| The biggest problem caused by the rapid development of industrialization is the depletion of natural resources and serious pollution,especially heavy metal pollution in water and soil,which seriously threatens the environment and human health.Heavy metal ions can be bioconcentrated through the food chain and pose a persistent risk to human health and other organisms.There are a variety of practical techniques to separate heavy metal contaminants from water systems and soils,but these methods have their own limitations.This paper comprehensively reviews and systematically describes the commonly used heavy metal pollutant treatment technologies.The adsorption method is currently the most widely used and highly efficient method,but the preparation of commonly used adsorbents is more complex and costly.Based on this,in order to develop environmentally friendly and industrialized adsorption materials,based on the idea of turning waste into treasure,a new class of corn stover/feather keratin composite materials(FOC)was designed and prepared.Firstly,agricultural waste corn stover and waste feathers were used as raw materials,and corn stover(SOC)was oxidized by hydrogen peroxide and sodium periodate to oxidize the surface part of the hydroxyl oxidation to aldehyde and carboxyl groups,and at the same time industrial sodium sulfide reduction was used to dissolve poultry feathers.Then,the two were mixed in proportion,and the aldehyde group on the surface of the straw was used to react with the amino group of keratin to prepare a corn stover/feather keratin composite material and granulate.The preparation process of the materials was optimized,the reaction conditions with the highest aldehyde content were screened,the effects of material-liquid ratio,granulation radius,preparation temperature,pH and reaction time on the adsorption performance were systematically investigated,and the adsorption effects of SOC and FOC on simulated heavy metals in different water environments were compared.Finally,the heavy metal fixation ability of FOC in soil was investigated by pot experiment.The experimental results showed that the process parameters with the highest aldehyde content were as follows: sodium periodate concentration was 0.1 mol/L,oxidation time was 4 h,pH was 4.5,and temperature was 30 °C.The optimal process parameters of FOC are: material-liquid ratio 0.5/10(g/mL),granulation radius of 0.5 cm,preparation temperature of 80 °C,reaction pH of 5,reaction time of 24 h.The adsorption efficiency of FOC materials is about 3 times that of SOC,and the removal rate of heavy metal cadmium ions can reach about 80 %.The results show that this adsorbent raw material preparation process has less waste liquid,no pollution to the environment,low cost,and has industrialization prospects.Slow-release fertilizer technology is also one of the research priorities in the agricultural field,which can reduce fertilizer nutrient loss and the number of operations,and avoid excessive fertilization.Therefore,according to the characteristics of the above materials,this paper prepared a corn stover/feather keratin composite FOCU with the dual effects of heavy metal fixation and fertilizer slow release using urea as a model fertilizer.The slow-release efficiency of FOC particles loaded with urea in water and the ability of FOC to fix heavy metal ions in soil were investigated,as well as the effects on plant physiological characteristics.The experimental results show that it has the ability to fix heavy metal ions in soil and has no effect on plant growth.Compared with the plants without FOC particles,the heavy metal ion content of plants with FOC granules was reduced by about 43 %,and the yield was increased by about 45 %.The slow-release efficiency of FOCU urea fertilizer is about 77 %,which exceeds the 75 % standard stipulated by the state and the industry,which meets the requirements,indicating that the material has a good slow-release effect and heavy metal fixing ability,and has broad application prospects. |
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