铅、镉污染废水树皮类吸附材料的筛选

Screening of bark adsorbents for Pb and Cd removal from polluted wastewater

近年来,水体重金属污染日趋严重,筛选出绿色高效处理重金属污染废水的吸附材料迫在眉睫.本文采用振荡吸附法研究了10种树皮类生物质吸附材料在不同投加量、初始浓度、pH和吸附时间下对模拟污染废水中Pb2+和Cd2+的吸附效率.结果表明,在25℃和180 r·min-1恒温振荡条件下,10种树皮对Pb2+和Cd2+的吸附效率存在明显差异(P<0.05).它们对模拟废水Pb2+和Cd2+的吸附量和吸附率,分别随初始浓度的增加呈递增和递减趋势;在0—120 min内随吸附时间的延长而提高;在pH 2.0—4.0范围内,随pH的增大而明显提升.红外光谱分析表明,羟基和羧基参与了Pb2+和Cd2+吸附.在投加量0.5 g·L-1、模拟废水初始浓度50 mg·g-1、pH 5.50和吸附时间120 min条件下,侧柏(Platycladus orientalis)皮、核桃树(Juglans regia)皮和构树(Broussonetia papyrifera)皮对Pb2+的吸附量可达71.77—83.61 mg·g-1,对Cd2+的吸附量达到64.69—70.33 mg·g-1,对实际污染废水具有较高的吸附率,最高可达98.21%.因此,侧柏皮、核桃树皮和构树皮可能是是吸附复合污染废水中铅镉的潜在材料.

Water pollution with heavy metals has become a non-negligible problem in environment,owing to their high toxicities,long persistence,and bio-magnification traits.Developing affordable and sustainable adsorbents are the prime factors for the success of removing heavy metal.Ten kinds of bark as adsorbent materials were selected in this study.Their performances were evaluated under different conditions of dosage,initial metal concentration,initial solution pH,and reaction time.Results showed that Pb2+and Cd2+removal efficiencies had significant differences under 25℃and 180 r·min-1(P<0.05).The metal adsorption capacities and removal efficiencies increased and decreased with the increase of initial concentrations of Pb2+and Cd2+,respectively.They promoted with increasing reaction times within 0—120 min,and rapidly increased by pH lift in the range of pH 2.0—4.0.According to the Fourier Infrared Spectrometer,hydroxyl and carboxyl groups were involved in Pb2+and Cd2+adsorption.In addition,Platycladus orientali,Juglans regia,and Broussonetia papyrifera exhibited excellent removal efficiencies for Pb2+and Cd2+with maximum adsorption capacities of 71.77—83.61 mg·g-1 and 64.69—70.33 mg·g-1 at the dosage of 0.5 g·L-1,initial concentration of 50 mg·L-1,pH 5.50,and adsorption time of 120 min,respectively.They also had high adsorption rates for industrial wastewater,up to 98.21%.Therefore,the barks of P.orientalis,J.geria,and B.papyrifera were the potential materials for the treatment of Pb2+and Cd2+pollution wastewater.