CN-121988290-A - Preparation and application of silicon and acetic acid combined modified biochar for adsorbing cadmium

CN121988290ACN 121988290 ACN121988290 ACN 121988290ACN-121988290-A

Abstract

The invention relates to preparation and application of silicon and acetic acid combined modified biochar for adsorbing cadmium. The silicon-acetic acid combined modified biochar is prepared from pennisetum hydridum straw powder, sodium silicate nonahydrate and acetic acid through two pyrolysis. Specifically, 15g of pennisetum hydridum straw powder and 10.15g of sodium silicate nonahydrate are placed in 150ml of pure water, immersed and stirred for 12 hours, dried, pyrolyzed at 600 ℃ for 2 hours under nitrogen atmosphere, cooled, oscillated with 0.5M acetic acid in a water bath with a solid-to-liquid ratio of 1g to 20mL for 12 hours, dried, pyrolyzed again at 600 ℃ for 2 hours, washed with pure water, dried and sieved to obtain the silicon-acetic acid combined modified biochar. The silicon and acetic acid combined modified biochar can efficiently adsorb Cd 2+ in a water body in a short time, the maximum adsorption capacity of the modified biochar on 200mg/L of Cd 2+ solution reaches 180.47mg/g and the optimal removal rate of the modified biochar reaches 90.24%, the removal rate of the modified biochar on 200mg/L of Cd 2+ solution can be kept at 70-90.24% under the condition of pH value of 3-8, and in addition, the modified biochar has stronger anti-interference capacity under different interference ions and different interference ion intensities. The silicon and acetic acid combined modified biochar has remarkable treatment effect on the cadmium pollution wastewater, and the raw materials and the medicaments thereof have low price, are environment-friendly and simple in preparation process, and are expected to be widely put into treatment of the wastewater containing Cd 2+ .

Inventors

YIN GUANGCAI
YANG XUBIN
Lin Dieyang
HONG YITING
Lin Aiqi

Assignees

广东工业大学
杨旭彬

Dates

Publication Date: 20260508
Application Date: 20260330

Claims (10)

1. The preparation method and application of the silicon and acetic acid combined modified biochar for adsorbing cadmium are characterized by comprising the following steps: 1) Dissolving the pennisetum sinese stalk powder and sodium silicate nonahydrate in pure water, performing ultrasonic treatment, fully stirring for 12 hours by adopting a dipping stirring method after the end of the ultrasonic treatment, and drying; 2) Grinding the dried solid, performing pyrolysis at the constant temperature of 600 ℃ for 2 hours in a nitrogen atmosphere, and taking out and cooling to obtain silicon modified biochar; 3) And (3) carrying out ultrasonic treatment on the cooled silicon modified biochar obtained in the step (2) and acetic acid, then placing the cooled silicon modified biochar in a water bath constant temperature oscillator for 12 hours, taking out and drying the cooled silicon modified biochar, carrying out constant temperature pyrolysis at 600 ℃ for 2 hours under a nitrogen atmosphere, taking out and cooling the cooled silicon modified biochar, washing and drying the cooled silicon modified biochar with pure water, and sieving the cooled silicon modified biochar to obtain the silicon modified biochar.
2. The preparation method according to claim 1, wherein the mass ratio of the pennisetum stalk powder to the sodium silicate nonahydrate in the step 1) is 15:10.15, and the solid-to-liquid ratio is 15g:150mL, wherein the mass of the solid is calculated by the mass of the pennisetum stalk powder.
3. The process according to claim 1, wherein the ultrasound conditions in step 1) are 60Hz for 30-60min, preferably 30min, the immersion stirring conditions are 25℃and the drying temperature is 60-80 ℃.
4. The process according to claim 1, characterized in that step 2) wherein the dried solid is ground and sieved through a 60-100 mesh sieve, preferably a 80-100 mesh sieve.
5. The process according to claim 1, wherein the pyrolysis rate in step 2) and step 3) is 5-10 ℃, preferably 5 ℃ per minute, and the calcination temperature in the protective atmosphere of N 2 is 500-700 ℃, preferably 600 ℃.
6. The process according to claim 1, wherein step 3) has an acetic acid concentration of 0.5M to 1.5M, preferably 0.5M, and the solid-to-liquid ratio of the silicon-modified biochar to acetic acid is 1g:20 to 30mL, preferably 1g:20mL.
7. The process according to claim 1, wherein the solid-to-liquid ratio of the washing of the silicon-acetic acid-modified biochar in step 3) is 1g of biochar to 200mL of pure water.
8. The silicon-acetic acid combined modified biochar material prepared by the method of any one of claims 1-7.
9. The use of the silicon and acetic acid combined modified biochar material according to claim 8 for treating cadmium-containing wastewater.
10. The use of the combined modified biochar material of silicon and acetic acid for treating wastewater containing cadmium according to claim 9, wherein the combined modified biochar material of silicon and acetic acid is added to the cadmium-polluted water body according to 0.3-2g/L, preferably 1g/L.

Description

Preparation and application of silicon and acetic acid combined modified biochar for adsorbing cadmium Technical Field The invention belongs to the technical field of environmental pollution treatment, and particularly relates to preparation and application of silicon and acetic acid combined modified biochar for adsorbing cadmium. Background Heavy metal pollution has been an environmental concern regarding natural ecological balance and human health safety, and in particular cadmium (Cd), which is considered a class 1 carcinogen, has become an environmental pollutant of global concern. It is counted that more than 1.5 hundred million people worldwide are exposed to high concentrations of potentially toxic Trace Elements (TEs) such as cadmium (Cd) containing surface and groundwater. The activities of mineral exploitation, electroplating, fertilizer production and the like can generate cadmium-containing wastewater, and cadmium mainly exists in the water in the form of Cd 2+. Cadmium can accumulate in aquatic organisms (phytoplankton, zooplankton and fish) organs, resulting in damage to the oxidation system, endocrine disruption and suppression of the immune system, severely affecting survival and growth. While food, water and gas contaminated with cadmium enter the human body, even with very low cadmium concentration, various organ injuries affecting the lung, kidney, liver, prostate, esophagus, stomach and skin are caused as the cadmium is accumulated in the body, and neurological diseases such as Alzheimer's disease and Parkinson's disease are also caused, which seriously threatens the health of the human body, so that the treatment of cadmium pollution is urgent. Currently, technologies for treating cadmium-containing wastewater include an electric flocculation method, a membrane separation method, a precipitation method, an adsorption method and an ion exchange method. The electric flocculation method has higher cost and certain operation requirement, the precipitation method needs to maintain an ideal pH level, additional observation and adjustment are needed, membrane pore channels are easy to deform and block by the membrane separation method, the ion exchange method exchanges cadmium ions in water and exchangeable ions of materials to remove heavy metals, however, secondary wastes such as sludge, waste resin and the like are generated by the ion exchange method, and the adsorption method is widely applied to the treatment of cadmium-containing wastewater due to low cost, simple operation and high efficiency. The biochar prepared from agricultural wastes such as straw has wide sources of raw materials, a large comparison area and rich functional groups, and is widely used as an economic adsorbent. Compared with unmodified biochar, the modified biochar has better adsorption performance on Cd 2+. The manganese dioxide modified biochar composite material is prepared by loading generated manganese dioxide on biochar through the centering reaction of permanganate and manganese element in divalent manganese salt, wherein the highest adsorption capacity of the manganese dioxide modified biochar composite material to cadmium can reach 45.75mg/g, but the problem that Mn 2+ probably causes secondary pollution to the environment exists in a large amount of use of the manganese dioxide modified biochar composite material. The Chinese patent literature of the invention (CN 111085170A) discloses a biochar adsorption material and application thereof, wherein biomass raw materials are added into a mixed solution of FeSO 4·7H2 O and ZnCl 2, and the mixture is stirred, filtered in vacuum, cleaned of residual solution and dried in vacuum to obtain a primary finished product, and the primary finished product is pyrolyzed at 500-600 ℃ to prepare the biochar adsorption material, but the potential risk of releasing Zn 2+ into the environment exists. While the use of silicate modified biochar can solve the above-mentioned problems, there is also a problem that silicate is agglomerated on the surface of biochar and occupies part of adsorption sites, resulting in failure to fully exert adsorption performance. Disclosure of Invention In order to solve the technical problems, the invention provides a preparation method of a silicon and acetic acid combined modified biochar material for adsorbing Cd 2+ in wastewater. The method not only avoids secondary pollution caused by leaching of metal ions (such as Mn 2+、Zn2+) in the use process of the metal salt modified material, but also can adjust the distribution of silicate on the surface of the biochar by acetic acid, thereby avoiding the problem of limiting the adsorption performance of the biochar due to silicate agglomeration. In addition, acetic acid is used as a low-molecular organic acid which is low in cost and mild, so that the reduction of the adsorption capacity of heavy metals by a mineral precipitation mechanism due to the damage of strong acids such as sulfuric acid, hy