Preparation And Application Performance Of Nano-copper Hydroxide For Bactericides

Copper hydroxide is an important industrial material that can be used in medicine,mordants,pigments,feed additives,pesticides,paper dyes,and catalysts.In recent years,researchers also have found it has the potential usage in energy storage and sensors.Among them,copper hydroxide,a rookie in inorganic copper preparations,is a broad-spectrum fungicide widely used in the prevention and cure of diseases in fruits,vegetables and crops.It has been included as one of the recommended varieties of pollution-free agricultural products by the Ministry of Agriculture.For bactericidal materials,the smaller the particle size,the better the dispersibility,and the larger the specific surface area,the better the germicidal efficacy.When the bactericidal material reaches the nanoscale,it has a stronger antibacterial activity,so the nanocrystallization of copper hydroxide will be the key to the bactericidal effect.In this paper,copper hydroxide was prepared by direct precipitation method,precursor method and coordination precipitation method.After studying the rules of preparing copper hydroxide under different conditions,copper hydroxide with good performance was selected to make water dispersible granules compared with a copper preparation made of purchased copper hydroxide.The main results of this paper are as follows:(1)Preparation of copper hydroxide by direct precipitation method was studied.The rapid addition of sodium hydroxide solution had better crystal performance of copper hydroxide than that obtained by dropwise addition,and the lower(n(Cu2+):n(OH-)=1:2 relative to n(Cu2+):n(OH-)=1:2.5)amount of sodium hydroxide was,the worse crystallization performance was.When n(Cu2+):n(OH-)=1:2.5,nanowires with a diameter of about 20 nm,a length of 1-2 μm,and bundle-like(or ribbon)structure assembled by them was piled up to be severely agglomerated and ununiformed particles of 1-20 μm.When n(Cu2+):n(OH-)=1:2,nanospheres piled up and formed agglomerated particles of 1-15 μm.Copper hydroxide particles obtained by the direct precipitation method were uneven in size with poor dispersibility and serious agglomeration.(2)Preparation of copper hydroxide by precursor method was studied.By sodium hydroxide method,Cu4SO4(OH)6 and Cu4SO4(OH)6·H2O nanosheet precursors with diameters of 200-300 nm could be obtained by dropping or rapidly pouring sodium hydroxide solution into copper sulfate solution.Regardless of which precursor,the copper hydroxide nanowires(or nanorods)obtained by treating the precursors with sodium hydroxide solution dropping method were always longer than those of the fastaddition method,and finally the nanowires(or rods)staggered and woven into non-uniformly sized particles.Precursor of micron-sized structure with a thickness of about 0.5 μm,a width of 1-2 μm,and a length of 1-10 μm was obtained by treating the precursor with urea method,comb-shaped particles consisting of aligned copper hydroxide nanowires with a diameter of about 30 nm and a length of 1-2 μm were obtained by dropwise addition of sodium hydroxide solution,which basically retained the original precursor’s morphology characteristics.The comb-shaped particles similar to the precursor morphology were woven by copper hydroxide nanowires with a diameter of about 30 nm and a length of 1-3 μm,but comb-shaped particles were easy to accumulate as to several micrometers.Copper hydroxide particles obtained by precursor method were uneven in size with poor dispersibility.(3)Preparation of copper hydroxide by coordination precipitation method was studied.The copper hydroxide particles obtained with different initial copper sulfate concentrations and different ammonia concentrations had similar morphological characteristics.With increaseing ammonia concentration,they were all transformed from agglomerated and ununiformed particles to ordered paiticles.Low ammonia concentrations(corresponding to 2-5 mol/L,1.5-2.5 mol/L and below,1-2 mol/L and below)yielded that copper hydroxide was basically agglomerated with nanowires or nanorods.and was severely agglomerated and ununiformed.Uniform flower-shaped cluster(or bundle)copper hydroxide particles obtained with high ammonia concentrations(corresponding to 6-9 mol/L,3-3.5 mol/L,2.5-3 mol/L)were assembled from nanowires of 20-30 nm in diameter and 0.5-2 μm in length.This flower-like cluster paticles had uniform particle size,good dispersibility and high purity,with high specific surface area up to 83.3 m2/g.(4)Preparation of copper hydroxide by surfactant-coordination precipitation method was studied.SDS,PEG 6000 and PVP 40000 had great influences on copper hydroxide morphology.Among them,SDS could reduce the length of nanowires while reducing the diameter of the bundled paitcles,but it was easy to introduce impurities.Different concentrations of PEG 6000 which could reduce the length of nanowires and increase the diameter of flower-shaped cluster particles,could obtained a nearly spherical flower-like cluster particles with diameter of about 1μm.PVP 40000 mainly affected copper hydroxide morphology by reducing the diameter of flower-like clusters(or bundles).(5)Copper hydroxide dispersible granules were studied.The specific surface area of the copper hydroxide obtained by the coordination precipitation method was much higher than that of the purchased copper hydroxide.This was because the former nanowires were not as dense as the latter,and the dispersion of bundles(or clusters)was also better.The suspension of water dispersible granules made of copper hydroxide obtained by the coordination precipitation method was superior to the water dispersible granules made of nano-copper hydroxide purchased from Suzhou.And they basically met the requirements of particle size,suspension rate and pH.