西辽河流域沙土对氨氮的吸附行为研究

采用小型回填式土柱动态吸附实验方法研究了西辽河流域沙土对氨氮的吸附行为。结果表明,西辽河流域沙土对氨氮的吸附行为符合Freundlich吸附等温式和Langmuir吸附等温式,最优模型为Langmuir吸附方程;西辽河流域沙土对氨氮的饱和吸附量在573.81～3 666.16 mg/kg之间,平均为1 733.83 mg/kg。吸附分配系数k在3.13～524.55之间,平均为93.47;沙土对氨氮的吸附方式以化学吸附为主,解吸可逆性较弱。被吸附的氨氮解吸淋失的环境风险较小;沙土氨氮饱和吸附量与土壤有机质含量、粘粒含量和粗粘粒含量呈极显著正相关,影响程度顺序为:有机质含量>粘粒含量>粗粘粒含量;不同利用结构沙土的氨氮饱和吸附量:林地(2 053.87 mg/kg)>农田(1 990.40 mg/kg)>草地(1 356.37 mg/kg)>沙荒地(813.30 mg/kg);农田、林地和草地结构由于土壤有机质和团聚体含量较高,对氨氮的固持能力较强,氨氮流失的环境风险较小,沙荒地结构对氨氮的固持能力最弱。氨氮流失的环境风险最大。     

吸附反应时间对除草剂阿特拉津吸附行为的影响

采用批量动态实验方法,对潮土中阿特拉津吸附特征随吸附反应时间变化进行了研究。结果表明,土壤吸附的阿特拉津量随反应时间的变化符合双曲线函数关系。在50μg·L-1～2000μg·L-1浓度系列下,在48h内,土壤颗粒对阿特拉津的吸附属于快反应,土壤吸附的阿特拉津量随吸附反应时间呈指数上升,为吸附实验结束(168h)时土壤吸附阿特拉津总量的58%到90%。当吸附反应时间超过48h后,随反应时间增加,土壤吸附阿特拉津量差异变化不显著。阿特拉津在潮土颗粒和土壤溶液中的相分配可用Freundlich方程描述。吸附容量因子Kf与吸附反应时间之间有极显著的线性正关系(r2=0.9063**,p<0.0001)。无量纲的非线性因子n与吸附反应时间之间也具有显著的线性负关系(r2=0.5666*,p=0.0192)。     

纳米α - Fe2O3微球对U(Ⅵ)的吸附特性研究

将海藻酸钠与纳米α-Fe2O3制成微球,用于吸附U(Ⅵ)。探讨了纳米α-Fe2O3含量、交联时间、pH值、投加量、浓度、温度等对吸附的影响。结果表明,pH值对U(Ⅵ)的吸附过程影响显著,适宜pH值为3。U(Ⅵ)在微球上的吸附量随着吸附时间的增加而增大,初始阶段(1.5 h)反应进行得很快,9 h时达到吸附平衡。当U(Ⅵ)初始质量浓度为10mg/L时,其饱和吸附量为2.64mg/g。准二级动力方程很好地拟合了吸附动力学数据,且R2>0.99。吸附率与温度呈正相关,Lang-muir与Freundlich吸附等温方程均能较好地拟合固定化微球对U(Ⅵ)的吸附过程(R2>0.99),但Freundlich等温线效果更好。吸附反应中ΔG<0,ΔH>0且小于40 kJ/mol,ΔS>0,这表明吸附过程能自发进行,为吸热反应。     

Isotherm and kinetic studies for the biosorption of cadmium from aqueous solution by Alhaji maurorum seed

Cadmium is an extremely toxic metal commonly found in industrial regions. Anthropogenic activity is the most important factor causing its interference to water, soil and air resources. The aim of many researches is to present remediation strategy or to remove cadmium from contaminated resources through an economical and efficient method. Cadmium adsorption from aqueous solution using Alhaji maurorum seed adsorbent has been investigated and optimized in this study. Moreover, isotherm and kinetics of adsorption process was studied. The seeds are washed by distilled water after separation from the plant, and then dried in room temperature for 48 h. They are powdered by grinder and passed through sieve no.18 as well. Adsorption process was optimized in 4 steps regarding pH, contact time, adsorption dose and initial concentration of cadmium effects. The cadmium concentration in solution was measured using ICP-OES method. The results of optimization tests showed that the optimum condition of cadmium adsorption (85.5% removal) occurs at pH of 6.5 with 20 g/L of adsorption dose for 45 min. In addition, the efficiency of adsorption process increases as the cadmium concentration reduces in the initial solution. Adsorption process follows the pseudo second-order kinetics and Freundlich isotherm with correlation coefficients of 0.999 and 0.99, respectively. According to the findings of this analysis, it was concluded that A. maurorum seed is a good biological adsorbent for adsorbing cadmium from aqueous solution.     

Evaluation of sorption-desorption processes for metalaxyl in natural and artificial soils

The main process controlling soil-pesticide interaction is the sorption-desorption as influenced by active soil surfaces. The sorption phenomena can influence translocation, volatility, persistence and bioactivity of a pesticide in soil. The present investigation was conducted on natural and artificial soils in order to enumerate the effect of soil components such as montmorillonite and ferrihydrite on the sorption behaviour of the fungicide metalaxyl and if sorption-desorption of the chiral pesticide affects the enantiomeric ratio. The sorption-desorption characteristics of metalaxyl were investigated by batch equilibration technique in a natural soil, two artificial soils, and in pure montmorillonite and ferrihydrite. After extraction, pesticide residues were analyzed by conventional and chiral chromatography using tandem mass spectrometry. A K_dSorp (2.3–6.5) suggests low level sorption of metalaxyl with an appreciable risk of run-off and leaching. Thus, metalaxyl poses a threat to surface and ground water contamination. Furthermore, desorption tests revealed a hysteretic effect (H ≤ 0.8) in natural and artificial soils. Significant amount of metalaxyl was found tightly bound to the adsorbents without desorbing readily after desorption cycle. Desorption of 22–56% of the total amount of the retained metalaxyl was determined. This study reveals that an artificial soil derived from different soil constituents can be used to assess their influence on sorption/desorption processes. The present investigation showed that both montmorillonite and ferrihydrite play a significant role in the sorption of metalaxyl. The sorption doesn't influence the enantiomeric ratio of racemic metalaxyl.     

Retention of 137cesium in acid sulphate soils of South Central Thailand

Adsorption and desorption of ¹³⁷Cs by acid sulphate soils from the Nakhon Nayok province, South Central Plain of Thailand located near the Ongkarak Nuclear Research Center (ONRC) were investigated using a batch equilibration technique. The influence of added limestone (12 and 18 tons ha^-1) on ¹³⁷Cs adsorption-desorption was studied. Based on Freundlich isotherms, both adsorption and desorption of ¹³⁷Cs were nonlinear. A large portion (98.26-99.97%) of added ¹³⁷Cs (3.7 × 10³-7.03 × 10⁵ Bq l^-1) was sorbed by the soils with or without added lime. The higher lime treatments, however, favoured stronger adsorption of ¹³⁷Cs as compared with soil with no lime, which was supported by higher K_ads values. The addition of lime, the cation exchange capacity and pH of the soil increased and hence favoured the stronger adsorption of ¹³⁷Cs. Acid sulphate soils with a high clay content, medium to high organic matter, high CEC, and predominant clay types consisting of a mixture of illite, kaolinite, and montmorillonite were the main soil factors contributing to the high ¹³⁷Cs adsorption capacity. Competing cations such as NH₄⁺, K⁺, Na⁺, Ca²⁺, and Mg²⁺ had little influence on ¹³⁷Cs adsorption as compared with liming, where a significant positive correlation between K_ads and soil pH was observed. The ¹³⁷Cs adsorption-desorption characteristics of the acid sulphate soils studied exhibited a very strong irreversible sorption pattern. Only a small portion (0.09-0.58%) of ¹³⁷Cs adsorbed at the highest added initial ¹³⁷Cs concentration was desorbed by four successive soil extractions. Results clearly demonstrated that Nakhon Nayok province acid sulphate soils have a high ¹³⁷Cs adsorption capacity, which limits the ¹³⁷Cs bioavailability.     

活性炭吸附法去除废水中重金属的研究进展

总结了活性炭吸附法去除废水中重金属的机理和规律进行了,其吸附机理有离子交换、络合、化学吸附等,吸附平衡模式除了有Langmuir模式和Freundlich模式之外,还有表面络合模式;分析了pH、溶液的离子强度和初始浓度对单组分溶液吸附去除率的影响;论述了多个金属离子共存时活性炭对金属离子的吸附影响以及金属离子与有机物共存时活性炭对金属离子的吸附影响;最后展望了活性炭在重金属废水处理中的应用前景,提出了一些建议。     

颗粒活性炭吸附去除尿中药活性化合物（PhACs）

研究了多组分背景下2种煤质颗粒状活性炭D1220、R08S对人尿中4种药活性化合物（PhACs）（1 mg/L）——苯扎贝特（BEZ）、卡马西平（CAR）、布洛芬（IBU）和美托洛尔（MET）——的吸附去除。结果表明,D1220（R08S）对4种PhAC的吸附均符合Freundlich等温式,均为优惠吸附;D1220（R08S）对各PhAC的吸附作用强弱顺序为BEZ〉CAR〉MET〉IBU（BEZ〉CAR〉IBU〉MET）;PhACs平衡浓度小于3.01（0.91）μg/L时,D1220（R08S）对4种PhACs中的BEZ的吸附性能最好,平衡浓度大于3.01（1.93）μg/L时,D1220（R08S）则对MET的吸附性能最好;活性炭投加量为2 g/L时,D1220（R08S）对4种PhAC的去除率均在88%以上;总体吸附性能D1220优于R08S。     

西辽河流域不同土地利用结构沙土磷解吸特征

采用小型回填式土柱淋溶试验方法,研究了西辽河流域沙土的磷解吸特征.结果表明,西辽河流域沙土的磷解吸特征符合Freundlich和Langmuir解吸等温式;沙土磷的解吸比率(D_r)在0.32～0.98之间,平均值为0.70;最大解吸量(D_m)与饱和吸附量(Г_m)呈极显著正相关;沙土对磷的吸附方式以物理吸附为主,解吸可逆性较强.被吸附的磷在环境中较易发生淋失,仍然存在一定的环境风险.土壤中w(有机质)和w(团聚体)对磷的固持能力有较大影响;不同土地利用结构磷的D_r排序为农田(0.64)=草地(0.64)＜林地(0.67)＜沙荒地(0.91),农田、草地和林地磷淋失的环境风险较小;沙荒地磷淋失的环境风险最大,D_r与土壤中w(粗黏粒),w(黏粒)和w(有机质)呈极显著负相关.      

Removal of C.I. acid brown 75 from aqueous solution by kaolinite

The adsorption of acid brown 75 onto kaolinite in aqueous solution was studied with respect to the pH, adsorbent dosage, contact time, initial concentration, and operating temperature. Desorption of dye from dye-saturated kaolinite was observed. Experimental data indicated that the adsorption capacity of kaolinite for the dye was higher in acidic rather than in basic solution. The maximum adsorption capacity of kaolinite towards the dye was found to be 96.5 mg g^?1 (pH 1.0). At the optimal adsorption condition, the dye removal ratio was 95.5%. Dye-saturated kaolinite could desorb at aqueous NaOH, the desorption ratio of dye was 78.8%. The linear Langmuir and Freundlich isotherm models are well fitting to represent the experimental data.