Soil salinity is a major limiting factor for crop production in coastal areas of Bangladesh. Cheap and sustainable management of soil salinity is hence most sought out topics in agricultural research. Conceptualizing ...Soil salinity is a major limiting factor for crop production in coastal areas of Bangladesh. Cheap and sustainable management of soil salinity is hence most sought out topics in agricultural research. Conceptualizing that idea in mind, a pot experiment was conducted in the Department of Soil, Water & Environment, University of Dhaka in order to analyze if common organic amendments (rice straw, saw dust) coupled with reduce photoperiod can mitigate salinity effect on the growth of bean (Phaseolus vulgaris). The experiment was set up following completely randomized design (CRD) with nine treatments and three replications containing Tc (Control), T1 (Ambient photoperiod + 110 mM Salinity treatment + Rice straw), T2 (Reduced photoperiod + 110 mM Salinity treatment + Rice straw), T3 (Ambient photoperiod + 220 mM Salinity treatment + Rice straw), T4 (Reduced photoperiod + 220 mM Salinity treatment + Rice straw), T5 (Ambient photoperiod + 110 mM Salinity treatment + Saw dust), T6 (Reduced photoperiod + 110 mM Salinity treatment + Saw dust), T7 (Ambient photoperiod + 220 mM Salinity treatment + Saw dust) and T8 (Reduced photoperiod + 220 mM Salinity treatment + Saw dust). Organic amendments were used separately at the rate of 12 ton/ha. The highest plant height (98.67 cm), root length (12.5 cm), pod number (10.33), leaf area (13.99 cm2), fresh weight (680 kg/ha), dry weight (316.67 kg/ha) were recorded with the treatment T1 while the second-best treatment was treatment T2 (with highest harvest index 0.040) and these results were statistically significant (p < 0.001). In post-harvest soil, pH, EC, OC, OM;available N, P, K, S;total Ca, Mg, Zn, Mn were increased significantly in treatment T1. The overall results illustrated that the best growth and yield performances were achieved in the treatment T1 and T2.展开更多
Physical-chemical characteristics of the band sawing dusts regarding to recovery of pure silicon from them were investigated.The experimental results show 50vol%-60vol% amorphous phases exist in the dusts,which is mos...Physical-chemical characteristics of the band sawing dusts regarding to recovery of pure silicon from them were investigated.The experimental results show 50vol%-60vol% amorphous phases exist in the dusts,which is mostly amorphous silica.The as-received saw dusts are found to form hard agglomerates of larger than 50 microns in diameter.The iron-based inclusions collected by magnets are found to match well with the band saw material in XRD patterns.Weight loss in heating was observed by thermal gravity tests,up to 900 ℃,presumably due to reaction of the amorphous silica with carbon contaminant in the dusts.The saw dusts were variously treated to examine their physical-chemical responses,and the results were also presented.展开更多
The ability of eight natural adsorbents were investigated for adsorptive removal of Cr(VI) from aqueous solutions. Various physico-chemical parameters such as pH, initial metal ion concentration, adsorbent dose level ...The ability of eight natural adsorbents were investigated for adsorptive removal of Cr(VI) from aqueous solutions. Various physico-chemical parameters such as pH, initial metal ion concentration, adsorbent dose level and equi-librium contact time were optimized in batch adsorption technique. A detailed Fourier Transform Infrared Spectrophotometer (FTIR) study of adsorbents and Cr(VI) loaded adsorbents at the optimized condition was carried out to identify the different functional groups that were responsible for the adsorption. The important functional groups like hydroxyl, alkene, aromatic nitro, carboxilate anion, silicon oxide, sulphonic acid etc. were present in the natural adsorbent and were responsible for the chemical adsorption of Cr(VI) from aqueous solutions. The sorption energy calculated from Dubinin-Radushkevich isotherm indicated that the adsorption process were chemical in nature.展开更多
[Objective]We aimed to study the preparation methods of impurely irrigated soil adsorbent from beaches,as well as its ability to absorb phenol.[Method]Using hydrochloric acid as activator,we compared the influences of...[Objective]We aimed to study the preparation methods of impurely irrigated soil adsorbent from beaches,as well as its ability to absorb phenol.[Method]Using hydrochloric acid as activator,we compared the influences of various soil adsorbents on the adsorption of phenol through the desired orthogonal tests where the usage of saw dust,concentration of hydrochloric acid,liquid-solid ratio and carbonization temperature varied.Afterwards,we characterized this soil adsorbent.[Result]The optimal conditions for preparing the soil adsorbent were as follows,that is,the usage of saw dust was 20%,concentration of HCl was 1 mol /L,the ratio of liquid to solid was 2:1,carbonization temperature was 500 ℃,and activation time was one hour,the absorption efficiency of phenol in water by the soil adsorbent reached above 90%.Characterization showed that the prepared soil adsorbent changed obviously in the structure,that is,soil pores and carbon content increased greatly,as well as its absorption efficiency.[Conclusion]The prepared soil adsorbent by this method greatly improved the absorption efficiency of phenol in water,which provided a novel method for the reasonable utilization of saw dust,with good prospects.展开更多
Zinc oxide nanoparticles(ZnOnp) are molecular nanoparticles synthesized by a chemical precipitation method from zinc nitrate tetrahydrate and sodium hydroxide.Carbonized sawdust(CSD) was prepared from sawdust obtained...Zinc oxide nanoparticles(ZnOnp) are molecular nanoparticles synthesized by a chemical precipitation method from zinc nitrate tetrahydrate and sodium hydroxide.Carbonized sawdust(CSD) was prepared from sawdust obtained from a local wood mill.The matrix of both provides a better material as an adsorbent.The present study applied the functionality of ZnOnp,CSD,and ZnOnp-CSD matrix as adsorbent materials for the removal of Pb(Ⅱ) ions from aqueous solution.The method of batch process was employed to investigate the potential of the adsorbents.The influence of pH,contact time,initial concentration of adsorbate,the dosage of adsorbents,and the temperature of adsorbate-adsorbent mixture on the adsorption capacity were revealed.The adsorption isotherm studies indicate that both Freundlich and Langmuir isotherms were suitable to express the experimental data obtained with theoretical maximum adsorption capacities(q_(m)) of 70.42,87.72,and 92.59 mg·g^(-1) for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix,respectively.The separation factors(R_(L)) calculated showed that the use of the adsorbents for the removal of Pb(Ⅱ) ions is a feasible process with R_(L) <1.The thermodynamic parameters obtained revealed that the processes are endothermic,feasible,and spontaneous in nature at 25-50℃.Evaluation of the kinetic model elected that the processes agreed better with pseudo-second order where the values of rate constant(k_2) obtained for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix are 0.00149,0.00188,and 0.00315 g·mg^(-1)·min^(-1),respectively.The reusability potential examined for four cycles indicated that the adsorbents have better potential and economic value of reuse and the ZnOnp-CSD matrix indicates improved adsorbent material to remove Pb(Ⅱ) ions from aqueous solution.展开更多
以重庆市九龙坡区白市驿镇蔬菜基地为试验平台,通过大田试验,研究了锯木灰渣不同施用量还田1年后对酸性紫色土改良效果,并进一步分析了锯木灰渣对土壤微生物群落及微生物碳、氮的影响,以期为紫色菜园退化土壤养分和酸化的修复提供合理措...以重庆市九龙坡区白市驿镇蔬菜基地为试验平台,通过大田试验,研究了锯木灰渣不同施用量还田1年后对酸性紫色土改良效果,并进一步分析了锯木灰渣对土壤微生物群落及微生物碳、氮的影响,以期为紫色菜园退化土壤养分和酸化的修复提供合理措施,同时实现循环农业的可持续发展。结果表明:(1)锯木灰渣施用能显著提高蔬菜产量,且随着施用量的增加呈增加趋势,其中锯木灰渣施用量为18 000 kg hm^(-2)时,产量较未施用锯木灰渣(A0)处理显著提高了76.1%~121.9%;(2)经锯木灰渣处理的退化紫色土表层和亚表层的有机质含量和pH提高,尤其是锯木灰渣施用量为18 000 kg hm^(-2)的改良效果较佳,但是过高的锯木灰渣施用量处理对土壤交换性H^+、Al^(3+)效果反而下降,而施用量为12 000~15 000 kg hm^(-2)处理的效果较佳,其中表层土壤交换性H^+、Al^(3+)分别为0.19~0.20,0.63~0.67 cmol kg^(-1);(3)12 000~15 000 kg hm^(-2)的锯木灰渣施用量对土壤碱解氮和速效钾的提升效果较佳,18 000 kg hm^(-2)处理的有效磷含量最大,较A0处理增加了55.3 mg kg^(-1);(4)无论在表层土壤还是亚表层土壤中,细菌的种群数量分布最多,其次为真菌和放线菌,分别在12 000,9 000,6 000 kg hm^(-2)锯木灰渣施用量下的种群数量达到最大值;9 000~12 000 kg hm^(-2)处理对提高表层土壤微生物量碳含量较为明显,较A0显著提高了70.4%~78.7%,18 000 kg hm^(-2)处理的土壤微生物生物量氮(SMBN)含量最大(40.54 mg kg^(-1)),其次为9 000 kg hm^(-2)处理(34.32 mg kg^(-1))。综上,锯木灰渣施用量为12 000~15 000 kg hm^(-2)时对退化紫色土的改良效果较好。展开更多
文摘Soil salinity is a major limiting factor for crop production in coastal areas of Bangladesh. Cheap and sustainable management of soil salinity is hence most sought out topics in agricultural research. Conceptualizing that idea in mind, a pot experiment was conducted in the Department of Soil, Water & Environment, University of Dhaka in order to analyze if common organic amendments (rice straw, saw dust) coupled with reduce photoperiod can mitigate salinity effect on the growth of bean (Phaseolus vulgaris). The experiment was set up following completely randomized design (CRD) with nine treatments and three replications containing Tc (Control), T1 (Ambient photoperiod + 110 mM Salinity treatment + Rice straw), T2 (Reduced photoperiod + 110 mM Salinity treatment + Rice straw), T3 (Ambient photoperiod + 220 mM Salinity treatment + Rice straw), T4 (Reduced photoperiod + 220 mM Salinity treatment + Rice straw), T5 (Ambient photoperiod + 110 mM Salinity treatment + Saw dust), T6 (Reduced photoperiod + 110 mM Salinity treatment + Saw dust), T7 (Ambient photoperiod + 220 mM Salinity treatment + Saw dust) and T8 (Reduced photoperiod + 220 mM Salinity treatment + Saw dust). Organic amendments were used separately at the rate of 12 ton/ha. The highest plant height (98.67 cm), root length (12.5 cm), pod number (10.33), leaf area (13.99 cm2), fresh weight (680 kg/ha), dry weight (316.67 kg/ha) were recorded with the treatment T1 while the second-best treatment was treatment T2 (with highest harvest index 0.040) and these results were statistically significant (p < 0.001). In post-harvest soil, pH, EC, OC, OM;available N, P, K, S;total Ca, Mg, Zn, Mn were increased significantly in treatment T1. The overall results illustrated that the best growth and yield performances were achieved in the treatment T1 and T2.
基金Funded by the LDK Solar(TC-NU-0004)the Science & Technology Project of Education Department of Jiangxi Province(No.GJJ10034)
文摘Physical-chemical characteristics of the band sawing dusts regarding to recovery of pure silicon from them were investigated.The experimental results show 50vol%-60vol% amorphous phases exist in the dusts,which is mostly amorphous silica.The as-received saw dusts are found to form hard agglomerates of larger than 50 microns in diameter.The iron-based inclusions collected by magnets are found to match well with the band saw material in XRD patterns.Weight loss in heating was observed by thermal gravity tests,up to 900 ℃,presumably due to reaction of the amorphous silica with carbon contaminant in the dusts.The saw dusts were variously treated to examine their physical-chemical responses,and the results were also presented.
文摘The ability of eight natural adsorbents were investigated for adsorptive removal of Cr(VI) from aqueous solutions. Various physico-chemical parameters such as pH, initial metal ion concentration, adsorbent dose level and equi-librium contact time were optimized in batch adsorption technique. A detailed Fourier Transform Infrared Spectrophotometer (FTIR) study of adsorbents and Cr(VI) loaded adsorbents at the optimized condition was carried out to identify the different functional groups that were responsible for the adsorption. The important functional groups like hydroxyl, alkene, aromatic nitro, carboxilate anion, silicon oxide, sulphonic acid etc. were present in the natural adsorbent and were responsible for the chemical adsorption of Cr(VI) from aqueous solutions. The sorption energy calculated from Dubinin-Radushkevich isotherm indicated that the adsorption process were chemical in nature.
基金Supported by Open Foundation of Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection (JL-CBE09004)
文摘[Objective]We aimed to study the preparation methods of impurely irrigated soil adsorbent from beaches,as well as its ability to absorb phenol.[Method]Using hydrochloric acid as activator,we compared the influences of various soil adsorbents on the adsorption of phenol through the desired orthogonal tests where the usage of saw dust,concentration of hydrochloric acid,liquid-solid ratio and carbonization temperature varied.Afterwards,we characterized this soil adsorbent.[Result]The optimal conditions for preparing the soil adsorbent were as follows,that is,the usage of saw dust was 20%,concentration of HCl was 1 mol /L,the ratio of liquid to solid was 2:1,carbonization temperature was 500 ℃,and activation time was one hour,the absorption efficiency of phenol in water by the soil adsorbent reached above 90%.Characterization showed that the prepared soil adsorbent changed obviously in the structure,that is,soil pores and carbon content increased greatly,as well as its absorption efficiency.[Conclusion]The prepared soil adsorbent by this method greatly improved the absorption efficiency of phenol in water,which provided a novel method for the reasonable utilization of saw dust,with good prospects.
文摘Zinc oxide nanoparticles(ZnOnp) are molecular nanoparticles synthesized by a chemical precipitation method from zinc nitrate tetrahydrate and sodium hydroxide.Carbonized sawdust(CSD) was prepared from sawdust obtained from a local wood mill.The matrix of both provides a better material as an adsorbent.The present study applied the functionality of ZnOnp,CSD,and ZnOnp-CSD matrix as adsorbent materials for the removal of Pb(Ⅱ) ions from aqueous solution.The method of batch process was employed to investigate the potential of the adsorbents.The influence of pH,contact time,initial concentration of adsorbate,the dosage of adsorbents,and the temperature of adsorbate-adsorbent mixture on the adsorption capacity were revealed.The adsorption isotherm studies indicate that both Freundlich and Langmuir isotherms were suitable to express the experimental data obtained with theoretical maximum adsorption capacities(q_(m)) of 70.42,87.72,and 92.59 mg·g^(-1) for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix,respectively.The separation factors(R_(L)) calculated showed that the use of the adsorbents for the removal of Pb(Ⅱ) ions is a feasible process with R_(L) <1.The thermodynamic parameters obtained revealed that the processes are endothermic,feasible,and spontaneous in nature at 25-50℃.Evaluation of the kinetic model elected that the processes agreed better with pseudo-second order where the values of rate constant(k_2) obtained for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix are 0.00149,0.00188,and 0.00315 g·mg^(-1)·min^(-1),respectively.The reusability potential examined for four cycles indicated that the adsorbents have better potential and economic value of reuse and the ZnOnp-CSD matrix indicates improved adsorbent material to remove Pb(Ⅱ) ions from aqueous solution.
文摘以重庆市九龙坡区白市驿镇蔬菜基地为试验平台,通过大田试验,研究了锯木灰渣不同施用量还田1年后对酸性紫色土改良效果,并进一步分析了锯木灰渣对土壤微生物群落及微生物碳、氮的影响,以期为紫色菜园退化土壤养分和酸化的修复提供合理措施,同时实现循环农业的可持续发展。结果表明:(1)锯木灰渣施用能显著提高蔬菜产量,且随着施用量的增加呈增加趋势,其中锯木灰渣施用量为18 000 kg hm^(-2)时,产量较未施用锯木灰渣(A0)处理显著提高了76.1%~121.9%;(2)经锯木灰渣处理的退化紫色土表层和亚表层的有机质含量和pH提高,尤其是锯木灰渣施用量为18 000 kg hm^(-2)的改良效果较佳,但是过高的锯木灰渣施用量处理对土壤交换性H^+、Al^(3+)效果反而下降,而施用量为12 000~15 000 kg hm^(-2)处理的效果较佳,其中表层土壤交换性H^+、Al^(3+)分别为0.19~0.20,0.63~0.67 cmol kg^(-1);(3)12 000~15 000 kg hm^(-2)的锯木灰渣施用量对土壤碱解氮和速效钾的提升效果较佳,18 000 kg hm^(-2)处理的有效磷含量最大,较A0处理增加了55.3 mg kg^(-1);(4)无论在表层土壤还是亚表层土壤中,细菌的种群数量分布最多,其次为真菌和放线菌,分别在12 000,9 000,6 000 kg hm^(-2)锯木灰渣施用量下的种群数量达到最大值;9 000~12 000 kg hm^(-2)处理对提高表层土壤微生物量碳含量较为明显,较A0显著提高了70.4%~78.7%,18 000 kg hm^(-2)处理的土壤微生物生物量氮(SMBN)含量最大(40.54 mg kg^(-1)),其次为9 000 kg hm^(-2)处理(34.32 mg kg^(-1))。综上,锯木灰渣施用量为12 000~15 000 kg hm^(-2)时对退化紫色土的改良效果较好。
