<PAGE>

                                                                     EXHIBIT 4.7

                 FIRST AMENDMENT TO LOAN AND SECURITY AGREEMENT


      THIS FIRST AMENDMENT TO LOAN AND SECURITY AGREEMENT (hereinafter referred
to as the "AMENDMENT") is made and entered into on this 15th day of April, 2002,
between and among, on the one hand, the lenders identified on the signature
pages hereof (such lenders, together with their respective successors and
assigns, are referred to hereinafter each individually as a "Lender" and
collectively as the "Lenders"), FOOTHILL CAPITAL CORPORATION, a California
corporation, as the arranger and administrative agent for the Lenders ("Agent"),
and, on the other hand, PCI CHEMICALS CANADA COMPANY, a Nova Scotia unlimited
liability company, and PIONEER AMERICAS LLC, a Delaware limited liability
company (hereinafter each individually is referred to as a "Borrower" and
collectively as the "Borrowers").

                                    RECITALS

      A. Agent, the Lenders and the Borrowers have entered into that certain
Loan and Security Agreement, dated as of December 31, 2001 (the "AGREEMENT").

      B. Agent, the Lenders and the Borrowers desire to amend the Agreement as
hereinafter set forth.

NOW, THEREFORE, in consideration of the premises herein contained and other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties, intending to be legally bound, hereby agree as
follows:

                                   ARTICLE I
                                  DEFINITIONS

      Section 1.01. Definitions. Capitalized terms used in this Amendment, to
the extent not otherwise defined herein, shall have the same meaning as in the
Agreement, as amended hereby.

                                   ARTICLE II
                                   AMENDMENTS

      Section 2.01. Amendment to Definition of Applicable Margin. EFFECTIVE AS
OF FEBRUARY 1, 2002, the definition of "Applicable Margin" in Section 1.1 of the
Agreement is hereby amended and restated in its entirety to read as follows:

            "Applicable Margin" means, on any day, and with respect to any
      Advance, the applicable per annum percentage set forth at the appropriate
      intersection in the table shown below, based on the average Excess
      Availability for the immediately preceding month:

<Table>
<Caption>
      -----------------------------------------------------------------------
        AVERAGE EXCESS                  MARGIN OVER          MARGIN OVER
         AVAILABILITY                    U.S. PRIME             LIBOR
      -----------------------------------------------------------------------
       <S>                                 <C>                  <C>
        $20MM +                             2.75%                N/A
      -----------------------------------------------------------------------
        $10MM <= $20MM                      3.00%                N/A
      ------------------------------------------------------------------------
        $5MM  <= $10MM                      3.25%                N/A
      -----------------------------------------------------------------------
        $0MM  <= $5MM                       3.50%                N/A
      -----------------------------------------------------------------------
</Table>

            It is understood and agreed that for the period from and after the
      date of the first Advance until the date of the initial calculation of
      average Excess Availability, the
<PAGE>
      Applicable Margin shall be calculated as if the Average Excess
      Availability were $10MM <= $20MM.

      Section 2.02. Amendment to Definition of EBITDA. The definition of
"EBITDA" is Section 1.1 of the Agreement is hereby amended and restated in its
entirety to read as follows:

            "EBITDA" means, with respect to any fiscal period, Parent and its
      Subsidiaries consolidated net earnings (or loss), minus extraordinary
      gains and gains on valuation of derivatives, plus interest expense, income
      taxes, depreciation and amortization, and losses on valuation of
      derivaties for such period, as determined in accordance with GAAP.

      Section 2.03. Termination of LIBOR Rate Loans. Notwithstanding anything to
the contrary contained in the Agreement or any other Loan Document, EFFECTIVE AS
OF FEBRUARY 1, 2002, the Agent and the Lenders shall have no obligation to make
Advances in the form of LIBOR Rate Loans and any commitment to make Advances in
the form of LIBOR Rate Loans are hereby terminated.

                                  ARTICLE III
                              CONDITIONS PRECEDENT

      Section 3.01. Conditions. The effectiveness of this Amendment is subject
to the satisfaction of the following conditions precedent, unless specifically
waived by Agent:

            (a) Agent shall have received the following documents, each in form
      and substance satisfactory to Agent:

                  (i) This Amendment, duly executed by Borrowers, together with
            the Consent and Ratification (the "Ratification") hereto, duly
            executed by the Guarantors; and

                  (ii) Company General Certificates dated as of the date of this
            Amendment, in form and substance satisfactory to Agent, certified by
            the Secretary of the Borrowers and the Guarantors certifying among
            other things, that the Borrowers' and Guarantors Board of Directors
            have met and have adopted, approved, consented to and ratified
            resolutions which authorize the execution, delivery and performance
            by Borrowers of this Amendment, and the Guarantors of the
            Ratification, and each other document, instrument and agreement
            executed in connection with or relating to the Agreement, this
            Amendment or the Ratification (hereinafter individually referred to
            as a "LOAN DOCUMENT" and collectively referred to as the "LOAN
            DOCUMENTS");

            (b) The representations and warranties contained herein, in the
      Agreement, as amended hereby, and/or in each other Loan Document shall be
      true and correct as of the date hereof, as if made on the date hereof;

            (c) No Event of Default shall have occurred and be continuing and no
      Default shall exist, unless such Event of Default or Default has been
      specifically waived in writing by Agent; and

            (d) All corporate proceedings taken in connection with the
      transactions contemplated by this Amendment and all documents, instruments
      and other legal matters incident thereto, shall be satisfactory to Agent.


<PAGE>
                                   ARTICLE IV
                  RATIFICATIONS, REPRESENTATIONS AND WARRANTIES

      Section 4.01. Ratifications. The terms and provisions set forth in this
Amendment shall modify and supersede all inconsistent terms and provisions set
forth in the Agreement and except as expressly modified and superseded by this
Amendment, the terms and provisions of the Agreement and the other Loan
Documents are ratified and confirmed and shall continue in full force and
effect. Borrowers and the Agent agree that the Agreement, as amended hereby, and
the other Loan Documents shall continue to be legal, valid, binding and
enforceable in accordance with their respective terms.

      Section 4.02. Representations and Warranties. Each Borrower hereby
represents and warrants to Agent as follows:

            (a) the execution, delivery and performance of this Amendment and
      any and all other Loan Documents executed and/or delivered in connection
      herewith have been authorized by all requisite corporate action on the
      part of Borrower and will not violate the Certificate of Incorporation or
      Bylaws of Borrower;

            (b) the representations and warranties contained in the Agreement,
      as amended hereby, and any other Loan Document are true and correct on and
      as of the date hereof as though made on and as of the date hereof, except
      to the extent such representations and warranties relate to an earlier
      date;

            (c) Borrower is in full compliance with all covenants and agreements
      contained in the Agreement, as amended hereby; and

            (d) Borrower has not amended its Articles of
      Incorporation/Organization or Bylaws/Operating Agreement or other
      organizational documents since the date of the execution of the Agreement.

                                   ARTICLE V
                                  MISCELLANEOUS

      Section 5.01. Survival of Representations and Warranties. All
representations and warranties made in the Agreement or any other document or
documents relating thereto, including, without limitation, any Loan Document
furnished in connection with this Amendment, shall survive the execution and
delivery of this Amendment and the other Loan Documents, and no investigation by
Agent or any closing shall affect the representations and warranties or the
right of Agent to rely upon them.

      Section 5.02. Reference to Agreement. Each of the Loan Documents,
including the Agreement and any and all other agreements, documents or
instruments now or hereafter executed and delivered pursuant to the terms hereof
or pursuant to the terms of the Agreement, as amended hereby, are hereby amended
so that any reference in such Loan Documents to the Agreement shall mean a
reference to the Agreement, as amended hereby.

      Section 5.03. Expenses of Agent. As provided in the Agreement, each
Borrower agrees to pay on demand all reasonable costs and expenses incurred by
Agent in connection with the preparation, negotiation and execution of this
Amendment and the other Loan Documents executed pursuant hereto and any and all
amendments, modifications, and supplements hereto, including, without
limitation, the reasonable costs and fees of Agent's legal counsel, and all
reasonable costs and expenses incurred by Agent in connection with the
enforcement or preservation of any rights under the Agreement, as amended

<PAGE>
hereby, or any other Loan Document, including, without limitation, the
reasonable costs and fees of Agent's legal counsel.

      Section 5.04. RELEASE. EACH BORROWER HEREBY ACKNOWLEDGES THAT IT HAS NO
DEFENSE, COUNTERCLAIM, OFFSET, CROSS-COMPLAINT, CLAIM OR DEMAND OF ANY KIND OR
NATURE WHATSOEVER THAT CAN BE ASSERTED TO REDUCE OR ELIMINATE ALL OR ANY PART OF
ITS LIABILITY TO REPAY THE OBLIGATIONS OR TO SEEK AFFIRMATIVE RELIEF OR DAMAGES
OF ANY KIND OR NATURE FROM THE AGENT OR THE LENDERS. EACH BORROWER HEREBY
VOLUNTARILY AND KNOWINGLY RELEASES AND FOREVER DISCHARGES THE AGENT AND THE
LENDERS, THEIR PREDECESSORS, AGENTS, EMPLOYEES, SUCCESSORS AND ASSIGNS, FROM ALL
POSSIBLE CLAIMS, DEMANDS, ACTIONS, CAUSES OF ACTION, DAMAGES, COSTS, EXPENSES,
AND LIABILITIES WHATSOEVER, KNOWN OR UNKNOWN, ANTICIPATED OR UNANTICIPATED,
SUSPECTED OR UNSUSPECTED, FIXED, CONTINGENT, OR CONDITIONAL, AT LAW OR IN
EQUITY, ORIGINATING IN WHOLE OR IN PART ON OR BEFORE THE DATE THIS AMENDMENT IS
EXECUTED, WHICH THE BORROWER MAY NOW OR HEREAFTER HAVE AGAINST THE AGENT AND THE
LENDERS, THEIR PREDECESSORS, AGENTS, EMPLOYEES, SUCCESSORS AND ASSIGNS, IF ANY,
AND IRRESPECTIVE OF WHETHER ANY SUCH CLAIMS ARISE OUT OF CONTRACT, TORT,
VIOLATION OF LAW OR REGULATIONS, OR OTHERWISE, AND ARISING FROM ANY OF THE
OBLIGATIONS, INCLUDING, WITHOUT LIMITATION, ANY CONTRACTING FOR, CHARGING,
TAKING, RESERVING, COLLECTING OR RECEIVING INTEREST IN EXCESS OF THE HIGHEST
LAWFUL RATE APPLICABLE, THE EXERCISE OF ANY RIGHTS AND REMEDIES UNDER THE
AGREEMENT OR OTHER LOAN DOCUMENTS, AND NEGOTIATION FOR AND EXECUTION OF THIS
AMENDMENT.

      Section 5.05. Severability. Any provision of this Amendment held by a
court of competent jurisdiction to be invalid or unenforceable shall not impair
or invalidate the remainder of this Amendment and the effect thereof shall be
confined to the provision so held to be invalid or unenforceable.

      Section 5.06. APPLICABLE LAW. THIS AMENDMENT AND ALL OTHER LOAN DOCUMENTS
EXECUTED PURSUANT HERTO SHALL BE DEEMED TO HAVE BEEN MADE AND TO BE PERFORMABLE
IN DALLAS, TEXAS, AND SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF TEXAS.

      Section 5.07. Successors and Assigns. This Amendment is binding upon and
shall inure to the benefit of Agent, the Lenders and the Borrowers and their
respective successors and assigns, except the Borrowers may not assign or
transfer any of their rights or obligations hereunder without the prior written
consent of Agent.

      Section 5.08. Counterparts. This Amendment may be executed in one or more
counterparts, each of which when so executed shall be deemed to be an original,
but all of which when taken together shall constitute one and the same
instrument.

      Section 5.09. Effect of Waiver. No consent or waiver, express or implied,
by Agent to or for any breach of or deviation from any covenant or condition of
the Agreement shall be deemed a consent or waiver to or of any other breach of
the same or any other covenant, condition or duty.

      Section 5.10. Headings. The headings, captions, and arrangements used in
this Amendment are for convenience only and shall not affect the interpretation
of this Amendment.


<PAGE>

      Section 5.11. FINAL AGREEMENT. THE AGREEMENT, AS AMENDED HEREBY AND THE
OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES RELATED
TO THE SUBJECT MATTER HEREOF AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

IN WITNESS WHEREOF, the Borrowers, Agent and the Lenders have caused this
Amendment to be executed on the date first written above by their duly
authorized officers.



                                PCI CHEMICALS CANADA COMPANY
                                a Nova Scotia unlimited liability company

                                By:
                                   ---------------------------------------------
                                Name:
                                     -------------------------------------------
                                Title:
                                      ------------------------------------------


                                PIONEER AMERICAS LLC
                                a Delaware limited liability company

                                By:
                                   ---------------------------------------------
                                Name:
                                     -------------------------------------------
                                Title:
                                      ------------------------------------------


                                FOOTHILL CAPITAL CORPORATION,
                                a California corporation, as Agent and
                                as a Lender

                                By:
                                   ---------------------------------------------
                                Name:
                                     -------------------------------------------
                                Title:
                                      ------------------------------------------




<PAGE>
                            CONSENT AND RATIFICATION


The undersigned, Pioneer Companies, Inc., Pioneer (East), Inc., Pioneer
Licensing, Inc., Imperial West Chemical Co., KNA California, Inc., Pioneer Water
Technologies, Inc., and KWT, Inc. (each a "GUARANTOR" and collectively the
"GUARANTORS") have executed that certain continuing general guaranty dated as of
December 31, 2001 (the "GUARANTY"), in favor of FOOTHILL CAPITAL CORPORATION, a
California corporation, as the arranger and administrative agent for the Lenders
(as defined in the Guaranty). The Guarantors hereby consent and agree to the
terms of the First Amendment to Loan and Security Agreement dated April 15, 2002
(the "AMENDMENT"), executed by PCI CHEMICALS CANADA COMPANY, a Nova Scotia
unlimited liability company, and PIONEER AMERICAS LLC, a Delaware limited
liability company (hereinafter each individually is referred to as a "Borrower"
and collectively as the "Borrowers"), the Lenders and Agent, a copy of which is
attached hereto, and the undersigned agree that the Guaranty shall remain in
full force and effect and shall continue to be the legal, valid and binding
obligation of the Guarantors in enforceable against the Guarantors in accordance
with its terms. Furthermore, each Guarantor hereby agrees and acknowledges that
(a) the Guaranty is a "Loan Document" as such term is defined in the Amendment
and as such term is defined in the Agreement, (b) the Guaranty is not subject to
any claims, defenses or offsets, (c) nothing contained in this Amendment or any
other Loan Document shall adversely affect any right or remedy of Agent under
the Guaranty, (d) the execution and delivery of the Amendment shall in no way
reduce, impair or discharge any obligations of the undersigned as guarantors
pursuant to the Guaranty and shall not constitute a waiver by Agent of any of
Agent's rights against the undersigned, (e) by virtue hereof and by virtue of
the Guaranty, each Guarantor hereby guarantees to Agent the prompt and full
payment and full and faithful performance by the Borrowers of the entirety of
the Obligations (as defined in the Agreement) on the terms and conditions set
forth in the Agreement as amended by the Amendment and any time further modified
or amended, (f) the Guarantors' consent is not required to the effectiveness of
the Amendment, and (g) no consent by the Guarantors is required for the
effectiveness of any future amendment, modification, forbearance or other action
with respect to the Agreement or any present or future Loan Document.

                                        Pioneer Companies, Inc.


                                        By:
                                           -------------------------------------
                                        Name:
                                                 -------------------------------
                                        Title:
                                              ----------------------------------


                                        Pioneer (East), Inc.


                                        By:
                                           -------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------

                                        Pioneer Licensing, Inc.


                                        By:
                                           -------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------
<PAGE>

                                        Imperial West Chemical Co.


                                        By:
                                           -------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------


                                        KNA California, Inc.


                                        By:
                                           -------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------


                                        Pioneer Water Technologies, Inc.


                                        By:
                                           -------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------


                                        KWT, Inc.


                                        By:
                                           -------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:
                                              ----------------------------------