cellulose nanofibers,polyvinyl alcohol and montmorillonite as raw materials,the CNF/PVA/MMT composite aerogel（CPMA）was successfully prepared by the method of liquid nitrogen directional freezing.After that,using methyltrimethoxysilane（MTMS）as the hydrophobic modifier,chemical vapor deposition（CVD）is used to impart high hydrophobicity and lipophilicity to the composite aerogel.A composite aerogel MTMS-CNF/PVA/MMT aerogel（MCPMA）with excellent mechanical properties with a density of 26.52 mg/cm³,a porosity of 96.1%,and a water contact angle>140°was obtained.The adsorption capacity of composite aerogel for various oils and organic solvents can reach 38-68 g/g and 40-64 g/g.At the same time,it can reach the maximum adsorption within one minute,and the adsorption rate is considerable.（4）Using cellulose nanofibers as the substrate,chitosan as the cross-linking agent,and modified montmorillonite as the additive,through a simple self-made directional freezing device,the growth direction of ice crystals during the freezing process is controlled to prepare a directional CNF/CS/MMT composite aerogel（d-CCMA）with three-dimensional interconnected network pore structure.Compared with the unoriented aerogel,the structural stability of the oriented aerogel is increased,and the mechanical properties are significantly enhanced.At the same time,the composite aerogel has a strong adsorption effect on different kinds of heavy metal ions,and the adsorption capacity of Cu²⁺,Pb²⁺and Cd²⁺can reach 181.95 mg/g,170.29mg/g and 163.85 mg/g,respectively.More importantly,after 5 cycles of adsorption-desorption,the adsorption capacity of the composite aerogel can still reach about 83% of the initial adsorption.