YIC-IR  > 中科院烟台海岸带研究所知识产出
农田土壤中结合态镉和铜的溶出机制与清除方法研究
Alternative TitleThe composite dissolution mechanisms and removal methods of bound Cadmium and Copper in farmland soils
杨帅
Subtype博士
Thesis Advisor骆永明
2022-06-23
Training institution中国科学院烟台海岸带研究所
Degree Grantor中国科学院大学
Degree Name工学博士
Degree Discipline环境科学
Keyword农田土壤 重金属 原位减量修复 增溶增排系统 废弃物浸提液 Farmland soil Heavy metals In-situ reduction remediation Solubilization and eluent drainage system Waste extract
Abstract农田重金属污染威胁着土壤资源的可持续利用和农产品的安全生产,而进入食物链的重金属会对人体健康带来风险,甚至危害。环境友好型去除土壤中重金属是农田土壤修复和安全利用的关键。温和的土壤淋洗是一种高效、经济且可永久性去除土壤中重金属的净化修复技术,但现行的农田土壤淋洗技术通常存在土壤结构难保持、肥力性能降低和洗脱废液难处理等问题。柠檬酸等小分子有机酸可有效去除土壤中的重金属,且生物降解性好,一般不会对土壤环境造成二次污染,可作为温和型土壤重金属淋洗剂,但目前相关研究多采用价格较高的分析纯柠檬酸开展室内振荡浸提参数优化试验,其野外应用成本较高,而关于低纯度下柠檬酸对土壤重金属增溶效果的研究还鲜有报道。近年来,农林工业生产过程产生的废弃物浸提液因易被生物降解、来源广泛和具有重金属去除效果被认为是传统人工合成淋洗剂的潜在替代品。然而,只有少数在高液土比下的废弃物浸提液(葡萄酒废渣、餐厨垃圾堆肥、秸秆废液等)被证明对污染土壤中的重金属有一定的去除能力,而对农林果皮废弃物材料研究较少,且缺乏简易有效的土壤重金属洗脱废液处理材料和方法。本论文采用环境友好型柠檬酸和农林废弃物浸提液作为绿色增溶剂,研发了一套土壤增溶-洗脱液增排-资源再利用相结合的农田重金属净土方法,系统探讨了绿色增溶剂在增溶增排净土方法下对土壤镉(Cd)和铜(Cu)的去除效果、溶出机理、形态分布、潜在生态风险、土壤肥力质量变化、土壤酶活性以及废弃物残渣处理洗脱废液可行性,以期为农用地重金属绿色节能低碳型修复技术体系的构建提供科学依据和新方法。本论文主要研究进展包括以下几个方面: (1)农用地增溶增排系统可有效去除土壤重金属,并可实现淋溶洗脱废液的回收再利用。两步梯度增溶法(工业级柠檬酸-水)较单一柠檬酸对土壤重金属的去除率显著增高,其对Cd和Cu的去除率分别为68.9%和41.4%,去除的土壤重金属主要以交换态和还原态为主。秸秆作为增排暗沟填料能有效地促进不同土层中Cd和Cu的溶出,柠檬酸-水梯度增溶后土壤中剩余Cd的潜在生态风险均由高风险降到低风险,降低约75%。两步柠檬酸-水洗梯度增溶显著缓解了单一柠檬酸造成的土壤酸化问题。不同增溶处理后大部分土壤肥力指标得以保持或显著增加,而秸秆暗沟填料下两步柠檬酸-水增溶后土壤有机质、速效铵和速效磷的平均含量分别提高了40.9%、57.3%、32.0%。废弃物花蛤贝壳粉可高效去除洗脱废液中的Cd(78.7%)和Cu(57.5%),而经废弃物贝壳粉处理回收的再生柠檬酸可实现对污染土壤中重金属的节能低碳快速去除。农用地重金属增溶增排净土方法可发展成为一种成本低、效率高、环境友好的具有应用潜力的土壤重金属污染修复技术。 (2)不同果皮和制酒废弃物浸提液可实现农用地土壤重金属的温和型修复。不同废弃物单一浸提液对农用地土壤重金属均具有一定的去除效果,且菠萝皮材料浸提液去除效果最佳,其中榨汁菠萝皮浸提液对土壤Cd平均去除率为15.9%,而粉碎菠萝皮浸提液为21.1%。通过粉碎菠萝皮浸提液增溶参数优化批试验,选定其最优土壤增溶参数为:菠萝皮浸提液浓度5.0%(50 g·L-1)、增溶反应时间180 min、菠萝皮浸提增溶液pH 3和固液比1:5。不同菠萝皮复配浸提液较单一菠萝皮浸提液对土壤的平均去除率显著增加。菠萝皮-柠檬酸复配浸提液两步梯度增溶方式较一步增溶对土壤Cd和Cu去除率分别增加2.2%-13.2%和3.1%-9.0%,其可有效降低农田土壤中重金属的潜在生态风险,缓解土壤酸化,同时提高大部分土壤养分指标,有利于修复后土壤的再利用。废弃物菠萝皮复配增溶液的两步梯度增溶方式在去除污染农用地土壤中的重金属方面具有潜在应用性。 (3)废弃菠萝皮浸提残渣可实现土壤增溶洗脱废液中重金属的简易友好型去除。浸提残渣在不同吸附条件下对洗脱废液中Cd的去除率存在较大差异,其对废液中重金属去除的最优化条件为:选用菠萝皮柠檬酸浸提改性残渣、材料投加量10 g L-1、废液pH>3.5和吸附反应时间60 min。菠萝皮改性残渣通过物理吸附和化学络合共同作用对不同实际污染土壤洗脱废液中的重金属均具有较高的去除率,其中来自湖南长沙的旱地红壤增溶洗脱废液Cd和Cu平均去除率分别为60.1%和57.4%,来自甘肃白银的旱地灰钙土壤增溶洗脱废液Cd和Cu平均去除率分别为64.1%和53.8%,山东烟台果园棕壤的增溶洗脱废液Cd和Cu平均去除率分别为78.8%和75.6%,表明通过改性浸提残渣吸附可以实现废弃菠萝皮残渣资源节约化循环再利用。 (4)温和型菠萝皮废弃物浸提液具有田间原位重金属净土修复应用潜力。温和型菠萝皮复配浸提液可有效去除田间土壤中重金属,其中菠萝皮(PP)和柠檬酸(CA)复配浸提液两步(CA+PP-H2O)梯度增溶法对烟台果园棕壤和白银旱地灰钙土壤Cd去除率分别为38.2%和29.6%,且两步梯度增溶后两种土壤中Cd剩余浓度均可以降低到风险筛选值以下。两步(H2O+PP-H2O和CA+PP-H2O)梯度较柠檬酸(CA-H2O)增溶后在两种土壤中脲酶活性分别平均增加了22.8%和29.7%,β葡萄糖苷酶活性分别平均增加了14.8%和12.2%;两步(CA+PP-H2O)梯度增溶后两种土壤微生物生物量碳和微生物生物量氮较原始土壤分别平均增加了151.65 mg kg-1和9.14 mg kg-1。不同菠萝皮复配浸提液两步梯度增溶后土壤较两种未增溶原始土壤生长的小麦发芽率、根长、芽长和生物量等指标均增加。菠萝皮改性残渣对烟台果园酸性棕壤和白银旱地碱性灰钙土壤增溶洗脱废液Cd平均去除率分别为65.0%和53.5%。温和型菠萝皮复配浸提液在农用地重金属增溶增排净土方法下可经济有效去除偏砂质酸碱性土壤和洗脱废液中重金属,其在农林废弃资源的综合利用和节能低碳型农用地重金属净土修复方面具有潜在的应用前景。 (5)废弃菠萝皮浸提液对农用地土壤重金属的溶出机制涉及多种因素。菠萝皮浸提液对农用地土壤中Cd和Cu的溶出去除过程可以分为快速反应阶段(0-3 h)和慢速反应阶段(3-24 h)。Elovich模型更适合描述菠萝皮浸提液对农用地土壤中Cd和Cu的溶出动力学特征,表明其溶出去除过程是非均相扩散过程,主要由扩散因子控制。不同废弃物浸提液对土壤重金属去除效率的差异与有机酸的浓度和组成有关,有机酸浓度在4715.5 mg L-1-15237.9 mg L-1,以柠檬酸作为主要有机酸组分时对土壤重金属的去除效率最好。羧基、羟基、胺基和羰基是菠萝皮浸提液与重金属离子络合的主要官能团。菠萝皮不同浸提处理后的增溶液含有与未浸提菠萝皮相似物理结构的物质,其破碎不规则状分布有利于与土壤中重金属的充分接触并溶出。
Other AbstractHeavy metal contamination of farmland seriously threatens the sustainable use of soil resources and the safe production of agricultural products, while heavy metals entering the food chain can pose great risks to human health. Environmentally friendly permanent removal of heavy metals from soils is the key to the remediation and safe utilization of farmland soils. Washing is an efficient, economical and permanent technique for soil heavy metals removal, but traditional washing technologies may destroy soil structure and decrease fertility while waste eluent are difficult to deal with. Small-molecule organic acids such as citric acid can effectively remove heavy metals in soil, and have good biodegradability, which will not cause secondary pollution to the soil environment. However, at present, related research mostly uses analytically pure citric acid with higher price to carry out indoor shaking washing parameter optimization experiments, and its field application costs are high, while there are few reports on the effect of citric acid on soil heavy metal removal efficiency at low purity. In recent years, waste extracts produced by agricultural and forestry industries have been considered as potential substitutes for traditional synthetic washing agents due to their easy biodegradation, wide range of waste sources and certain removal efficiency of heavy metal. However, only a few waste extracts washing agents (wine residue, kitchen waste compost, straw waste liquid, etc.) with high liquid-soil ratio have been proved to have a certain removal efficiency of heavy metals in polluted soil. There are relatively few studies on agricultural and forestry peel waste materials, and lack of simple and effective soil heavy metal elution waste liquid treatment materials and methods. We proposed and verified a feasible and eco-friendly solubilization and eluent drainage system using industrial grade citric acid and/or extracts from agro-forestry waste to remove cadmium (Cd) and copper (Cu) from farmland soil. The removal efficiencies of Cd and Cu, washing mechanism, fraction distribution, potential ecological risk, soil fertility, soil enzyme activity and the feasibility of waste eluent treatment method using waste residue were discussed to provide a scientific reference for the construction of a green energy-saving and consumption-reducing remediation technologies for agricultural soil. The main findings of this paper include the following aspects: (1) The agricultural land solubilization and drainage system can effectively remove heavy metals from soil, and can realize the recycling and reuse of waste eluent. The sequential citric acid-water washing method had higher removal rates of heavy metals in soil than single citric acid, and the removal efficiencies of Cd and Cu were 68.9% and 41.4%, respectively. The Cd and Cu at different soil depth were removed more effectively using the two-stage (citric acid-water) washing with wheat straw than crushed stone as underdrainfilling material. The potential risks of Cd in soils all decreased by approximately 75% from considerable to low risk. The citric acid-water washing with wheat strawfilling significantly mitigated the soil acidification and increased soil organic matter (SOM), available ammonium (N-NH4) and available phosphorus (AP) increased by 40.9%, 57.3%, 32.0%, respectively. The clam powder could efficiently removed 78.7% Cd and 57.5% Cu from the waste eluent, and the regenerated citric acid after shell powder treatment can achieve rapid systemization remediation of heavy metals in polluted soil. The combined solubilization and eluent drainage system is thus a low-cost, high-efficiency, environmentally friendly and potentially practical agricultural soil heavy metal remediation technology. (2) The extracts of different agricultural and forestry peels and wine-making wastes can realize mild remediation of heavy metals in agricultural soil. Different mild peel and wine-making waste extracts have certain removal effects on soil heavy metals in agricultural land, and the mild pineapple peel material extract has the best heavy metals removal efficiency (juiced pineapple peel extract has an average removal of 15.9% Cd, while the crushed pineapple peel extract is 21.1% Cd from soil). The optimal parameters were selected through the soil washing batch test of crushed pineapple peel extract: the concentration of pineapple peel extract was 5.0% (50 g·L-1), the washing reaction time was 180 min, the pineapple peel extract solution was pH 3 and the solid-liquid ratio 1:5. The average removal rate of different pineapple peel mixed extracts was significantly increased than the single pineapple peel extract. Compared with one-stage washing, the two-stage washing method of pineapple peel citric acid mixed extract increased soil Cd and Cu removal rates by 2.2%-13.2% and 3.1%-9.0%, respectively, which could effectively reduce the potential ecological potential risk of heavy metals in farmland soil, alleviate soil acidification, improve most soil nutrient indicators, and promote the reuse of soil after remediation. The two-stage sequential washing method of pineapple peel mixed washing agents has potential application feasibility in removing heavy metals from polluted agricultural soils. (3) The residue of waste pineapple peel extracts can realize the simple and friendly removal of heavy metals in waste eluent.The removal efficiency of Cd from the waste eluent by the adsorption materials varied greatly under different conditions. The optimal conditions were as follows: citric acid extraction modified residue of pineapple peel as the optimal material, the modified residue of pineapple peel dosage 10 g L-1, the waste eluent pH> 3.5, and the adsorption reaction time 60 min. The modified residue of pineapple peel has a high removal efficiency of heavy metals from the waste eluent through the combined effect of physical adsorption and chemical complexation. The average removal efficiencies of Cd and Cu in Changsha dryland waste eluent by the modified residue of pineapple peel were 60.1% and 57.4%, Baiyin dryland waste eluent were 64.1% and 53.8%, and Yantai orchard brown soil waste eluent were 78.8% and 75.6%, respectively, which indicated that the waste pineapple peel residue could be recycled and reused by modifying the residue. (4) The mild pineapple peel waste extract has the potential for field soil remediation of heavy metals. The mild pineapple peel mixed washing agents could effectively remove the heavy metals in the field farmland soil under the combined solubilization and eluent drainage system. The two-stage (PP+CA-H2O) sequential washing method of pineapple peel (PP) and citric acid (CA) mixed washing agents to Yantai orchard brown soil and Baiyin dryland sierozem soil Cd removal efficiencies were 38.21% and 29.58%, respectively, and the residual concentration of Cd in two field soil could be reduced below below the risk screening value of heavy metals in agricultural land in China. Compared with citric acid (CA-H2O), the two-stage (H2O+PP-H2O and CA+PP-H2O) sequential washing method increased the urease activity in the Yantai orchard brown soil and Baiyin dryland sierozem soil by 22.8% and 29.7%, and the soil β-glucosidase activity averaged increased by 14.8% and 12.2%, respectively. The two-stage (CA+PP-H2O) sequential washing of the two soils increased soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) by an average of 151.65 mg kg and 9.14 m-1g kg-1 than the original soil, respectively. The germination rate, root length, shoot length and dry weight of wheat grown in the soil after two-stage sequential washing of the different pineapple peel mixed extracts were increased than the two original soils. The average removal efficiencies of Cd from the waste eluent of Yantai orchard brown soil and Baiyin dryland sierozem soil were 65.0% and 53.5% by the modified residue of pineapple peel, which achieved the comprehensive utilization of agricultural and forestry waste resources and heavy metal remediation of energy-saving and consumption-reducing for agricultural soils. (5) The dissolution mechanism of waste pineapple peel extracts to heavy metals in agricultural soils involves many factors.The removal process of Cd and Cu in agricultural soil from pineapple peel extract can be divided into a fast reaction stage (0-3 h) and a slow reaction stage (3-24 h). The Elovich equation is more suitable to describe the kinetics of the dissolution of soil Cd and Cu from pineapple peel extract. The dissolution and removal process is a heterogeneous diffusion process, which is mainly controlled by the diffusion factor. The differences in the removal efficiency of soil heavy metals from different waste extracts were related to the different concentrations and compositions of organic acids, and the concentration of total organic acids is 4715.5 mg L-1-15237.9 mg L-1. Among them, the removal efficiency of soil heavy metals was the best when citric acid was used as the main organic acid component. The carboxyl, hydroxyl, amine and carbonyl groups were the main functional groups complexed with heavy metal ions in pineapple peel extracts. The washing agents of pineapple peel after different extraction treatments have similar physical structures to those of un-extracted pineapple peels, and their broken and irregular distribution is conducive to full reaction and removal of heavy metals in soil.
Language中文
Document Type学位论文
Identifierhttp://ir.yic.ac.cn/handle/133337/30980
Collection中科院烟台海岸带研究所知识产出
Recommended Citation
GB/T 7714
杨帅. 农田土壤中结合态镉和铜的溶出机制与清除方法研究[D]. 中国科学院大学,2022.
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