Removing contaminants from tannery wastewater by chemical precipitation using CaO and Ca(OH)2

作     者：Adriana Reyes-Serrano Joel ELópez-Alejo Manuel AHernández-Cortázar Ignacio Elizalde Adriana Reyes-Serrano;Joel E. López-Alejo;Manuel A. Hernández-Cortázar;Ignacio Elizalde

作者机构：Instituto Politécnico NacionalCentro Mexicano para la Producción más LimpiaCiudad de México 07340Mexico 

出 版 物：《Chinese Journal of Chemical Engineering》 (中国化学工程学报（英文版）)

年 卷 期：2020年第28卷第4期

页      面：1107-1111页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 08[工学] 

基　　金：financial support from IPN-México through grants 20170292,20180385,and 20195583 financial support from CONACyT-México through grant 246176 

主　　题：Tannery wastewater Alkali Removal Chromium Sulfates Synergistic effect 

摘      要：The removal of Cr,sulfates and Chemical Oxygen Demand(COD)from industrial tannery wastewater by chemical precipitation was carried out using Calcium oxide(CaO)and Calcium hydroxide(Ca(OH)2).Different doses of alkalis,ranging from deficiency to excess hydroxyl species over the stoichiometric necessary,were used to remove theoretically the 100%of Cr[0.3-3.2 g alkali·(g Cr^3+)^-1].The precipitation was carried out at room temperature,10 min of vigorous stirring,200 r·min^-1 and a settling time of 24 h,followed by separation and characterization of liquid *** result of addition of alkalis,pH underwent increase as did the alkali *** removal of Cr,and sulfates also increased as alkali concentration did,although for first species the changes at higher alkali contents were less *** removal on the other hand,did not follow a unique trend,instead exhibited a *** on our results,selection of a specific dose of alkali was carried out taking as reference the efficiency on total chromium removal,keeping the pH in the range 7 to 9 to ensure Cr precipitation as chromium *** those conditions,jar test was used to produce enough liquid product in order to determine the removal percent of several other *** removal percent of the species was as follows:Cr,SO4^2-,ZnSO4,FeSO4,CN^-1,NiSO4,Fe2[Fe(CN)6]at 99.8%,66.9%,99.6%,21.4%,70.9%,52.8%and 76.4%with CaO,and 99.8%,61.6%,99.9%,7.1%,84.0%,54.4%and 90.5%with Ca(OH)2,respectively.