Preparation Of Modified Biomass Adsorbent And Adsorption Treatment Of Emulsified Oil Wastewater

In this study,the emulsified oil wastewater produced during the production of reflective cups was firstly subjected to emulsion-breaking experiments,and calcium chloride（Ca Cl₂）was selected as the emulsion-breaking agent to explore the influence of various factors on the emulsion-breaking effect and to determine the best emulsion-breaking conditions,and then polymeric aluminium chloride was added to study its synergistic effect with calcium chloride（Ca Cl₂）in treating emulsified oil wastewater.Afterwards,using agricultural and forestry waste as raw material,walnut shells of 100 mesh to 120 mesh were selected to have better oil absorption effect than the others.The oil adsorbent was modified with stearic acid,and the stearic acid-modified walnut shells were then modified with bentonite,and two oil adsorbents,stearic acid-modified walnut shells and stearic acid-modified walnut shells-bentonite composites,were prepared and characterised.The adsorption behaviour and the main adsorption mechanism were investigated.The main findings of the study are as follows.（1）Emulsion breaking experiments revealed that calcium chloride had a good emulsion breaking effect on the emulsified oil wastewater produced during the production of reflector cups.The emulsified oil wastewater concentration was 997.3 mg/L.A good emulsion breaking and oil removal effect was achieved at 40℃,a dosage of 5 g/L,stirring at 80 r/min for 10 min,and then standing for 30 min.After adding 5 g/L calcium chloride and keeping other experimental conditions unchanged,the continued addition of polymeric aluminium chloride 5 g/L can achieve better emulsion breaking and oil removal effect,indicating that the two have a good synergistic effect on the treatment of emulsified oil wastewater.（2）The adsorption experiments were carried out with stearic acid modified walnut shells at a concentration of 78.4 mg/L in emulsified oil wastewater,and the adsorption equilibrium was reached at 25℃,p H=7.2,stirring intensity of 220 r/min and the dosage of 5 g/L for 180min with the adsorption amount of 5.94 mg/L.The adsorption kinetic study showed that the quasi-secondary kinetic model could better describe the kinetic adsorption process of oil in emulsified oil wastewater.The Langmuir isotherm model was a good fit for the isotherm adsorption of oil from stearic acid-modified walnut shells.The stearic acid-modified walnut shells were more effective in treating emulsified oil wastewater,with an increase of 42%in the adsorption capacity of 7.4 mg/g of oil compared to 5.21 mg/g before modification.This is because the carboxyl groups on the stearic acid reacted with the hydroxyl groups of the cellulose and lignin of the walnut shell to form ester groups that can be linked to the alkyl chains of the stearic acid,thus improving the oil adsorption capacity of the material.Through desorption-regeneration experiments,the adsorption efficiency of stearic acid modified walnut shells does not decrease significantly due to repeated use,and has a more stable adsorption performance.（3）The adsorption experiments were carried out with the stearic acid-modified walnut shell-bentonite composite material,and the adsorption equilibrium was reached at 25℃,p H=7.2 and an oscillation speed of 220 r/min for 150 min with the adsorption amount of 8.2mg/L.The adsorption kinetics study showed that the quasi-secondary kinetic model could better describe the adsorption capacity of the composite material on the emulsified oil wastewater.The Langmuir isotherm model was found to be a good fit for the isotherm adsorption of oil from the stearic acid modified walnut shell-bentonite composite.The stearic acid-modified walnut shell-bentonite composite was effective in treating emulsified oily wastewater,with a very significant increase of 38.4%in oil adsorption capacity of 10.24mg/g compared to 7.4 mg/g before the modification.This is due to the fact that the composite of bentonite and stearic acid modified walnut shell material forms a better spatial structure for oil adsorption,thus allowing better oil adsorption.Through desorption-regeneration experiments,the adsorption efficiency of the stearic acid modified walnut shell-bentonite composite did not decrease significantly due to multiple reuse,demonstrating the stability of its adsorption performance.This study identifies salting agents for the breakage of emulsified oil wastewater generated during the production of reflector cups and determines the optimal breakage conditions.Some operational guidelines will be provided for the breaking of emulsion and treatment of similar industrial emulsified oil wastewater.Two new modified biomass oil absorbents were prepared,which will provide material support for adsorption treatment of emulsified oil wastewater.