ABSTRACT

To investigate the effect of different chitosan composites on the immobilisation of chromium in soil, a pot factorial experiment was conducted in greenhouse conditions using a completely randomised design with three replications. Factors studied were soil chromium levels (0, 20, 60, and 180 mg kg⁻¹) and types of adsorbent applied to the soil, including pure chitosan, biochar, zeolite, manganese dioxide and composites of chitosan-biochar, chitosan-zeolite, chitosan-manganese dioxide and control. The application of different adsorbents to soil decreased the concentrations of DTPA and MgCl₂ extractable chromium and chitosan composites, especially chitosan-manganese dioxide, were more effective for the immobilisation of chromium in the soil than the pure adsorbents. Reductions in DTPA-extractable chromium by pure biochar, zeolite, manganese dioxide, and chitosan were 34.9%, 29.4%, 19.8%, and 15.1% and by composites of chitosan-manganese dioxide, chitosan-biochar and chitosan-zeolite were 54.8%, 46.8%, and 39.7% respectively when compared to the control treatment. The use of different adsorbents significantly reduced the labile forms and thus the mobility of chromium in the soil and the composite adsorbents were more effective than the pure adsorbents. It is concluded that coating different adsorbents with chitosan increases their efficiency in immobilising chromium in soil.

摘要

为了研究不同壳聚糖复合材料对土壤中铬的固定化的影响，在温室条件下使用具有三个重复的完全随机设计进行了盆因子试验。研究的因素是土壤铬水平（0、20、60 和 180 mg kg ^-1）和应用于土壤的吸附剂类型，包括纯壳聚糖、生物炭、沸石、二氧化锰和壳聚糖-生物炭、壳聚糖-沸石的复合材料，壳聚糖-二氧化锰及其控制。不同吸附剂在土壤中的施用降低了 DTPA 和 MgCl _2的浓度可萃取铬和壳聚糖复合材料，尤其是壳聚糖-二氧化锰，比纯吸附剂更有效地固定土壤中的铬。纯生物炭、沸石、二氧化锰和壳聚糖对 DTPA 可萃取铬的降低分别为 34.9%、29.4%、19.8% 和 15.1%，壳聚糖-二氧化锰、壳聚糖-生物炭和壳聚糖-沸石的复合材料降低了 54.8%，与对照处理相比，分别为 46.8% 和 39.7%。不同吸附剂的使用显着降低了铬在土壤中的不稳定形态，因此复合吸附剂比纯吸附剂更有效。得出的结论是，用壳聚糖涂覆不同的吸附剂可以提高它们在土壤中固定铬的效率。