Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide an inorganic-organic flocculant and a preparation method thereof, which solve the technical problems that the traditional flocculant has poor heavy metal flocculation capability and cannot be degraded by biology.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a method for preparing an inorganic-organic flocculant, comprising the steps of:
(1) Preparing calcium alginate-xanthan gum microsphere: adding sodium alginate and xanthan gum into deionized water, stirring, mixing, and adding CaCl dropwise 2 Carrying out a crosslinking reaction on the solution, and after the reaction is finished, filtering, washing and drying the reaction product to obtain the calcium alginate-xanthan gum microsphere;
(2) Preparation of SiO 2 Crosslinked calcium alginate-xanthan gum microspheres: stirring tetraethyl orthosilicate, absolute ethyl alcohol, deionized water and HCl solution, mixing uniformly, adding calcium alginate-xanthan gum microsphere prepared in the step (1), transferring to a baking oven for reaction after mixing uniformly, washing and drying a reaction product after the reaction is finished, and obtaining SiO 2 Crosslinked calcium alginate-xanthan gum microspheres;
(3) Preparation of inorganic-organic flocculant: adding the SiO prepared in the step (2) into a mixed solvent of ethanol and water 2 Crosslinking calcium alginate-xanthan gum microsphere, reflux reacting, standing and cooling to room temperature after the reaction is finished, and addingAdding dopamine hydrochloride, stirring uniformly, and then adding FeCl 3 And (3) oscillating the solution, and obtaining the inorganic-organic flocculant after the oscillation is finished.
Preferably, in step (1), sodium alginate, xanthan gum, deionized water and CaCl 2 The mass ratio of (2) is 1.5-3:1-1.5:100:4-8.
Preferably, in the step (1), the stirring speed is 450-550rpm, the stirring time is 2-3h, and the crosslinking reaction time is 10-15h.
Preferably, in the step (2), the mass ratio of tetraethyl orthosilicate, ethanol, deionized water, HCl and calcium alginate-xanthan gum microsphere is 1-1.5:1:2:0.002-0.01:3-4.
Preferably, in the step (2), the reaction temperature is 60-70 ℃ and the reaction time is 3-6h.
Preferably, in the step (3), the mass ratio of ethanol to water is 7:3, siO 2 The mass ratio of the crosslinked calcium alginate-xanthan gum microsphere to the mixed solvent is 2-3:100.
Preferably, in the step (3), the reflux reaction temperature is 75-85 ℃ and the reflux time is 2-3h.
Preferably, in step (3), siO 2 Crosslinked calcium alginate-xanthan gum microsphere, dopamine hydrochloride and FeCl 3 The mass ratio of (2) is 10-15:1:0.06-0.1.
Preferably, in the step (3), the shaking time is 30-60min.
The invention also provides an inorganic-organic flocculant obtained by the preparation method.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention provides an inorganic-organic flocculant and a preparation method thereof, wherein natural polysaccharide calcium alginate and xanthan gum are crosslinked into a soft gum adsorption matrix, a layer of silica shell is formed on the surface of the soft gum adsorption matrix through a sol-gel process to ensure the stability of a spherical structure of the soft gum adsorption matrix, the soft gum adsorption matrix is grafted onto a Dopamine (DA) macromolecular chain through crosslinking, and meanwhile, dopamine residues and Fe are grafted on the Dopamine (DA) macromolecular chain 3+ Coordinated and further oxidized cross-linked to form DA-Fe 3+ Nano-aggregates.
(2) The present invention provides an inorganic materialThe organic flocculant and the preparation method thereof, hydroxyl in xanthan gum molecules and carboxyl in sodium alginate molecules are subjected to intermolecular condensation, are connected with each other in a hydrogen bond mode, and the introduced xanthan gum promotes the formation of mesopores, so that the specific surface area of the microsphere is obviously increased, the active groups adsorbed on organic polymers are utilized to generate a net capturing effect through the self bridging effect, the adsorption capacity of the microsphere is enhanced, and in addition, the introduced SiO is improved 2 The shell layer can protect the structural integrity of the microsphere, improve the mechanical strength of the whole microsphere system and prevent the microsphere system from being compounded with Fe 3+ Interference results in a decrease in the ability to adsorb heavy metals.
(3) The invention provides an inorganic-organic flocculant and a preparation method thereof, wherein Dopamine (DA) with spontaneous polymerization capability is adopted as a precursor, and Fe is used as a catalyst 3+ Under the action of (a) to coordinate and further oxidize and crosslink, DA-Fe is formed in situ in the system 3+ Nano aggregate beneficial to Fe 3+ At the same time, has a certain biological self-degradation capability, fe 3+ Can adsorb impurities and suspended particles, so that the adsorbed particles are gradually increased, fe 3+ The flocculant has good flocculation performance, plays a role in synergism of cations, plays a role in bridging, and improves the capability of the flocculant for adsorbing heavy metals.
Detailed Description
The present invention will be described in further detail with reference to the following preferred examples, but the present invention is not limited to the following examples.
Unless otherwise specified, the chemical reagents involved in the present invention are all commercially available.
Example 1
A method for preparing an inorganic-organic flocculant, comprising the steps of:
(1) Preparing calcium alginate-xanthan gum microsphere: to 1000g deionized water, 20g sodium alginate and 10g xanthan gum were added, followed by stirring in an electric stirrer at 450rpm for 2 hours, and then 20mL, 20g/L CaCl was added dropwise thereto 2 The solution is crosslinked for 12 hours, and after the reaction is finished, the reaction product is filtered, washed and dried to obtain the seaCalcium alginate-xanthan gum microspheres;
(2) Preparation of SiO 2 Crosslinked calcium alginate-xanthan gum microspheres: stirring and mixing 10g of tetraethyl orthosilicate, 10g of absolute ethyl alcohol, 20g of deionized water, 0.5mL of 1g/L of HCl solution uniformly, adding 30g of calcium alginate-xanthan gum microsphere prepared in the step (1) into the mixture, uniformly mixing, transferring the mixture to a 65 ℃ oven for thermal insulation reaction for 3 hours, washing and drying a reaction product after the reaction is finished, and obtaining SiO 2 Crosslinked calcium alginate-xanthan gum microspheres;
(3) Preparation of inorganic-organic flocculant: adding 30g of SiO prepared in the step (2) to a mixed solvent of 700g of ethanol and 300g of water 2 The crosslinked calcium alginate-xanthan gum microsphere is refluxed and stirred for 2 hours at 80 ℃, and after the reaction is finished, the mixture is stood and cooled to room temperature, 3g of dopamine hydrochloride is added into the mixture and stirred evenly, and then 15mL of FeCl with the concentration of 10g/L is added into the mixture 3 And (3) oscillating the solution for 30min, and obtaining the inorganic-organic flocculant after the oscillation is finished.
Example 2
A method for preparing an inorganic-organic flocculant, comprising the steps of:
(1) Preparing calcium alginate-xanthan gum microsphere: 15g sodium alginate and 10g xanthan gum were added to 1000g deionized water, followed by stirring in an electric stirrer at 450rpm for 2 hours, and then 20mL, 30g/L CaCl was added dropwise thereto 2 The solution is subjected to a crosslinking reaction for 10 hours, and after the reaction is finished, the reaction product is filtered, washed and dried to obtain the calcium alginate-xanthan gum microsphere;
(2) Preparation of SiO 2 Crosslinked calcium alginate-xanthan gum microspheres: stirring and mixing 12g of tetraethyl orthosilicate, 10g of absolute ethyl alcohol, 20g of deionized water, 0.5mL of 1g/L of HCl solution uniformly, adding 30g of calcium alginate-xanthan gum microsphere prepared in the step (1) into the mixture, uniformly mixing, transferring the mixture to a 65 ℃ oven for thermal insulation reaction for 3 hours, washing and drying a reaction product after the reaction is finished, and obtaining SiO 2 Crosslinked calcium alginate-xanthan gum microspheres;
(3) Preparation of inorganic-organic flocculant: adding 20g of SiO prepared in the step (2) into a mixed solvent of 700g of ethanol and 300g of water 2 The crosslinked calcium alginate-xanthan gum microsphere is refluxed and stirred for 2 hours at 85 ℃, and after the reaction is finished, the mixture is stood and cooled to room temperature, 2g of dopamine hydrochloride is added into the mixture and stirred evenly, and then 15mL of FeCl with the concentration of 10g/L is added into the mixture 3 And (5) oscillating the solution for 45min, and obtaining the inorganic-organic flocculant after the oscillation is finished.
Example 3
A method for preparing an inorganic-organic flocculant, comprising the steps of:
(1) Preparing calcium alginate-xanthan gum microsphere: to 1000g deionized water, 18g sodium alginate and 10g xanthan gum were added, followed by stirring in an electric stirrer at 480rpm for 2 hours, and then 20mL, 25g/L CaCl was added dropwise thereto 2 The solution is subjected to a crosslinking reaction for 12 hours, and after the reaction is finished, the reaction product is filtered, washed and dried to obtain the calcium alginate-xanthan gum microsphere;
(2) Preparation of SiO 2 Crosslinked calcium alginate-xanthan gum microspheres: stirring and mixing 10g of tetraethyl orthosilicate, 10g of absolute ethyl alcohol, 20g of deionized water, 0.5mL of 1g/L of HCl solution uniformly, adding 35g of calcium alginate-xanthan gum microsphere prepared in the step (1) into the mixture, uniformly mixing, transferring the mixture to a 65 ℃ oven for thermal insulation reaction for 3 hours, washing and drying a reaction product after the reaction is finished, and obtaining SiO 2 Crosslinked calcium alginate-xanthan gum microspheres;
(3) Preparation of inorganic-organic flocculant: 15g of SiO prepared in step (2) was added to a mixed solvent of 700g of ethanol and 300g of water 2 The crosslinked calcium alginate-xanthan gum microsphere is refluxed and stirred for 2 hours at 85 ℃, and is kept stand and cooled to room temperature after the reaction is finished, 1g of dopamine hydrochloride is added into the microsphere and stirred evenly, and then 10mL and 10g/L FeCl are added into the microsphere 3 And (5) oscillating the solution for 45min, and obtaining the inorganic-organic flocculant after the oscillation is finished.
Example 4
A method for preparing an inorganic-organic flocculant, comprising the steps of:
(1) Preparing calcium alginate-xanthan gum microsphere: to 1000g of deionized water, 20g of sodium alginate and 10g of xanthan gum were added, followed by stirring in an electric stirrer at 550rpm for 3 hours, and then 20m was added dropwise theretoL、30g/L CaCl 2 The solution is subjected to a crosslinking reaction for 10 hours, and after the reaction is finished, the reaction product is filtered, washed and dried to obtain the calcium alginate-xanthan gum microsphere;
(2) Preparation of SiO 2 Crosslinked calcium alginate-xanthan gum microspheres: stirring and mixing 12g of tetraethyl orthosilicate, 10g of absolute ethyl alcohol, 20g of deionized water, 0.5mL of 1g/L of HCl solution uniformly, adding 40g of calcium alginate-xanthan gum microsphere prepared in the step (1) into the mixture, uniformly mixing, transferring the mixture to a 65 ℃ oven for thermal insulation reaction for 3 hours, washing and drying a reaction product after the reaction is finished, and obtaining SiO 2 Crosslinked calcium alginate-xanthan gum microspheres;
(3) Preparation of inorganic-organic flocculant: adding 30g of SiO prepared in the step (2) to a mixed solvent of 700g of ethanol and 300g of water 2 The crosslinked calcium alginate-xanthan gum microsphere is refluxed and stirred for 2 hours at 85 ℃, and after the reaction is finished, the mixture is stood and cooled to room temperature, 2g of dopamine hydrochloride is added into the mixture and stirred evenly, and then 20mL of FeCl with the concentration of 10g/L is added into the mixture 3 And (5) oscillating the solution for 45min, and obtaining the inorganic-organic flocculant after the oscillation is finished.
Comparative example 1
A method for preparing a flocculant, comprising the steps of:
(1) Preparing calcium alginate microspheres: 20g sodium alginate was added to 1000g deionized water, followed by stirring in an electric stirrer at 550rpm for 3 hours, and then 20mL, 30g/L CaCl was added dropwise thereto 2 The solution is subjected to a crosslinking reaction for 10 hours, and after the reaction is finished, the reaction product is filtered, washed and dried to obtain calcium alginate microspheres;
(2) Preparation of SiO 2 Crosslinked calcium alginate microspheres: stirring and mixing 12g of tetraethyl orthosilicate, 10g of absolute ethyl alcohol, 20g of deionized water, 0.5mL of 1g/L of HCl solution uniformly, adding 40g of calcium alginate microspheres prepared in the step (1), transferring to a 65 ℃ oven for thermal insulation reaction for 3 hours after uniform mixing, and washing and drying a reaction product after the reaction is finished to obtain SiO 2 Crosslinked calcium alginate microspheres;
(3) Preparing a flocculating agent: adding into a mixed solvent of 700g of ethanol and 300g of water30g of SiO prepared in step (2) are introduced 2 The crosslinked calcium alginate microsphere is refluxed and stirred for 2 hours at 85 ℃, and after the reaction is finished, the mixture is stood and cooled to room temperature, 2g of dopamine hydrochloride is added into the mixture and stirred evenly, and then 20mL of FeCl with the concentration of 10g/L is added into the mixture 3 And (5) oscillating the solution for 45min, and obtaining the flocculant after the oscillation is finished.
Comparative example 2
A method for preparing a flocculant, comprising the steps of:
(1) Preparing calcium alginate-xanthan gum microsphere: to 1000g deionized water, 18g sodium alginate and 10g xanthan gum were added, followed by stirring in an electric stirrer at 480rpm for 2 hours, and then 20mL, 25g/L CaCl was added dropwise thereto 2 The solution is subjected to a crosslinking reaction for 12 hours, and after the reaction is finished, the reaction product is filtered, washed and dried to obtain the calcium alginate-xanthan gum microsphere;
(2) Preparation of SiO 2 Crosslinked calcium alginate-xanthan gum microspheres: stirring and mixing 10g of tetraethyl orthosilicate, 10g of absolute ethyl alcohol, 20g of deionized water, 0.5mL of 1g/L of HCl solution uniformly, adding 35g of calcium alginate-xanthan gum microsphere prepared in the step (1) into the mixture, uniformly mixing, transferring the mixture to a 65 ℃ oven for thermal insulation reaction for 3 hours, washing and drying a reaction product after the reaction is finished, and obtaining SiO 2 Crosslinked calcium alginate-xanthan gum microspheres;
(3) Preparing a flocculating agent: 15g of SiO prepared in step (2) was added to a mixed solvent of 700g of ethanol and 300g of water 2 The crosslinked calcium alginate-xanthan gum microsphere is refluxed and stirred for 2 hours at 85 ℃, and is kept stand and cooled to room temperature after the reaction is finished, and then 10mL and 10g/L FeCl are added into the mixture 3 And (5) oscillating the solution for 45min, and obtaining the flocculant after the oscillation is finished.
The flocculant prepared in examples 1-4 and comparative examples 1-2 was subjected to a heavy metal adsorption experiment, and the specific experimental procedure was as follows:
1) Selecting a 200ml polyethylene collecting bottle, then repeatedly eluting with ultrapure water to remove metal ions possibly existing, drying, and sealing for preservation to prevent dust pollution;
2) Collecting a sewage sample by using a polyethylene bottle, filtering the sewage sample by using a 0.45 mu m mixed cellulose ester microporous filter membrane to remove insoluble particles in the sample, transferring the corresponding filtrate into the sample bottle, and adjusting the pH value to be below 2.0 by using dilute nitric acid so as to prevent the wall of the bottle from influencing the adsorption of heavy metal ions;
3) Weighing 0.01g of the flocculant prepared in the examples 1-4 and the flocculant prepared in the comparative examples 1-2 respectively, adding 100mL of the treated sewage sample in the step (2), placing the sewage sample in a polyethylene centrifuge tube, shaking the sewage sample on a shaking table at 200rpm for 150min, transferring the supernatant to a clean centrifuge tube, measuring the lead content in the supernatant by ICP-MS, and calculating the removal rate, wherein the experimental results are shown in the following table:
as can be seen from the table, the flocculant prepared in the embodiment has good adsorption effect on heavy metals, the removal rate can reach more than 98%, xanthan gum is not added in the comparative example 1, the adsorption capacity on the heavy metals is obviously reduced, the introduction of the xanthan gum can promote the formation of mesopores, the specific surface area of the microsphere is increased, the heavy metal ions are adsorbed, dopamine is not added in the comparative example 2, the adsorption capacity on the heavy metals is reduced, the introduction of a dopamine precursor is demonstrated, and Fe 3+ Can coordinate with the catalyst and further oxidize and crosslink with the catalyst to form DA-Fe in situ in the system 3+ Nano aggregate beneficial to Fe 3+ And enhances the adsorption capacity thereof.
Finally, it should be noted that: the above examples are not intended to limit the present invention in any way. Modifications and improvements will readily occur to those skilled in the art upon the basis of the present invention. Accordingly, any modification or improvement made without departing from the spirit of the invention is within the scope of the invention as claimed.