Adsorption Of Heavy Metals In Electroplating Wastewater By Modified Natural Mineral Attapulgite

In recent years,more and more attention has been paid to the treatment of heavy metal wastewater.The total amount of heavy metal pollutants discharged into the water body is huge every year.Some studies have found that zinc,copper,mercury and cadmium in offshore basins have exceeded the standard in varying degrees,and the over-standard rate of total heavy metal pollution is up to 62.9%.The heavy metals in the water are complicated,different in form and difficult to be managed,which seriously threaten the environment.Electroplating is one of the main industries to produce heavy metal polluted wastewater.Most of the heavy metal pollutants in the water environment exist in the form of sediment and suspended matter,so it is easy to change from water phase to solid phase.70%-90%of heavy metal ions migrate to sludge by adsorption or precipitation.When pH changed into acid in water environment,heavy metal ions were precipitated from sediment,which resulted in secondary pollution.The contents and toxicity of heavy metals such as Zn²⁺,Ni²⁺,Cu²⁺and Cr⁶⁺in electroplating wastewater are high.The variation data of these heavy metals in wastewater show that the heavy metal pollution in electroplating industry should be paid more attention.Otherwise the heavy metals in the sewage enter the human body,because of the enrichment and damage,serious can lead to cancer.Water pollution has a great impact on agricultural production,resulting in a sharp decline in soil quality.Heavy metal pollution will increase the cost of industrial production at the same time,which is not conducive to industrial production.Heavy metal contamination can also lead to mass death of organisms in water.In this paper,the preparation of attapulgite and its modified adsorptive materials are studied and applied to the treatment of electroplating industrial wastewater.The problems of heavy metal pollution and difficult treatment of electroplating wastewater are solved at low cost.At the same time,the application of natural mineral resources is explored.The study of new environmentally friendly adsorption materials opens up an effective way for the comprehensive utilization of natural minerals.Therefore,it has important scientific significance and wide practical value.The adsorption property of attapulgite was improved by vulcanization modification of attapulgite.The optimum adsorption conditions were determined as follows:medium pH is 8,adsorption time is 4 h,amount of adsorbent is 50g/L.It was found that the removal rates of Cu²⁺,Zn²⁺,Ni²⁺,Cr⁶⁺and other metal ions were obviously improved by the modified attapulgite adsorbent,in which the adsorption of Cu²⁺was the most affected,followed by Zn²⁺,Ni²⁺and Cr⁶⁺.The structure and morphological characteristics of modified attapulgite were obtained by XRD?SEM?Zeta potential and BET analysis.The average pore size,water absorption and porosity of modified attapulgite were 26.19 nm,32.64%and 59.62%,respectively.The volume density is 1.37 kg/m³,the compressive strength is 12.7 MPa,and the specific surface area is 54.02m²/g.The adsorption kinetics equation and the adsorption mechanism are explored.The adsorption process accords with the quasi-second order kinetic model.